GRB120804A

This page lists all entries on GRB120804A in GRBweb

Summary IPN Swift GCN 13573 GCN 13577 GCN 13579 GCN 13580 GCN 13581 GCN 13582 GCN 13584 GCN 13585 GCN 13586 GCN 13587 GCN 13601 GCN 13606 GCN 13611 GCN 13614 GCN 13640 GCN 13643 GCN 13715 GCN 13841

Summary table
Variable Value Source
T0 0:54:14 UTC GCN_circulars,Swift Det
ra 233.9480° Swift
decl -28.7825° Swift
pos_error 1.81e-04° Swift
T90 0.81 s Swift
T90_start 0:54:14 UTC Swift
fluence 8.80e-07 erg/cm² Swift
T100 0.81 s
GBM_located False
mjd 56143.03766203704 GCN_circulars,Swift Det
IPN table
GRB_name GRB120804A
ra 233.9292°
decl -28.7667°
pos_error 5.00e-02°
Swift table
GRB_name GRB120804A
t_trigger 0:54:14 UTC
ra 233.9480°
decl -28.7825°
pos_error 1.81e-04°
T90 0.81 s
fluence 8.80e-07 erg/cm²
GCN 13573 table
GRB_name GRB120804A
GCN_number 13573
Detection_method Swift Det
t_trigger 0:54:14 UTC
ra 233.9290°
decl -28.7610°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13573 SUBJECT: GRB 120804A: Swift detection of a short burst DATE: 12/08/04 01:07:03 GMT FROM: David Palmer at LANL A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), S. T. Holland (STScI), J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 00:54:14 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120804A (trigger=529686). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 233.929, -28.761 which is RA(J2000) = 15h 35m 43s Dec(J2000) = -28d 45' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a fast double-peaked structure with a duration of about 1.5 sec. The peak count rate was ~15000 counts/sec (15-350 keV), at ~0.5 sec after the trigger. The XRT began observing the field at 00:55:47.8 UT, 93.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 233.94815, -28.78102 which is equivalent to: RA(J2000) = 15h 35m 47.56s Dec(J2000) = -28d 46' 51.7" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 94 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 in excess of the Galactic value (9.29 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 1.9 (+1.89/-1.67) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 96 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 none of the XRT error circle. 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 0.23. Burst Advocate for this burst is A. Y. Lien (yarleen AT gmail.com). 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.)
GCN 13577 table
GRB_name GRB120804A
GCN_number 13577
Detection_method Swift-XRT Det
ra 233.9481°
decl -28.7825°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13577 SUBJECT: GRB 120804A: Enhanced Swift-XRT position DATE: 12/08/04 06:42:04 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 797 s of XRT Photon Counting mode data and 1 UVOT images for GRB 120804A, 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 = 233.94813, -28.78248 which is equivalent to: RA (J2000): 15h 35m 47.55s Dec (J2000): -28d 46' 56.9" with an uncertainty of 1.8 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.
GCN 13579 table
GRB_name GRB120804A
GCN_number 13579
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 13579 SUBJECT: GRB 120804A: GROND upper limits DATE: 12/08/04 09:07:02 GMT FROM: Vladimir Sudilovsky at MPE V. Sudilovsky, J. Elliott, and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 120804A (Swift trigger 529686; Lien et al., GCN 13573) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile). Observations started at 02:22 UT on 2012-08-04, 1.5 hrs after the GRB trigger. We do not detect any sources within the XRT position reported by Osborne et al (GCN 13577). We do note that observations were severely limited by unfavorable weather conditions, including moon-illuminated visible cirrus towards the field. Based on six co-added exposures of 370s (g'r'i'z') and 240s (JHK) taken at a mean airmass of 1.3 and a mean seeing of 3.0", we derive the following upper limits (all AB system): g' > 21.9 r' > 22.1 i' > 22.0 z' > 21.9 J' > 20.6 H' > 20.0 K' > 19.5 The magnitudes are derived based on GROND zeropoints (g'r'i'z') and 2MASS stars (JHK). The above upper limits are not corrected for the Galactic extinction of E(B-V) = 0.23 mag along the line of sight (Schlegel et al. 1998).
