//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17611 SUBJECT: GRB 150323A: Swift detection of a burst DATE: 15/03/23 03:01:27 GMT FROM: David Palmer at LANL A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC), F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 02:49:14 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150323A (trigger=635887). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 128.191, +45.434 which is RA(J2000) = 08h 32m 46s Dec(J2000) = +45d 26' 03" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a small peak at the time of the trigger, followed by a much larger peak at T+130 s, for a total duration of at least 170 sec. The peak count rate was ~5600 counts/sec (15-350 keV), at ~130 sec after the trigger. The XRT began observing the field at 02:51:41.2 UT, 146.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 128.17951, 45.46355 which is equivalent to: RA(J2000) = 08h 32m 43.08s Dec(J2000) = +45d 27' 48.8" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 110 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.05 x 10^20 cm^-2 (Willingale et al. 2013). The initial flux in the 0.1 s image was 3.25e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 156 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is A. Amaral-Rogers (aar14 AT le.ac.uk). 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: 17612 SUBJECT: GRB 150323A: P60 Optical Afterglow Candidate DATE: 15/03/23 03:51:38 GMT FROM: S. Bradley Cenko at NASA/GSFC S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report on behalf of a larger collaboration: We observed the location of the Swift GRB150323A (Amaral-Rogers et al., GCN 17611) with the robotic Palomar 60 inch telescope. Observations began at 2:57 UT (~ 8 minutes after the Swift trigger) and were obtained in the Sloan r, i, and z filters. In a stacked r-band image with a mid-point of 3:07 UT, we detect a source at the edge of the XRT error circle, with coordinates: RA: 08:32:42.83 Dec: +45:27:53.5 (J2000.0) At this time, we measure an r-band magnitude of ~ 20.6 (photometric calibration performed with respect to nearby point sources from SDSS). Given the lack of a quiescent counterpart in SDSS at this location, we consider this likely to be the afterglow of GRB150323A. Observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17613 SUBJECT: GRB 150323A: RATIR Optical Afterglow Observations DATE: 15/03/23 04:09:49 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 150323A (Amaral-Rogers, et al., GCN 17611) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2015/03 23.12 to 2015/03 23.16 UTC (9.6 to 58.8 minutes after the BAT trigger), obtaining a total of 42.6 minutes exposure in the r, i, and z bands. For the source on the edge of the Swift-XRT error circle (Cenko et al., GCN 17612), in comparison with the SDSS DR9, we obtain the following measurements and upper-limit (3-sigma): r = 21.16 +/- 0.11 i = 20.39 +/- 0.05 z > 19.30 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We note that this source appears to be fading during our observation. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17615 SUBJECT: GRB 150323A: Enhanced Swift-XRT position DATE: 15/03/23 06:29:57 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1311 s of XRT Photon Counting mode data and 2 UVOT images for GRB 150323A, 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 = 128.17800, +45.46464 which is equivalent to: RA (J2000): 08h 32m 42.72s Dec (J2000): +45d 27' 52.7" with an uncertainty of 1.9 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: 17616 SUBJECT: GRB 150323A: Keck redshift DATE: 15/03/23 07:20:09 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) and S. B. Cenko (GSFC) report: Using the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m telescope, we acquired a single 900s spectrum of the optical afterglow (Cenko et al., GCN 17612) of GRB 150323A (Amaral-Roger et al., GCN 17611) beginning at 06:11 UT, at the end of evening twilight. A number of absorption and emission lines are detected in the 1D spectrum, including e.g. Fe II (2344,2374,2383,2585,2599), Mg II (2796,2803), Mg I (2853), OII (3727), OIII (4959, 5007), and H-beta at a common redshift of z=0.593. We acknowledge S. Kulkarni for the observing time. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17617 SUBJECT: GRB150323A: Swift-UVOT detection of the afterglow DATE: 15/03/23 11:40:56 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and Amaral-Rogers (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150323A 156 s after the BAT trigger (Amaral-Rogers et al., GCN Circ. 17611). A weak optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 17615) or the P60 position (GCN Circ. 17612) is be present in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 156 306 147 20.53+/-0.30 u_FC 314 564 246 >20.0 white 4066 5702 1635 20.96+/-0.33 v 5912 6112 197 18.93+/-0.29 u 314 5291 442 >20.7 u 4991 5191 197 19.86+/-0.35 w1 4887 5086 197 >20.2 m2 4682 4881 197 >20.9 w2 4272 4472 197 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17618 SUBJECT: GRB 150323A: Swift-XRT refined Analysis DATE: 15/03/23 15:01:04 GMT FROM: Phil Evans at U of Leicester A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and A. Amaral-Rogers report on behalf of the Swift-XRT team: We have analysed 6.5 ks of XRT data for GRB 150323A (Amaral-Rogers et al. GCN Circ. 17611), from 136 s to 29.5 ks after the BAT trigger. The data comprise 169 s in Windowed Timing (WT) mode (the first 8 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 Goad et al. (GCN Circ. 17615). The late-time light curve (from T0+4.1 ks) can be modelled with a power-law decay with a decay index of alpha=0.72 (+0.19, -0.16). