//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1399 SUBJECT: GRB020531(=H2042): A Short, Hard Burst Localized by HETE DATE: 02/05/31 05:34:01 GMT FROM: Don Lamb at U.Chicago G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of the HETE Science Team; J. Doty, R. Vanderspek, J. Villasenor, G. Crew,G. Monnelly, N. Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and T. Donaghy, on behalf of the HETE WXM Team; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE FREGATE Team; write: At 00:26:18.73 UTC (1578.73 s UT) on 31 May 2002, the HETE FREGATE and WXM instruments detected event H2042, a short (~200 msec), hard GRB. The WXM flight localization software produced a valid location in spacecraft (relative) coordinates. However, since no real-time star camera aspect was available, an absolute localization could not be disseminated. A preliminary localization was reported as a GCN Position Notice at 01:54:22 UT, ~88 min after the burst. The ground analysis has produced a refined location which can be expressed as a 90% confidence rectangle that is 43 arcminutes by 67 arcminutes. The corners of the rectangle lie at the following J2000 coordinates: RA = 15h 17m 00s, -19o 43' 00" RA = 15h 17m 00s, -19o 00' 00" RA = 15h 12m 30s, -19o 00' 00" RA = 15h 12m 30s, -19o 43' 00". In the FREGATE 30-400 keV band, H2042 had a duration of ~260 milliseconds. In the FREGATE 8-40 keV band, the burst had a duration of ~1000 milliseconds. A total of 705 net counts were detected in the 8-40 keV band during this interval, corresponding to a fluence of ~1 x 10-7 ergs cm-2. The peak flux averaged over 0.20 s was >3 x 10-7 ergs cm-2 s-1 (i.e., >10 x Crab flux). In the WXM 2-25 keV band, the localization SNR was >7. Further information (including a light curve) for GRB020531 is provided at the following URL: http://space.mit.edu/HETE/Bursts/ This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1400 SUBJECT: GRB020531: Optical observations DATE: 02/05/31 13:02:15 GMT FROM: Derek Fox at CIT D.W. Fox and J.S. Bloom (Caltech) report on behalf of a larger collaboration: "We have observed the full error box of GRB020531 (Ricker et al., GCN #1399) with the Palomar Oschin Telescope + NEAT with three 120s exposures beginning on 04:50 UT 31 May 2002, less then 4.5 hours after the burst. The summed exposure reaches to the POSS plate limit, R~18. Visual comparison of the image against the Digitized Sky Survey (DSS/SES) has not yet allowed us to identify any bright new stationary objects. We identify two asteroids which are present at J2000 coordinates Ast 1: 15:13:08.12 -19:22:13.1 Ast 2: 15:13:49.81 -19:29:13.1 at the epoch of our first image. Further analysis of these data are in progress." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1401 SUBJECT: GRB020531(=H2042): Optical Observations DATE: 02/05/31 17:20:00 GMT FROM: Don Lamb at U.Chicago S. Snedden, D. Q. Lamb, B. C. Lee, D. L. Tucker, D. E. Vanden Berk, M. Harvanek, A. N. Kleinman, S. Kleinman, J. Krzesinski, D. Long, and P. R. Newman, on behalf of the SDSS GRB team, report: "We have observed the field of GRB020531 (=H2042) (GCN 1399) using the SDSS 0.5-m "Photometric Telescope" (PT) at APO under clear skies, a bright moon, and poor seeing on UTC 2002 May 31 from 04:54 to 09:32 UTC, beginning less than 4.5 hours after the burst. We took a series of ten 600 second r'-band exposures and fifteen 600 second i'-band exposures (41.5' x 41.5' field of view) that cover the entire improved HETE error rectangle for GRB020531 (GCN 1399). The summed images in r' reach deeper than the POSS plate limit, R~18. Visual comparison of the images and the DSS has not yet allowed us to identify any bright new object." This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1402 SUBJECT: IPN triangulation of the short, hard GRB020531 (=H2042) DATE: 02/05/31 18:27:48 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses, Mars Odyssey, and HETE GRB