GCN 13580 table
GRB_name GRB120804A
GCN_number 13580
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13580 SUBJECT: GRB 120804A: Swift-XRT refined Analysis DATE: 12/08/04 13:07:05 GMT FROM: Phil Evans at U of Leicester M.C. Stroh (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), J.A. Kennea (PSU) and A.Y. Lien report on behalf of the Swift-XRT team: We have analysed 9.2 ks of XRT data for GRB 120804A (Lien et al. GCN Circ. 13573), from 78 s to 28.8 ks after the BAT trigger. The data comprise 33 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 Osborne et al. (GCN. Circ 13577). The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+/-0.03). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.98 (+0.21, -0.20). The best-fitting absorption column is 3.5 (+0.9, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 9.3 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.3 x 10^-11 (7.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.5 (+0.9, -0.8) x 10^21 cm^-2 Galactic foreground: 9.3 x 10^20 cm^-2 Excess significance: 5.3 sigma Photon index: 1.98 (+0.21, -0.20) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00529686. This circular is an official product of the Swift-XRT team.
GCN 13581 table
GRB_name GRB120804A
GCN_number 13581
Detection_method Swift-BAT Det
ra 233.9510°
decl -28.7680°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13581 SUBJECT: GRB 120804A: Swift-BAT refined analysis DATE: 12/08/04 13:20:44 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120804A (trigger #529686) (Lien, et al., GCN Circ. 13573). The BAT ground-calculated position is RA, Dec = 233.951, -28.768 deg, which is RA(J2000) = 15h 35m 48.1s Dec(J2000) = -28d 46' 06.1" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 24%. The mask-weighted light curve shows two overlapping peaks starting at ~T-0.2 sec, peaking at ~T+0.1 and ~T+0.5 sec, and ending at ~T+1.0 sec. T90 (15-350 keV) is 0.81 +- 0.08 sec (estimated error including systematics). The time-averaged spectrum from T-0.16 to T+0.83 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.34 +- 0.08. The fluence in the 15-150 keV band is 8.8 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.16 sec in the 15-150 keV band is 10.8 +- 0.6 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/529686/BA/
GCN 13582 table
GRB_name GRB120804A
GCN_number 13582
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13582 SUBJECT: GRB 120804A: Swift/UVOT Upper Limits DATE: 12/08/04 13:40:29 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU) and A. Y. Lien (NASA/GSFC/ORAU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120804A 97 s after the BAT trigger (Lien et al., GCN Circ. 13573). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 13577) 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) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 97 247 147 >21.4 u_FC 310 560 246 >20.7 white 97 5665 453 >22.0 v 640 6077 432 >20.6 b 566 6706 243 >20.9 u 310 6692 659 >21.3 w1 689 6487 413 >20.3 m2 4646 6282 393 >21.3 w2 4237 5872 393 >21.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.23 in the direction of the burst (Schlegel et al. 1998).
GCN 13584 table
GRB_name GRB120804A
GCN_number 13584
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 13584 SUBJECT: GRB 120804A: MITSuME Okayama Optical upper limits DATE: 12/08/05 00:54:39 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 120804A (Lien et al., GCNC 13573) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2012-08-04 11:04:43 UT (~10.2 h after the burst) We did not find any new point source within the enhanced XRT circle (Osborne et al., GCNC 13577) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.46585 12:05:03 6240.0 >19.9 >19.8 >19.1 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 13585 table
GRB_name GRB120804A
GCN_number 13585
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 13585 SUBJECT: GRB 120804A: Swift-BAT Spectral lag analysis DATE: 12/08/05 03:36:54 GMT FROM: Scott Barthelmy at NASA/GSFC J. Norris (BSU), N. Gehrels (GSFC), S. D. Barthelmy (GSFC) We report the spectral lag analysis for GRB 120804A (GCN Circ. 13573 & 13581) based on the BAT data. Using 8-ms binned light curves, the spectral lag for the 15-25 keV to 50-100 keV bands is 16 +-12 msec, and -5 +-6 msec for the 25-50 keV to 100-350 keV bands for both peaks combined. These lag values place this burst in the short burst category.