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.26 (+0.06, -0.05). The best-fitting absorption column is 6.2 (+/-0.5) x 10^21 cm^-2, at a redshift of 0.593, in addition to the Galactic value of 3.0 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.03 (+0.20, -0.19) and a best-fitting absorption column of 4.6 (+1.8, -1.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 3.0 x 10^20 cm^-2 Intrinsic column: 4.6 (+1.8, -1.6) x 10^21 cm^-2 at z=0.593 Photon index: 2.03 (+0.20, -0.19) If the light curve continues to decay with a power-law decay index of 0.72, the count rate at T+24 hours will be 0.012 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x 10^-13 (5.9 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00635887. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17619 SUBJECT: GRB 150323B detected in ground analysis of Swift-BAT data DATE: 15/03/23 15:47:19 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings (CPI) on behalf of the Swift-BAT science team At 09:28:38, Swift-BAT triggered (635929) on GRB 150323B. Imaging attempts were prematurely terminated by a preplanned slew. A bright source was detected in ground analysis at 260.447, +38.316, which is RA (J2000) 17h 21m 47.3s Dec (J2000) 38d 18' 59" with an estimated 90% error radius of 1.5 arcmin. The burst had multiple peaks with a T90 of about 60 seconds. We have event data for only the first peak. This is the same event as Fermi GBM 448795722. A Swift TOO has been requested. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17620 SUBJECT: GRB 150323B: Swift ToO observations DATE: 15/03/23 16:42:36 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Swift/BAT GRB 150323B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020485 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Swift/BAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17621 SUBJECT: GRB 150323C: Swift detection of a burst DATE: 15/03/23 17:15:23 GMT FROM: David Palmer at LANL A. Amaral-Rogers (U Leicester), W. H. Baumgartner (GSFC/UMBC), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 17:05:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150323C (trigger=636005). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 192.613, +50.198 which is RA(J2000) = 12h 50m 27s Dec(J2000) = +50d 11' 54" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of at least 40 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 17:08:11.3 UT, 169.8 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 192.6177, 50.1910 which is equivalent to: RA(J2000) = +12h 50m 28.25s Dec(J2000) = +50d 11' 27.6" with an uncertainty of 5.2 arcseconds (radius, 90% containment). This location is 27 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. UVOT took a finding chart exposure of 150 seconds with the White filter starting 178 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is A. Amaral-Rogers (aar14 AT le.ac.uk). 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: 17622 SUBJECT: GRB 150323C: MASTER-net optical observation DATE: 15/03/23 17:22:58 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University E. Gorbovskoy, V. Lipunov, M.Pruzhinskaya, V.Kornilov, D.Kuvshinov, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University V.Krushinsky, I.Zalozhnih, A. Popov Ural Federal University, Yekaterinburg, Kourovka V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory 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) D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB150323C 42 sec after notice time and 88 sec after trigger time at 2015-03-23 17:09:39 UT in two polarizations. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box (Amaral-Rogers et al. GCN17621). The 5-sigma upper limit has been about 17.6 mag MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Ural was pointed to the GRB150323C 35 after notice time and 79 sec after trigger time at 2015-03-23 17:09:31 UT in two polarizations. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box (ra=12 50 28 dec=+50 11 25 r=0.001400). The 5-sigma upper limit has been about 17.9 mag The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17623 SUBJECT: GRB 150323B: Fermi GBM observation DATE: 15/03/23 17:24:20 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 09:28:39.21 UT on 23 March 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150323B (trigger 448795722 / 150323395), which was also detected by the Swift (Cummings et al. 2015, GCN 17619). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 69 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 54 s (50-300 keV). The time-averaged spectrum from T0-0.512 s to T0+60.929 s is best fit by a Band function with Epeak = 99.14 (+4.50/-6.02) keV, alpha = -0.89 (+0.07/-0.05), and beta = -2.04 (+0.03/-0.03). The event fluence (10-1000 keV) in this time interval is (2.19 +/- 0.03)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+1.152 s in the 10-1000 keV band is 8.2 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17624 SUBJECT: GRB 150323C: Prompt enhanced Swift-XRT position DATE: 15/03/23 17:48:13 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 150323C, we find an enhanced XRT position of the afterglow: RA, Dec: 192.6169, 50.1918 which is equivalent to: RA (J2000) = 12 50 28.05 Dec (J2000) = +50 11 30.4 with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/636005. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17625 SUBJECT: GRB 150323C: Nanshan optical afterglow detection DATE: 15/03/23 18:10:39 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), H.-B. Niu, J.-Z. Liu, G.-X. Pu, A. Esamdin, L. Ma (XAO) report: We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621) using the 1m telescope at Nanshan, Xinjiang, China. Observations were carried out in R-band, starting at 17:19:50 UT on 2015-03-23, i.e., 869 s after the burst. A source, not present in SDSS and DSS, is well detected in individual images at coordinates RA(J2000) = 12:50:27.92 Dec(J2000) = +50:11:28.75 with an uncertainty of ~ 1 arcsec, being consistent with the enhanced Swift-XRT position (Evans, GCN 17624). We thus think it's the optical afterglow of the burst, and it has m(R) = 21.3 +/- 0.2 at a median time of 1344s post-burst, calibrated with the SDSS field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17626 SUBJECT: GRB 150323A: KAIT Optical Observations DATE: 15/03/23 21:09:12 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 150323A (Amaral-Rogers et al., GCN 17611) starting at 03:23:43 UT, ~34 minutes after the burst. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. The afterglow reported by Cenko & Perley (GCN 17612) was not detected in any single image, but was marginally detected in the co-add image of 20 clear band images. We estimated the brightness is R~20.3 +/- 0.3 at a mean time of 71.2 minutes after the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17627 SUBJECT: GRB150323C: Fermi GBM detection DATE: 15/03/24 00:25:37 GMT FROM: Matthew Stanbro at UAH/Fermi Matthew Stanbro (UAH) reports on behalf of the Fermi GBM Team: "At 17:05:09.64 UT on 23 March 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150323C (trigger 448823112 / 150323712) which was also detected by the Swift/BAT (Amaral-Rogers et al. 2015, GCN 17621) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 58 degrees. The GBM light curve consists of several episodes with a duration (T90) of about 43 s (50-300 keV). The time-averaged spectrum from T0-10.24 s to T0+30.72 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.15 +/- 0.16 and the cutoff energy, parameterized as Epeak, is 107 +/- 18 keV. The event fluence (10-1000 keV) in this time interval is (2.50 +/- 0.19)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.22 s in the 8-1000 keV band is 1.64 +/- 0.20 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17628 SUBJECT: GRB 150323A, Swift-BAT refined analysis DATE: 15/03/24 01:11:42 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-235 to T+967 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150323A (trigger #635887) (Amaral-Rogers, et al., GCN Circ. 17611). The BAT ground-calculated position is RA, Dec = 128.173, 45.442 deg which is RA(J2000) = 08h 32m 41.52s Dec(J2000) = +45d 26' 29.76" with an uncertainty of 2.07 arcmin, (radius, sys+stat, 90% containment). The partial coding was 32%. The mask-weighted light curve shows a multi-peaked structure with two main pulses. The first weaker pulse starts at ~ T0, peaks at ~ T+7 s, and ends at ~ T+25 s. The second brighter pulse starts at ~ T+125 s , peaks at ~ T+135 s, and ends at ~ T+160 s. T90 (15-350 keV) is 149.6 +- 8.9 sec (estimated error including systematics). The time-averaged spectrum from T+2.6 to T+195.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.85 +- 0.07. The fluence in the 15-150 keV band is 6.1 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+135.64 sec in the 15-150 keV band is 5.4 +- 0.3 ph/cm2/sec. 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/635887/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17629 SUBJECT: GRB 150323C: Xingming upper limit DATE: 15/03/24 04:09:25 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), X. Gao (Urumqi No.1 Senior High School, Xinjiang), and Z.