GRB100823A

This page lists all entries on GRB100823A in GRBweb

Summary IPN Swift GCN 11135 GCN 11136 GCN 11137 GCN 11138 GCN 11139 GCN 11140 GCN 11141 GCN 11142 GCN 11143 GCN 11144 GCN 11145 GCN 11146 GCN 11148 GCN 11151 GCN 11152 GCN 11154

Summary table
Variable Value Source
T0 17:25:25 UTC GCN_circulars,MAXI Det
ra 20.7043° Swift
decl 5.8351° Swift
pos_error 1.16e-04° Swift
T90 16.9 s Swift
T90_start 17:25:35 UTC Swift
fluence 4.10e-07 erg/cm² Swift
T100 26.9 s
GBM_located False
mjd 55431.7259837963 GCN_circulars,MAXI Det
IPN table
GRB_name GRB100823A
ra 20.7042°
decl 5.8500°
pos_error 5.00e-02°
Swift table
GRB_name GRB100823A
t_trigger 17:25:35 UTC
ra 20.7043°
decl 5.8351°
pos_error 1.16e-04°
T90 16.9 s
fluence 4.10e-07 erg/cm²
GCN 11135 table
GRB_name GRB100823A
GCN_number 11135
Detection_method Swift Det
t_trigger 17:25:35 UTC
ra 20.7030°
decl 5.8420°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11135 SUBJECT: GRB 100823A: Swift detection of a burst DATE: 10/08/23 17:38:11 GMT FROM: Scott Barthelmy at NASA/GSFC V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), T. Sakamoto (NASA/UMBC), M. C. Stroh (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 17:25:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100823A (trigger=432420). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 20.703, +5.842, which is RA(J2000) = 01h 22m 49s Dec(J2000) = +05d 50' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single FRED-like peak with a duration of about 25 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 17:26:44.6 UT, 68.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 20.70383, 5.83361 which is equivalent to: RA(J2000) = 01h 22m 48.92s Dec(J2000) = +05d 50' 01.0" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 30 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 (3.73e+20 cm^-2, Kalberla et al. 2005), with an excess column of 2.1 (+1.87/-1.66) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 5.93e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 77 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 3-sigma upper limit is 19.3 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 0.04. Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). 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 11136 table
GRB_name GRB100823A
GCN_number 11136
Detection_method Swift-XRT Det
ra 20.7043°
decl 5.8351°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11136 SUBJECT: GRB 100823A: Enhanced Swift-XRT position DATE: 10/08/23 20:20:57 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 251 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100823A, 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 = 20.70428, +5.83510 which is equivalent to: RA (J2000): 01h 22m 49.03s Dec (J2000): +05d 50' 06.4" with an uncertainty of 2.1 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 11137 table
GRB_name GRB100823A
GCN_number 11137
Detection_method Swift-BAT Det
ra 20.7060°
decl 5.8480°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11137 SUBJECT: GRB 100823A: Swift-BAT refined analysis DATE: 10/08/23 22:25:08 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (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 100823A (trigger #432420) (Mangano, et al., GCN Circ. 11135). The BAT ground-calculated position is RA, Dec = 20.706, 5.848 deg, which is RA(J2000) = 01h 22m 49.4s Dec(J2000) = +05d 50' 52.6" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%. The mask-weighted light curve shows a single FRED peak starting at ~T-2 sec, peaking at ~T+1 sec, and ending at T+150 sec. T90 (15-350 keV) is 16.9 +- 3.5 sec (estimated error including systematics). The time-averaged spectrum from T-1.2 to T+18.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.19 +- 0.18. The fluence in the 15-150 keV band is 4.1 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.14 sec in the 15-150 keV band is 1.0 +- 0.1 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/432420/BA/
GCN 11138 table
GRB_name GRB100823A
GCN_number 11138
Detection_method Other
ra 20.7040°