GCN 13586 table
GRB_name GRB120804A
GCN_number 13586
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 13586 SUBJECT: GRB 120804A: Gemini-North observations DATE: 12/08/05 05:57:28 GMT FROM: Ryan Chornock at Harvard R. Chornock and E. Berger (Harvard) report on behalf of a larger collaboration: We observed the position of the X-ray afterglow of the short GRB 120804A (Lien et al., GCN 13573) using GMOS on the Gemini-North 8-m telescope. Observations began at 05:47 UT on 2012 August 4 (approximately 4.9 hours after the BAT trigger). We obtained 11x180s of observations in both the r and i filters. We find a pair of faint sources in the i band observations within the enhanced XRT position (Osborne et al., GCN 13577) with coordinates (J2000): S1: 15:35:47.48, -28:46:56.2 S2: 15:35:47.53, -28:46:57.6 with astrometric errors of about 0.3" relative to 2MASS. S1 is slightly brighter than S2 in i. Neither source is detected in r. Further observations are planned in order to search for variability of these sources. We thank the Gemini staff, particularly Chad Trujillo, for their assistance with these observations.
GCN 13587 table
GRB_name GRB120804A
GCN_number 13587
Detection_method VLA Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 13587 SUBJECT: GRB 120804A: EVLA Detection DATE: 12/08/05 15:06:22 GMT FROM: Ashley Zauderer at CfA W. Fong, A. Zauderer, E. Berger (Harvard) report on behalf of a larger collaboration: "We observed the position of the short GRB 120804A (Lien et al., GCN 13573) with the EVLA at 5.8 GHz beginning 2012 Aug 4.97 UT (dt=0.93 d after the trigger). We detect a radio source within the Swift-XRT error circle (Osborne et al., GCN 13577) at the position RA 15:35:47.49 (+/- 0.01) Dec -28:46:56.7 (+/- 0.1) Followup observations are planned."
GCN 13601 table
GRB_name GRB120804A
GCN_number 13601
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13601 SUBJECT: GRB 120804A: ATCA 34GHz upper limit DATE: 12/08/07 03:17:14 GMT FROM: Paul Hancock at U of Sydney P. Hancock, T. Murphy, B. Gaensler, M. Bell, D. Burlon (University of Sydney/CAASTRO), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI) We observed GRB120804A (GCN 13573) with the Australia Telescope Compact Array at 34GHz for 56 minutes centered on 04:35UT Aug 06 2012 (T0+2.15days). We detect no radio source at the location of the GRB afterglow seen by the EVLA (GCN 13587) and place a 3sigma upper limit of 200uJy on the flux of an afterglow at 34GHz. Further observations are planned. These observations were obtained as part of ATCA project C2689. We thank the observatory staff for their support and scheduling the observations. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. [GCN OPS NOTE(07aug12): Per author's request, the "120824A" in the Subject-line was changed to "120804A".]
GCN 13606 table
GRB_name GRB120804A
GCN_number 13606
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13606 SUBJECT: GRB 120804A: Gemini-North detection of an optical afterglow and putative host galaxy DATE: 12/08/07 16:04:57 GMT FROM: Wen-fai Fong at CFA W. Fong, R. Chornock, and E. Berger (Harvard) report: "We re-observed the location of the short-duration GRB 120804A (GCN 13573) with the Gemini Multi-Object Spectrograph (GMOS) mounted on the Gemini-North 8-meter telescope to check for the presence of a fading optical source. We obtained 16x180-sec of i-band observations in good seeing conditions (FWHM=0.65") starting on 2012 August 07.30 UT, 3.3 days after the BAT trigger and 3.0 days after our initial observations (GCN 13586). Digital image subtraction of the two GMOS epochs using the ISIS software package reveals a fading source slightly offset from the center of S1, suggesting this to be the optical afterglow of GRB 120804A. There are no additional residuals in or around the refined XRT position (improved upon from GCN 13577; http://www.swift.ac.uk/xrt_positions/00529686/). Both S1 and S2 appear to be extended, indicating that S1 is likely to be the host galaxy of GRB 120804A and S2 is likely unrelated to the GRB. We thank the Gemini staff for their assistance with these observations."