teams, I. Mitrofanov, D. Anfimov, A.Kozyrev, M. Litvak and A.Sanin on behalf of the HEND/Odyssey GRB team, W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R.Starr, on behalf of the GRS/Odyssey GRB team, G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew,G. Monnelly, N. Butler, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, report: Ulysses and Mars Odyssey (HEND) observed the short-duration, hard spectrum GRB020531 (=H2042; GCN 1399). While the HEND response was quite intense, the Ulysses signal was particularly weak and could only be identified by restricting the search to the crossing window defined by the HETE position. We have triangulated this burst to an ~46 square arcminute (3 sigma) error box whose coordinates are: 15 h 15 m 04.10 s -19 o 24 ' 48.53 " (CENTER) 15 h 14 m 20.83 s -19 o 28 ' 36.33 " (CORNER) 15 h 15 m 14.46 s -19 o 21 ' 38.39 " (CORNER) 15 h 14 m 53.75 s -19 o 27 ' 58.57 " (CORNER) 15 h 15 m 47.53 s -19 o 20 ' 59.17 " (CORNER) This error box may be improved. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1403 SUBJECT: GRB020531(=H2042): Optical Observations DATE: 02/06/01 00:08:19 GMT FROM: Don Lamb at U.Chicago D. Q. Lamb, S. Snedden, D. E. Vanden Berk, S. Allam, D. L. Tucker, B. C. Lee, M. Harvanek, A. N. Kleinman, S. Kleinman, J. Krzesinski, D. Long, and P. R. Newman, on behalf of the SDSS GRB team, report: "Visual comparison of one 600 second r'-band image (41.5' x 41.5' field of view) covering more than 90% of the IPN error box (GCN 1402) for GRB020531 (=H2042) (GCN 1399), which was taken using the SDSS 0.5-m "Photometric Telescope" (PT) at APO less than 4.5 hours after the burst (GCN 1401), and the UK Schmidt second epoch Southern Survey (emulsion IIaf) plate for this region (taken at 1993.389) shows no new object brighter than the limiting magnitude of the UK Schmidt plate, which is R ~ 20.5." This message is citeable //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1404 SUBJECT: GRB020531, optical observation DATE: 02/06/01 21:20:18 GMT FROM: Hye-Sook Park at LLNL H. S. Park, G. G. Williams, K. Lindsay on behalf of the Super-LOTIS collaboration: Super-LOTIS observed 95% of the IPN error box for GRB020531(GCNC#1402). The observation began at UTC 2002 May 31 04:04 (3.6 hrs after the burst). We find no optical transient in a sum of 20 images (60 s integration each). The limiting magnitude is R~17.5. This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1405 SUBJECT: GRB020531: optical observations DATE: 02/06/02 09:41:10 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. D. Li, A. V. Filippenko, and R. Chornock (UC Berkeley) report on behalf of the Lick Observatory and Tenagra Observatory Supernova Search (LOTOSS): "We have observed a rectangle region of about 21' x 7' around the position of GRB020531 (Richer et al., GCN #1399) with the 0.8-m Katzman Automatic Imaging Telescope (KAIT) with 4x120s and 4x300s unfiltered exposures beginning on May 31 04:56 UT, 2002, less than 4.5 hours after the burst. The individual exposure reaches or exceeds the POSS II plate limit, R~20.5. The same region was imaged again beginning on Jun 1 06:05 UT, 2002. We used image subtraction to compare the observations from these two nights, but have not yet found any bright new stationary objects. We identified two asteroids whose J2000 coordinates are reported below: Asteroid 1: mag about 19.5 R. A. = 15h14m35s.85, Decl. = -19 23'49".0 at May 31 4:57 UT R. A. = 15h14m35s.70, Decl. = -19 23'48".7 at May 31 5:02 UT Asteroid 2: mag about 20.0 R. A. = 15h14m54s.51, Decl. = -19 24'35".8 at May 31 5:06 UT R. A. = 15h14m54s.36, Decl. = -19 24'36".4 at May 31 5:10 UT." This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1406 SUBJECT: GRB020531, optical observations DATE: 02/06/02 23:57:21 GMT FROM: Arne A. Henden at USNO/USRA D. West (Mulvane, KS), on behalf of the AAVSO International GRB Network, reports: The IPN error box for GRB020531 (Ricker et al, GCN 1399 and Hurley et al., GCN 1402) has been observed, using a 20cm telescope and SBIG ST-9E CCD under clear conditions. Unfiltered exposures covering a 29x29arcmin field were made; these frames cover 99percent of the IPN error box, perhaps missing the extreme eastern point. A series of 60sec exposures began at 0250UT on 020531 (2.4hrs after the burst), with the best 7 combined to form a composite image. No new source down to a V magnitude of 17.7 (GSC1.1) was seen. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1407 SUBJECT: Refined IPN error box for GRB020531 DATE: 02/06/05 01:26:07 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses, Mars Odyssey, and HETE GRB teams, I. Mitrofanov, D. Anfimov, A.Kozyrev, M. Litvak and A.Sanin on behalf of the HEND/Odyssey GRB team, W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R.Starr, on behalf of the GRS/Odyssey GRB team, G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew,G. Monnelly, N. Butler, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, report: We have refined the IPN error box of the short duration, hard spectrum GRB020531 (GCN 1402) to the following preliminary 3 sigma polygon with approximately 22 square arcminute area. Its maximum dimension is about 10 arcminutes, which may facilitate deeper searches. 15 h 15 m 03.57 s -19 o 24 ' 51.00 " (CENTER) 15 h 14 m 53.98 s -19 o 24 ' 18.15 " (CORNER) 15 h 15 m 14.46 s -19 o 21 ' 38.39 " (CORNER) 15 h 15 m 17.07 s -19 o 21 ' 35.32 " (CORNER) 15 h 15 m 12.51 s -19 o 25 ' 32.46 " (CORNER) 15 h 14 m 53.75 s -19 o 27 ' 58.57 " (CORNER) 15 h 14 m 49.67 s -19 o 28 ' 03.27 " (CORNER) This error box may be refined further. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1408 SUBJECT: GRB 020531 optical observations with TAROT DATE: 02/06/05 11:01:05 GMT FROM: Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse M. Boer, A. Klotz (CESR/CNRS) J.L. Atteia (LAT/OMP), C. Pollas (OCA) and H. Pinna (CEMES/CNRS) communicate: "We have observed the entire IPN error box for GRB020531 (Ricker et al, GCN 1399 and Hurley et al., GCN 1402) with the 25cm robotic TAROT telescope starting on May 31 01:55:12 UT (89 minutes after the burst and 50 seconds after the GCN notice) under clear sky conditions. 11 unfiltered 30s exposures were acquired between 01:55:12 and 02:06:30 UT and were coadded. Limit of magnitude is about R=18.0. The coadded image can be seen at URL : http://alain.klotz.free.fr/tarot/GRB020531 Two very faint sources were found that do not appear on the POSS I : source A : Ra(J2000.0) = 15h14min51s (+/- 1s) Dec(J2000.0) = -19d25'06" (+/- 2") R = 17.4 (+/- 0.4) This could be asteroid 2 of GCN #1405. source B: Ra(J2000.0) = 15h14min57s (+/- 1s) Dec(J2000.0) = -19d28'12" (+/- 2") R = 17.1 (+/- 0.4) Since we have no images taken at later times for comparison, it is difficult to conclude on the nature of sources A and B. We consider however that A is a likely asteroid. Source B, if real, is a possible candidate for the GRB counterpart. This message is citeable //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1411 SUBJECT: GRB020531: Upper Limit for Detection of Two TAROT Sources DATE: 02/06/05 20:47:35 GMT FROM: George Ricker at MIT GRB020531: Upper Limit for Detection of Two TAROT Sources A. Dullighan, G. Monnelly, N. Butler, R. Vanderspek, P. Ford, and G. Ricker (MIT) write: We obtained early epoch observations of the HETE error region of the short gamma-ray burst GRB020531 (H2042; Ricker et al., GCN #1399) with the Baade 6.5m telescope at the Magellan Observatory on 2002 June 1.17 UT using the LDSS-2 instrument. The observations took place 1.19 days after the burst. A mosaic of seven 300s R-band exposures covered the entire IPN error region (Hurley et al., GCN #1402). We detect neither source A nor source B that were reported by Boer et al. (GCN #1408) from TAROT observations taken 1.5 hours after the burst. For each of these two source locations, our 3 sigma upper limit is R=23.3. If source B were the afterglow of GRB020531, our result implies that the decay power law index was steeper than 1.93 between the epoch of the earlier TAROT observations and that of our later Magellan observations. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1415 SUBJECT: GRB020531: Observations with the Chandra X-ray Observatory DATE: 02/06/06 21:59:33 GMT FROM: George Ricker at MIT GRB020531: Observations with the Chandra X-ray Observatory N. Butler, A. Dullighan, P. Ford, G. Monnelly, G. Ricker, R. Vanderspek (MIT); K. Hurley (U.C.- Berkeley); and D. Lamb (U.Chicago) on behalf of the Chandra GRB ToO Team and the HETE Science Team write: On 5 June, the Chandra Observatory targeted the field of the short duration gamma-ray burst GRB020531 that was initially localized by the HETE satellite (Ricker et al., GCN1399). The observations, lasting 20 ksec, spanned the interval 04:00-10:04 UT, 5.15 - 5.40 days after the burst. The refined IPN error region from Hurley et al. (GCN1407) was completely contained within the field-of-view of the Chandra ACIS-I array. The ACIS-I data set for the 20 ksec observation was received at 22:23 UT, 18.4 hours after the observation began. Within the refined IPN error region, we detect 10 sources in the 0.5-8 keV band: # Chandra Name RA DEC dR(s) dD(") Cts 28 CXOU J151459.7-192532 15 14 59.74 -19 25 31.91 0.019 1.36 12 36 CXOU J151459.2-192609 15 14 59.18 -19 26 8.50 0.021 1.36 8 41 CXOU J151503.6-192423 15 15 3.59 -19 24 23.49 0.022 1.36 7 47 CXOU J151514.7-192221 15 15 14.69 -19 22 21.42 0.020 1.37 6 48 CXOU J151455.8-192454 15 14 55.76 -19 24 54.02 0.023 1.36 6 51 CXOU J151513.3-192450 15 15 13.30 -19 24 49.94 0.019 1.36 5 52 CXOU J151501.9-192358 15 15 1.86 -19 23 58.48 0.022 1.36 5 55 CXOU J151457.0-192439 15 14 56.96 -19 24 39.26 0.022 1.36 4 56 CXOU J151514.1-192428 15 15 14.14 -19 24 27.58 0.022 1.37 4 58 CXOU J151508.0-192338 15 15 7.96 -19 23 37.69 0.021 1.36 3 The # column refers to the source's relative ranking (in terms of total counts) among all the sources detected in the entire ACIS-I field-of-view. In addition, we detect 3 bright sources just outside of the refined IPN error region: 0 CXOU J151515.3-192511 15 15 15.31 -19 25 10.71 0.019 1.35 67 5 CXOU J151517.8-192102 15 15 17.80 -19 21 2.20 0.020 1.36 44 15 CXOU J151458.3-192322 15 14 58.34 -19 23 22.32 0.020 1.35 19 For these three bright sources, we note that there are conspicuous optical counterparts visible in an observation carried out with the Baade 6.5 meter telescope at the Magellan Observatory on 1 June, 1.19 days after the GRB (see Dulligan et al., GCN1411, for observation details). The three counterparts for #0, #5, and #15 have approximate R magnitudes of 20.4, 23.6, and 20.8, respectively. For both the TAROT A and B source locations (Boer et al., GCN1408), no X-ray counts are detected in excess of the background rate. The astrometry was calibrated using three USNO A2 catalog stars with detectable X-ray emission and lying within the ACIS-I field-of-view. In the above 2 tables, dR, the uncertainty in RA, and dD, the uncertainty in DEC, were established by summing the following in quadrature for each coordinate: the error reported by celldetect, the correlation error between the X-ray and optical positions, and the error estimate from the star reference catalog. We gratefully acknowledge the timely assistance of the personnel at the Chandra Science Center in the acquisition and preliminary processing of these data. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1416 SUBJECT: GRB020531 Optical Observations DATE: 02/06/07 01:16:18 GMT FROM: Don Lamb at U.Chicago A. Miceli, D. Q. Lamb, D. Zucker, K. Covey, J. Dembicky, and N. C. Hastings report: We have observed the field of GRB020531 (=H2042) (Ricker et al., GCN 1399) using the SPIcam (4.78' x 4.78' field of view) on the ARC 3.5-meter telescope at APO under clear skies and a bright moon on UTC 2002 June 1 from 07:27:53 to 07:43:05 UTC (beginning 1.3 days after the burst), and under mostly clear skies but poor seeing on UTC 2002 June 6 from 04:38:33 to 04:54:22 UTC (beginning 7.2 days after the burst). On both nights we took three 400-second r'-band exposures that cover the entire refined hexagonal IPN error region for GRB020531 (Hurley et al., GCN 1407). We have examined these images in the vicinity of the ten X-ray sources seen in the first Chandra follow-up observation that lie inside the refined IPN error region and the three bright X-ray sources that lie just outside the refined IPN error region (Ricker et al., GCN 1415). The table below lists the approximate r* magnitude or the approximate limiting r* magnitude of any object that lies at the location of these thirteen X-ray sources, based on a preliminary analysis of a single r'-band image taken on each night. SPIcam RMS astrometric errors are 0.2 arcsec or less. --------------------------------------------------------------------------- Nearest X-ray Optical RA Dec r* mag r* mag Comment Source Source (deg) (deg) (June 1) (June 6) --------------------------------------------------------------------------- cxo00 arc00 228.8139 -19.4194 --- 20.6 Outside June 1 FOV cxo05 mag05 ----- ----- > 22.5 > 22.0 Magellan R ~ 23.6 cxo15 arc15 228.7431 -19.3892 20.7 20.7 cxo28 --- ----- ----- > 22.5 > 22.0 cxo36 --- ----- ----- > 22.5 > 22.0 cxo41 --- ----- ----- > 22.5 > 22.0 cxo47 --- ----- ----- > 22.5 > 22.0 cxo48 --- ----- ----- > 22.5 > 22.0 cxo51 --- ----- ----- > 22.5 > 22.0 cxo52 --- ----- ----- > 22.5 > 22.0 cxo55 arc55 228.7374 -19.4107 22.3 --- Outside June 6 FOV cxo56 arc56 228.8091 -19.4073 20.5 20.5 cxo58 --- ----- ----- > 22.5 > 22.0 --------------------------------------------------------------------------- This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1418 SUBJECT: GRB 020531, Radio Observations DATE: 02/06/07 23:35:17 GMT FROM: Edo Berger at Caltech D. A. Frail (Caltech/NRAO) and E. Berger (Caltech) report on behalf of a larger collaboration: "On 2002 June 1.16, 3.15 and 4.17 UT the VLA was used to image the original IPN error box of GRB 020531 (GCN 1402) at a frequency of 4.86 GHz. Observations were also conducted at a frequency of 8.46 GHz on 2002 June 4.23 UT. No sources were detected within the entire IPN error box at 4.86 GHz above a 5-sigma level of 255 microJy at any epoch. Further, an image was made by combining all three 4.86 GHz epochs and a search was conducted for radio emission at the positions of the 10 Chandra X-ray sources (GCN 1415). No radio sources brighter than 100 microJy (~3-sigma) at 4.86 GHz and 180 microJy (~3-sigma) at 8.46 GHz, were found coincident with the Chandra sources. These limits are two to three times deeper than previous searches for short durations bursts with the VLA (Hurley et al. ApJ, 567, 447, 2002)." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1420 SUBJECT: GRB020531 Optical observations with TAROT DATE: 02/06/11 13:32:57 GMT FROM: Michel Boer at CESR-CNRS A. Klotz, M. Boer (CESR/OMP/CNRS), and J.L. Atteia (LAT/OMP/CNRS), on behalf of the TAROT collaboration communicate: Following our first analysis (Boer et al., GCN #1408), we performed a refined analysis of the images acquired by TAROT after the alert sent by HETE for GRB 020531 (Ricker et al., GCN #1399). Within the IPN error box we find a 3 sigma excess, elongated in the direction of the telescope aberration, at the following position: RA =3D 15h15m12s, DEC = -19=B024=9233=94, with an error box of 7 arcsec, and a magnitude of = 17.5. Though this possible source is close to CXOU J151514.1-192428 (source # 56 in Butler et al., GCN #1415) both sources seem different. In addition, the exposures taken by TAROT started at 01h54m28s UT, 6s after the alert was sent by the GCN (and not 50s as mentioned in the earlier circular). This message is