-J. Xu (Nanjing Putian Telecommunications Co. Ltd., Jiangsu) report: We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621) using the 0.35m robotic Xingming telescope located at Nanshan, Xinjiang, China. Observations started at 17:08:06 UT on 2015-03-23, i.e., 165 s after the burst, and a series of 40s, 60s, and 90s unfiltered exposures were obtained. No optical source is detected at the enhanced Swift-XRT position (Evans, GCN 17624), down to a limiting magnitude of ~19.2 mag since the starting of our observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17630 SUBJECT: GRB 150323C: Swift-XRT refined Analysis DATE: 15/03/24 05:15:04 GMT FROM: Phil Evans at U of Leicester V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A. Maselli (INAF-IASFPA) and A. Amaral-Rogers report on behalf of the Swift-XRT team: We have analysed 6.1 ks of XRT data for GRB 150323C (Amaral-Rogers et al. GCN Circ. 17621), from 160 s to 12.6 ks after the BAT trigger. The data comprise 312 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 192.6169, 50.1918 which is equivalent to: RA (J2000): 12 50 28.05 Dec(J2000): +50 11 30.4 with an uncertainty of 2.1 arcsec (radius, 90% confidence). The late-time light curve (from T0+5.1 ks) can be modelled with a power-law decay with a decay index of alpha=1.0 (+/-0.5). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.34 (+/-0.05). The best-fitting absorption column is 1.55 (+0.13, -0.12) x 10^21 cm^-2, in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.52 (+0.25, -0.23) and a best-fitting absorption column of 6.5 (+4.5, -3.9) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.7 x 10^-11 (3.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.5 (+4.5, -3.9) x 10^20 cm^-2 Galactic foreground: 1.2 x 10^20 cm^-2 Excess significance: 2.2 sigma Photon index: 2.52 (+0.25, -0.23) If the light curve continues to decay with a power-law decay index of 1.0, the count rate at T+24 hours will be 3.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.8 x 10^-14 (1.3 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00636005. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17631 SUBJECT: GRB 150323C : Xinglong TNT optical observation DATE: 15/03/24 05:34:21 GMT FROM: L.P. Xin at NAOC L. P. Xin, X. F. Wang, J. Y. Wei, Y. L. Qiu, J. S. Deng, J. Wang, X. H. Han and C. Wu on behalf of EAFON report: We began to observe GRB 150323C (Amaral-Rogers et al., GCN 17621) with Xinglong 0.8-m TNT telescope at 2015-03-23, 17:07:27(UT), about 126 sec after the Swift trigger time. The new source within XRT circle (Amaral-Rogers et al., GCN 17621 ) reported by Xu et al., ( GCN 17625 ) was clearly detected in our coadded images. Preliminary analysis shows that the brightness of this optical transient in R band is rising from 21.6 to 20.2 and then decaying, indicating that this source is the optical afterglow of the burst. All the magnitudes are calibrated by a nearby USNO B1.0 object ( RA: 16:50:26 DEC: 50:11:48, R2=16.47mag ). The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17632 SUBJECT: GRB 150323C: RATIR Optical Afterglow Observations DATE: 15/03/24 06:49:44 GMT FROM: Owen Littlejohns at Az State U Alan M. Watson (UNAM), Owen Littlejohns (ASU), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 150323C (Amaral-Rogers, et al., GCN 17621) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2015/03 24.14 to 2015/03 24.27 UTC (10.20 to 13.42 hours after the BAT trigger), obtaining a total of 2.49 hours exposure in the r, i and z bands. For a source within the Swift-XRT error circle (D'Elia, et al., GCN 17630), in comparison with the SDSS DR9, we obtain the following detections and upper limit (3-sigma): r 23.00 +/- 0.15 i 22.63 +/- 0.11 z > 20.61 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. In comparison to an earlier epoch of observations (Xin, et al., GCN 17631) we find this magnitude to be consistent with a power-law decay with an approximate temporal decay index alpha = 0.5. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17633 SUBJECT: GRB 150323C: Enhanced Swift-XRT position DATE: 15/03/24 09:02:46 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 5836 s of XRT Photon Counting mode data and 7 UVOT images for GRB 150323C, 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 = 192.61686, +50.19121 which is equivalent to: RA (J2000): 12h 50m 28.05s Dec (J2000): +50d 11' 28.4" with an uncertainty of 1.6 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: 17634 SUBJECT: GRB 150323B: Swift-XRT observations DATE: 15/03/24 11:07:30 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 150323B (Cummings et al. GCN Circ. 17619), collecting 4.6 ks of Photon Counting (PC) mode data between T0+40.4 ks and T0+63.2 ks. Two uncatalogued X-ray sources have been detected inside or close to the Swift/BAT error region, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 260.4534 = 17:21:48.83 Dec (J2000.0): +38.3179 = +38:19:04.6 Error: 4.3 arcsec (radius, 90% conf.) Count-rate: 0.0103 +/- 0.0018 ct s^-1 Flux: (4.62 +/- 0.80)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 260.4598 = 17:21:50.35 Dec (J2000.0): +38.2829 = +38:16:58.5 Error: 6.6 arcsec (radius, 90% conf.) Count-rate: (2.3 +/- 1.0)e-3 ct s^-1 Flux: (9.2 +/- 4.1)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020485. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17635 SUBJECT: GRB 150323C: Swift/UVOT Upper Limits DATE: 15/03/24 12:55:50 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and A. Amaral-Rogers (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150323C 179 s after the BAT trigger (Amaral-Rogers et al., GCN Circ. 17621). No optical afterglow consistent with the optical position (Xu et al. GCN Circ. 17625) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 179 328 147 >21.5 u_FC 337 587 246 >20.7 white 179 11759 1513 >22.4 v 669 12698 555 >21.0 b 594 7661 444 >21.1 u 337 7541 717 >21.0 w1 718 7337 432 >21.2 m2 5494 7131 393 >20.6 w2 5084 12665 1279 >22.