GCN 13611 table
GRB_name GRB120804A
GCN_number 13611
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13611 SUBJECT: GRB 120804A: ATCA 34GHz upper limit DATE: 12/08/08 10:29:43 GMT FROM: Paul Hancock at U of Sydney P. Hancock, T. Murphy, B. Gaensler, M. Bell, D. Burlon (University of Sydney/CAASTRO), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI) We observed GRB120804A (GCN 13573) with the Australia Telescope Compact Array at 34GHz for 96 minutes centered on 04:35UT Aug 08 2012 (T0+4.15days). We detect no radio source at the location of the GRB afterglow seen by the EVLA (GCN 13587) and place a 3sigma upper limit of 120uJy on the flux of an afterglow at 34GHz. These observations were obtained as part of ATCA project C2689. We thank the observatory staff for their support and scheduling the observations. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
GCN 13614 table
GRB_name GRB120804A
GCN_number 13614
Detection_method Konus-Wind Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 13614 SUBJECT: GRB 120804A: Konus-Wind and Swift/BAT joint spectral analysis DATE: 12/08/09 19:48:56 GMT FROM: Valentin Pal'shin at Ioffe Inst T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), and T. Ukwatta (MSU) on behalf of the Swift-BAT team, V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, report: The short GRB 120804A (Swift/BAT trigger #529686: Lien et al., GCN Circ. 13573, Baumgartner et al. GCN Circ. 13581) triggered Konus-Wind at T0=3255.749 s UT (00:54:15.749), but since the incident angle on the triggered detector was 99.2 deg (i.e. the burst accidentally triggered the S2 detector which observes the northern ecliptic hemisphere, although the burst came from the southern ecliptic hemisphere: b = -9.2 deg) the standard analysis of the Konus-Wind spectral data is impossible. To derive the broad-band spectral parameters of this burst, we performed joint spectral analysis of the Swift/BAT data and the Konus-Wind 3-channel spectral data (obtained in the waiting mode from the detector S1), which covers the energy range from 24 keV to 1.4 MeV. The time intervals of the spectral data are chosen for the Konus-Wind from T0(BAT)-0.916 s to T0(BAT)+2.028 s (single KW bin which comprises the burst) and for the Swift/BAT from T0(BAT)-0.16 s to T0(BAT)+0.83 s (that is the BAT T100 interval), where T0(BAT) is the trigger time of BAT at 00:54:14.18 UTC. The energy ranges which we used in the joint spectral analysis are 24-1400 keV and 14-150 keV for the Konus-Wind and the Swift/BAT respectively. The spectral data of the two instruments are fitted with the spectral model multiplied by a constant factor to take into account the systematic effective area uncertainties in the response matrices of each instrument and the difference in the chosen intervals. The spectrum is well fitted with a power-law with exponential cutoff model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). No systematic residual from the best fit model is seen in the spectral data of each instrument. The best fit spectral parameters are: alpha = -0.89 (-0.28, +0.24) and Epeak = 135 (-29, +66) keV (chi2/dof = 56/58). The energy fluence and 16-ms peak flux in the 15-1000 keV band are 1.45 (-0.31,+0.30) x 10^-6 erg/cm2 and (6.0 ± 2.7) x 10^-6 erg/cm2/s respectively. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB120804_T03255/ All the quoted errors are at the 90% confidence level.
GCN 13640 table
GRB_name GRB120804A
GCN_number 13640
Detection_method Swift-XRT Other
ra 233.9479°
decl -28.7823°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13640 SUBJECT: GRB120804A: Chandra observations and afterglow detection DATE: 12/08/14 12:30:14 GMT FROM: Eleonora Troja at GSFC E. Troja (NASA/GSFC/UMCP), T. Sakamoto (NASA/GSFC/UMCB), N. Gehrels (NASA/GSFC), D. Donato (NASA/GSFC/UMCP), and J. L. Racusin (NASA/GSFC) report: We observed the field of GRB 120804A (Lien et al., GCN Circ. 13573) with the Chandra ACIS-S starting on August 13, 2012 10:52:08 UT (~9.4 d after the GRB trigger) for a total exposure of 19.8 ks. Within the Swift/XRT enhanced position (Osborne et al., GCN Circ. 13577) we clearly detect a source at Ra, Dec = 233.94786, -28.7823 which is equivalent to: RA (J2000) = 15h 35m 47.49s Dec (J2000) = -28d 46' 56.3" with an uncertainty of 0.6 arcsec (radius, sys+stat, 90% containment). This position is consistent with the putative host galaxy S1 (Chornock et al., GCN Circ. 13586). The X-ray afterglow is detected at a count rate of (1.6 +/- 0.3)E-03 cts/s (0.5-8.0 keV). By using the spectral parameters derived from the Swift/XRT observations (Stroh et al., GCN Circ. 13580) we estimate an observed X-ray flux of (1.5 +/-0.3)E-14 erg/cm2/s in the 0.3-10 keV energy band. Our measurement is consistent with the power-law decay of ~1.1 reported by Stroh et al. (GCN Circ. 13580), and sets a lower limit to the jet-break time of t_j>9 d. We thank Harvey Tananbaum and the entire Chandra staff for approving and rapidly executing this observation.
