///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18330 SUBJECT: LIGO/Virgo G184098: Burst candidate in LIGO engineering run data DATE: 15/09/20 00:53:16 GMT FROM: Leo Singer at NASA/GSFC Dear colleagues, We would like to bring to your attention a trigger identified by the online Burst analysis during the ongoing Engineering Run 8 (ER8). Normally, we would send this in the form of a private GCN Circular, but the LIGO/Virgo GCN Circular list is not ready yet. The LIGO Scientific Collaboration and Virgo report that the cWB unmodeled burst analysis identified candidate G184098 during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2015-09-14 09:50:45 UTC (GPS time: 1126259462.3910). Alerts were not sent in real-time because the candidate occurred in ER8 data; however, we have now sent GCN notices through our normal channel. G184098 is an unvetted event of interest, as the false alarm rate (FAR) determined by the online analysis would have passed our stated alert threshold of ~1/month. The event's properties can be found at this URL: https://gracedb.ligo.org/events/G184098 There are important caveats associated to this event: * It occurred before the initiation of the planned observing run; * The detectors were not in their final O1 configuration; * Calibration is not finalized. In particular, calibration uncertainties may imply systematic errors in sky localization. Nevertheless, the trigger is of sufficient interest to present an important opportunity to exercise the EM follow-up process, and we invite you to make use of the information in the above link. Two sky maps are available at the moment: the rapid localization from cWB itself, and a refined localization from LALInference Burst (LIB). They are in good qualitative agreement with each other. The 50% credible region spans about 200 deg2 and the 90% region about 750 deg2. Updates on our analysis of this event will be sent as they become available. ***PLEASE REMEMBER*** that this message is being sent only to groups that have signed MOUs with LIGO and Virgo and have observing capabilities during O1, and that this event and the LIGO/Virgo data related to it remain confidential at this time. We are looking forward to learn what you will see, and to an exciting time in the Advanced LIGO/Virgo era. Best wishes, Leo, Marica, Peter [GCN OPS NOTE(19sep15): This Circular was originally published on 05:39 16-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18331 SUBJECT: LIGO/Virgo G184098: Swift follow-up observations DATE: 15/09/20 01:08:38 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), Scott Barthelmy (NASA/GSFC), Dave Burrows (PSU), Sergio Campana (INAF-OAB), Brad Cenko (NASA/GSFC), Neil Gehrels (NASA/GSFC), Paolo Giommi (ASI), Frank Marshall (NASA/GSFC), John Nousek (PSU), Paul O'Brien (U. Leicester), Julian Osborne (U. Leicester), David Palmer (LANL), Matteo Perri (ASDC), Judy Racusin (NASA/GSFC), Mike Siegel (PSU), Gianpiero Tagliaferri (INAF-OAB) report on behalf of the Swift team: Swift is observing part of the aLIGO error region for the aLIGO trigger G184098, using the 'LIB_skymap' GW localisation map, and has so far observed 2 fields, covering the locations of galaxies (from the GWGC catalogue) within the aLIGO error region. The observations currently span from 192 ks to 198 ks after the aLIGO trigger, and cover 0.3 sq degrees on the sky (corrected for overlaps). We have detected a 3 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described athttp://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 0 sources of rank 3 * 3 sources of rank 4 We assumed a power-law spectrum with NH=3e20 cm^2, and Gamma=1.7 RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. Source 1: ============= RA: 138.5272 ( = 09h 14m 6.53s) J2000 Dec: -60.5355 ( = -60d 32' 07.8") J2000 Error: +4.8 (radius, 90% confidence). Peak Rate: 4.5e-02 +/- 1.1e-02 ct/sec (0.3-10 keV) Peak Flux: 1.9e-12 +/- 4.5e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: XMMSL1 J091406.5-603212 in the XMM-NEWTON/XMMSLEWCLN catalogue Separation: 4.0" from the XRT source Cat Rate: 1.1e+00 +/- 3.3e-01 ct/sec (0.3-10 keV) Cat Flux: 1.2e-11 +/- 3.4e-12 erg cm^-2 s^-1 (0.3-10 keV) So the source is not above the catalogued flux There is no evidence for fading NOTE: this source is not within 200 kpc of a GWGC galaxy. A SIMBAD object `HD 79905' is 2.4" away There are 2 2MASS objects within the source's 3-sigma error radius This source lies outside the UVOT field of view, but the HD 79905 star is in USNO-B1 with R=7.42, B=7.47 Source 2: ============= RA: 138.3760 ( = 09h 13m 30.24s) J2000 Dec: -60.7884 ( = -60d 47' 18.2") J2000 Error: +6.1 (radius, 90% confidence). Peak Rate: 1.2e-02 +/- 4.6e-03 ct/sec (0.3-10 keV) Peak Flux: 5.3e-13 +/- 2.0e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J091330.1-604707 in the ROSAT/RASSFSC catalogue Separation: 11.2" from the XRT source Cat Rate: 4.6e-02 +/- 1.1e-02 ct/sec (0.3-10 keV) Cat Flux: 1.3e-12 +/- 3.1e-13 erg cm^-2 s^-1 (0.3-10 keV) So the source is not above the catalogued flux There is no evidence for fading There is 1 GWGC galaxy within 200 kpc of the source. A SIMBAD object `ESO 126-2' is 4" away There are 3 2MASS objects within the source's 3-sigma error radius ESO 126-2, a known AGN, is clearly detected in the UVOT image at the XRT position. Source 3: ============= RA: 124.3776 ( = 08h 17m 30.62s) J2000 Dec: -67.7344 ( = -67d 44' 03.8") J2000 Error: +4.7 (radius, 90% confidence). Peak Rate: 2.1e-02 +/- 5.5e-03 ct/sec (0.3-10 keV) Peak Flux: 8.8e-13 +/- 2.4e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J081731.6-674414 in the ROSAT/RASSFSC catalogue Separation: 11.9" from the XRT source Cat Rate: 3.1e-02 +/- 9.6e-03 ct/sec (0.3-10 keV) Cat Flux: 8.6e-13 +/- 2.7e-13 erg cm^-2 s^-1 (0.3-10 keV) So the source is 0.1-sigma above the catalogued flux There is no evidence for fading NOTE: this source is not within 200 kpc of a GWGC galaxy. There is 1 2MASS object within the source's 3-sigma error radius. UVOT detects an object consistent with this source (RA=124.37690, Dec=-69.73395), with a u magnitude of 17.53 with a 1-sigma statistical error of about 0.05. This circular is an official product of the Swift team. [GCN OPS NOTE(19sep15): This Circular was originally published on 20:47 16-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18332 SUBJECT: LIGO/Virgo G184098: TAROT La Silla Observatory optical observations (TZAC) DATE: 15/09/20 01:14:46 GMT FROM: Michel Boer at CESR-CNRS A. Klotz (IRAP, CNRS/UPS) and M. Boer (ARTEMIS, CNRS/OCA/UNS) report, on behalf of the TZAC collaboration: We have imaged part of the error box of the candidate event GW 150914 == ALIGO trigger 184098 with the TAROT robotic telescope located at La Silla Observatory (ESO). Observations started during the second part of the night because of localization constrains and adverse conditions at the beginning of the night. TAROT Calern (OCA) could not be used because of bad weather. TAROT has a field of view of 1.9° x 1.9°, and a typical limiting magnitude with the C (clear) position of R < 18 for 120s exposure time. 54 images were acquired within the 20% probability contour. 5 fields were chosen to maximise the number of galaxies surveyed. The log of the observations is given below. No obvious candidate is apparent on the images, beside some mis-catalogued stars. Further analysis of the image is in progress and will be reported later. Date-Obs exp f ra dec (radec corner1) (radec corner2) (radec corner3) (radec corner4) 2015-09-17T04:59:59 120 C 90.151 -69.613 ( 92.946 -70.516) ( 87.373 -70.523) ( 92.694 -68.662) ( 87.586 -68.669) 2015-09-17T05:02:09 120 C 90.149 -69.614 ( 92.944 -70.516) ( 87.371 -70.524) ( 92.692 -68.662) ( 87.584 -68.669) 2015-09-17T05:04:20 120 B 90.162 -69.616 ( 92.960 -70.519) ( 87.380 -70.527) ( 92.707 -68.663) ( 87.593 -68.671) 2015-09-17T05:10:00 120 C 103.487 -70.333 (106.387 -71.234) (100.607 -71.243) (106.113 -69.380) (100.834 -69.389) 2015-09-17T05:19:59 120 C 109.489 -69.719 (112.300 -70.621) (106.696 -70.630) (112.044 -68.766) (106.911 -68.775) 2015-09-17T05:22:09 120 C 109.487 -69.720 (112.298 -70.622) (106.695 -70.631) (112.042 -68.767) (106.909 -68.776) 2015-09-17T05:24:19 120 B 109.500 -69.722 (112.315 -70.624) (106.705 -70.634) (112.057 -68.768) (106.918 -68.778) 2015-09-17T05:34:24 120 B 90.145 -69.618 ( 92.943 -70.522) ( 87.363 -70.529) ( 92.691 -68.666) ( 87.578 -68.672) 2015-09-17T05:42:10 120 C 103.462 -70.318 (106.358 -71.219) (100.584 -71.227) (106.087 -69.365) (100.813 -69.373) 2015-09-17T05:44:20 120 B 103.473 -70.320 (106.374 -71.222) (100.592 -71.231) (106.101 -69.366) (100.820 -69.374) 2015-09-17T05:50:00 120 C 109.478 -69.718 (112.288 -70.620) (106.686 -70.629) (112.033 -68.766) (106.901 -68.774) 2015-09-17T05:52:10 120 C 109.477 -69.719 (112.287 -70.621) (106.684 -70.629) (112.032 -68.767) (106.899 -68.775) 2015-09-17T05:54:20 120 B 109.489 -69.721 (112.302 -70.624) (106.693 -70.633) (112.046 -68.768) (106.908 -68.776) 2015-09-17T06:00:00 120 C 103.443 -70.331 (106.340 -71.232) (100.562 -71.240) (106.070 -69.379) (100.792 -69.386) 2015-09-17T06:02:11 120 C 103.440 -70.331 (106.338 -71.233) (100.559 -71.241) (106.067 -69.379) (100.790 -69.386) 2015-09-17T06:09:59 120 C 109.461 -69.732 (112.272 -70.634) (106.666 -70.642) (112.018 -68.780) (106.882 -68.787) 2015-09-17T06:12:10 120 C 109.458 -69.733 (112.269 -70.635) (106.663 -70.643) (112.015 -68.781) (106.879 -68.788) 2015-09-17T06:14:20 120 B 109.469 -69.735 (112.284 -70.638) (106.672 -70.646) (112.028 -68.782) (106.888 -68.789) 2015-09-17T06:20:00 120 C 114.974 -69.632 (117.771 -70.534) (112.193 -70.542) (117.519 -68.680) (112.407 -68.687) 2015-09-17T06:22:11 120 C 114.971 -69.632 (117.768 -70.535) (112.190 -70.543) (117.516 -68.681) (112.404 -68.688) 2015-09-17T06:24:21 120 B 114.982 -69.635 (117.782 -70.538) (112.197 -70.546) (117.529 -68.682) (112.411 -68.689) 2015-09-17T06:29:59 120 C 103.427 -70.328 (106.323 -71.230) (100.547 -71.237) (106.054 -69.376) (100.778 -69.382) 2015-09-17T06:32:09 120 C 103.424 -70.329 (106.321 -71.231) (100.544 -71.237) (106.052 -69.377) (100.776 -69.383) 2015-09-17T06:34:20 120 B 103.437 -70.330 (106.337 -71.233) (100.554 -71.240) (106.067 -69.378) (100.785 -69.384) 2015-09-17T06:40:00 120 C 109.434 -69.730 (112.244 -70.633) (106.639 -70.639) (111.991 -68.779) (106.857 -68.785) 2015-09-17T06:42:10 120 C 109.431 -69.730 (112.241 -70.633) (106.636 -70.640) (111.989 -68.779) (106.855 -68.785) 2015-09-17T06:44:20 120 B 109.443 -69.732 (112.256 -70.636) (106.646 -70.643) (112.003 -68.780) (106.863 -68.787) 2015-09-17T06:49:59 120 C 114.941 -69.629 (117.736 -70.532) (112.160 -70.539) (117.486 -68.678) (112.375 -68.684) 2015-09-17T06:52:09 120 C 114.939 -69.630 (117.734 -70.533) (112.157 -70.539) (117.484 -68.679) (112.373 -68.685) 2015-09-17T06:54:20 120 B 114.950 -69.632 (117.750 -70.535) (112.166 -70.543) (117.499 -68.679) (112.382 -68.686) 2015-09-17T07:09:59 120 C 109.422 -69.726 (112.230 -70.629) (106.627 -70.635) (111.979 -68.775) (106.847 -68.781) 2015-09-17T07:12:09 120 C 109.419 -69.727 (112.227 -70.630) (106.624 -70.636) (111.977 -68.776) (106.844 -68.781) 2015-09-17T07:14:19 120 B 109.431 -69.729 (112.242 -70.633) (106.633 -70.639) (111.990 -68.777) (106.852 -68.783) 2015-09-17T07:20:00 120 C 114.931 -69.617 (117.724 -70.520) (112.151 -70.526) (117.476 -68.666) (112.368 -68.672) 2015-09-17T07:22:10 120 C 114.930 -69.617 (117.722 -70.521) (112.150 -70.526) (117.475 -68.667) (112.367 -68.672) 2015-09-17T07:24:20 120 B 114.942 -69.619 (117.738 -70.523) (112.159 -70.530) (117.489 -68.667) (112.376 -68.673) 2015-09-17T07:30:00 120 C 103.394 -70.308 (106.284 -71.211) (100.515 -71.216) (106.020 -69.357) (100.750 -69.362) 2015-09-17T07:32:10 120 C 103.392 -70.308 (106.283 -71.211) (100.514 -71.216) (106.019 -69.357) (100.749 -69.362) 2015-09-17T07:34:21 120 B 103.405 -70.310 (106.300 -71.214) (100.524 -71.219) (106.034 -69.358) (100.758 -69.363) 2015-09-17T07:50:00 120 C 114.908 -69.612 (117.699 -70.516) (112.128 -70.520) (117.453 -68.662) (112.347 -68.666) 2015-09-17T07:52:10 120 C 114.906 -69.612 (117.697 -70.516) (112.127 -70.521) (117.451 -68.662) (112.345 -68.666) 2015-09-17T07:54:20 120 B 114.919 -69.614 (117.714 -70.518) (112.136 -70.524) (117.466 -68.662) (112.355 -68.667) 2015-09-17T07:59:59 120 C 109.397 -69.717 (112.202 -70.621) (106.602 -70.625) (111.954 -68.767) (106.824 -68.771) 2015-09-17T08:02:09 120 C 109.394 -69.717 (112.199 -70.621) (106.600 -70.625) (111.952 -68.767) (106.822 -68.771) 2015-09-17T08:04:20 120 B 109.407 -69.718 (112.215 -70.623) (106.610 -70.628) (111.966 -68.767) (106.831 -68.772) 2015-09-17T08:10:00 120 C 114.901 -69.609 (117.691 -70.513) (112.121 -70.518) (117.446 -68.659) (112.341 -68.663) 2015-09-17T08:12:11 120 C 114.900 -69.609 (117.690 -70.513) (112.120 -70.518) (117.445 -68.659) (112.340 -68.663) 2015-09-17T08:14:21 120 B 114.912 -69.611 (117.706 -70.516) (112.129 -70.521) (117.459 -68.660) (112.349 -68.664) 2015-09-17T08:19:59 120 C 124.921 -68.013 (127.508 -68.919) (122.342 -68.923) (127.298 -67.064) (122.531 -67.068) 2015-09-17T08:22:09 120 C 124.920 -68.013 (127.507 -68.919) (122.341 -68.923) (127.297 -67.065) (122.529 -67.069) 2015-09-17T08:24:19 120 B 124.931 -68.015 (127.522 -68.922) (122.350 -68.926) (127.310 -67.065) (122.537 -67.069) 2015-09-17T08:30:00 120 C 109.383 -69.713 (112.186 -70.617) (106.589 -70.621) (111.940 -68.763) (106.812 -68.767) 2015-09-17T08:32:11 120 C 109.382 -69.713 (112.185 -70.618) (106.588 -70.622) (111.939 -68.764) (106.811 -68.767) 2015-09-17T08:34:21 120 B 109.394 -69.715 (112.201 -70.620) (106.597 -70.624) (111.954 -68.764) (106.820 -68.768) [GCN OPS NOTE(19sep15): This Circular was originally published on 09:20 17-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18333 SUBJECT: LIGO/Virgo G184098: observations by MASTER DATE: 15/09/20 01:18:59 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory N.M.Budnev, O.Gres, K.Ivanov, S.A.Yazev, A.V.Poleshuk Irkutsk State University A. Tlatov, V.Sennik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II twin robotic telescope (MASTER-Net: http://observ.pereplet.ru, FOV= 2x4 square degrees) located in SAAO was starting survey on the aLIGO trigger G184098 error-box 220517 sec after trigger time at 2015-09-16 20:18:11 UT. The 5-sigma upper limit on our sets is about 18.4 mag - 19.9 mag . We observed 212 square degrees by 3 images for each field during ~2 hours. There are LMC near the center error box and Milky Way at the east edge of the error box. Because large number of stars the redaction is delay and continueted. The cover map is available at http://master.sai.msu.ru/static/G184098.png . We started from the left edge of the error box as its rise. The gap between green sets is due to meteo restrictions. This circular is an official product of the MASTER team. [GCN OPS NOTE(19sep15): This Circular was originally published on 19:01 17-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18334 SUBJECT: Instructions for reporting follow-up observations related to LIGO/Virgo G184098 DATE: 15/09/20 01:26:47 GMT FROM: Leo Singer at NASA/GSFC Dear colleagues, This is a reminder to share the coordinates of the observations associated with G184098 within 12 hours of the observing time. To communicate coordinates of EM observations, you can use circulars, the Electromagnetic Bulletin Board and GraceDB. - Submitting a GCN Circular. Several of you have asked how to send prose reports of observations and results on G184098. Because the private LIGO/Virgo GCN Circulars list is not yet ready, for the time being please send reports to this list, lv-em-observers@gw-astronomy.org. The subject line should start with â<80><9c>LIGO/Virgo G184098: â<80><9c> and the body of the message should be in the format and style of an ordinary GCN Circular. When the private GCN Circulars list is ready, we will re-ingest your messages so that they are archived and assigned circular numbers for citation purposes. - Submitting footprints of observations to GraceDB. You can upload footprints of your observations into GraceDB manually in the â<80><9c>EM Observationsâ<80><9d> section of the GraceDB event page (https://gracedb.ligo.org/events/G184098), or in a scripted fashion using any of the following code samples: http://nbviewer.ipython.org/github/lpsinger/ligo-virgo-emfollowup-tutorial/blob/master/ligo-virgo-emfollowup-tutorial.ipynb#7.-Submitting-observation-coordinates-to-GraceDB https://gw-astronomy.org/wiki/LV_EM/CurlUploadFootprints https://gw-astronomy.org/wiki/LV_EM/PythonUploadFootprints - Using GraceDB and the Electromagnetic Bulletin Board. https://www.youtube.com/watch?v=oIJE4dTISs4 Cheers, Marica, Leo, Peter [GCN OPS NOTE(19sep15): This Circular was originally published on 20:37 17-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18335 SUBJECT: LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region DATE: 15/09/20 01:30:42 GMT FROM: S. J. Smartt at Queens U Belfast K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), S.J. Smartt, K. W. Smith, D. Young, D. Wright (Queenâ<80><99>s University Belfast), C. Stubbs (Harvard) With the Pan-STARRS1 telescope (3 degree FOV) on Maui, Hawaii, we imaged the northern error region of the ALIGO GW burst trigger G184098 released on 2015-09-14. In the dawn twilight of 2015-09-17 (14:53-15:31 UT) we took a set of 9 images (3x3 grid), stepping through RA=129.8503, 132.5503, 135.2503 and DEC=3.699, 6.399, 9.099 in each of i and z (60s and 45s each respectively). One exposure, with some edge overlap was taken at each position, producing approximately 63 sq degrees coverage in i and z bands. A set of y-band images was taken at the central pointing position. The fill factor of the GPC1 camera on Pan-STARRS1 is about 80%, due to focal plane gaps. Difference imaging with respect to the PS1 3Pi stacked sky images is ongoing to identify any new transients candidates. Further imaging will be taken in this pattern as weather allows and reported in the GraceDB EM observations. Any candidates will be reported to this email list. [GCN OPS NOTE(19sep15): This Circular was originally published on 20:44 17-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18336 SUBJECT: LIGO/Virgo G184098: VST-ESO PARANAL observations DATE: 15/09/20 01:34:12 GMT FROM: Silvia Piranomonte at INAF E. Brocato (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPd), S. Covino (INAF-OAB), P. Dâ<80><99>Avanzo (INAF-OAB), L.Grado (INAF-OAC), G.Greco (Urbino University/INFN Firenze), L. Nicastro (INAF-IASF-Bo), E. Palazzi (INAF-IASF-Bo), E. Pian (SNS-Pisa), S. Piranomonte (INAF-OAR), G. Stratta (Urbino University/INFN Firenze) on behalf of the INAF Gravitational Astronomy group. We observed part of the skymap of the avanced LIGO and Virgo trigger G184098, with the VLT Survey Telescope (VST) at ESO-Paranal equipped with OMEGACAM (FOV=1 square degree). The observations were taken in the r-sloan band and started at 2015-09-17T06:26:25.645 UT. The coverd area was ~ 54 square degrees divided in 6 pointings of 9 square degrees and 80 sec exptime each. The 3 x 3 deg pointings are centered on the following coordinates RA, Dec (J2000): 05:22:57 -67:30:00; 05:58:00 -70:43:48; 06:34:45 -70:43:48; 07:47:40 -70:38:24; 08:05:57 -67:31:12; 08:38:40 -67:31:12 The image anaysis is ongoing. Further observations of these fields plus four new fields near these pointings are planned for this night. [GCN OPS NOTE(19sep15): This Circular was originally published on 22:04 17-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18337 SUBJECT: LIGO/Virgo G184098: iPTF Optical Transient Candidates DATE: 15/09/20 01:39:01 GMT FROM: Leo Singer at NASA/GSFC L. P. Singer (NASA/GSFC), M. M. Kasliwal (Caltech), S. B. Cenko (NASA/GSFC), V. Bhalerao (IUCAA), A. Miller (Caltech), T. Barlow (Caltech), E. Bellm (Caltech), I. Manulis (WIS), A. Singhal (IUCAA), and J. Rana (IUCAA) report on behalf of the intermediate Palomar Transient Factory (iPTF) collaboration: We have performed tiled observations of LIGO/Virgo G184098 using the Palomar 48-inch Oschin telescope (P48). We imaged 18 fields spanning 135 deg2. Based on the LIB localization, we estimate a 2.3% prior probability that these fields contain the true location of the source. The small containment probability is because the southern mode of the updated ("LIB") localization was too far south to be observable from Palomar, whereas most of the northern mode rose after 12° twilight. Sifting through candidate variable sources using image subtraction by both our NERSC and IPAC pipelines, and applying standard iPTF vetting procedures, we flagged the following optical transient candidates for further follow-up: iPTF15cyo, at the coordinates: RA(J2000) = 8h 19m 56.18s (124.984069 deg) Dec(J2000) = +13d 52' 42.0" (+13.878337 deg) Our P48 photometry includes: -483 days: R > 20.88 +3 days: R = 17.75 +/- 0.01 The position is consistent with the galaxy SDSS J081956.62+135241.7, whose spectroscopic redshift of z = 0.02963 implies an absolute magnitude for the transient of M_R = -17.8, suggestive of a supernova. iPTF15cyq, at the coordinates: RA(J2000) = 8h 10m 00.86s (122.503586 deg) Dec(J2000) = +18d 42' 18.1" (+18.705039 deg) Our P48 photometry includes: -172 days: R > 20.90 +3 days: R = 20.05 +/- 0.10 The position is consistent with the galaxy SDSS J081000.49+184213.1, whose spectroscopic redshift of z = 0.063192 implies an absolute magnitude of M_R = -17.2, also suggestive of a supernova. iPTF15cys, at the coordinates: RA(J2000) = 8h 11m 55.59s (122.981632 deg) Dec(J2000) = +16d 43' 10.1" (+16.719465 deg) Our P48 photometry includes: -611 days: R > 19.99 +3 days: R = 17.84 +/- 0.03 The position is consistent with the galaxy SDSS J081155.51+164313.6 with a photometric redshift of z ~ 0.087. iPTF15cyk, at the coordinates: RA(J2000) = 7h 42m 14.87s (115.561947 deg) Dec(J2000) = +20d 36' 43.4" (+20.612062 deg) Our P48 photometry includes: -614 days: R > 22.59 +3 days: R = 20.28 +/- 0.12 This position is consistent with the faint object SDSS J074215.02+203648.7, which is classified by SDSS as a galaxy. The photometric redshift is z ~ 0.77. iPTF15cym, at the coordinates: RA(J2000) = 7h 52m 35.67s (118.148623 deg) Dec(J2000) = +16d 45' 59.6" (+16.766542 deg) Our P48 photometry includes: -157 days: R > 20.84 +3 days: R = 19.88 +/- 0.20 This position is consistent with the faint galaxy SDSS J075235.81+164600.4, whose photometric redshift is z ~ 0.341. iPTF15cyn, at the coordinates: RA(J2000) = 7h 59m 14.93s (119.812227 deg) Dec(J2000) = +18d 12' 54.9" (+18.215261 deg) Our P48 photometry includes: -232 days: R > 21.69 +3 days: R = 20.34 +/- 0.28 The position is in the nucleus of the galaxy SDSS J075914.91+181255.1, whose spectroscopic redshift of z = 0.06158 implies an absolute magnitude of M_R = -16.9, also consistent with a supernova. iPTF15cyt, at the coordinates: RA(J2000) = 7h 38m 59.35s (114.747288 deg) Dec(J2000) = +21d 45' 43.2" (+21.761996 deg) Our P48 photometry includes: -240 days: R > 20.26 +3 days: R = 19.65 +/- 0.09 The position is in the nucleus of the galaxy SDSS J073859.32+214543.1, whose photometric redshift is z ~ 0.077. iPTF15cyp, at the coordinates: RA(J2000) = 8h 21m 43.68s (125.432006 deg) Dec(J2000) = +16d 12' 42.0" (+16.211667 deg) Our P48 photometry includes: +3 days: R = 19.48 +/- 0.05 Earlier limits may be unreliable due to the presence of a nearby saturated star. The position is in the nucleus of the galaxy SDSS J082143.68+161241.6, whose spectroscopic redshift of z = 0.02822 implies an absolute magnitude of M_R = -16.0. We have obtained Keck II + DEIMOS spectra of all of the above targets. We will report our analyses of these spectra shortly. Times are relative to the LIGO/Virgo trigger. Magnitudes are in the Mould R filter and in the AB system, calibrated with respect to point sources in SDSS as described in Ofek et al. (2012, http://dx.doi.org/10.1086/664065). The diagram https://gracedb.ligo.org/apiweb/events/G184098/files/iptf.pdf shows the locations of our candidates and the P48 fields in relation to the LIGO/Virgo localization. [GCN OPS NOTE(19sep15): This Circular was originally published on 03:09 18-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18338 SUBJECT: LIGO/Virgo G184098: Observations from the TOROS collaboration DATE: 15/09/20 01:42:09 GMT FROM: Mario Diaz at U of Texas Carlos Colazo, Diego Garcia Lambas, Bruno Sanchez, Mariano Dominguez (Astronomical Observatory of Cordoba), and Martin Beroiz, Tania Peñuela and Mario C. Diaz (U of Texas, Rio Grande Valley) on behalf of the TOROS team reports: The TOROS collaboration observed for a few hours Wednesday Sep 16 and Thursday Sep 17 at the Bosque Alegre Astrophysical Station (located in Cordoba province). Two instruments were used the 1.5 m reflector with a FOV 22â<80><99>X14â<80><99> with a limiting magnitude of ~20 and a 0.40 cm reflector with a 0.5x0.5 deg FOV. Due to the limited FOV instead of performing systematic surveys of regions within a given error a few objects were followed for some time. For Sept 16: These are for the 1.5 m: Object RAJ2000[h] DecJ2000[deg] AppMag IC1933 3.42774 -52.78547 12.5 NGC1529 4.12222 -62.89993 14.52 IC2038 4.14835 -55.99074 14.3 IC2039 4.15066 -56.01172 14.93 With the 0.40 cm (Toritos) the following was followed: PGC383392 3.98036 -57.98515 16.96 For Sep 17 Toritos Telescope 0.4m Number Object RAJ2000 DecJ2000 Lim Mag. FoV Filter 1 ESO057-080 6.38592 -68.7328 18.5 30â<80><99>x30â<80><99> Clear 2 ESO085-030 5.02499 -63.29273 18.5 30â<80><99>x30â<80><99> Clear 3 IC2049 4.20121 -58.5573 18.5 30â<80><99>x30â<80><99> Clear 4 IC2056 4.27348 -60.20683 18.5 30â<80><99>x30â<80><99> Clear 5 NGC1809 5.03488 -69.56724 18.5 30â<80><99>x30â<80><99> Clear 6 NGC1892 5.28585 -64.95983 18.5 