//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19098 SUBJECT: GRB 160227A: Swift detection of a burst with an optical counterpart DATE: 16/02/27 19:46:27 GMT FROM: David Palmer at LANL M. H. Siegel (PSU), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), L. M. McCauley (PSU), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 19:32:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160227A (trigger=676423). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 194.788, +78.639 which is RA(J2000) = 12h 59m 09s Dec(J2000) = +78d 38' 21" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a early complex structure followed by a stronger peak at around 100 s after the trigger, for a total duration of at least 160 s. The peak count rate was ~700 counts/sec (15-350 keV), at ~100 sec after the trigger. The XRT began observing the field at 19:34:39.9 UT, 151.8 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 194.7974, 78.6768 which is equivalent to: RA(J2000) = +12h 59m 11.38s Dec(J2000) = +78d 40' 36.5" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 136 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 2.67e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 161 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 12:59:13.84 = 194.80767 DEC(J2000) = +78:40:44.9 = 78.67913 with a 90%-confidence error radius of about 0.77 arc sec. This position is 11.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.32 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.05. Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19099 SUBJECT: GRB 160227A: MASTER OT Detection DATE: 16/02/27 19:49:53 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov,N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, N.M.Budnev, O.Gres, V.A.Poleshchuk Irkutsk State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias D.Buckley, S. Potter, M.Kotze South African Astronomical Observatory MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Ural was pointed to the GRB160227A 30 after notice time and 115 sec after trigger time at 2016-02-27 19:34:03 UT. On our first (20s exposure) set we found 1 optical transient within SWIFT error-box (ra=12 59 08 dec=+78 38 19 r=0.050000) brighter then 17.6. RA 12h 59m 14.13s DEC +78d 40m 44.2s mag~17.36 The 5-sigma upper limit has been about 18.0 The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19100 SUBJECT: GRB 160227A: Mt. Terskol observatory optical observation DATE: 16/02/27 20:13:58 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev (Terskol Branch of INASAN), E. Mazaeva (IKI), V. Kozlov (IC AMER, NASU), A. Sergeev (Terskol Branch of INASAN), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 160227A (Siegel et al., GCN 19098) with Zeiss-600 telescope of Mt. Terskol observatory in R-filter starting on Feb. 27 (UT) 19:45:26. We obtained several images in R-filter. We clearly detect source in coordinates (J2000) 12 59 13.7 +78 40 44.9 which is apparently the afterglow of GRB GRB 160227A (Siegel et al., GCN 19098; Gorbovskoy et al., GCN 19099). The afterglow is clearly detected in a single images of 30 s exposure with brightness of ~19.0 magnitude in R-filter at Feb. 27 (UT) 19:49:36. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19101 SUBJECT: GRB 160227A: ISON-Kislovodsk optical observation DATE: 16/02/27 20:48:55 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Nevskiy (ISON), V. Vikhrov(ISON), K. Polyakov (ISON), N. Rudenko (IAON), A. Kalinichenko (ISON), E. Mazaeva (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger collaboration: We observed the field of GRB 160227A (Siegel et al., GCN 19098) with HGB-500 telescope (0.5-m, f/2) of ISON-Kislovodsk observatory starting on Feb. 27 (UT) 19:38:53, i.e. ~400 s after burst trigger. We obtained several unfiltered images of 60 s exposure. We clearly detect the afterglow of GRB 160227A (Siegel et al., GCN 19098; Gorbovskoy et al., GCN 19099; Andreev et al., GCN 19100). The afterglow brightness is ~18.0 magnitude at Feb. 27 (UT) 19:38:53. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19103 SUBJECT: GRB 160227A: MAXI/GSC detection DATE: 16/02/28 04:50:29 GMT FROM: H. Negoro at Nihon U. T. Yoshii (Tokyo Tech), M. Nakajima, H. Negoro (Nihon U.), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, M. Arimoto, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, R. Imatani (Osaka U.), 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, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Morii (ISM) report on behalf of the MAXI team: The MAXI/GSC detected an uncatalogued X-ray transient source at 19:35:13 UT on 2016 February 27. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (192.924 deg, 78.686 deg) = (12 51 41, +78 41 09) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.39 deg and 0.38 deg, respectively. The roll angle of long axis from the north direction is 46.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 130 +- 27 mCrab (4-10keV, 1 sigma error). Without assumptions on the source constancy,we obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (197.530 deg, 78.335 deg) = (13 10 07, +78 20 05) (J2000) (R.A., Dec) = (194.899 deg, 77.788 deg) = (12 59 35, +77 47 15) (J2000) (R.A., Dec) = (185.390 deg, 79.282 deg) = (12 21 33, +79 16 55) (J2000) (R.A., Dec) = (187.705 deg, 79.931 deg) = (12 30 49, +79 55 52) (J2000) The position is consistent with that of GRB 160227A (Siegel et al., GCN 19098), and the detected time is 185 sec after the BAT trigger. There was no significant excess flux in the previous transit at 18:02 UT on 2016 February 27 and in the next transit at 21:07 UT on 2016 February 27 with an upper limit of 20 mCrab for each. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19104 SUBJECT: GRB 160227A: Enhanced Swift-XRT position DATE: 16/02/28 05:23:00 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1604 s of XRT Photon Counting mode data and 1 UVOT images for GRB 160227A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 194.80719, +78.67917 which is equivalent to: RA (J2000): 12h 59m 13.73s Dec (J2000): +78d 40' 45.0" with an uncertainty of 1.7 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19105 SUBJECT: GRB 160227A: Swift-XRT refined Analysis DATE: 16/02/28 08:25:09 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester) and M.H. Siegel report on behalf of the Swift-XRT team: We have analysed 6.9 ks of XRT data for GRB 160227A (Siegel et al. GCN Circ. 19098), from 147 s to 31.1 ks after the BAT trigger. The data comprise 691 s in Windowed Timing (WT) mode (the first 3 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 19104). The late-time light curve (from T0+5.9 ks) can be modelled with a power-law decay with a decay index of alpha=0.41 (+0.11, -0.10). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.79 (+/-0.03). The best-fitting absorption column is 7.3 (+0.9, -0.8) x 10^20 cm^-2, in excess of the Galactic value of 4.1 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.76 (+/-0.10) and a best-fitting absorption column of 6.6 (+2.8, -2.5) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.6 (+2.8, -2.5) x 10^20 cm^-2 Galactic foreground: 4.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.76 (+/-0.10) If the light curve continues to decay with a power-law decay index of 0.41, the count rate at T+24 hours will be 0.15 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x 10^-12 (6.3 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00676423. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19106 SUBJECT: GRB 160227A, Swift-BAT refined analysis DATE: 16/02/28 17:12:21 GMT FROM: Amy Lien at GSFC T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+800 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160227A (trigger #676423) (Siegel et al., GCN Circ. 19098). The BAT ground-calculated position is RA, Dec = 195.034, 78.672 deg which is RA(J2000) = 13h 00m 08.1s Dec(J2000) = +78d 40' 19.9" with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The mask-weighted light curve shows a multi-peaked structure that starts at ~ T0-100 s and ends at ~ T0+270 s. There are roughly four pulses with peaks at ~ T0-100 s, ~ T0-20 s, ~ T0+100 s, and ~ T0+200 s, respectively. T90 (15-350 keV) is 316.5 +- 75.4 sec (estimated error including systematics). The time-averaged spectrum from T-99.8 to T+236.2 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.75 +- 0.51, and Epeak of 65.8 +- 16.4 keV (chi squared 40.42 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.1 +- 0.2 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+198.62 sec in the 15-150 keV band is 0.6 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.65 +- 0.10 (chi squared 51.62 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/676423/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19109 SUBJECT: GRB 160227A: NOT redshift DATE: 16/02/28 18:34:30 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC/CAS), J. P. U. Fynbo, D. Malesani (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), T. Petrushevska (Stockholm U.), P. M. Sorensen, J. Saario, J. Telting (NOT) report on behalf of a larger collaboration: We observed the field of GRB 160227A (Siegel et al., GCN 19098) using the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 20:19:12 UT on 2016-02-27 (i.e., 0.784 hr post-burst) and 2x120s R-band frames were obtained, followed by 2x1800s+1x1200s spectroscopy (i.e., at a median time of ~1.87 hr post-burst) covering 3200A - 9000A, all in a seeing of ~2.0 arcsec. The previously reported optical afterglow (e.g., Siegel et al., GCN 19098; Gorbovskoy et al., GCN 19099) is clearly detected in our stacked R-band image, with R~19.3 mag calibrated with nearby USNO B1 stars. Preliminary analysis of the spectrum shows a clear trough at the blue end of the spectral continuum, indicating Ly-alpha absorption from H I. We also detect several narrow absorption features, though at low signal-to-noise, which we interpret as due to, e.g., C II, Si II, O I, C II, Fe II, all consistent with a redshift of z = 2.38. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19115 SUBJECT: GRB 160227A: AROMA-N Optical Observation DATE: 16/02/29 13:07:42 GMT FROM: Takanori Sakamoto at AGU Y. Kitaoka, T. Sakamoto, A. Yoshida (AGU) We observed the field of GRB 160227A detected by Swift (trigger #676423; Siegel et al., GCN Circ. 19098) with the 12-inch AGU Robotic Optical Monitor for Astrophysical object - Narrow (AROMA-N) located at the Sagamihara campus of Aoyama Gakuin University. 10 images of 60 sec exposures and 5 images of 180 sec exposures were taken in the R filter starting from February 27 19:36:28 (UT) about 260 seconds after the trigger and stopped on February 27 20:02:05 (UT). Because the target was a low elevation (44.4 deg at the start time) and the telescope was slightly out of focus, the quality of the obtained images was not ideal. We do not detect the optical afterglow both in the individual images and the stacked image. The estimated five sigma upper limit of the combined image (total exposure of 1500 sec) is ~16.4 mag using the USNO-B1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19116 SUBJECT: GRB 160227A: MASTER prompt OT Detection and LC DATE: 16/02/29 17:15:15 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Krushinski, I.Zalozhnich, A. Popov Ural State University, Kourovka E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, N.M.Budnev, O.Gres, V.A.Poleshchuk Irkutsk State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias Five telescopes of MASTER Net of robotic telescope participated in the observation of the GRB 160227A. Two telescopes detected prompt optical emission. We discovery very strong OT variations with time ~100 sec correlated with gamma ray flux (Sakamoto et al., 19106). MASTER-Ural robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Ural was pointed to the GRB160227A 30 sec after notice time and 115 sec after trigger time