GCN 13643 table
GRB_name GRB120804A
GCN_number 13643
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13643 SUBJECT: GRB 120804A: Possible temporal break in the X-ray light-curve DATE: 12/08/14 20:56:06 GMT FROM: Wen-fai Fong at CFA R. Margutti, W. Fong, and E. Berger (Harvard) report: "We analyzed the Swift-XRT and Chandra observations of the short GRB 120804A (Lien et al. GCN 13573; Troja et al., GCN 13640). Using the data at t>10^4 sec, when the light curve appears less susceptible to variability, we find moderate evidence for a temporal break with a pre-break index of alpha1= 0.7 +\- 0.1, a post-break index of alpha2= 1.9 +\- 0.5, and a break time of about 2x10^5 sec. The F-test indicates 5% probability of chance improvement with respect to a single power-law fit. Plots are available from: https://www.cfa.harvard.edu/~rmargutt/flux_lightcurvefitBPL.pdf https://www.cfa.harvard.edu/~rmargutt/flux_lightcurvefitSPL.pdf Further X-ray observations are required to clarify the nature/presence of the temporal break."
GCN 13715 table
GRB_name GRB120804A
GCN_number 13715
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13715 SUBJECT: XMM observations of the short GRB120804A DATE: 12/09/05 19:53:38 GMT FROM: Raffaella Margutti at Harvard R. Margutti (Harvard), V. Mangano (INAF IASF-Palermo), E. Berger, and W. Fong (Harvard) report: "We observed the short GRB120804A (GCN 13573) with XMM-Newton starting on 2012 August 22, 21:51:29 UT (18.8 days after the burst). GRB120804A is clearly detected at a level of 6 sigma with count-rate of (4.3 +\- 0.7)e-3 cps (0.2-10 keV) in the pn. The pn net exposure time is 25.5 ks. Using our best estimate of the intrinsic neutral hydrogen absorption (NH_int=3.2e21 cm-2) and the Galactic absorption in the direction of the burst (NH_gal=9.3e20 cm-2, Kalberla et al., 2005), this translates into an unabsorbed 0.3-10 keV flux of 2.4e-14 erg/s/cm2. Our analysis does not support the presence of a jet break for t< 18.8 days. Combining the Swift-XRT (GCN 13580), Chandra (GCN 13640, 13643) and XMM observations, for t>10^4 s the X-ray afterglow of GRB120804A is best modeled by a simple power-law decay with index=1.0 +\- 0.1. We thank the XMM-Newton staff for approving this observation."
GCN 13841 table
GRB_name GRB120804A
GCN_number 13841
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13841 SUBJECT: GRB 120804A: Late-time Chandra observation DATE: 12/10/04 17:56:15 GMT FROM: David Burrows at PSU/Swift GRB 120804A: Late-time Chandra observation David N. Burrows (PSU), Bin-Bin Zhang (PSU) and Eleonora Troja (NASA/GSFC/UMCP) report: We re-observed the field of GRB 120804A (Lien et al., GCN Circ. 13573) with the Chandra ACIS instrument, starting on September 18, 2012 16:04:50 UT (~46 days after the GRB trigger), for a total exposure of 60 ks. The X-ray afterglow is clearly detected at the 10 sigma level. The inferred flux is consistent with an extrapolation of the earlier Swift XRT observations (Troja et al., GCN Circ. 13640) and the XMM observation (Margutti et al. (GCN Circ. 13715), and shows a continuing decline in flux with a power-law decay slope of ~1.0 and no evidence for a jet break, consistent with Berger et al. (arXiv:1209:5423). We thank Dan Schwartz and the entire Chandra staff for rapidly executing this observation.