decl 5.8356°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11138 SUBJECT: GRB 100823A: WHT observations DATE: 10/08/24 04:28:24 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report for a larger collaboration: We observed the field of GRB 100823A (Mangano et al. GCN 11135) using the William Herschel Telescope on La Palma with the ACAM instrument. Observations were conducted in the z-band, and began at 00:37 UT, approximately 7.2 hours after the burst. Within the refined X-ray error circle (Goad et al. GCN 11136) we identify a source, at A: RA(J2000): 01:22:48.97 DEC(J2000) 05:50:08.1 However, we note that a source is also present in the DSS2 images of the field at this position. Additionally we note the presence of a brighter source, not present in the DSS images at B: RA(J2000): 01:22:48.79 DEC(J2000) 05:50:10.9 This source may be the afterglow of GRB 100823A (offset approximately ~6 arcseconds from the XRT position), or alternatively could either be a red source, not visible in the DSS2 red image, or a source with high proper motion. Further observations will be required to assess the nature of any variability. Images can be found at http://www.star.le.ac.uk/~anl/100823A
GCN 11139 table
GRB_name GRB100823A
GCN_number 11139
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 11139 SUBJECT: GRB 100823A: Swift/UVOT Upper Limits DATE: 10/08/24 04:37:39 GMT FROM: Margaret Chester at PSU M.M. Chester (PSU) and V. Mangano (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100823A 78 s after the BAT trigger (Mangano et al., GCN Circ. 11135). No optical afterglow consistent with the enhanced Swift/XRT position (Goad et al., GCN Circ. 11136) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the white and u finding chart (FC) and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 78 227 147 >20.1 u_FC 290 539 246 >19.4 white 78 17439 2181 >21.9 v 619 22361 1331 >20.5 b 545 16528 1278 >21.3 u 290 6512 639 >20.4 w1 669 6307 432 >20.2 m2 816 6102 413 >20.8 w2 767 18242 2082 >21.2 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).
GCN 11140 table
GRB_name GRB100823A
GCN_number 11140
Detection_method Swift Other
ra 20.6896°
decl 5.8175°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11140 SUBJECT: GRB 100823: 1.5m OSN I-band observations DATE: 10/08/24 09:48:06 GMT FROM: Sergey Guziy at IAA CSIC S. Guziy, A. Sota, J. Gorosabel and A.J. Castro-Tirado (IAA-CSIC Granada), on behalf of a larger collaboration, report: "We have carried out I-band observations of the Swift GRB 100823A Mangano et al., GCNC 11135) error circle with the 1.5m telescope at Observatorio de Sierra Nevada, Spain. The data were acquired on Aug 24.1333-24.1890 UT with a total exposure time of 15x300s. The two objects reported by Levan et al. (GCNC 11138) are clearly detected with preliminary magnitudes of I = 20.8 for the one within the XRT error box and 20.4 for the one reported by Levan et al. using as photometric reference the USNO-B1.0 star located at RA(J2000) = 01:22:45.502, DEC(J2000) = +05:49:03.02. At the present stage we can not confirm variability in any of the two sources. Further observations are planned."
GCN 11141 table
GRB_name GRB100823A
GCN_number 11141
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 11141 SUBJECT: GRB 100823A: TNG NIR observations DATE: 10/08/24 12:02:37 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), A.J. Levan (U. Warwick), D. Malesani (DARK/NBI), N.R. Tanvir (U. Leicester), E. Palazzi (INAF-IASFBo), A. Fiorenzano (INAF-TNG), report: We observed the field of GRB 100823A (Mangano et al. GCN 11135) using the Italian 3.6m TNG telescope, located in the Canary Islands. A set of J-band images were acquired on Aug 24.03490 UT (~7.4 hours after the burst; mid exposure time) for a total exposure time of 16 minutes. We detect the two objects reported by Levan et al. (GCN 11138) and Guziy et al. (GCN 11140) with magnitudes J=21.0 for object "A" (the one within the refined XRT error circle; Goad et al. GCN 11136) and J=19.4 for object "B", calibrated against the 2MASS catalogue. Although we have yet to photometrically calibrate the z-band image, from a comparison of the TNG and WHT images (Levan et al. GCN 11138) we note that object "B" has a z-J color significantly redder with respect to the average color of field stars. As suggested by Levan et al (GCN 11138) object "B" can thus be a red source not visible in the DSS2 red image. In light of this, its location outside the XRT refined error circle would make it likely unrelated to the GRB.