at 2016-02-27 19:34:03 UT. On our first (20s exposure) set we found 1 optical transient within SWIFT error-box (Siegel et al GCN 19098; Gorbovskoy et al GCN 19099) at a position: RA 12h 59m 14.13s Dec +78d 40m 44.2s With magnitude automatical magnitude ~ 17.3 We definetly see OT at a number of single and coadd images. OT was observed during ~ 1 hours. We see OT decay from 17.0 to 19.1 mag in the time interval from 115 to 2647 sec atger the trigger. The 5-sigma upper limit has been about 17.5 mag on first single image and up to 19.5 mag at on coadd images in later time. MASTER-Kislovodsk robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB160227A (Siegel et al GCN 19098) 52 sec after notice time and 137 sec after trigger time at 2016-02-27 19:34:25 UT. On our first (30s exposure) set we marginaly see optical transient (Siegel et al GCN 19098, Gorbovskoy et al GCN 19099) within SWIFT error-box. OT also definetly seen at a number of coadd images. OT was observed for about 4 hours. We see OT decay from 18.1 to ~ 20.5 mag in the time interval from 152 to 12900 sec atger the trigger. The 5-sigma upper limit has been about 17.5 mag on first single image and up to 21.0 mag at on coadd images in later time. MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC was pointed to the GRB160227A 49 sec after notice time and 137 sec after trigger time at 2016-02-27 19:34:25 UT. On our first (30s exposure) set we haven`t found optical transient within SWIFT error-box. The observations started on evening sky (Sun altitude ~ -6 deg). Therefore, the first exposure upper limit is very low. We definetly see OT at a number of coadd images, starting ~ 1 hour after the trigger. OT was observed for about 2 hours. We see OT decay from 19.0 to 20.0 mag in the time interval from 3400 to 9200 sec atger the trigger. The 5-sigma upper limit has been about 14.5 mag (due to bright evening sky ) on first single image and up to 21.0 mag at on coadd images in later time. MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Astrophysical Center Tunka was pointed to the GRB160227A 17 sec after notice time and 103 sec after trigger time at 2016-02-27 19:33:51 UT. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box. The observations made on not very well weather condition and was finished 10 after GRB, due to snow coming. The 5-sigma upper limit has been about 15.3 mag on first single image. MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB160227A 8 sec after notice time and 93 sec after trigger time at 2016-02-27 19:33:41 UT. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box. The 5-sigma upper limit has been about 16.0 mag on first single image. Out preliminary photometry results available at table 1 Light curve available here: http://master.sai.msu.ru/static/grb160227.png Table 1. T0-Tmig Expt. Mag Site Coadd -------|-------|------|---------------------|------ 125 20 17.0 MASTER Ural 152 30 18.1 MASTER Kislovodsk 174 30 18.5 MASTER Ural 207 120 17.8 MASTER Kislovodsk 3 231 40 17.7 MASTER Ural 299 50 18.9 MASTER Ural 383 70 19.6 MASTER Ural 485 90 17.9 MASTER Ural 607 110 18.0 MASTER Ural 621 550 18.7 MASTER Kislovodsk 4 757 140 18.7 MASTER Ural 935 170 18.2 MASTER Ural 1133 180 19.1 MASTER Ural 1349 180 19.0 MASTER Ural 1566 180 18.9 MASTER Ural 1765 1080 18.9 MASTER Kislovodsk 6 1781 180 19.1 MASTER Ural 1998 180 19.1 MASTER Ural 2647 900 19.1 MASTER Ural 5 2789 360 19.7 MASTER Kislovodsk 2 3423 540 19.0 MASTER IAC 3 4261 900 19.2 MASTER IAC 5 4527 900 19.4 MASTER Kislovodsk 5 5966 1080 19.5 MASTER Kislovodsk 6 6401 1800 20.0 MASTER IAC 10 7771 3600 19.9 MASTER IAC 20 9196 1800 19.8 MASTER IAC 10 10608 1620 20.9 MASTER Kislovodsk 9 12824 1800 20.3 MASTER Kislovodsk 10 The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19122 SUBJECT: GRB 160227A: Swift/UVOT Detection DATE: 16/02/29 21:48:36 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160227A 161 s after the BAT trigger (Siegel et al., GCN Circ. 19098). A source