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17636 SUBJECT: GRB 150323C: RATIR Optical Afterglow Observations - Errata DATE: 15/03/24 17:19:02 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Owen Littlejohns (ASU), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: In Watson et al. (GCN Circular 17632), we compared our RATIR observations of GRB 150323C to earlier observations to derive an approximate temporal power-law index of 0.5. We unfortunately gave an incorrect reference to the earlier observations; the correct reference is Xu et al. (GCN Circular 17625). We apologise for any confusion. TITLE: GCN CIRCULAR NUMBER: 17636 SUBJECT: GRB 150323C: RATIR Optical Afterglow Observations - Errata DATE: 15/03/24 17:19:02 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Owen Littlejohns (ASU), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: In Watson et al. (GCN Circular 17632), we compared our RATIR observations of GRB 150323C to earlier observations to derive an approximate temporal power-law index of 0.5. We unfortunately gave an incorrect reference to the earlier observations; the correct reference is Xu et al. (GCN Circular 17625). We apologise for any confusion. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17637 SUBJECT: GRB 150323C, Swift-BAT refined analysis DATE: 15/03/24 20:28:56 GMT FROM: Amy Lien at GSFC D. M. Palmer (LANL), Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-274 to T+800 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150323C (trigger #636005) (Amaral-Rogers, et al., GCN Circ. 17621). The BAT ground-calculated position is RA, Dec = 192.625, 50.165 deg which is RA(J2000) = 12h 50m 30.1s Dec(J2000) = +50d 09' 55.3" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%. The mask-weighted light curve shows several weak overlapping pulses. The main burst structure starts at ~ T-20 s and ends at ~T+20 s, followed by another weaker pulse lasting till ~ T+160 s. T90 (15-350 keV) is 159.4 +- 54.0 sec (estimated error including systematics). The time-averaged spectrum from T-22.9 to T+166.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.09 +- 0.32. The fluence in the 15-150 keV band is 1.3 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+5.98 sec in the 15-150 keV band is 1.1 +- 0.3 ph/cm2/sec. 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/636005/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17638 SUBJECT: GRB 150323B : Xinglong TNT upper limit DATE: 15/03/25 07:03:31 GMT FROM: L.P. Xin at NAOC L. P. Xin, X. F. Wang, J. Y. Wei, Y. L. Qiu, J. S. Deng, J. Wang, X. H. Han and C. Wu on behalf of EAFON report: We began to observe GRB 150323B (Cumming., GCN 17619; Kienlin., GCN 17623) with Xinglong 0.8-m TNT telescope at 2015-03-23, 18:19:24(UT), about 8.85 hour after the Swift trigger time. No any new source was detected in our 10*300sec coadded image within the errorbox of BAT (Cumming., GCN 17619), and the errorbox of two uncatalogured X-ray sources (Avanzo et al., 17632) down to the 3 sigma limit of 21.8 mag in R-band, calibrated by USNO B1.0 R2 mag, at the mean time of 9.28 hours after the burst. We noted that there was a source in USNO B1.0 catalog ( 17:21:50.446 +38:17:00.13 R2=20.5 mag ), which was located in the errorbox of the Source 2 (Avanzo et al., 17632), but the variation of its brightness was not decided. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17639 SUBJECT: GRB 150323C: Mondy optical observations DATE: 15/03/25 13:29:01 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev (ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 150323C (Amaral-Rogers et al., GCN 17621) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Mar., 23 (UT) 11:42:02. We obtained several images in R-filter of 120 s exposure. Within enhanced Swift-XRT error circle (Osborne et al., GCN 17633) we clearly detect optical afterglow (Xu et al. GCN 17625, Xin et al. GCN 17631; Watson et al. GCN 17632) in a combined image. Preliminary photometry of the afterglow is following Date UT start t-T0 Filter Exp. OT Err. (mid, days) (s) 2015-03-24 15:14:09 0.95405 R 44*120 22.4 0.3 Photometry is based on SDSS DR9 stars: SDSS9_id R(Lupton) J125023.08+501048.2 16.84 J125032.04+501021.5 18.37 J125016.28+501035.8 18.22 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17640 SUBJECT: Konus-Wind observation of GRB 150323A DATE: 15/03/25 14:47:56 GMT FROM: Anastasia Tsvetkova at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 150323A (Swift-BAT trigger #635887: Amaral-Rogers et al., GCN 17611; Markwardt et al., GCN 17628) triggered Konus-Wind at T0=10282.369 s UT (02:51:22.369). The burst light curve shows a weak precursor at ~T0-135 s, which triggered BAT, followed by the main episode which started at ~T0-3 s and has a duration of ~38 s. The emission is seen up to ~5 MeV. As observed by Konus-Wind, the burst had a fluence of 1.1(-0.1,+0.1)x10^-5 