GCN 11142 table
GRB_name GRB100823A
GCN_number 11142
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 11142 SUBJECT: GRB 100823A - second epoch WHT observations DATE: 10/08/24 12:16:50 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report for a larger collaboration: We obtained a second epoch of observations of GRB 100823A (Mangano et al. GCN 11135) with the WHT, beginning at 05:38 UT, approximately 5 hours after our first epoch of observations (Levan et al. GCN 11138), and 12 hours after the GRB. In our images we detect both sources A and B, both of which are constant within the photometric errors. Additionally, we have inspected archival images of the field obtained with the UKIRT Wide Field Camera (WFCAM) in November 2008 in the YJHK bands. Object B is faintly detected in all bands, while object A is below the detection limit of the shallow observations. Given the location of object B well outside the refined XRT error circle (Goad et al. GCN 11136) these results imply that it is not related to GRB 100823A, confirming the conclusion of D'Avanzo et al. (GCN 11141). We cannot rule out a faint contribution of afterglow to object A, but it non-variability in our observations, coupled with its detection in DSS2 suggest that it is not afterglow dominated."
GCN 11143 table
GRB_name GRB100823A
GCN_number 11143
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 11143 SUBJECT: GRB 100823A: VLT/X-Shooter spectroscopy DATE: 10/08/24 13:33:09 GMT FROM: Nial Tanvir at U.Leicester P. D'Avanzo (INAF/Brera), P. Jakobsson (Reykjavik), H. Flores (Paris Obs.), P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), D. Malesani, J. P. U. Fynbo, and B. Milvang-Jensen (DARK), report on behalf of a larger collaboration: We observed the location of GRB 100823A (Mangano et al. GCN 11135) with the ESO VLT equipped with the X-shooter spectrograph on 2010 Aug 24, beginning 08:17 UT (15.5 hr after the GRB). The slit was aligned so to include both objects A and B first mentioned by Levan et al. (GCN 11138; see also Guziy et al., GCN 11140; D'Avanzo et al., GCN 11141). We detect both objects in the acquisition image, and confirm that object B is fainter than the DSS limit. In the spectra, we detect continuum from source A, and identify its spectrum as being that of an M-dwarf based on evident TiO bands. Given that object B is also likely unrelated to the GRB (D'Avanzo et al., GCN 11141; Levan et al., GCN 11142), we conclude that either the GRB event is itself associated with a flare from this star, or that the GRB afterglow is a fainter source not reported so far. We acknowledge the support of the VLT staff, in particular Claudia Cid, Stephane Brillant, Jonathan Smoker, and Christophe Martayan.
GCN 11144 table
GRB_name GRB100823A
GCN_number 11144
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 11144 SUBJECT: GRB 100823A: Swift XRT refined analysis DATE: 10/08/24 13:59:54 GMT FROM: Vanessa Mangano at INAF-IASFPA V. Mangano (INAF IASF-PA) and B. Sbarufatti (INAF OAB/INAF IASF-PA) report on behalf of the Swift-XRT team: We have analyzed 8.7 ks of XRT data for GRB 100823A (Mangano et al. GCN Circ. 11135), from 59 s to 22 ks after the BAT trigger. The data comprise 68 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 light curve can be modeled with a broken power-law decay with an initial decay index of alpha1=2.9 (+/-0.2) , a break at T+163 (+/-11) s and a final decay index of alpha2=1.19 (+/-0.03). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 3.6 (+0.8, -0.6). The best-fitting absorption column is 2.8 (+1.2, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 3.7 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum (extracted from T+137.5 s to T+22.3 ks, 8.65 ks exposure) has a photon index of 2.2 (+0.3, -0.2) and a best-fitting absorption column of 2.1 (+0.6, -0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (6.6 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.87, the count rate at T+48 hours will be 9.0 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x 10-14 (5.9 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00432420. This circular is an official product of the Swift-XRT team.
GCN 11145 table
GRB_name GRB100823A
GCN_number 11145
Detection_method Other
ra 20.7039°
decl 5.8350°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11145 SUBJECT: GRB 100823A: Candidate IR afterglow DATE: 10/08/24 17:13:52 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), K. Wiersema, N. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report on behalf of a larger collaboration: We obtained infrared imaging of the location of GRB 100823A ( using LIRIS on the 4.2m WHT, beginning at 01:34 UT, ~8 hours after the burst. Observations were obtained in the JH and K bands, with a total exposure time of 540 s in each band. We detect sources A and B of Levan et al. (GCN), but also find a new source within the XRT error circle of Goad et al. GCN 11135, but see also, http://www.swift.ac.uk/xrt_positions/00432420/image.php with a position of, C: RA(J2000) 01:22:48.94 DEC(J2000) 05:50:05.9 The object has K=19.6 calibrated against 2MASS, and is faintly visible in the H-band, but not in the J or z, suggestive of a red colour. At the current time we cannot make statements as to the variability of the source, but its red colour, akin to extinguished GRB afterglows, coupled with a location within the XRT error circle leads us to suggest that it is the afterglow of GRB 100823A.