30â<80><99>x30â<80><99> Clear 7 NGC2187 6.06456 -69.57743 18.5 30â<80><99>x30â<80><99> Clear EABA 1.54m Number Object RAJ2000 DecJ2000 FoV Filter 1 ESO058-018 6.83959 -71.03123 12â<80><99>x8â<80><99> Clear 2 ESO084-015 4.37003 -63.61097 12â<80><99>x8â<80><99> Clear 3 ESO119-005 4.80483 -60.29376 12â<80><99>x8â<80><99> Clear 4 NGC1559 4.29326 -62.78358 12â<80><99>x8â<80><99> Clear 5 PGC128075 4.32400 -60.53844 12â<80><99>x8â<80><99> Clear 6 PGC381152 4.23897 -58.20726 12â<80><99>x8â<80><99> Clear 7 PGC075108 4.24469 -58.13199 12â<80><99>x8â<80><99> Clear 8 PGC016318 4.91526 -61.56747 12â<80><99>x8â<80><99> Clear 9 PGC269445 6.68061 -71.33026 12â<80><99>x8â<80><99> Clear 10 PGC280995 6.4255 -69.15257 12â<80><99>x8â<80><99> Clear A crew from OAC has started preparation to start the follow-up campaign for O1 at the Macon site (Atacama region), but it was not ready for G184098. The analysis has not been completed yet. [GCN OPS NOTE(19sep15): This Circular was originally published on 03:29 18-Sep-2015 UT.] [GCN OPS NOTE(19sep15): The Sept 17 results were added to the original posting about ? day later.] ` ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18339 SUBJECT: LIGO/Virgo G184098: Fermi-GBM ground-based follow-up DATE: 15/09/20 01:46:08 GMT FROM: Lindy Blackburn at CfA Lindy Blackburn (CfA), Michael S. Briggs (UAH), Eric Burns (UAH), Jordan Camp (NASA/GSFC), Nelson Christensen (Carleton College), Valerie Connaughton (USRA), Adam Goldstein (NASA/MSFC), Tyson Littenberg (UAH), John Veitch (Birmingham), Judith Racusin (NASA/GSFC), Peter Shawhan (UMD), Leo Singer (NASA/GSFC), Binbin Zhang (UAH) We report on a sub-threshold targeted followup of LIGO candidate event G184098 in Fermi-GBM survey data for bursts between 0.256s and 8s in duration, and covering a range of GRB spectral models. Although there was no on-board GBM trigger at the time of the event, Fermi-GBM was exposed to a large fraction of the LIGO sky position and thus we searched offline data for untriggered events. The GBM FOV is blocked by the Earth which occults 67 degrees from (RA, DEC) = (355.14, -21.23). Thus GBM observation is able to cover about 87.8% of the cWB sky posterior, and 91.5% of the LIB posterior. We scanned several minutes of GBM live-time centered on the GW event time using a pipeline developed specifically for following-up LIGO-Virgo events in GBM archival data during the LIGO-Virgo S6/VSR3 run [1]. The search identified a possible transient beginning at 150914 09:50:45.8, about 0.4s after the reported LIGO burst trigger time of 09:50:45.39, and it lasted for about 1 second. The intrinsic time resolution for this search was 0.256s. Of the three GRB model spectra tested in the search, the event was best matched to the one corresponding to the hardest spectrum. Using GBM transient background from the S6 analysis (2010), the rate of hard events with equal or greater statistical significance is 1e-4 Hz. However, preliminary analysis of local data in the minutes surrounding the event indicate a background rate that could be higher by a factor of a few. Analysis of more local live-time is required to get an accurate estimate of the local rate. There is an additional trials factor from the three model spectra used in the search. Therefore we believe a conservative rate for events of this quality could be around 1e-3 Hz. Due to the low SNR of the event, we are not able to confidently localize it on the sky. A substantial fraction of the SNR is from a high-energy BGO detector which is largely omni-directional. The event is seen primarily in the BGO-0 and NaI detectors on the X-side of the instrument, at energies above 100 keV. The search also revealed a soft transient at 09:50:56.8 and lasting for about 2 seconds. Although the soft transient has higher SNR than the hard event, it is associated with a somewhat higher background rate (1.4e-4 Hz according to the 2010 distribution) due to an astrophysical background of short X-ray bursts. This event is able to be localized, and is broadly inconsistent with the LIGO sky annulus defined by the H1-L1 travel time. Because of the known background population, distance from the LIGO trigger time, and inconsistency with the LIGO sky location, we do not consider this transient to be related to the GW candidate. [1] L. Blackburn et al. 2015, ApjS 217, 8 [GCN OPS NOTE(19sep15): This Circular was originally published on 04:35 18-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18340 SUBJECT: LIGO/Virgo G184098: Nearby Galaxies in Error Circle DATE: 15/09/20 01:48:52 GMT FROM: Mansi M. Kasliwal at Caltech M. M. Kasliwal (Caltech), J. K. Cannizzo (NASA/UMBC), N. Gehrels (NASA GSFC) and P. Evans (U. Leicester) report on behalf of a larger collaboration We cross-matched the LIGO/Virgo G184098 trigger (95% containment contour) with our Census of the Local Universe (CLU) galaxy catalog. The biggest, nearby galaxy is of course the Large Magellanic Cloud. But if we limit our search to galaxies that constitute the top half of the Schechter function in the 80 Mpc volume, we find about 170 galaxies. Furthermore, weighing the galaxy luminosity with the underlying containment probability, here are the top ten potential host galaxies in our list: Name RA(J2000) DEC(J2000) ESO088-G017 112.250 -66.897 NGC2442 114.099 -69.531 IC2202 111.977 -67.574 ESO090-G011 134.577 -65.368 NGC3110 151.009 -6.475 NGC3145 152.541 -12.434 NGC2967 145.514 0.336 ESO126-G003 138.663 -60.434 NGC2187A 90.934 -69.588 NGC2150 88.943 -69.561 We caution that the probability contained in these galaxies is a small fraction of the total. Yet, these may be interesting for deeper searches where wide-angle is unavailable. For example, see Evans et al. notice for Swift satellite follow-up of this trigger. For more details about the rationale for selection and the CLU galaxy catalog, see Gehrels et al. 2015; http://arxiv.org/abs/1508.03608 [GCN OPS NOTE(19sep15): This Circular was originally published on 08:49 18-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18341 SUBJECT: LIGO/Virgo G184098: Keck II DEIMOS Spectra of iPTF Optical Candidates DATE: 15/09/20 01:53:22 GMT FROM: Mansi M. Kasliwal at Caltech M. M. Kasliwal (Caltech), S. B. Cenko (NASA GSFC), Y. Cao (Caltech) and G. Duggan (Caltech) report on behalf of a larger collaboration We obtained spectra of the following iPTF candidates with the DEIMOS spectrograph on the Keck II telescope on 2015 Sep 17 between approx. 11.3 and 13.3 UTC. Cross-correlating with supernova spectral libraries (SNID and Superfit), we find the following candidates are unlikely to be related: iPTF15cym: Supernova, Type II, z~0.055 iPTF15cyo: Supernova, Type Ia, z=0.0296 iPTF15cyq: Supernova, Type II, z=0.063 iPTF15cys: Supernova, Type Ia, z~0.05 In addition, we note that iPTF15cyk is unlikely to be related due to its high redshift. iPTF15cyn, iPTF14cyp and iPTF5cyt spectra are dominated by nuclear continuum. Further analysis and follow-up is underway. We thank S. R. Kulkarni for the DEIMOS observing time. [GCN OPS NOTE(19sep15): This Circular was originally published on 09:28 18-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18343 SUBJECT: LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region DATE: 15/09/20 02:00:26 GMT FROM: S. J. Smartt at Queens U Belfast S.J. Smartt, K. W. Smith, ((Queenâ<80><99>s University Belfast),K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), D. Young, D. Wright (Queenâ<80><99>s University Belfast), C. Stubbs (Harvard) Following our report of Pan-STARRS pointing coordinates for the field of LIGO/Virgo G184098, we have carried out difference imaging of the i, z and y-band exposures with respect to the Pan-STARRS1 3Pi reference sky stacks. The nine Pan-STARRS fields were centred on the â<80><9c>LIBâ<80><9d> localisation map, although were observed during astronomical twilight and airmass between 2.8 and 2. The difference images were processed as described in Huber et al. (Atel 7153) and on the Pan-STARRS Survey for Transients (PSST) pages (http://star.pst.qub.ac.uk/ps1threepi/psdb/). An initial sift through the data, with machine learning algorithms and human eyeballing resulted in the following candidates within the northern LIGO/Virgo error region for G184098. All candidates were detected in two filters. Three fairly secure candidates were discovered and about a dozen other more marginal detections (variable stars and variable known AGNs are not considered). We prefer to wait for another epoch to confirm/discount the other dozen or so candidates. The three candidates which appear secure, and are most likely supernovae are as follows (a sky map will be uploaded to GraceDB). They lie within the central 20% probability map and all have z-i colours which are not particularly red. We emphasise that we did not dither and the GPC1 camera has an 80% fill factor, therefore we do not claim to be complete in this region. They all appear to be consistent with being normal population supernovae, but spectroscopic observations would be useful. PS15cbm 08:49:19.85 +03:48:17.9 i=18.6 +/- 0.1 12â<80><9d> from the core of galaxy 2MASX J08492024+0348280, located within its visible optical disk. With a spectroscopic z=0.059 (250 Mpc) it has M_i = -18.6 (A_i=0.07) This is consistent with being a supernova PS15cbj 08:38:49.71 +05:00:16.4 i=18.2 +/- 0.1 11â<80><9d> from the core of 2MASX J08385048+0500140 with spectroscopic z=0.076 (330 Mpc). Hence, M_i = -19.5 (A_i=0.06) This is consistent with being a supernova, although it is quite bright and some 15kpc projected from the host. PS15cbn 08:52:38.36 +06:49:50.4 i=18.8 +/- 0.1 3.7â<80><9d> from the galaxy SDSS J085238.20+064947.6 which has no spectroscopic redshift. The object appears to be a supernova (A_i = 0.1) [GCN OPS NOTE(19sep15): This Circular was originally published on 19:58 18-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18344 SUBJECT: LIGO/Virgo G184098: DESGW followup program DATE: 15/09/20 02:09:36 GMT FROM: M. Soares-Santos at Fermi Lab M. Soares-Santos (Fermilab), J. Annis (Fermilab), E. Berger (Harvard) D. J. Brout (UPenn), H.-Y. Chen (UChicago), P. Cowperthwaite (Harvard), H. T. Diehl (Fermilab), B. Farr (UChicago), J. Frieman (UChicago), M. Garcia (CIEMAT/Madrid), R. Gruendl (NCSA), D. Hollowood (UCSC), D. Holz (UChicago), R. Kessler (UChicago), A. Kim (LBNL), K. Hefner (Fermilab), E. Neilsen (Fermilab), M. Sako (UPenn), B. Yanny (Fermilab) On behalf of the DESGW team: We report on observations done with the Dark Energy camera (DECam) on the Blanco telescope at CTIO on the night of 2015-09-17 in response to the LVC trigger G184098. Our observations were delayed by 1 night due to the mag 8.1 earthquake near CTIO. DECam has a 3 sq-deg field of view, and typically reaches i,z = 23rd limiting magnitudes for 90 sec exposure times. We covered 5% of the LIGO probability map in 2h of observing time. We covered 80 sq-deg to 23.25 5-sigma point source limiting magnitude in i,z bands. Coordinates are given below. Analysis is underway. ra dec 105.241671 -69.46246 72.711983 -65.40533 99.430667 -69.84 68.298046 -63.8895 95.986417 -68.35239 110.757033 -68.87642 115.898475 -68.09865 109.488283 -70.73343 103.3931 -71.25164 115.164875 -70.00358 120.35765 -69.0844 65.041267 -62.8751 93.434754 -69.99717 65.802783 -60.8461 62.9234 -59.8316 125.044417 -67.99968 129.235458 -66.77258 68.870837 -61.8606 125.215963 -69.94243 72.150367 -62.8751 62.107867 -57.8027 87.38715 -69.92876 83.908596 -71.39367 81.427092 -69.63706 84.793617 -68.22478 82.565254 -66.48404 79.328883 -67.84927 77.530833 -66.03508 [GCN OPS NOTE(19sep15): This Circular was originally published on 22:20 18-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18345 SUBJECT: LIGO/Virgo G184098: MWA Followup DATE: 15/09/20 02:13:49 GMT FROM: David Kaplan at UW-Milwaukee D. Kaplan (UWM), S. Croft (UC Berkeley/Eureka Scientific), K. Bannister (CSIRO), T. Murphy (Sydney University), A. Rowlinson (UvA/Astron), S. Tingay (Curtin University), R. Wayth (Curtin University), T. Franzen (Curtin University), A. Williams (Curtin University) on behalf of the Murchison Widefield Array collaboration We observed three pointings designed to cover the majority of the skymap of the advanced LIGO/Virgo trigger G184098 with the Murchison Widefield Array radio telescope. The observations each cover roughly 30deg x 30deg (FWHM) centered at: 04:16:48 -63:06:00 2015-09-17 20:44 UT 08:08:00 -72:00:00 2015-09-18 00:36 UT 08:52:24 +01:54:00 2015-09-18 00:52 UT The observations are at a center frequency of 118 MHz, with a 30 MHz bandwidth. Each field was observed for a total of 12min, with 2s integrations and 10 kHz frequency resolution. These fields will be revisited starting on 2015-09-26. Analysis is ongoing. [GCN OPS NOTE(19sep15): This Circular was originally published on 01:32 19-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18346 SUBJECT: LIGO/Virgo