erg/cm2, and a 64-ms peak energy flux, measured from T0+0.152 s, of 1.2(-0.6,+0.6)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+24.832 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.22(-0.28,+0.32), and Ep = 95(-13,+16) keV (chi2 = 70/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.80 (chi2 = 70/97 dof). The spectrum near the peak count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 3 MeV range by the power law with exponential cutoff model with alpha = -1.21(-0.26,+0.30), and Ep = 121(-18,+25) keV (chi2 = 71/68 dof). Fitting by a GRB (Band) model yields almost the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.43 (chi2 = 71/67 dof). Assuming the redshift z=0.593 (Perley and Cenko, GCN 17616) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release 1.0(-0.1,+0.1)x10^52 erg, the peak luminosity L_iso is 1.7(-0.8,+0.8)x10^51 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is 151(-21,+25) keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150323_T10282/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17641 SUBJECT: Konus-Wind observation of GRB 150323B DATE: 15/03/25 16:39:15 GMT FROM: Anastasia Tsvetkova at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 150323B (Swift-BAT trigger #635929: Cummings, GCN 17619; Fermi-GBM observation: von Kienlin, GCN 17623) triggered Konus-Wind at T0=34121.196 s UT (09:28:41.196). The burst light curve shows several bright peaks during first ~60 s after the trigger. In the instrument's soft energy channel, the flaring can be traced up to ~T0+150 s. As observed by Konus-Wind, the burst had a fluence of 2.0(-0.1,+0.2)x10^-5 erg/cm2, and a 64-ms peak energy flux, measured from T0+22.656 s, of 1.4(-0.6,+0.6)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+65.792 s) is best fit in the 20 keV - 15 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.53(-0.10,+0.11), and Ep = 109(-12,+15) keV (chi2 = 109/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.90 (chi2 = 109/97 dof). The spectrum near the peak count rate (measured from T0+16.640 to T0+24.832 s) is best fit in the 20 keV - 1 MeV range by the power law with exponential cutoff model with alpha = -1.15(-0.25,+0.29), and Ep = 215(-51,+108) keV (chi2 = 35/59 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.97 (chi2 = 35/58 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150323_T34121/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17642 SUBJECT: Subject: GRB 150323A; Konkoly optical observations DATE: 15/03/25 20:36:46 GMT FROM: Janos Kelemen at Konkoly Obs/Hungary J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program at the Konkoly Observatory. Starting on the evening 23/03/2015 18:30 UT we observed the field GRB 150323A (A. Amaral-Rogers et al. GCN 17611, and M.R. Goad et al. GCN 17615). We can confirm the presence of the supposed afterglow reported by S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) (GCN 17612) at the position RA: 08:32:42.69 DEC: 45:27:53.6 Our position and the P60 position are the same within 1 pixel. On the coadded images (total exposure time = 2400 sec) we measured an R -band magnitude of m(R) = 20.3 +/- 0.14 with respect to nearby USNO-B1.0 stars. time from GRB. exp filter Mag. ------------------------------------------------ 56136 s. 2400 s R 20.3 +/-0.14 ------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17643 SUBJECT: GRB 150323B; Konkoly optical observations DATE: 15/03/25 20:49:43 GMT FROM: Janos Kelemen at Konkoly Obs/Hungary J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program at the Konkoly Observatory. Starting on the night 24/03/2015 02:48 UT we observed the field GRB 150323B (J. R. Cummings GCN 17619 ). We imaged the X-ray positions published by P. D'Avanzo et al. GCN 17634. On the coadded R band images (total exposure = 1500 sec) we found marginal optical sources on the positions coincide with soure 1 and source 2. Source 1 /GCN 17634/ our work R mag.(Based on USNO-B1.0 stars) -------------------------------------------------------- RA: 17:21:48.83 RA: 17:21:48.62 20.8 +/-0.14 DEC: 38:19:04.6 DEC: 38:19:08.8 Source 2 /GCN 17634/ our work R mag.(Based on USNO-B1.0 stars) -------------------------------------------------------- RA: 17:21:50.35 RA: 17:21:50.47 19.9 +/-0.14 DEC: 38:16:58.5 DEC: 38:16:59.7 Due to the bad weather variability was not confirmed. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17644 SUBJECT: Subject: GRB 150323C; Konkoly optical observations DATE: 15/03/25 21:02:06 GMT FROM: Janos Kelemen at Konkoly Obs/Hungary J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program at the Konkoly Observatory. Starting on the night 23/03/2015 we observed the field GRB 150323C (A. Amaral-Rogers et al. GCN 17621 ). On the position reported by D. Xu et al. (GCN 17625) according our coadded R images we confirmed the presence of a marginal optical source in R band. Position from D. Xu our work --------------------------------------------------------------- RA(J2000) = 12:50:27.92 RA: 12:50:28.02 Dec(J2000) = +50:11:28.75 DEC: 50:11:28.3 Photometric results: (Based on nearby USNO-B1.0 stars) time from GRB. exp filter Mag. ------------------------------------------------ 10653 s. 1800 s R 21.7 +/-0.18 ------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17646 SUBJECT: GRB 150323C: MITSuME Akeno Optical observation DATE: 15/03/26 14:10:07 GMT FROM: Taketoshi Yoshii at Tokyo Tech T.Fujiwara, Y. Saito, T. Yoshii, Y. Tachibana, H. Ohuchi, Y. Yano, S.Kurita, Y. Ono, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 150323C (Amaral-Rogers et al. GCN Circular #17621) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started at 2015-03-23 17:06:46 UT (85 sec after the burst). We detected the previously reported optical afterglow (Xu et al. GCN Circular #17625) in the Rc band. The measured magnitudes are listed below. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ---------------------------------------------------------------------- 85 17:09:24 270 > 19.9 > 19.6 > 18.5 1069 17:34:06 1200 > 20.9 20.3 $B!^(B 0.5 > 19.5 6681 19:18:53 2400 > 20.4 > 20.4 > 19.4 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17647 SUBJECT: GRB 150323A: AAO optical observations DATE: 15/03/26 18:41:23 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO), A. Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 150323A (Amaral-Rogers et al., GCN 17611) with AS-32 (0.7m) telescope of Abastumani Observatory starting on Mar. 23 (UT) 22:47:06. Within the enhanced XRT position (Goad et al., GCN 17615) we do not detect any object. An upper limit is following Date UT start t-T0 Filter Exp. UL(3 sigma) (mid, days) (s) 2015-03-23 22:47:06 0.85076 None 15*180 21.2 The photometry is based on nearby USNO-B1.0 stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17648 SUBJECT: GRB 150323C: Nishi-Harima NIR Observations DATE: 15/03/26 19:33:31 GMT FROM: Taketoshi Yoshii at Tokyo Tech S. Honda. J. Takahashi, Y. Takagi, K. Morihana, Y. Itoh (Univ. of Hyogo), and Y. Saito (Tokyo Tech) report on behalf of Nayuta team and OISTER collaboration: We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621) with Nishiharima Infrared Camera (NIC) attached to the Nayuta 2-m telescope at the Nishi-Harima Astronomical Observatory. The observations were started at 17:30 UT on 2015-03-23. We detected the near-infrared afterglow in J, H and Ks bands. Photometric results of our observations are shown below. We used 2MASS 12502614+5011480, 12502605+5011289, 12503202+5010217, and 12503649+5012012 as reference stars for photometry. # MID-UT Tmid-T0 T-EXP J_mag H_mag Ks_mag -------------------------------------------------------------------------------- 17:33:16 28 1200 18.22 +/- 0.10 17.25 +/- 0.10 16.44 +/- 0.13 17:59:27 54 1200 18.68 +/- 0.11 17.59 +/- 0.11 16.94 +/- 0.14 18:25:32 80 1200 19.40 +/- 0.20 17.77 +/- 0.13 17.23 +/- 0.14 --------------------------------------------------------------------------------- Tmid-T0: Elapsed time after the burst (minutes) T-EXP: Total Exposure time (seconds) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17649 SUBJECT: GRB 150323B: Khureltogot optical observations DATE: 15/03/27 19:01:34 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of Astronomy and Geophysics MAS), A. Volnova (IKI), I.Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 150323B (Cummings et al., GCN 17619) with ORI-40 telescope of Khureltogot observatory starting on Mar., 23 (UT) 16:06:11. We obtained 60 unfiltered images of 60 s exposure. Following detection of XRT sources (D'Avanzo et al., GCN 17634) we do not detect any source within XRT error circle of the source #1 up to a limiting magnitude 21.2. In particular we do detect the optical source found by Kelemen et al. (GCN 17643). At the position of XRT source #2 we found optical source which coincides with USNO star mentioned by Xin et al. (GCN 17638) and the star of SDSS DR9 catalog J172150.45+381700.1. Photometry of the sources is following Source# Date UT start t-T0 Filter Exp. mag. UL(3sigma) (mid, days) (s) 1 2015-03-23 16:06:11 0.29859 none 60*60 n/d 21.2 2 2015-03-23 16:06:11 0.29859 none 60*60 20.7+/-0.25 21.2 The photometry is based on R magnitudes of nearby SDSS DR9 stars SDSS9_id R(Lupton) J172146.77+381659.6 15.65 J172126.47+382201.1 18.14 J172127.98+382239.0 15.39 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17655 SUBJECT: GRB 150323C: possible host galaxy detection DATE: 15/03/29 20:03:27 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani (DARK/NBI), Dong Xu (DARK/NBI), Pall Jakobsson (Univ. Iceland) and Jussi Harmanen (NOT and Univ. Turku) report on behalf of a larger collaboration: We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621; Stanbro, GCN 17627) using the Nordic Optical Telescope (NOT) located in La Palma. The mean time of the observation was March 28.21 UT, that is 4.49 days after the GRB. A 20 min exposure was collected using the SDSS r filter. Close to the position of the optical afterglow (Xu et al., GCN 17625; Watson et al., GCN 17632), we detect an object with r = 23.6 +- 0.2 AB (calibrated against nearby SDSS stars). This source is also marginally detected in the archival SDSS images with a comparable (though uncertain) brightness, and therefore an underlying galaxy must be contributing a significant fraction of the light. We note a small, but significant offset between the afterglow and the galaxy positions. By registering astrometrically the afterglow image by Xu et al. (GCN 17625) with the new NOT data, we find an offset of approximately 0.65". Such an offset is not unprecedented, so that the SDSS/NOT object is still a viable host galaxy candidate for GRB 150323C. [GCN OPS NOTE(30mar15): Per author's request, JH's affiliation was changed.