GCN 11146 table
GRB_name GRB100823A
GCN_number 11146
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 11146 SUBJECT: GRB100823A : MOA optical observation DATE: 10/08/25 12:41:45 GMT FROM: Suzuki Daisuke at MOA-II D. Suzuki, K. Omori, N. Miyake, S. Kobara, H. Naito and T. Sako (STE Lab, Nagoya Univ.), T. Saito (Tokyo Metropolitan College of Industrial Technology) and K. Wada (Konan Univ.) on behalf of the MOA Collaboration report: We searched for an optical afterglow of GRB 100823A (GCN 11135, Mangano et al.) starting from 17:30:34 UT on 2010 Aug 23 (5 minutes after the burst) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand. In a single image of a 60sec exposure with a wideband Red filter (center wavelength ~ 750nm and FWHM ~ 250nm), we found an object not found in the USNO-B1.0 catalog within the error circle of the Swift XRT source position (GCN 11136 Goad et al.). The position coincides with the source C (GCN 11145, Levan et al.) and the magnitude is estimated to be I=17.1mag. Additionally, we obtained a second epoch of observation of GRB 100823A starting from 14:59:16 UT on 2010 Aug 24 (approximately 21.5 hours after the burst). In a single image of a 300sec exposure with a wideband Red filter, we detected source A (GCN 11138, Levan et al.) with magnitude I=21.3mag ,but we did not detect the source C in this epoch. This photometry were done by using the DoPhot and calibrated against the USNO-B1.0 catalog stars, and not corrected for the Galactic extinction.
GCN 11148 table
GRB_name GRB100823A
GCN_number 11148
Detection_method Swift-UVOT Other
ra 20.7043°
decl 5.8351°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11148 SUBJECT: GRB 100823A: Swift/UVOT Evidence for Fading Afterglow Emission DATE: 10/08/26 19:03:19 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU), T.S. Koch (PSU), E. A. Hoversten (PSU), and V. Mangano (INAF-IASFPA) report on behalf of the Swift/UVOT team: Further examination of Swift/UVOT observations of GRB 100823A show that a source detected in the white finding chart exposure, initially thought to correspond to the DSS2 source mentioned in Levan et al., GCN Circ. 11138, faded in subsequent exposures to an apparently steady level. The source was marginally detected in the u finding chart exposure. The position of the source in both the finding chart and later images is consistent with the enhanced XRT position (Goad et al., GCN Circ. 11136). We propose this result as further evidence that Source C in Levan et al., GCN Circ. 11145, and referenced in Suzuki et al., GCN Circ. 11146, is the afterglow of GRB 100823A. Magnitudes for the white and u finding charts and white optimally co- added exposures are given in the following table. All photometry was performed using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627). The values quoted are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). Filter T_start(s) T_stop(s) Exp(s) Mag Error S/N white_FC 78 227 147 20.7 +/-0.3 2.9 u_FC 290 539 246 20.4 +/-0.4 2.1 white 576 57266 3157 23.4 +/-0.8 2.3 white 61907 63386 1453 22.9 +/-0.7 2.4 white 67668 73670 2674 23.3 +/-0.8 2.1 white 73673 75876 2168 23.0 +/-0.7 2.5 The UVOT position determined from co-adding all of the later images (after T=56215s) is: RA (J2000) 01:22:49.03 = 20.70429 (deg) Dec (J2000) +05:50:06.4 = +5.83511 (deg) with an estimated uncertainty of 0.9 arcsec (radius, 90% confidence, statistical + systematic).