G184098: Swift follow-up observations DATE: 15/09/20 02:16:31 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), Scott Barthelmy (NASA/GSFC), Dave Burrows (PSU), Sergio Campana (INAF-OAB), Brad Cenko (NASA/GSFC), Neil Gehrels (NASA/GSFC), Paolo Giommi (ASI), Frank Marshall (NASA/GSFC), John Nousek (PSU), Paul O'Brien (U. Leicester), Julian Osborne (U. Leicester), David Palmer (LANL), Matteo Perri (ASDC), Judy Racusin (NASA/GSFC), Mike Siegel (PSU), Gianpiero Tagliaferri (INAF-OAB) report on behalf of the Swift team: Swift has performed further observations of the error region of advanced LIGO trigger G184098. The previously-reported observations covered 8 galaxies within the error region, listed below; the typical upper limit from these observations is 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV). Subsequently a 37-point tiled observation has been performed, covering a portion of the LMC within the GW error region, centred on RA,Dec = 103.8877, -68.3023 (06h 55m 33.04s, -68d 18' 08.3"), with ~60 s exposure per tile. No X-ray sources were found in these observations. The upper limits from these observations range from 3.3e-12 to 1.3e-11 erg cm^-2 s^-1 (0.3-10 keV). The galaxies covered by the original observations were: ESO089-015 ESO089-016 ESO088-018 ESO088-017 PGC298845 ESO126-002 ESO126-004 ESO089-009 ESO090-011 PGC314417 Details of these observations have been uploaded to the GraceDB. This circular is an official product of the Swift team. [GCN OPS NOTE(19sep15): This Circular was originally published on 14:01 19-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18347 SUBJECT: LIGO/Virgo G184098: La Silla - QUEST Followup DATE: 15/09/20 02:19:15 GMT FROM: David Rabinowitz at Yale U D. Rabinowitz, C. Baltay, N. Ellman (Yale), P. Nugent (LBNL) The La Silla-QUEST survey operating the 10-sq-deg QUEST camera on the 1.0m ESO Schmidt at La Silla, Chile covered the following ~40 sq. deg area overlapping the southern portion of the ~90% confidence area of LVC event G184098 : RA 92.043 to 115.39 deg; Dec -71.053 to -66.261 deg 3 transients were detected with high confidence: LSQ Desig V-mag hh:mm:ss dd:mm:ss ______________________________________________ LSQ15bbj 19.8 07:16:14.45 -69:36:00.36 LSQ15bbc 19.5 07:06:16.63 -67:12:12.24 LSQ15bbb 17.4 07:25:16.51 -69:04:01.20 LSQ15bbb appears to be a supernova 3.1" north-east of 2MASS galaxy J07251616-6904038 at z = 0.037 LSQ15bbc is a likely variable star, with positions appearing in USNO, WISE, and GALEX catalogs LSQ15bbj appears to be a supernova ~3" north of the core of an uncatalogued galaxy The QUEST survey will continue to take nightly observations of the target area described above. [GCN OPS NOTE(19sep15): This Circular was originally published on 19:18 19-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18348 SUBJECT: LIGO/Virgo G184098: TAROT network optical observations DATE: 15/09/20 02:48:44 GMT FROM: Michel Boer at CESR-CNRS A. Klotz (IRAP, CNRS/UPS) and M. Boer (ARTEMIS, CNRS/OCA/UNS) report, on behalf of the TZAC (TAROT - Zadko - Aures - C2PU) collaboration: ve continued to image the error box of the candidate event GW 150914 == ALIGO trigger 184098 with the TAROT robotic telescopes located at the La Silla (ESO) and at Calern (OCA) observatories. The TAROTs telescopes have a field of view of 1.9° x 1.9°, and a typical limiting magnitude with the C (clear) position equivalent to R < 18 for 120s exposure time. 148 images were acquired within the 20% probability contour. 5 fields were examined in the Southern part of the error box. 3 fields were examined in the Northern part of the error box. The full log of the observations is given below. No obvious candidate has been found. Detailled analysis of the images is in progress and will be reported later. Date-Obs exp f ra dec (Field of view) 2015-09-17T04:59:59 120 C 90.151 -69.613 (1.9 deg x 1.9 deg) 2015-09-17T05:02:09 120 C 90.149 -69.614 (1.9 deg x 1.9 deg) 2015-09-17T05:04:20 120 B 90.162 -69.616 (1.9 deg x 1.9 deg) 2015-09-17T05:10:00 120 C 103.487 -70.333 (1.9 deg x 1.9 deg) 2015-09-17T05:19:59 120 C 109.489 -69.719 (1.9 deg x 1.9 deg) 2015-09-17T05:22:09 120 C 109.487 -69.720 (1.9 deg x 1.9 deg) 2015-09-17T05:24:19 120 B 109.500 -69.722 (1.9 deg x 1.9 deg) 2015-09-17T05:34:24 120 B 90.145 -69.618 (1.9 deg x 1.9 deg) 2015-09-17T05:42:10 120 C 103.462 -70.318 (1.9 deg x 1.9 deg) 2015-09-17T05:44:20 120 B 103.473 -70.320 (1.9 deg x 1.9 deg) 2015-09-17T05:50:00 120 C 109.478 -69.718 (1.9 deg x 1.9 deg) 2015-09-17T05:52:10 120 C 109.477 -69.719 (1.9 deg x 1.9 deg) 2015-09-17T05:54:20 120 B 109.489 -69.721 (1.9 deg x 1.9 deg) 2015-09-17T06:00:00 120 C 103.443 -70.331 (1.9 deg x 1.9 deg) 2015-09-17T06:02:11 120 C 103.440 -70.331 (1.9 deg x 1.9 deg) 2015-09-17T06:09:59 120 C 109.461 -69.732 (1.9 deg x 1.9 deg) 2015-09-17T06:12:10 120 C 109.458 -69.733 (1.9 deg x 1.9 deg) 2015-09-17T06:14:20 120 B 109.469 -69.735 (1.9 deg x 1.9 deg) 2015-09-17T06:20:00 120 C 114.974 -69.632 (1.9 deg x 1.9 deg) 2015-09-17T06:22:11 120 C 114.971 -69.632 (1.9 deg x 1.9 deg) 2015-09-17T06:24:21 120 B 114.982 -69.635 (1.9 deg x 1.9 deg) 2015-09-17T06:29:59 120 C 103.427 -70.328 (1.9 deg x 1.9 deg) 2015-09-17T06:32:09 120 C 103.424 -70.329 (1.9 deg x 1.9 deg) 2015-09-17T06:34:20 120 B 103.437 -70.330 (1.9 deg x 1.9 deg) 2015-09-17T06:40:00 120 C 109.434 -69.730 (1.9 deg x 1.9 deg) 2015-09-17T06:42:10 120 C 109.431 -69.730 (1.9 deg x 1.9 deg) 2015-09-17T06:44:20 120 B 109.443 -69.732 (1.9 deg x 1.9 deg) 2015-09-17T06:49:59 120 C 114.941 -69.629 (1.9 deg x 1.9 deg) 2015-09-17T06:52:09 120 C 114.939 -69.630 (1.9 deg x 1.9 deg) 2015-09-17T06:54:20 120 B 114.950 -69.632 (1.9 deg x 1.9 deg) 2015-09-17T07:09:59 120 C 109.422 -69.726 (1.9 deg x 1.9 deg) 2015-09-17T07:12:09 120 C 109.419 -69.727 (1.9 deg x 1.9 deg) 2015-09-17T07:14:19 120 B 109.431 -69.729 (1.9 deg x 1.9 deg) 2015-09-17T07:20:00 120 C 114.931 -69.617 (1.9 deg x 1.9 deg) 2015-09-17T07:22:10 120 C 114.930 -69.617 (1.9 deg x 1.9 deg) 2015-09-17T07:24:20 120 B 114.942 -69.619 (1.9 deg x 1.9 deg) 2015-09-17T07:30:00 120 C 103.394 -70.308 (1.9 deg x 1.9 deg) 2015-09-17T07:32:10 120 C 103.392 -70.308 (1.9 deg x 1.9 deg) 2015-09-17T07:34:21 120 B 103.405 -70.310 (1.9 deg x 1.9 deg) 2015-09-17T07:50:00 120 C 114.908 -69.612 (1.9 deg x 1.9 deg) 2015-09-17T07:52:10 120 C 114.906 -69.612 (1.9 deg x 1.9 deg) 2015-09-17T07:54:20 120 B 114.919 -69.614 (1.9 deg x 1.9 deg) 2015-09-17T07:59:59 120 C 109.397 -69.717 (1.9 deg x 1.9 deg) 2015-09-17T08:02:09 120 C 109.394 -69.717 (1.9 deg x 1.9 deg) 2015-09-17T08:04:20 120 B 109.407 -69.718 (1.9 deg x 1.9 deg) 2015-09-17T08:10:00 120 C 114.901 -69.609 (1.9 deg x 1.9 deg) 2015-09-17T08:12:11 120 C 114.900 -69.609 (1.9 deg x 1.9 deg) 2015-09-17T08:14:21 120 B 114.912 -69.611 (1.9 deg x 1.9 deg) 2015-09-17T08:19:59 120 C 124.921 -68.013 (1.9 deg x 1.9 deg) 2015-09-17T08:22:09 120 C 124.920 -68.013 (1.9 deg x 1.9 deg) 2015-09-17T08:24:19 120 B 124.931 -68.015 (1.9 deg x 1.9 deg) 2015-09-17T08:30:00 120 C 109.383 -69.713 (1.9 deg x 1.9 deg) 2015-09-17T08:32:11 120 C 109.382 -69.713 (1.9 deg x 1.9 deg) 2015-09-17T08:34:21 120 B 109.394 -69.715 (1.9 deg x 1.9 deg) 2015-09-18T03:30:00 120 C 129.841 +5.217 (1.9 deg x 1.9 deg) 2015-09-18T03:32:10 120 C 129.842 +5.217 (1.9 deg x 1.9 deg) 2015-09-18T03:34:21 120 C 129.842 +5.217 (1.9 deg x 1.9 deg) 2015-09-18T03:40:01 120 C 134.241 +3.220 (1.9 deg x 1.9 deg) 2015-09-18T03:42:11 120 C 134.241 +3.220 (1.9 deg x 1.9 deg) 2015-09-18T03:44:22 120 C 134.241 +3.220 (1.9 deg x 1.9 deg) 2015-09-18T03:50:01 120 C 134.444 +6.220 (1.9 deg x 1.9 deg) 2015-09-18T03:52:12 120 C 134.444 +6.221 (1.9 deg x 1.9 deg) 2015-09-18T03:54:23 120 C 134.445 +6.221 (1.9 deg x 1.9 deg) 2015-09-18T04:00:01 120 C 129.844 +5.215 (1.9 deg x 1.9 deg) 2015-09-18T04:02:11 120 C 129.847 +5.215 (1.9 deg x 1.9 deg) 2015-09-18T04:04:23 120 C 129.847 +5.215 (1.9 deg x 1.9 deg) 2015-09-18T04:10:00 120 C 134.242 +3.216 (1.9 deg x 1.9 deg) 2015-09-18T04:12:12 120 C 134.245 +3.217 (1.9 deg x 1.9 deg) 2015-09-18T04:14:22 120 C 134.245 +3.217 (1.9 deg x 1.9 deg) 2015-09-18T05:39:59 120 C 103.462 -70.317 (1.9 deg x 1.9 deg) 2015-09-18T05:42:11 120 C 103.458 -70.318 (1.9 deg x 1.9 deg) 2015-09-18T05:44:24 120 C 103.456 -70.318 (1.9 deg x 1.9 deg) 2015-09-18T05:50:00 120 C 109.477 -69.716 (1.9 deg x 1.9 deg) 2015-09-18T05:52:12 120 C 109.476 -69.716 (1.9 deg x 1.9 deg) 2015-09-18T05:54:25 120 C 109.473 -69.717 (1.9 deg x 1.9 deg) 2015-09-18T06:02:12 120 C 103.439 -70.327 (1.9 deg x 1.9 deg) 2015-09-18T06:04:24 120 C 103.437 -70.327 (1.9 deg x 1.9 deg) 2015-09-18T06:09:59 120 C 109.457 -69.714 (1.9 deg x 1.9 deg) 2015-09-18T06:12:12 120 C 109.455 -69.715 (1.9 deg x 1.9 deg) 2015-09-18T06:14:23 120 C 109.453 -69.715 (1.9 deg x 1.9 deg) 2015-09-18T06:29:59 120 C 103.429 -70.321 (1.9 deg x 1.9 deg) 2015-09-18T06:32:11 120 C 103.426 -70.322 (1.9 deg x 1.9 deg) 2015-09-18T06:34:22 120 C 103.424 -70.322 (1.9 deg x 1.9 deg) 2015-09-18T06:40:00 120 C 109.435 -69.725 (1.9 deg x 1.9 deg) 2015-09-18T06:42:12 120 C 109.432 -69.725 (1.9 deg x 1.9 deg) 2015-09-18T06:44:24 120 C 109.430 -69.726 (1.9 deg x 1.9 deg) 2015-09-18T06:49:59 120 C 114.942 -69.627 (1.9 deg x 1.9 deg) 2015-09-18T06:52:11 120 C 114.939 -69.627 (1.9 deg x 1.9 deg) 2015-09-18T06:54:23 120 C 114.937 -69.628 (1.9 deg x 1.9 deg) 2015-09-18T07:00:00 120 C 103.407 -70.318 (1.9 deg x 1.9 deg) 2015-09-18T07:02:12 120 C 103.405 -70.319 (1.9 deg x 1.9 deg) 2015-09-18T07:04:24 120 C 103.404 -70.319 (1.9 deg x 1.9 deg) 2015-09-18T07:09:59 120 C 109.422 -69.722 (1.9 deg x 1.9 deg) 2015-09-18T07:12:11 120 C 109.419 -69.722 (1.9 deg x 1.9 deg) 2015-09-18T07:14:23 120 C 109.417 -69.723 (1.9 deg x 1.9 deg) 2015-09-18T07:20:00 120 C 114.929 -69.611 (1.9 deg x 1.9 deg) 2015-09-18T07:22:12 120 C 114.928 -69.611 (1.9 deg x 1.9 deg) 2015-09-18T07:24:24 120 C 114.926 -69.611 (1.9 deg x 1.9 deg) 2015-09-18T07:30:00 120 C 103.397 -70.305 (1.9 deg x 1.9 deg) 2015-09-18T07:32:12 120 C 103.397 -70.305 (1.9 deg x 1.9 deg) 2015-09-18T07:34:24 120 C 103.395 -70.305 (1.9 deg x 1.9 deg) 2015-09-18T07:39:59 120 C 109.403 -69.706 (1.9 deg x 1.9 deg) 2015-09-18T07:42:11 120 C 109.402 -69.706 (1.9 deg x 1.9 deg) 2015-09-18T07:44:23 120 C 109.401 -69.706 (1.9 deg x 1.9 deg) 2015-09-18T07:50:00 120 C 114.911 -69.608 (1.9 deg x 1.9 deg) 2015-09-18T07:52:11 120 C 114.911 -69.608 (1.9 deg x 1.9 deg) 2015-09-18T07:54:23 120 C 114.909 -69.608 (1.9 deg x 1.9 deg) 2015-09-18T07:59:59 120 C 109.398 -69.710 (1.9 deg x 1.9 deg) 2015-09-18T08:02:11 120 C 109.396 -69.711 (1.9 deg x 1.9 deg) 2015-09-18T08:04:23 120 C 109.393 -69.711 (1.9 deg x 1.9 deg) 2015-09-18T08:10:00 120 C 114.903 -69.605 (1.9 deg x 1.9 deg) 2015-09-18T08:12:12 120 C 114.902 -69.605 (1.9 deg x 1.9 deg) 2015-09-18T08:14:24 120 C 114.901 -69.605 (1.9 deg x 1.9 deg) 2015-09-18T08:30:00 120 C 109.385 -69.704 (1.9 deg x 1.9 deg) 2015-09-18T08:32:12 120 C 109.383 -69.705 (1.9 deg x 1.9 deg) 2015-09-18T08:34:24 120 C 109.380 -69.705 (1.9 deg x 1.9 deg) 2015-09-18T08:39:59 120 C 114.888 -69.602 (1.9 deg x 1.9 deg) 2015-09-18T08:42:11 120 C 114.887 -69.602 (1.9 deg x 1.9 deg) 2015-09-18T08:44:23 120 C 114.885 -69.601 (1.9 deg x 1.9 deg) 2015-09-18T09:00:00 120 C 109.376 -69.707 (1.9 deg x 1.9 deg) 2015-09-18T09:02:12 120 C 109.375 -69.707 (1.9 deg x 1.9 deg) 2015-09-18T09:04:24 120 C 109.373 -69.706 (1.9 deg x 1.9 deg) 2015-09-18T09:09:59 120 C 114.880 -69.602 (1.9 deg x 1.9 deg) 2015-09-18T09:12:11 120 C 114.877 -69.602 (1.9 deg x 1.9 deg) 2015-09-18T09:14:23 120 C 114.876 -69.602 (1.9 deg x 1.9 deg) 2015-09-18T09:29:59 120 C 109.372 -69.701 (1.9 deg x 1.9 deg) 2015-09-18T09:32:11 120 C 109.370 -69.701 (1.9 deg x 1.9 deg) 2015-09-18T09:34:23 120 C 109.369 -69.701 (1.9 deg x 1.9 deg) 2015-09-18T09:40:00 120 C 114.872 -69.604 (1.9 deg x 1.9 deg) 2015-09-18T09:42:12 120 C 114.871 -69.604 (1.9 deg x 1.9 deg) 2015-09-18T09:44:24 120 C 114.869 -69.603 (1.9 deg x 1.9 deg) 2015-09-18T09:49:59 120 C 124.890 -67.995 (1.9 deg x 1.9 deg) 2015-09-18T09:52:11 120 C 124.889 -67.994 (1.9 deg x 1.9 deg) 2015-09-19T03:30:01 120 C 129.861 +5.232 (1.9 deg x 1.9 deg) 2015-09-19T03:32:11 120 C 129.862 +5.232 (1.9 deg x 1.9 deg) 2015-09-19T03:34:22 120 C 129.865 +5.232 (1.9 deg x 1.9 deg) 2015-09-19T03:40:01 120 C 134.260 +3.229 (1.9 deg x 1.9 deg) 2015-09-19T03:42:12 120 C 134.261 +3.229 (1.9 deg x 1.9 deg) 2015-09-19T03:44:22 120 C 134.263 +3.229 (1.9 deg x 1.9 deg) 2015-09-19T03:50:01 120 C 134.462 +6.236 (1.9 deg x 1.9 deg) 2015-09-19T03:52:11 120 C 134.465 +6.236 (1.9 deg x 1.9 deg) 2015-09-19T03:54:22 120 C 134.466 +6.236 (1.9 deg x 1.9 deg) 2015-09-19T04:00:01 120 C 129.864 +5.231 (1.9 deg x 1.9 deg) 2015-09-19T04:02:13 120 C 129.864 +5.231 (1.9 deg x 1.9 deg) 2015-09-19T04:04:24 120 C 129.865 +5.231 (1.9 deg x 1.9 deg) 2015-09-19T04:10:01 120 C 134.263 +3.230 (1.9 deg x 1.9 deg) 2015-09-19T04:12:11 120 C 134.264 +3.230 (1.9 deg x 