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17657 SUBJECT: GRB 150323B: Swift-XRT afterglow detection DATE: 15/03/30 14:10:10 GMT FROM: Alex Amaral-Rogers at U.of Leicester P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the Swift/BAT-detected burst GRB 150323B (Cummings et al. GCN Circ. 17619). The observations now extend from T0+40.4 ks to T0+483.5 ks. Of the sources reported by D'Avanzo et al. (GCN Circ. 17634), "Source 1" is fading with 3-sigma significance, and is therefore likely the GRB afterglow. The position of this source is RA, Dec=260.4534, +38.3179 which is equivalent to: RA (J2000): 17:21:48.83 Dec(J2000): +38:19:04.6 with an uncertainty of 4.3 arcsec (radius, 90% confidence). This position is 18 arcsec from the Swift/BAT position. The source is fading with alpha >0.3. The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/ToO_GRBs/00020485/index_1.php. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00020485. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17669 SUBJECT: GRB 150323C: Khureltogot optical observations DATE: 15/04/04 11:07:51 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of Astronomy and Geophysics MAS), A. Volnova (IKI), I.Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 150323C (Amaral-Rogers et al., GCN 17621) with ORI-40 telescope of Khureltogot observatory starting on Mar., 23 (UT) 17:20:51, i.e. ~15 minutes after burst trigger. We obtained 180 unfiltered images of 60 s exposure. Within enhanced Swift-XRT error circle (Osborne et al., GCN 17633) we detect optical afterglow (Xu et al. GCN 17625, Xin et al. GCN 17631; Watson et al. GCN 17632). Preliminary photometry of the afterglow in combined images is following Date UT start t-T0 Filter Exp. OT OT_err (mid, days) (s) 2015-01-23 17:20:51 0.01449 none 10*60 21.1 0.3 2015-01-23 17:31:40 0.02199 none 10*60 20.5 0.25 2015-01-23 17:42:28 0.02950 none 10*60 20.8 0.25 2015-01-23 17:53:17 0.03700 none 10*60 20.2 0.2 2015-01-23 18:04:04 0.04451 none 10*60 20.0 0.2 2015-01-23 18:14:54 0.06199 none 35*60 21.3 0.3 2015-01-23 18:54:26 0.09409 none 39*60 21.0 0.3 2015-01-23 19:57:04 0.13649 none 40*60 21.5 0.4 Photometry is based on SDSS DR9 stars: SDSS9_id R(Lupton) J125026.13+501147.9 16.16 J125023.08+501048.2 16.84 Our photometry confirms non-monotonic behaiviour of a lighr curve of the afterglow mentioned by Xin et al. (GCN 17631). The light curve of GRB 150323C afterglow can be found in http://grb.rssi.ru/GRB150323C/GRB150323C_ORI40_lc.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17670 SUBJECT: GRB 150323C: additional optical observations in Mondy DATE: 15/04/04 11:16:29 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev (ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We additionally observed the field of the GRB 150323C (Amaral-Rogers et al., GCN 17621) with AZT-33IK telescope of Sayan observatory (Mondy) on Mar., 27 and Mar. 30 under good weather conditions and mean FWHV of 1.8 arcsec. We obtained several images in R-filter of 120 s exposure. In both epochs we detect a source in coordinates (J2000) 12 50 27.90 +50 11 29.0 (+/- 0.45" ) which is within afterglow coordinates (Xu et al., GCN 17625) and within the enhanced Swift-XRT position (Osborne et al., GCN 17633). Our object is apparently the same object suggested as a possible host galaxy (Malesani et al., GCN 17655). Preliminary photometry of the source is following Date UT start t-T0 Filter Exp. OT Err. (mid, days) (s) 2015-03-27 18:22:30 4.11333 R 85*120 22.7 0.25 2015-03-30 14:09:29 7.02068 R 194*120 22.3 0.15 Photometry is based on SDSS DR9 stars: SDSS9_id R(Lupton) J125023.08+501048.2 16.84 J125032.04+501021.5 18.37 Also we note that our photometry reported early (Mazaeva et al., GCN 17639) may by significantly be significantly influenced by the possible host galaxy. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17671 SUBJECT: GRB 150323C: CrAO optical observations DATE: 15/04/04 11:23:31 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev (CrAO), K. Antoniuk (CrAO), E. Mazaeva (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 150323C (Amaral-Rogers et al., GCN 17621) with AZT-11 telescope of CrAO observatory starting on Mar. 23 (UT) 20:09:58. We obtained ages in R-filter of 180 s exposure under non-optimal weather conditions and mean FWHM of about 4.7 arcsec. In the enhanced XRT position (Osborne et al., GCN 17633) we do not detect any object. In particular we do no detect optical afterglow (Xu et al. GCN 17625, Xin et al. GCN 17631; Watson et al. GCN 17632). An upper limit is following Date UT start, t-t0 Filter Exp. OT UL (3 sigma) (mid, days) (s) 2015-03-23 20:09:58 0.14949 R 20*180 n/d 21.0 The photometry is based on nearby USNO-B1.0 stars.