GCN 11151 table
GRB_name GRB100823A
GCN_number 11151
Detection_method MAXI Det
t_trigger 17:25:25 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 11151 SUBJECT: GRB 100823A: MAXI/GSC detection DATE: 10/08/27 16:06:32 GMT FROM: Motoko Suzuki at RIKEN M. Serino, T. Mihara, Y.E. Nakagawa, M. Sugizaki, T. Yamamoto, T. Sootome, M. Matsuoka (RIKEN), N. Kawai, M. Morii, K. Sugimori, R. Usui (Tokyo Tech), K. Kawasaki, S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA), A. Yoshida, K. Yamaoka, S. Nakahira (AGU), H. Tsunemi, M. Kimura (Osaka U.), H. Negoro, M. Nakajima H. Ozawa, F. Suwa (Nihon U.), Y. Ueda, N. Isobe, S. Eguchi, K. Hiroi (Kyoto U.), A. Daikyuji (Miyazaki U.), A. Uzawa, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team: The Gas Slit Camera (GSC) of MAXI detected a bright X-ray source at the position consistent with GRB 100823A (Mangano et al, GCN 11135). Assuming the XRT position (Goad et al., GCN 11136), the transit of GSC over the source started at 17:25:25 UT on 23 August 2010, 10 seconds before the Swift/BAT trigger time. A significant (8 sigma in 2-20 keV) rise of the count rate above the background was observed at 17:25:33, and the burst was detected significantly for 25 seconds. The peak X-ray flux (4-10 keV) was about 2.5 Crab, which was corrected for the collimator transmission efficiency assuming the source position by Swift XRT. There are significant time structure within the transit light curve, which would be simply triangular for a steady source. From the preliminary spectral analysis, the time-averaged spectrum from T+0 to T+25 sec is best fit by a power-law model with a photon index of 2.0 +/- 0.2. The fluence in the 2-20 keV band is 5.1 +0.5 -0.9 x 10^-7 erg/cm2. The sky image and the transit light curve is shown at the MAXI web site http://maxi.riken.jp/ in the "News" section.
GCN 11152 table
GRB_name GRB100823A
GCN_number 11152
Detection_method Optical
ra 20.6896°
decl 5.8175°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11152 SUBJECT: GRB 100823A: optical observations DATE: 10/08/27 20:23:43 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), A. Volnova (SAI MSU), B. Satovski (Astrotel), M. Ibrahimov (MAO) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100823A (Mangano et al. GCN 11135) with AZT-22 telescope of Maidanak observatory. Several images in I-filter were obtained starting on Aug. 23 (UT) 20:47:02. We do not detect the object C (Levan et al. GCN 11145; Suzuki et al. GCN 11146) up to I=22.2m. We clearly detect both objects A and B (Levan et al. GCN 11138). The photometry of stacked image is based on USNO-B1.0 star 0958-0013520 located at RA(J2000) = 01:22:45.50, DEC(J2000) = +05:49:03.0 and used as reference star in GCN 11140 (Guziy et al). Object, t-T0, Filter, Exposure, OT, Upper limit (3 sigma) (mid, d) (s) A 0.16605 I 19*180 21.06+/-0.09 22.2 B 0.16605 I 19*180 20.60+/-0.06 22.2 The photometry of the object A is compatible with photometry reported in GCN 11146 (Suzuki et al). Using photometry of the object C starting 5 minutes after burst (Suzuki et al. GCN 11146) and upper limit I=22.2m at 0.16605 days one can estimate power law decay index alpha > 1.25. We thank Otabek Burhonov for performing the observations and for his support.
GCN 11154 table
GRB_name GRB100823A
GCN_number 11154
Detection_method Optical
ra 20.6896°
decl 5.8175°
Circular_text TITLE: GCN CIRCULAR NUMBER: 11154 SUBJECT: GRB 100823A: optical upper limit DATE: 10/08/27 20:45:22 GMT FROM: Alexei Pozanenko at IKI, Moscow K. Antoniuk, V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100823A (Mangano et al. GCN 11135) with AZT-11 telescope of CrAO observatory. Several images in R-filter were obtained on Aug. 23 between (UT) 22:05 - 22:53. In enhanced XRT position (Goad et al. GCN 11136) we do not detect any source up to R=20.7. The photometry of stacked image is based on USNO-B1.0 star 0958-0013520 located at RA(J2000) = 01:22:45.50, DEC(J2000) = +05:49:03.0 (assuming R=16.75): t-T0, Filter, Exposure, OT, Upper limit (3 sigma) (mid, d) (s) 0.2111 R 15*180 n/d 20.7