1.9 deg) 2015-09-19T04:14:23 120 C 134.266 +3.230 (1.9 deg x 1.9 deg) [GCN OPS NOTE(20sep15): This Circular was originally published on 20:41 19-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18349 SUBJECT: LIGO/Virgo G184098: SkyMapper observations DATE: 15/09/20 02:53:43 GMT FROM: Fang Yuan at ANU Fang Yuan, Christian Wolf, Richard Scalzo, Brian Schmidt (ANU) We report tiled observations of LIGO/Virgo G184098 using the 1.3m SkyMapper telescope located at Siding Spring Observatory in Australia. Starting UTC 2015-09-18 17:11:53 (4.3 days after the trigger), SkyMapper observed 5 fields, covering a sky area of about 27.5 sq. deg, with 2x60s i-band exposures. Footprint of the observations has been uploaded to GraceDB. These fields are selected based on weight calculated from the GW skymap, the GW Galaxy Catalogue (augmented by 2MASS Ks photometry) and existence of SkyMapper pre-trigger observations. Using the latest GW skymap, we estimate a chance of 6% that these fields contain the true location of the source. Images were taken under poor (>4") seeing with limiting mag of about 19. Image subtraction have been performed against SkyMapper templates taken in January and March 2015 as part of the Southern Sky Survey. No transient source has been detected in preliminary analysis. The same fields are observed again on 2015-09-19, and analysis is ongoing. In addition, at UTC 2015-9-16 16:56:54 (2.3 days after the trigger), one 120s v-band image (limiting mag ~17.7), centered at ra, dec =115.9322, -68.888 was taken as part of the SkyMapper Transient Search. No transient was detected, comparing to template taken in June 2015. [GCN OPS NOTE(19sep15): This Circular was originally published on 00:06 20-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18350 SUBJECT: LIGO/Virgo G184098: DESGW followup program DATE: 15/09/20 21:41:34 GMT FROM: M. Soares-Santos at Fermi Lab M. Soares-Santos (Fermilab), J. Annis (Fermilab), E. Berger (Harvard), D. J. Brout (UPenn), H.-Y. Chen (UChicago), P. Cowperthwaite (Harvard), H. T. Diehl (Fermilab), B. Farr (UChicago), D. A. Finley (Fermilab), J. Frieman (Fermilab/UChicago), M. Garcia (CIEMAT/Madrid), R. Gruendl (NCSA), D. Hollowood (UCSC), D. Holz (UChicago), R. Kessler (UChicago), A. Kim (LBNL), K. Herner (Fermilab), E. Neilsen (Fermilab), M. Sako (UPenn), B. Yanny (Fermilab) On behalf of the DESGW team: We report on observations done with the Dark Energy camera (DECam) on the Blanco telescope at CTIO on the night of 2015-09-18 in response to the LVC trigger G184098. These observations complement those taken on 2015-09-17, increasing the area coverage by about 20%. Our observations were delayed by 1 night due to the mag 8.1 earthquake near CTIO. DECam has a 3 sq-deg field of view, and typically reaches i,z = 23rd limiting magnitudes for 90 sec exposure times. In 2015-09-18 and 2015-09-17, we covered a total of 6% of the LIGO probability map in 3 hours of observing time. We imaged a total of 93 sq-deg to 23.25 5-sigma point source limiting magnitude in i,z bands. Coordinates for both nights are given below. Analysis is underway. 6 pointings in 2015-09-18 ra dec 62.107867 -57.8027 120.622213 -67.14873 129.784212 -68.71983 132.961775 -65.42426 133.801654 -67.3675 77.530833 -66.03508 28 pointings in 2015-09-17 ra dec 105.241671 -69.46246 72.711983 -65.40533 99.430667 -69.84 68.298046 -63.8895 95.986417 -68.35239 110.757033 -68.87642 115.898475 -68.09865 109.488283 -70.73343 103.3931 -71.25164 115.164875 -70.00358 120.35765 -69.0844 65.041267 -62.8751 93.434754 -69.99717 65.802783 -60.8461 62.9234 -59.8316 125.044417 -67.99968 129.235458 -66.77258 68.870837 -61.8606 125.215963 -69.94243 72.150367 -62.8751 62.107867 -57.8027 87.38715 -69.92876 83.908596 -71.39367 81.427092 -69.63706 84.793617 -68.22478 82.565254 -66.48404 79.328883 -67.84927 77.530833 -66.03508 [GCN OPS NOTE(20sep15): This Circular was originally published on 19:51 20-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18353 SUBJECT: LIGO/Virgo G184098: transient search with VISTA DATE: 15/09/21 18:50:17 GMT FROM: Nial Tanvir at U of Leicester N. R. Tanvir (U. Leicester), A. J. Levan, D. White (U. Warwick), P. T. O'Brien, K. Wiersema (U. Leicester) report on behalf of a larger collaboration: We have initiated a sequence of observations with the 4m ESO VISTA telescope at Cerro Paranal, Chile, to map most of the region between 4h40m and 6h30m in RA and -65 degs to -73 degs in dec (total area ~60 sq deg). We are observing in the Y, J and K bands (30 s integrations in each), and the observations are expected to take 5 or 6 nights, depending on weather, beginning on 20th Sept. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18354 SUBJECT: LIGO/Virgo G184098: INTEGRAL search of temporally coincident prompt hard X-ray emission DATE: 15/09/21 18:52:51 GMT FROM: Carlo Ferrigno at ISDC/INTEGRAL C. Ferrigno (ISDC, University of Geneva, CH), V. Savchenko (APC Paris, France), S. Mereghetti (IASF-Mi, Italy), E. Kuulkers (ESAC/ESA, Madrid, Spain), A. Bazzano (IAPS-Roma, Italy), E. Bozzo, T. J.-L. Courvoisier (ISDC, University of Geneva, CH) The anti-coincidence shield of the spectrometer on board of INTEGRAL (SPI/ACS) is sensitive to gamma-rays above ~50 keV. We investigates the light curve at -300 +900 s from the trigger time (2015-09-14 09:50:45 UTC) on temporal scales from 0.1 to 100 s and derived a maximum post-trial peak significance of ~1.5 sigma with a temporal scale of 9 s, at 200 s before the GW trigger. This excess is not significant. The SPI/ACS light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the incident angle. We estimate typical 3-sigma upper limits corresponding to fluences of 1.4e-6 erg/cm2 for a 100 s duration, 4e-7 erg/cm2 for 10 s, 1.3e-7 erg/cm2 for 1 s, and 6e-8 erg/cm2 for 0.1 s. This assumes an optimal perpendicular direction of the burst to the INTEGRAL pointing direction, low threshold at 100 keV, and Band model parameters â<88><92>1, â<88><92>2.5 with peak E_0 ~ 500 keV. This orientation is compatible with part of the high-probability sky area of the trigger; for the remaining probability region, the upper limits are roughly a factor two higher. A detailed sensitivity map is under computation. The upper limit provided by SPI-ACS disfavours a cosmic origin of the hard X-ray transient detected by Fermi/GBM at 09:50:45.79 (Blackburn et al 2015). We have also investigated the coded-mask imager (IBIS) data on 2015-09-14 in the time interval 09:28 -10:00 UTC, while the instrument was pointing at the sky coordinates RA=270.79 Dec=-31.18, tens of degrees far from the probability peaks of the trigger. No transient point sources appeared in the image at a significance higher than ~3 sigma (post-trial) at a temporal scale of 5 s. The minimum peak flux of gamma-ray bursts detected with IBIS is 0.1 ph/s/cm2 in the 20-200 keV energy band in the central 9x9 deg of the detector, which has a zero response field of view of 29x29 degrees. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18359 SUBJECT: LIGO/VIRGO G184098 : classifications of transients from the LSQ observations DATE: 15/09/23 12:03:39 GMT FROM: S. J. Smartt at Queens U Belfast K. Takats, C. Agliozzo (UNAB, MAS), A. Razza (DAS, MAS), F. Olivares (UNAB, MAS), I. Pessa (PUC, MAS), H. Campbell (IOA), N. Elias-Rosa, E. Cappellaro (INAF - OAPd), C. Inserra (QUB), K. Maguire (ESO), S. J. Smartt (QUB), K. W. Smith (QUB), M. Sullivan (Southampton), S. Valenti (LCOGT), O. Yaron (Weizmann), D. Young (QUB), Ilan Manulis (Weizmann), C. Baltay, N. Ellman, E. Hadjiyska, R. McKinnon, D. Rabinowitz, S. Rostami (Yale University), U. Feindt, M. Kowalski (Universitat Bonn), P. Nugent (LBL Berkeley) on behalf of PESSTO. Following the LSQ discovery (Rabinowitz et al, GCN 18347) of candidates in the G184098 southern error box, PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org), reports the following classifications. All observations were performed on the ESO New Technology Telescope at La Silla on the night of 2015-09-22, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). Classification spectra can be obtained from http://www.pessto.org (via WISeREP). Name | RA (J2000) | Dec (J2000) | Disc. Date | Source | Disc Mag | z | Type | Phase | LSQ15bbb | 07:25:16.50 | -69:04:01.1 | 20150918 | LSQ | 17.36 | 0.037 | Ia | around max | LSQ15bbj | 07:16:14.45 | -69:36:00.2 | 20150918 | LSQ | 19.75 | 0.086 | Ia | +4-5d | The two transients are normal looking type Ia supernovae and almost certainly unrelated to the GW trigger. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18361 SUBJECT: LIGO/Virgo G184098: optical transient search with Kiso Schmidt telescope and KWFC on behalf of J-GEM collaboration DATE: 15/09/24 01:38:06 GMT FROM: Tomoki Morokuma at U.TokyoJ-GEM Tomoki Morokuma (The University of Tokyo), Masaomi Tanaka (National Astronomical Observatory of Japan), Michitoshi Yoshida, Koji S. Kawabata, Yousuke Utsumi (Hiroshima University), Mamoru Doi, Kentaro Motohara, Yoichi Tamura (The University of Tokyo), Fumio Abe (Nagoya University), Kenta Fujisawa (Yamaguchi University), Nobuyuki Kawai (Tokyo Tech), Koji Ohta (Kyoto University), and Kenshi Yanagisawa (National Astronomical Observatory of Japan) on behalf of J-GEM collaboration We report optical imaging follow-up observations for a part of the northern skymap regions of G184098 with 1.05-m Kiso Schmidt telescope and its 2.2 deg x 2.2 deg field-of-view camera, Kiso Wide Field Camera (KWFC; Sako et al. 2012, SPIE, 8446, 84466L). We took 180-sec exposure images in i-band for 5 fields as below (about 24 deg2 in total). RA(J2000) Dec(J2000) starting UTC 09:05:35.52 +10:27:00.0 2015-09-17 19:07:34 09:14:32.16 +10:27:00.0 2015-09-17 19:13:09 09:23:28.80 +10:27:00.0 2015-09-17 19:18:31 09:32:25.44 +10:27:00.0 2015-09-17 19:23:54 09:41:22.08 +10:27:00.0 2015-09-17 19:36:01 The 5-sigma limiting magnitudes (AB) are 18.8 mag and 16.2 mag in the first four exposures and the last exposure, respectively. The data reduction and transient finding with image subtraction were performed with the pipeline developed for Kiso Supernova Survey (KISS) as described in Morokuma et al. (2014, PASJ, 66, 114). The SDSS i-band data was used as reference images for the subtraction. We do not find any transients which are likely associated with external galaxies. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18362 SUBJECT: LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients DATE: 15/09/24 13:29:47 GMT FROM: S. J. Smartt at Queens U Belfast S.J. Smartt, K. W. Smith, (Queenâ<80><99>s University Belfast), K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), D. Young, D. Wright (Queenâ<80><99>s University Belfast), C. Stubbs (Harvard) Following our reports of Pan-STARRS pointing coordinates for the field of LIGO/Virgo G184098 and the search for transients, an update is provided here. The coordinates of 4 nights of observations are given on the GraceDB webpages. Images in i, z and y-band were taken on 2015-09-17, 19, 22, 23. The difference images were processed as described in Huber et al. (Atel 7153) and on the Pan-STARRS Survey for Transients (PSST) pages (http://star.pst.qub.ac.uk/ps1threepi/psdb/). We initially reported first night detections of PS15cbm, PS15cbj, PS15cbn (2015-09-17). However subsequent data show that only PS15cbm is real. The other two were not recovered in later images and are almost certainly instrumental ghosts. Over these four nights, we now have 5 objects which are detected in multiple nights and multiple filters (and different camera orientations) and are likely to be extragalactic transients (they are all associated with a galaxy in SDSS and PS1 reference images). Obj RA(J2000) Dec(J2000) mag z PS15cbm 08:49:19.85 +03:48:17.8 18.54(i) 0.059 PS15cci 09:13:22.76 +06:10:47.2 18.33(i) â<80>¦ PS15ccx 08:18:03.90 +04:18:04.2 19.42(z) â<80>¦ PS15ccv 08:55:23.07 +04:41:19.0 19.57(i) 0.071 PS15ccw 08:57:30.60 +04:31:56.1 19.33(i) 0.072 The mag is the discovery magnitude (AB system). The reported redshift is the spectroscopic redshift of the apparent host galaxy from SDSS DR12. The other two have no spectroscopic redshifts, but have detected host galaxies. >From the data in hand, all appear to be likely supernovae. The object furthest north-east (PS15cci) is close to the 90% confidence contour of the G182098 'LIB_skymap' GW localisation map. The others are outside this region but within the 'skyprobcc_cWBâ<80><99> map. Twilight restricted us pointing at the centre of the 'LIB_skymap' GW localisation map. Our survey area is slightly further south than the iPTF survey area (Singer et al. GCN 18337) and the J-GEM area (Morokuma et al. GCN 18361). Observations are continuing this week when the weather cooperates. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18363 SUBJECT: LIGO/Virgo G184098: ASKAP followup DATE: 15/09/24 21:07:32 GMT FROM: Keith Bannister at ATNF K. Bannister (CSIRO), J. Marvil (CSIRO), I. Heywood (CSIRO), R. Wark (CSIRO), M. Bell (CSIRO), T. Murphy (University of Sydney), D. Kaplan (UWM) on behalf of the ASKAP/VAST team We observed the Northern probability maximum with BETA - the ASKAP engineering test array. The observations cover a 9.5 x 9.5 degree square centered on 08h52m16s +06d32m00s with 8 pointings, each comprising 9 beams. We observed at center frequency of 863.5 MHz with a a bandwidth of 300 MHz. Observing began at 2015-09-21 20:40 UT and continued for 9 hrs. We expect a spatial resolution of around 165x45 arcseconds, and a detection limit of around 3 mJy. Progress on downloading, checking and processing these data has been slowed by scheduled maintenance at our primary computing facility. We will report on the result in the next few days. -- KEITH BANNISTER | Bolton Fellow CSIRO Astronomy and Space Science T +61 2 9372 4295 E keith.bannister@csiro.au ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18364 SUBJECT: LIGO/Virgo G184098: LOFAR follow-up DATE: 15/09/24 21:59:56 GMT FROM: Peter Jonker at SRON/RU J. Broderick (ASTRON), P.G. Jonker (SRON/RU), R.P. Fender (Oxford), A. Rowlinson (UvA, ASTRON), R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester) report on behalf of the LOFAR Transients Key Science project: On Sept 21, 2015, starting at 06.00 (UTC), we observed a large fraction of the localization error range at declinations larger than 0 degrees of the Advanced LIGO trigger G184098 with the ILT (International Low-Frequency Array [LOFAR] Telescope). The observations were obtained with the High-Band Antennas (HBA) at a centre frequency of 145 MHz (bandwidth 11.9 MHz). In this configuration, the ILT can provide 8 simultaneous beams on the sky, where each beam has a field of view of approximately 12 deg^2 (beam FWHM 3.9 degrees). The beam centres are given below: 1) 132.500000 5.166667 08:50:00.00 +05:10:00.0 2) 135.287125 5.166667 09:01:08.91 +05:10:00.0 3) 129.712875 5.166667 08:38:51.09 +05:10:00.0 4) 131.106458 7.572944 08:44:25.55 +07:34:22.6 5) 131.106458 2.760389 08:44:25.55 +02:45:37.4 6) 133.893542 7.572944 08:55:34.45 +07:34:22.6 7) 133.893542 2.760389 08:55:34.45 +02:45:37.4 8) 128.319333 2.760389 08:33:16.64 +02:45:37.4 The observations cover roughly 50 square degrees in total. Each field was observed for a total of 3 hr with 10s time resolution after pre-processing. These fields will be revisited two times with the same exposures, on provisional time-scales of 1 month and 3 months. Analysis is ongoing. [GCN OPS NOTE(24sep15): This Circular was originally published on 18:05421-Sep-2015 UT.] ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18370 SUBJECT: LIGO/Virgo G184098: Liverpool Telescope Spectroscopy of PS15ccx DATE: 15/09/27 15:33:04 GMT FROM: Iain Steele at Liverpool/JMU I.A. Steele, C.M. Copperwheat, A.S. Piascik (Liverpool JMU) report on behalf of the larger ARI-LJMU collaboration. The extragalactic transient PS15ccx was reported by Smartt et al. (GCN 18362) on 2015-09-24 as part of the Pan-STARRS EM followup of GW trigger G184098. A spectrum of the transient with exposure time 1800 seconds was obtained using the SPRAT spectrograph on the 2.0 metre Liverpool Telescope on La Palma on 2015-09-27 starting at 05:32 UT. The spectrum was obtained in morning twilight, and consequently has poor signal to-noise ratio. Due to the poor signal-to-noise no automatic classification could be made using SNID. However a “by eye” comparison with template spectra shows that the spectrum is consistent with a Supernova Type Ia with redshift around 0.07. ________________________________ Important Notice: the information in this email and any attachments is for the sole use of the intended recipient(s). If you are not an intended recipient, or a person responsible for delivering it to an intended recipient, you should delete it from your system immediately without disclosing its contents elsewhere and advise the sender by returning the email or by telephoning a number contained in the body of the email. No responsibility is accepted for loss or damage arising from viruses or changes made to this message after it was sent. The views contained in this email are those of the author and not necessarily those of Liverpool John Moores University. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18371 SUBJECT: LIGO/Virgo G184098: Update to LT Spectroscopy of PS15ccx DATE: 15/09/27 16:15:17 GMT FROM: Iain Steele at Liverpool/JMU I.A Steele, C.M. Copperwheat, A.S. Piascik (Liverpool JMU) report on behalf of the larger ARI-LJMU collaboration In further analysis of the LT spectrum reported in GCN 18370 of PS15ccx we have now succeeded in obtaining a classification of the spectrum using SNID by truncating the wavelength range to between 4500 and 7500 Angstroms to remove the regions of poorest signal to noise ratio. SNID reports a 96% probability that the transient is a Supernova Type Ia at age 15-23 days post maximum with z~0.097. ________________________________ Important Notice: the information in this email and any attachments is for the sole use of the intended recipient(s). If you are not an intended recipient, or a person responsible for delivering it to an intended recipient, you should delete it from your system immediately without disclosing its contents elsewhere and advise the sender by returning the email or by telephoning a number contained in the body of the email. No responsibility is accepted for loss or damage arising from viruses or changes made to this message after it was sent. The views contained in this email are those of the author and not necessarily those of Liverpool John Moores University. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18372 SUBJECT: LIGO/Virgo G184098: spectral classification of PS15cci DATE: 15/09/27 19:46:24 GMT FROM: S. J. Smartt at Queens U Belfast S.J. Smartt (Queen’s University Belfast), T. Kupfer (Caltech), K. Chambers (IfA, University of Hawaii), K. W. Smith, (QUB), M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA), D. Young, D. Wright, (QUB), C. Stubbs (Harvard) Further to GCN 18362, and the Pan-STARRS wide-field search of the accessible area of the northern ALIGO/VIRGO area. We report a spectrum of the transient PS15cci. Thomas Kupfer took a 25min exposure with the Palomar 200-inch and DBSP on 2015-09-25 covering 3200-9000 Angs. This transient is in the faint dwarf galaxy SDSS J091322.78+061047.6, and clear emission lines from the host ([OII] 3727, [OIII] 5009, H-alpha) are detected at z=0.055 ( giving M_r ~ -17 for the host), The transient is a type Ia supernova with SNID suggesting a good match with a 1991T-like SN at an epoch of a few days before peak brightness. PS15cci lies within the 90% contour of the LIB area, and to date has been the only candidate within this contour (in the northern probability region). Pan-STARRS continues to observe the accessible north-western spur of the ALIGO/VIRGO LIB region (nightly when weather allows), pushing eastwards as far as possible. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18388 SUBJECT: LIGO/Virgo G184098: Ongoing gravitational-wave analysis DATE: 15/10/03 23:41:43 GMT FROM: Leo Singer at NASA/GSFC The LIGO Scientific Collaboration and Virgo report: An update is available regarding the gravitational-wave event candidate G184098, identified on 2015-09-14. Analysis of this event is still in progress. The preliminary waveform reconstruction (if it is a real gravitational-wave event) appears consistent with expectations for a binary black hole coalescence. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18390 SUBJECT: LIGO/Virgo G184098: MASTER OTs detection and Scenario Machine prediction DATE: 15/10/04 19:00:08 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov (Lomonosov Moscow State University, SAI MSU), E.S. Gorbovskoy (SAI Lomonosow MSU) and D. Buckley(SAAO) behalf MASTER-team MASTER-SAAO twin robotic telescope (MASTER-Net: http://observ.pereplet.ru, FOV= 2x4 square degrees) located in SAAO was starting survey on the aLIGO trigger G184098 error-box 220517 sec after trigger time at 2015-09-16 20:18:11 UT. The 5-sigma upper limit on our sets is about 18.4 mag - 19.9 mag (GCN ) . At this first night we observed 212 square degrees by 3 images for each field during ~2 hours. There are LMC near the center error box and Milky Way at the east edge of the error box. Because large number of stars the redaction is delay and continueted. The cover map is available at http://master.sai.msu.ru/static/G184098.png . We started from the left edge of the error box as its rise (see previous MASTER Circular). MASTER-SAAO continued survey in the coming days. By 22 September, we received about 900 images inside the error box. Each area was covered several times. The full time cover map is available at http://master.sai.msu.ru/static/G184098_full.png The total probability by covered fields is about 58%. We found two OT inside error box ( http://master.sai.msu.ru/static/G184098_tra.png). Unfortunatelly, both transient fall to common MASTER DATA Base OTs and automatically was published in usual way (ATel #8065 http://www.astronomerstelegram.org/?read=8065). I am sorry (VL). This is connected with new type error box (without edge) in our robotic system and some mixing between alerts and survey observations. 1) MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 04h 09m 38.68s -54d 13m 16.9s on 2015-09-16.87912 UT. The OT unfiltered magnitude is 17.3m (the limit is 17.8m). The OT is seen in 5 images. There is no minor planet at this place. We have reference image without OT on 2015-02-14.89772 UT with 20.0 unfiltered magnitude limit. This PSN is in 0.9"W and 3.6"N from the center of galaxy PGC421615 (Btot=18.4m). Spectral observations are required. The discovery and reference images are http://master.sai.msu.ru/static/OT/040938.68-541316.9.png There is no published spectrum and distance. 2)(ATel #8087 http://www.astronomerstelegram.org/?read=8087) MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 07h 07m 47.72s -67d 22m 05.6s on 2015-09-21.99535 UT. The OT unfiltered magnitude is 16.9m (limit 19.2m). The OT is seen in 8 images. There is no minor planet at this place. We have reference images without OT on 2014-12-25.02683 UT with unfiltered magnitude limit 20.0m, on 2015-02-24.863UT with m_lim=20.3. There is USNO-B1 star (0226-0200013) in 3.8" with blue B2=20.97 and R2=20.01, but AAVSO decided that our OT is this star - dwarf nova U Gem-type (accreting white dwarf in binary system). http://www.aavso.org/vsx/index.php?view=detail.top&oid=410052. Spectral observations are required. The discovery and reference images are available at http://master.sai.msu.ru/static/OT/MASTEROTJ070747.72-672205.6.png The possible BH nature of the LIGO/Virgo G184098 alert (GCN 18388) is in agreement with Scenario Machine Binary Population Synthesis prediction (Lipunov, V. M.; Postnov, K. A.; Prokhorov, M. E., First LIGO events: binary black holes mergings, New Astronomy, Volume 2, Issue 1, p. 43-52, 1997, http://www.sciencedirect.com/science/article/pii/S1384107697000079).See also Lipunov et al., 1997, Black holes and gravitational waves: Possibilities for simultaneous detection using first-generation laser interferometers, Astronomy Letters, vol.23, 1997, 492-497. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18394 SUBJECT: LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients DATE: 15/10/05 15:03:34 GMT FROM: S. J. Smartt at Queens U Belfast S.J. Smartt, K. W. Smith, (Queen’s University Belfast), K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), D. Young, D. Wright (Queen’s University Belfast), C. Stubbs (Harvard) Following our reports of Pan-STARRS observations of the field of LIGO/Virgo G184098, and identification/classification of transients (GCN18362, GCN18372, also see Steele et al. GCN18371). We report further imaging has been continuing in the localisation region of the ‘LIB_skymap’, pushing east south into the higher probability regions. Eight transients have been discovered. All are likely supernovae/AGN which are in the field but unrelated to the GW source. A summary is given below and a sky map is being uploaded to the GraceDB for visualisation. Name | RA (J2000) | Dec (J2000) | Disc. Date | Disc Mag | filter | z and SpType PS15ccw | 08 57 30.60 | +04 31 56.1 | 20150917 | 19.31 | i |0.072 PS15cbm | 08 49 19.85 | +03 48 17.8 | 20150917 | 18.55 | i |0.059 Ia PS15ccx | 08 18 03.91 | +04 18 04.2 | 20150919 | 19.42 | z |0.097 Ia PS15cci | 09 13 22.76 | +06 10 47.3 | 20150919 | 18.32 | i |0.055 Ia PS15ccv | 08 55 23.05 | +04 41 19.0 | 20150922 | 19.57 | i |0.071 PS15cel | 09 34 11.58 | +05 46 45.2 | 20150923 | 19.53 | i |... PS15cej | 09 35 19.41 | +10 11 50.7 | 20151002 | 18.13 | i |0.049 PS15cek | 09 36 41.04 | +10 14 16.2 | 20151002 | 17.24 | z |0.06 AGN The mag is the discovery AB magnitude. The reported redshift is the spectroscopic redshift of the apparent host galaxy from SDSS DR12 or that from the transient. P15cek is the variable core of SDSS J093641.05+101415.9 which has an SDSS spectrum showing AGN/QSO characteristics. The host of PS15cel has no spectroscopic redshift reported, but from the data in hand, appears likely to be a supernova. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18395 SUBJECT: LIGO/VIRGO G184098 : PESSTO classification of PS15cbm in the northern region DATE: 15/10/05 15:09:22 GMT FROM: S. J. Smartt at Queens U Belfast H. Campbell (Cambridge), J. Lyman (Warwick), M. Fraser (Cambridge), J. Anderson (ESO), C. Inserra (QUB), I. Manulis (Weizmann), K. Maguire (QUB), S. J. Smartt (QUB), K. W. +Smith (QUB), M. Sullivan (Southampton), S. Valenti (LCOGT), O. Yaron (Weizmann), D. Young, D. Wright (QUB), K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. +Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), C. Stubbs (Harvard) Following the Pan-STARSS discovery (Smartt et al, GCN 18394) of candidates in the G184098 northern error box, PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org), reports that PS15cbm is a type Ia supernova a t z=0.06 at +2-3w past maximum light. All observations were performed on the ESO New Technology Telescope at La Silla on the night of 2015-10-03, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). Classification spectra can be obtained from http://www.pessto.org (via WISeREP). ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18397 SUBJECT: LIGO/Virgo G184098: Further VST-ESO PARANAL observations DATE: 15/10/06 08:42:52 GMT FROM: Enzo Brocato at INAF-OA Roma E. Brocato (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), A.Grado (INAF-OAC), G.Greco (Urbino University/INFN Firenze), L. Limatola (INAF-OAC), A. Melandri +(INAF_OAB), E. Cappellaro (INAF-OAPd), L. Nicastro (INAF-IASF-Bo), E. Pian (SNS-Pisa), S. Campana (INAF-OAB), M. Capaccioli (INAF-OAC), S. Covino (INAF-OAB), P. D�Avanzo +(INAF-OAB), F. Getman (INAF-OAC), M. Lisi (INAF-OAR), E. Palazzi (INAF-IASF-Bo), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), G. Stratta (Urbino University/INFN +Firenze). On behalf of the INAF Gravitational Astronomy group. We report on further observations performed with the VLT Survey Telescope (VST) at ESO-Paranal equipped with OMEGACAM (FOV=1 square degree) to improve the coverage of the +skymap of the advanced LIGO/Virgo trigger G184098. Since September 17, the area of the sky covered by VST observations increased to ~90 square degree, overlapping the 54 square degree observed on September 16. These new se +ts of observations were taken in the r-sloan band and 80 sec exposure time each and have been performed on 17/09, 21/09, 24/09 and 30/09. The 3 x 3 degree pointings are centered on the following coordinates RA, Dec (J2000): 03:48:53 -56:29:24 03:58:22 -59:24:00 04:30:46 -64:21:00 04:53:29 -66:20:24 05:22:57 -67:30:00 05:58:00 -70:43:48 06:34:45 -70:43:48 07:47:40 -70:38:24 08:05:57 -67:31:12 08:38:40 -67:31:12 The image analysis is ongoing. Further observations of these fields are planned for one more night. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18418 SUBJECT: LIGO/VIRGO G184098 : PESSTO classifications of PanSTARRS transients in the northern region DATE: 15/10/13 12:03:31 GMT FROM: S. J. Smartt at Queens U Belfast M. Fraser (Cambridge), J. Lyman (Warwick), H. Campbell (Cambridge), T.-W. Chen (Bonn), A. De Cia (ESO), I. Manulis (Weizmann), C. Inserra (QUB), K. Maguire (QUB), E. Cappellaro (INAF), S. J. Smartt (QUB), K. W. Smith (QUB), M. Sullivan (Southampton), S. Valenti (LCOGT), O. Yaron (Weizmann), D. Young, D. Wright (QUB), K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), C. Stubbs (Harvard) Following the Pan-STARSS discovery (Smartt et al, GCN 18394) of candidates in the G184098 northern error region, PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org), reports two further classifications. PS15cej is a type Ia supernova around maximum light (spectrum taken on 2015-10-02) at z=0.049. PS15cel is a type II supernova, probably 2-3 weeks after maximum light (spectrum taken on 2015-10-12) at z=0.05 All observations were performed on the ESO New Technology Telescope at La Silla using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). Classification spectra can be obtained from http://www.pessto.org (via WISeREP). Eight optical transients have been detected to date (see GCN 18394, 18395). The sky positions and G184098 localisation region is now visualised on a plot on the GraceDB event webpage. Six have spectral classifications, while the other two are most likely now fainter than i ~ 21 mag. We thank Leo Singer and Roy Henderson for assistance in clarifying the contours, healpix interpretation and upload mechanisms. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18420 SUBJECT: LIGO/Virgo G184098: VLA follow-up of iPTF15cyk DATE: 15/10/15 21:35:29 GMT FROM: Nipuni Palliyaguru at TTU Nipuni Palliyaguru (TTU) and Alessandra Corsi (TTU) report on behalf of a larger collaboration: We imaged the position of the iPTF transient 15cyk (Singer et al.; RA(J2000)=7h 42m 14.87s Dec(J2000)=+20d 36' 43.4”), located in the error region of LIGO/Virgo G184098, with the Karl G. Jansky Very Large Array (VLA). The observations started on 15Oct 11:20:32 UT and were carried out in C-band (central frequency of about 6 GHz) with the VLA in its D configuration. Analysis is ongoing. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18424 SUBJECT: LIGO/Virgo G184098: LOFAR follow-up DATE: 15/10/19 21:03:56 GMT FROM: Antonia Rowlinson at U van Amsterdam J. Broderick (ASTRON), P.G. Jonker (SRON/RU), R.P. Fender (Oxford), A. Rowlinson (UvA, ASTRON), R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester) report on behalf of the LOFAR Transients Key Science project On Oct 16, 2015, starting at 03.41 (UTC), we observed a large fraction of the localization error range at declinations larger than 0 degrees of the Advanced LIGO trigger G184098 with the ILT (International Low-Frequency Array [LOFAR] Telescope). The observations were obtained with the High-Band Antennas (HBA) at a centre frequency of 145 MHz (bandwidth 11.9 MHz). In this configuration, the ILT can provide 8 simultaneous beams on the sky, where each beam has a field of view of approximately 12 deg^2 (beam FWHM 3.9 degrees). The beam centres are given below: 1) 132.500000 5.166667 08:50:00.00 +05:10:00.0 2) 135.287125 5.166667 09:01:08.91 +05:10:00.0 3) 129.712875 5.166667 08:38:51.09 +05:10:00.0 4) 131.106458 7.572944 08:44:25.55 +07:34:22.6 5) 131.106458 2.760389 08:44:25.55 +02:45:37.4 6) 133.893542 7.572944 08:55:34.45 +07:34:22.6 7) 133.893542 2.760389 08:55:34.45 +02:45:37.4 8) 128.319333 2.760389 08:33:16.64 +02:45:37.4 The observations cover roughly 50 square degrees in total. Each field was observed for a total of 3.7 hr with 10s time resolution after pre-processing. This is the second set of observations of these fields, after our initial run on Sept 21, 2015 (GCN 18364). The fields will be revisited once more with the same exposures, on a provisional time-scale of 2 months from now. Analysis is ongoing. ///////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18474 SUBJECT: LIGO/Virgo G184098: VLA follow-up of iPTF15cyk DATE: 15/10/27 00:34:10 GMT FROM: Nipuni Palliyaguru at TTU Nipuni Palliyaguru (TTU) and Alessandra Corsi (TTU) report on behalf of a larger collaboration: We analyzed the VLA image of the field of iPTF15cyk (Singer et al. GCN 18330, Palliyaguru et al. GCN 18420), located in the error region of LIGO/Virgo G184098. A provisional reduction shows no radio emission above the 3-sigma level of 45 uJy (the map rms is ~15 uJy at 5 GHz) at the iPTF position of the transient. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18655 SUBJECT: LIGO/Virgo G184098: Results of of 2nd epoch of ASKAP follow-up DATE: 15/12/02 12:42:58 GMT FROM: Keith Bannister at ATNF K. Bannister (CSIRO), J. Marvil (CSIRO), I. Heywood (CSIRO), R. Wark (CSIRO), M. Bell (CSIRO), T. Murphy (University of Sydney), D. Kaplan (UWM), S. Chatterjee (Cornell) on behalf of the ASKAP/VAST team. We observed the Southern probability maximum with BETA - the ASKAP engineering test array. The observations comprise 18 pointings covering a strip approximately 40 degrees long and 5 degrees high, centered on 07h27m51s -70d15m39s (J2000) and following the ridge of the probability maximum. We observed at center frequency of 863.5 MHz with a a bandwidth of 300 MHz. Observing began at 2015-09-26 13:15:00 UT and continued for 19.5 hrs. Our images have an average RMS of 1 mJy/beam. We cross matched all sources from our images with the SUMSS and MGPS2 catalogs, which are complete above 14 mJy. We found 3 sources not in the catalog, but visual inspection of the SUMSS [1] and MPGS2 [2] images indicates the presence of a source in all cases. Thus, we detect no transients above 14 mJy with respect to those surveys. We continue to process another earlier observation of the same field. [1] Mauch et al. 2003, MNRAS, 342, 1117 [2] Murphy et al. 2007, MNRAS, 382, 382 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18690 SUBJECT: LIGO/Virgo G184098: LOFAR follow-up DATE: 15/12/14 16:54:15 GMT FROM: Antonia Rowlinson at U van Amsterdam A. Rowlinson (UvA, ASTRON), J. Broderick (ASTRON), P.G. Jonker (SRON/RU), R.P. Fender (Oxford), R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester) report on behalf of the LOFAR Transients Key Science project On Dec 14, 2015, starting at 02.00 (UTC), we observed a large fraction of the localization error range at declinations larger than 0 degrees of the Advanced LIGO trigger G184098 with the ILT (International Low-Frequency Array [LOFAR] Telescope). This is the final set of LOFAR observations of these fields, our other two runs were completed on Sept 21, 2015 (GCN 18364) and Oct 16, 2015 (GCN 18424). The observations were obtained with the High-Band Antennas (HBA) at a centre frequency of 145 MHz (bandwidth 11.9 MHz). In this configuration, the ILT can provide 8 simultaneous beams on the sky, where each beam has a field of view of approximately 12 deg^2 (beam FWHM 3.9 degrees). The beam centres are given below: 1) 132.500000 5.166667 08:50:00.00 +05:10:00.0 2) 135.287125 5.166667 09:01:08.91 +05:10:00.0 3) 129.712875 5.166667 08:38:51.09 +05:10:00.0 4) 131.106458 7.572944 08:44:25.55 +07:34:22.6 5) 131.106458 2.760389 08:44:25.55 +02:45:37.4 6) 133.893542 7.572944 08:55:34.45 +07:34:22.6 7) 133.893542 2.760389 08:55:34.45 +02:45:37.4 8) 128.319333 2.760389 08:33:16.64 +02:45:37.4 The observations cover roughly 50 square degrees in total. Each field was observed for a total of 3.7 hr with 10s time resolution after pre-processing. Analysis is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18709 SUBJECT: LIGO/Virgo G184098: Fermi-LAT search for high-energy gamma-ray counterpart DATE: 15/12/17 22:43:56 GMT FROM: Nicola Omodei at Stanford U Nicola Omodei (Stanford), Julie McEnery (GSFC), and Giacomo Vianello (Stanford) report on behalf of the Fermi-LAT team: We have searched Fermi-LAT data for possible high-energy gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger G184098. We have mapped the LIGO/Virgo probability map into 8 different Region Of Interests (ROIs), each with a radius if 10 degrees centered on the following coordinates (J2000, degrees): a) R.A., Dec. = 132.60, 5.60 b) R.A., Dec. = 144.00, -6.00 c) R.A., Dec. = 146.00, -60.00 d) R.A., Dec. = 131.00, -66.00 e) R.A., Dec. = 115.00, -68.00 f) R.A., Dec. = 98.00, -69.00 g) R.A., Dec. = 78.00, -67.00 h) R.A., Dec. = 63.00, -60.00 None of the ROIs enters the LAT Field Of View (FOV) prior to 4200 seconds after the trigger time (2015-09-14 09:50:45 UTC). For every passage of each ROI inside the LAT FOV within -3/+1 day from the trigger, we searched for point-like excess gamma-ray emission integrated over the transit time (typically a few thousand seconds). A comparison of the distributions of the maximum Test Statistic (TS) within the ROIs before and after the trigger shows no significant excess. The Fermi-LAT point of contact for this candidate is Nicola Omodei (nicola.omodei@stanford.edu). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18851 SUBJECT: LIGO/Virgo G184098: Updated FAR estimate DATE: 16/01/11 10:20:22 GMT FROM: Marica Branchesi at LSC The LIGO Scientific Collaboration and Virgo report: We have completed offline calibration and re-analysis of the segment of data containing the gravitational-wave trigger G184098, which was first recovered on 2015-09-14 (GCN 18330, GCN 18388). We have calculated a revised false alarm rate based on four detection pipelines: the cWB (with and without BayesWave follow-up) and oLIB searches for un-modeled bursts plus the PyCBC and GSTLAL offline searches for compact binary coalescences of neutron stars and/or stellar-mass black holes. All four pipelines estimate that G184098 is more significant than one per hundred years. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18858 SUBJECT: LIGO/Virgo G184098: Refined localizations from CBC parameter estimation DATE: 16/01/13 20:15:04 GMT FROM: Leo Singer at NASA/GSFC The LIGO Scientific Collaboration and Virgo report: We have completed a Bayesian parameter estimation analysis of the GW candidate G184098 (GCN 18330) under the assumption that the signal arises from a compact binary coalescence (CBC) and using the latest offline calibration of the GW strain data (GCN 18851). The data is still found to be most consistent with a binary black hole merger (GCN 18388). Two refined sky maps are now available and can be retrieved from GraceDB (https://gracedb.ligo.org/events/G184098): * bayestar_gstlal_C01.fits.gz, produced by rapid triangulation of times, phases, and amplitudes on arrival. It was not available in low latency because at the time of the event our online CBC template banks were configured for neutron star but not binary black hole mergers. This localization is based upon the recovery of the CBC candidate from the offline GSTLAL search (GCN 18851), though it is practically interchangeable with the BAYESTAR sky map based on the PyCBC recovery. * LALInference_skymap.fits.gz, using Bayesian Markov-chain Monte Carlo and nested sampling to perform forward modeling of the full GW signal including spin precession and regression of systematic calibration errors. We regard the LALInference sky map as the most accurate and *authoritative* localization for this event. Though additional parameter estimation runs with different waveform approximants are ongoing, we expect that they will agree closely with this one. Both of the sky maps above agree with the initial LALinference Burst (LIB) localization (GCN 18330, LIB_skymap.fits.gz) on favoring the southern portion of the annulus determined by an arrival time difference between LIGO Hanford and LIGO Livingston of about 7 ms. The table below presents a quantitative comparison of the available localizations along the lines of Sec. 4.5 of Essick et al. (2015, http://adsabs.harvard.edu/abs/2015ApJ...800...81E). The first column gives the area in deg2 of the 90% credible region, and the second column gives the area in deg2 of the overlap with the LALInference 90% credible region. Area Overlap Algorithm (filename) ------------------------------------------------------------- 310 230 cWB (skyprobcc_cWB_complete.fits) 750 270 LIB (LIB_skymap.fits.gz) 400 350 BAYESTAR (bayestar_gstlal_C01.fits.gz) 600 - LALInference (LALInference_skymap.fits.gz) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18903 SUBJECT: LIGO/Virgo G184098: MASTER final result DATE: 16/01/19 20:53:36 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, N.Tyurina Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias N.M.Budnev, K.Ivanov, O.Gress Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory We reducted our images corresponds to final error box (GCN 18858). We observed localizations of the G184098 since 2015-09-20 03:25:02 till 2015-09-20 03:25:02 to every night for ~2 hours before sunrise, when the field reached a 15 degrees altitude. We miss full 2015-09-18 night due to bad weather. Totaly we cover 44.88% of full probability of final error box with upper limits ~19.0. MASTER SAAO observations of G184098 cover map available here: http://master.sai.msu.ru/static/G184098/G184098_3.png MASTER SAAO all observations during a 6 days after G184098 http://master.sai.msu.ru/static/G184098/G184098_2.png MASTER-NET all observations during a 6 days after G184098 http://master.sai.msu.ru/static/G184098/G184098_4.png No interesting from gravitational waves point of view OTs was found. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18914 SUBJECT: LIGO/VIRGO G184098: Summary of VLA results for iPTF15cyk DATE: 16/01/21 14:42:07 GMT FROM: Nipuni Palliyaguru at TTU N. Palliyaguru (TTU) and A. Corsi (TTU) report on behalf of a larger collaboration: We imaged again the position of the iPTF transient 15cyk (Singer et al. GCN 18337) located in the error region of LIGO/Virgo G184098 (LVC GCN 18330), with the Karl G. Jansky Very Large Array (VLA). A provisional reduction of the images collected during our observations gives the upper-limits (3 sigma) reported in the summary below, where we also include the results of the first VLA epoch (Palliyaguru et al. GCN 18420, GCN 18474). Epoch 1 (15 Oct 2015 11:20:32-12:05:27 UT) Freq | Flux (3 sigma UL) ----------------------------------- 6 GHz | < 45 uJy =================================== Epoch 2 (06 Dec 2015 04:52:11-05:00:07 UTC) Freq | Flux ----------------------------------- 6 GHz | < 34 uJy =================================== Epoch 3 (20 Jan 01:55:31-02:59:40 UTC) Freq | Flux ----------------------------------- 6 GHz | < 30 uJy //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19013 SUBJECT: MAXI/GSC search for an X-ray counterpart of GW150914 DATE: 16/02/16 12:31:05 GMT FROM: Nobuyuki Kawai at Tokyo Tech M. Serino (RIKEN), H. Negoro (Nihon U.), N. Kawai (Tokyo Tech) S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech), A. Yoshida, T. Sakamoto, H. Ohtsuki Y. Kawakubo (AGU), H. Tsunemi, R. Imatani (Osaka U.), M. Nakajima, K. Tanaka, T. Masumitsu (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.), Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, D. Itoh, (Miyazaki U.) K. Yamaoka (Nagoya U.), M. Morii (ISM) report on behalf of the MAXI team: We reexamined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained in the orbits preceding and following the gravitational wave event LIGO/Virgo G184098 at 2015-09-14T09:50:45 UTC (GW150914; Abbott et al. 2016). In each of the 92-min orbits, MAXI/GSC scanned more than 90% of the localization (90% confidence) regions in the bayestar skymap. No significant new source was found in these scans. The elapsed time of each scan since the trigger time is: -5147 ~ -4614 s (preceding the event) +409 ~ +937 s (scan in the orbit immediately after the event) +5964 ~ +6492 s (second orbit after the event) +11530 ~ +12050 s (third orbit after the event) +17082 ~ +17593 s (fourth orbit after the event) The 3-sigma upper limit of each scan for the X-ray flux is about 1x10^-9 erg/s/cm^2 in 2-20 keV. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19017 SUBJECT: LIGO/Virgo G184098: Correction for GCN Circular 18361 DATE: 16/02/17 05:26:05 GMT FROM: Tomoki Morokuma at U.TokyoJ-GEM Tomoki Morokuma (The University of Tokyo), Masaomi Tanaka (National Astronomical Observatory of Japan), Michitoshi Yoshida, Koji S. Kawabata, Yousuke Utsumi (Hiroshima University), Mamoru Doi, Kentaro Motohara, Yoichi Tamura (The University of Tokyo), Fumio Abe (Nagoya University), Kenta Fujisawa (Yamaguchi University), Nobuyuki Kawai (Tokyo Tech), Koji Ohta (Kyoto University), and Kenshi Yanagisawa (National Astronomical Observatory of Japan) on behalf of J-GEM collaboration We apologize for the incorrect dates and times of the observations in GCN Circ. 18361. The whole report with the correct information is given below. We report optical imaging follow-up observations for a part of the northern skymap regions of G184098 with 1.05-m Kiso Schmidt telescope and its 2.2 deg x 2.2 deg field-of-view camera, Kiso Wide Field Camera (KWFC; Sako et al. 2012, SPIE, 8446, 84466L). We took 180-sec exposure images in i-band for 5 fields as below (about 24 deg2 in total). RA(J2000) Dec(J2000) starting UTC 09:05:35.52 +10:27:00.0 2015-09-18 19:06:02 09:14:32.16 +10:27:00.0 2015-09-18 19:11:37 09:23:28.80 +10:27:00.0 2015-09-18 19:16:59 09:32:25.44 +10:27:00.0 2015-09-18 19:22:22 09:41:22.08 +10:27:00.0 2015-09-18 19:34:29 The 5-sigma limiting magnitudes (AB) are 18.8 mag and 16.2 mag in the first four exposures and the last exposure, respectively. The data reduction and transient finding with image subtraction were performed with the pipeline developed for Kiso Supernova Survey (KISS) as described in Morokuma et al. (2014, PASJ, 66, 114). The SDSS i-band data was used as reference images for the subtraction. We do not find any transients which are likely associated with external galaxies. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19021 SUBJECT: LIGO/Virgo G184098: MASTER arhival results DATE: 16/02/17 16:13:27 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, N.Tyurina Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias N.M.Budnev, K.Ivanov, O.Gress Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, V.Sennik, A.Parkhomenko Kislovodsk Solar Station of the Pulkovo Observatory We found 30 images in MASTER DataBase included to initial LIGO error box starting 15 september 2015 year 03h 24m 22s UT during MASTER inspection of the Fermi trigger 463976197. So the first optical images obtained by MASTER was started 1.094d before notice time and 0.732 after trigger. This images covered 16 square degrees (summ limit 19.0). We do not find OTs. The covering arhival DataBase map http://master.sai.msu.ru/static/G184098/G184098_arh.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19022 SUBJECT: LIGO/Virgo GW150914: BOOTES-3 simultaneous imaging DATE: 16/02/18 22:51:31 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC A. J. Castro-Tirado (IAA-CSIC Granada & ISA-UMA Málaga), J. C. Tello, R. Cunniffe, S. R. Oates, B.-B. Zhang, S. Jeong (IAA-CSIC Granada), A. Castellón (Univ. of Málaga), M. Jelinek (ASU-CAS Ondrejov), N. Rattenbury and Ph. Yock (Univ. of Auckland) and R. Querel (NIWA, Lauder) report: A search of the CASANDRA-3 allsky camera database at the BOOTES-3 astronomical station in Lauder (New Zealand), reveals a series of 36s images taken during the night of the LIGO/Virgo alert, covering the entire southern sky error-box. In particular, amongst the hundreds of exposures, there is one starting at 09:50:22 UT that is contemporaneous to the LIGO/Virgo GW150914 event. Although a detailed investigation is ongoing, a limit of ~5th magnitude (due to poor weather conditions) is obtained for any optical transient within that error box. [GCN OPS NOTE(18feb16): Per author's request, RC was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19034 SUBJECT: LIGO/Virgo GW150914 DATE: 16/02/20 19:59:19 GMT FROM: Adam Zadrozny at Pi of the Sky A. Cwiek (NCBJ), A. F. Zarnecki (UW), A. Mankiewicz (CFT PAS), A. Zadrozny (NCBJ) on behalf of the Pi of the Sky Pi of the Sky telescope surveyed whole sky visible from San Pedro de Atacama Observatory during each night (that weather permitted) of last days of September 2015 (26th, 27th, 28th, 29th, 30th) and October 2015, that also included an area of GW150914 (12 days after the alert). Data was searched for slowly fading bright optical transients visible to the instrument that might be connected to GW150914. All of the objects visible to us were previously observed. Data analysis showed that it is unlikely to have an slowly fading optical transient. We have performed our observations using two cameras, both observing same field, one using R filter and second using only IR-cut filter. For each field, the telescope has made three 10 s exposures. During Observations have limiting brightness between 11mag-11.5mag. This email is send in case this analysis might be useful for any future purposes. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19048 SUBJECT: LVC GW 150914: TAROT/TZAC Final analysis DATE: 16/02/22 10:07:11 GMT FROM: Michel Boer at CESR-CNRS A. Klotz (IRAP, CNRS/UPS), and M. Boer (ARTEMIS, CNRS/OCA/UNS) report on behalf of the TZAC collaboration: We have reduced and analysed the whole set of images acquired from TAROT-Chile (see LV GCN 18348, 18332 for the field coordinates and observing log). Depending on the field, the final limits are between R >18.5 and 19.8. If we take a conservative limit of R> 18.5 at 2.8 days after the GW event, this corresponds to an absolute magnitude of 19.6 at the distance of GW 150914. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19055 SUBJECT: LVC GW 150914: TAROT/TZAC Final analysis correction DATE: 16/02/22 16:48:20 GMT FROM: Michel Boer at CESR-CNRS An error was introduced in the last circular on the absolute magnitude corresponding to our observations of GW 150914. The absolute magnitude limit is -19.6. Below the corrected circular: A. Klotz (IRAP, CNRS/UPS), and M. Boer (ARTEMIS, CNRS/OCA/UNS) report on behalf of the TZAC collaboration: We have reduced and analysed the whole set of images acquired from TAROT-Chile (see LV GCN 18348, 18332 for the field coordinates and observing log). Depending on the field, the final limits are between R >18.5 and 19.8. If we take a conservative limit of R> 18.5 at 2.8 days after the GW event, this corresponds to an absolute magnitude of -19.6 at the distance of GW 150914.