consistent with the XRT position (Osborne et al. GCN Circ. 19104) is detected in the initial UVOT exposures but had faded away in later exposures. The preliminary UVOT position is: RA (J2000) = 12:59:13.80 = 194.80750 (deg.) Dec (J2000) = +78:40:45.1 = 78.67920 (deg.) with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 161 311 147 19.34 +/- 0.10 white 600 2418 341 19.80 +/- 0.13 white 6755 8196 201 >20.82 v 650 7366 400 19.40 +/- 0.25 b 575 2393 194 19.71 +/- 0.35 b 6550 8186 393 >20.10 u (fc) 319 569 245 19.44 +/- 0.20 u 724 2368 174 >19.22 w1 699 7776 540 >20.5 m2 1082 7570 432 >21.1 w2 1206 7161 294 >20.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19124 SUBJECT: GRB 160227A: McDonald 0.8m Detection DATE: 16/03/01 01:56:44 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Changsu Choi, Gu Lim (CEOU/SNU), Soomin Jeong (SKKU/IAA-CSIC) on behalf of a larger collaboration We observed the field of GRB 160227A (Palmer et al. GCN19098) using the 0.8m telescope at the McDonald Observatory. The observation started at 2016-02-28 03:03:38 UT, or about 7.5 hours after the BAT alert. We identify the afterglow at the location of the UVOT detection, and our preliminary analysis shows the afterglow at R ~ 20.8 +- 0.15 mag in a stacked image of 21 x 3 min frames. The mid-point of the observation is 2016-02-28 03:47. The photometry is calibrated against a star at RA=194.74877 and Dec=78.68984 (J2000) with R=15.72, taken from APASS catalog. A second epoch data was taken at about 6 hours later, and the analysis of the data is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19125 SUBJECT: GRB 160227A: LOAO 1.0m optical detection DATE: 16/03/01 09:07:13 GMT FROM: Soomin Jeong at IAA-CSIC Soomin Jeong (SKKU/IAA-CSIC), Myungshin Im (SNU), Yuji Urata (NCU), Il H. Park (SKKU) on behalf of a larger collaboration: We observed the field of GRB 160227A (Siegel, et al., GCN 19098) with the 1m telescope of Mt. Lemmon Optical Astronomy Observatory (LOAO) in Arizona. The series of images are taken in R- & B-filter starting on Feb. 28 05:11:27 UT (~ 9.7 hr post burst). The optical counterpart is clearly detected in a median combined image of R at the previously reported optical afterglow position (e.g., Siegel et al., GCN 19098; Gorbovskoy et al., GCN 19099; Mazaeva et al., GCN19102). We confirmed marginal detection of OT in a median combined B. The observed magnitudes are as following: Mid Time(hr) Exposure(s) Filter Magnitude ——————————————————————————— 10.19 12x300 R 21.16 +/- 0.14 10.15 4x300 B 22.19 +/- 0.41 ——————————————————————————— The fields are calibrated to the near by star at RA=194.74877, Dec=78.68984 (R2=15.84, USNO-B1.0). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19404 SUBJECT: GRB 160227A: MAXI/GSC detection DATE: 16/05/09 10:09:49 GMT FROM: Taketoshi Yoshii at Tokyo Tech Y.Ono (Tokyo Tech), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. E. Nakagawa, Y. Sugawara (JAXA), T. Mihara, M. Sugizaki, M. Serino, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, N.Isobe, S.Sugita, T. Yoshii, Y. Tachibana, T. Fujiwara (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R.Imatani (Osaka U.), H. Negoro, M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 2016-05-09T09:04:16. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (312.131 deg, 75.810 deg) = (20 48 31, +75 48 36) (J2000) with a 90% C.L. statistical error of 0.06 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 1307 +- 69 mCrab (4-10keV, 1 sigma error). Without assumptions on the source constancy,we obtain a rectangular error box for the transient source with the following corners: (310.897 deg, 75.728 deg) = (20 43 35, +75 43 40) (J2000) (311.105 deg, 75.626 deg) = (20 44 25, +75 37 34) (J2000) (313.379 deg, 75.887 deg) = (20 53 30, +75 53 14) (J2000) (313.181 deg, 75.991 deg) = (20 52 43, +75 59 27) (J2000) There was no significant excess flux in the previous transit at UT 2016-0509T07:32 with an upper limit of 20 mCrab.