citeable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1421 SUBJECT: GRB020531 Optical observations with TAROT DATE: 02/06/11 14:33:39 GMT FROM: Michel Boer at CESR-CNRS The mailer has formatted the previous circular in an almost un-readable way. Below the text, I hope it will be readable this time. My apologies, Michel A. Klotz, M. Boer (CESR/OMP/CNRS), and J.L. Atteia (LAT/OMP/CNRS), on behalf of the TAROT collaboration communicate: Following our first analysis (Boer et al., GCN #1408), we performed a refined analysis of the images acquired by TAROT after the alert sent by HETE for GRB 020531 (Ricker et al., GCN #1399).  Within the IPN error box we find a 3 sigma excess, elongated in the direction of the telescope aberration, at the following position: RA = 15h15m12s, DEC = -19°24’33”, with an error box of 7 arcsec, and a magnitude of 17.5. Though this possible source is close to CXOU J151514.1-192428 (source # 56 in Butler et al., GCN #1415) both sources seem different.   In addition, the exposures taken by TAROT started at 01h54m28s UT, 6s after the alert was sent by the GCN (and not 50s as mentioned in the earlier circular).   This message is citeable //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1422 SUBJECT: GRB020531, BVRcIc field photometry DATE: 02/06/11 19:41:46 GMT FROM: Arne A. Henden at USNO/USRA A. Henden (USRA/USNO) reports on behalf of the USNO GRB team: We have acquired BVRcIc all-sky photometry for an 11x11 arcmin field centered at the IPN coordinates for the HETE burst GRB020531 (Ricker et al, GCN 1399 and Hurley et al., GCN 1402/1407) with the USNOFS 1.0-m telescope on two photometric nights. Stars brighter than V=14.0 are saturated and should be used with care. We have placed the photometric data on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb020531.dat The astrometry in this file is based on linear plate solutions with respect to UCAC2. The external errors are less than 50mas. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1426 SUBJECT: GRB020531: Second epoch Chandra observations DATE: 02/06/11 22:11:28 GMT FROM: Roland Vanderspek at MIT GRB020531: Results of a Second Epoch Observation with the Chandra X-ray Observatory N. Butler, A. Dullighan, P. Ford, G. Monnelly, G. Ricker, R. Vanderspek (MIT); and D. Lamb (U.Chicago) on behalf of the Chandra GRB ToO Team and the HETE Science Team write: Between 10 June 20:59 UT to 11 June 00:13 UT, the Chandra Observatory targeted the field of the short duration gamma-ray burst GRB020531 that was initially localized by the HETE satellite (Ricker et al., GCN1399). This observation began 10.86 days after the GRB. This was a 10 ksec observation with ACIS-I, following up the 20 ksec observation performed with ACIS-I on 5 June (Butler et al., GCN 1415). Of the 10 sources reported in GCN1415 lying within the refined IPN error region (Hurley et al. GCN1407), only one source declined in brightness with a significance greater than 2 sigma: # Chandra Name RA DEC E1 Cnts E2 Cnts 48 CXOU J151455.8-192454 15 14 55.76 -19 24 54.02 6 ~0 This source faded in a manner that is consistent with the power-law behavior that is characteristic of (long duration) gamma-ray burst afterglows. (A power law index of -1.3 implies a decline in brightness by a factor of 2.6 between our 1st and 2nd epoch observations.) We note that source #0 declined in brightness with a significance of 2.0 sigma, but remained ~2x brighter than would be expected based on a t^-1.3 extrapolation. 0 CXOU J151515.3-192511 15 15 15.31 -19 25 10.71 67 21 Here "E1 Cnts" and "E2 Cnts" denote, respectively, the epoch 1 and epoch 2 net counts for the source. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1427 SUBJECT: GRB020531: Detection of Candidate Host Galaxy DATE: 02/06/12 00:32:17 GMT FROM: Derek Fox at CIT D.W. Fox and S.R. Kulkarni (Caltech), with P. Weissman (JPL) report: "We have observed the error region of the short/hard gamma-ray burst GRB020531 (GCN 1407) with the Hale Telescope and Large Format Camera on Mt. Palomar on two occasions, June 1.3 and June 2.3 UT, for a total integration of 1200s at each epoch. Within less than 1" of the position of Chandra Source 48 of Butler et al. (GCN 1415, 1426), aka CXOU J151455.8-192454, we find an object with r'~22.4 mag that appears slightly extended in our (FWHM ~ 1.4") images, and varies less than 0.1 mag between our two epochs. We tentatively identify this object as the host galaxy of GRB020531. Images will be posted shortly at http://www.astro.caltech.edu/~derekfox/grb020531/ " //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1428 SUBJECT: GRB 020531/Candidate Redshift DATE: 02/06/12 11:38:15 GMT FROM: Shri Kulkarni at Caltech S. R. Kulkarni, R. Goodrich, E. Berger, D. W. Fox, J. S. Bloom and C. A. Blake report, on behalf of the Caltech-NRAO-CARA collaboration: N. Butler et al. (GCN 1426) suggested that a fading X-ray source, CXOU J151455.8-192454 is the afterglow of the short hard burst GRB 020531 (Hurley et al. GCN 1407). Fox, Kulkarni and Weissman (GCN 1427) identified an object within 1 arcsecond of CXOU J151455.8-192454 and suggested that the object is the host galaxy of GRB 020531. On June 12, 2002 (UT) we undertook imaging and spectroscopic observations with the Echelle Spectrograph & Imager (ESI) on Keck II. With a seeing of 0.6 arcseconds in the R and I bands we confirm that the candidate object is indeed extended, with a size of about 1 arcsecond. Next, we obtained four 1800-s spectroscopic exposures (Echelle mode) and found two features: a broad feature (Gaussian full width at half maximum of 11.6 A) centered on 7455 Angstrom (A) and a fainter feature centered around 9725 A. We suggest that the broad feature is the [O II] 3728.8/3726.0 doublet with an intrinsic velocity dispersion of 330 km/s and the fainter feature is Hbeta. If these identifications are correct then the redshift of the candidate host galaxy is 1.00. The fluence and peak flux of GRB 020531 over the energy range 50 to 300 keV are 8E-7 erg cm^-2 and 6.4E-7 erg cm^-2 s^-1, respectively (Lamb et al. 2002; astro-ph/0206151). Assuming, H0=65 km/s/Mpc and flat universe with Omega-m=0.3, the isotropic energy release (without any k correction) is 2.4E51 erg and 3.9E51 erg/s. Lamb et al. (ibid) argue that GRB 020531 is a burst which belongs to the short duration group. The isotropic energy release of this short burst is not different from that of the true energy release (i.e. after accounting for the opening angles of the jets; see Frail et al. 2001, ApJ 562, L55) inferred for the long duration bursts. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1430 SUBJECT: GRB 020531, simultaneous optical observations DATE: 02/06/14 00:21:53 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA A. J. Castro-Tirado (IAA-CSIC and LAEFF-INTA), J. M. Castro Cerón (ROA), A. de Ugarte Postigo (UCM), R. Hudec, M. Jélinek (ASU), M. Bernas, P. Páta (CVUT) and J. Á. Berná (Univ. de Alicante) on behalf of the BOOTES team, report: "We have obtained about 120 unfiltred exposures (120-s each) under poor metereological conditions covering the possible short/hard GRB 020531 error box (HETE trigger 7688 at To = 00:26:18 UT, GCN 1399) during the period 20:15 UT 30 May 2002 - 02:15 UT 31 May 2002 (i.e. between 4.19-hours before the trigger and 1.82-hours after the trigger) with the wide-field camera of BOOTES-1 (http://www.laeff.esa.es/BOOTES). After a visual inspection of the IPN error box (GCN 1407) in all frames, we do not find evidence of optical emission, in particular simultaneously to the burst itself. We derive the following upper limits : Date of mid-exposure Limiting magnitude Sky conditions ----------------------------- ------------------ -------------- May 30, 22:18 UT (To - 2 hr) 10.5 thin cirrus May 31, 00:26 UT (To) 8.0 thick cirrus May 31, 00:56 UT (T0 + 0.5 hr) 8.0 thick cirrus The fact that no optical afterglow has been found for this GRB (cf. GCN 1403, 1404, 1405, 1406, 1408, 1416, 1421, 1427) supports the idea that most short GRBs might occur in a low density medium. This would be also implied by the BOOTES detection of an optical transient (OT) following the short/hard GRB 000313, if both, the OT and the GRB are related (Castro-Tirado et al. 2002, submitted to A&A, astro-ph/0206201)." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1433 SUBJECT: GRB 020531, INT+WFC deep optical upper limits DATE: 02/06/19 21:08:00 GMT FROM: Evert Rol at U.Amsterdam Isabel Salamanca, Evert Rol (University of Amsterdam), Nial Tanvir (University of Hertfordshire), Lex Kaper (UoA), on behalf of a larger collaboration, report: "We have observed the error box of GRB 020531 (GCN #1399, #1402) with the Wide Field Camera on the 2.5m Isaac Newton Telescope, La Palma. The observations were performed in Harris V filter*, under non-photometric conditions. The field was calibrated with the calibration provided by Henden (GCN #1422). The results are summarized below: mid-exposure exposure time lim. magn. seeing (UT days) (min) (3 sigma) (arcsec) May 31.92 30 24.7 1.4 June 2.99 40 25.2 1.2 We do not measure any source fading by more than 0.3 magnitude between the two epochs. A refined analysis of the Chandra sources (GCN #1415, #1426) visible in our images is being carried out and will be published in a following GCN Circular. An image including the IPN errorbox can be found at http://www.astro.uva.nl/~evert/grb020531/. We acknowledge the assistance of the ING staff." This message can be cited. *) The Harris V filter is close to the standard Landolt V filter. For the calibration, color correction terms have been used and can be found at http://www.ast.cam.ac.uk/~wfcsur/photom.html. [GCN OPS NOTE (19Jun02): This Circular was delayed 1.5 hours because of an obselete address in the vetted list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1434 SUBJECT: Fading Optical Source in the Field of GRB020531 DATE: 02/06/20 02:49:35 GMT FROM: George Ricker at MIT Fading Optical Source in the Field of GRB020531 A. Dullighan, G. Monnelly, N. Butler, R. Vanderspek, P. Ford, G. Ricker (MIT); H. Ebeling, R. Wainscoat (U. Hawaii); N. Kawai, A. Yoshida (RIKEN, Japan) write: We have observed the error box of the short-hard burst source GRB020531 (GCN #1399, #1402) with the Baade 6.5m telescope at the Magellan Observatory on June 1.16 and June 10.13 UT, and with the Subaru 8.2m telescope at Mauna Kea Observatory on June 5.43 UT. The R band images were calibrated using the data provided by Henden et al.(GCN #1422). Our observations were as follows: 2002 Date Instrument, Exposure Time Limiting R Mag. UT Telescope (sec) (3 sigma) June 1.16 LDSS2, Baade 180 23.6 June 5.43 SuprimeCam, Subaru 420 25.5 June 10.13 LDSS2, Baade 360 x 2 24.0 We detect a fading optical counterpart for Chandra Source #5 (GCN #1415) in all three epochs. 2002 Date R Mag Error UT of #5 June 1.16 23.12 0.20 June 5.43 23.79 0.06 June 10.13 23.96 0.20 The decline in brightness of the counterpart between the measurements is consistent with a power law decay with alpha = 0.35 +/- 0.05. The relative X-ray brightness of Chandra Source #5 at the two epochs of the Chandra observations is consistent with the optical decay index. However, the independent significance of any X-ray decline is low (1.4 sigma level-of-confidence). Since Source #5 lies just outside the current error box for GRB020531 (GCN #1407), its possible association, if any, with GRB020531 is unclear. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1443 SUBJECT: GRB 020531: optical photometry of Chandra sources DATE: 02/06/27 09:07:40 GMT FROM: Isabel Salamanca at U. of Amsterdam Isabel Salamanca, Evert Rol (University of Amsterdam), Nial Tanvir (University of Hertfordshire), Lex Kaper (UoA), on behalf of a larger collaboration, report: We have performed differential photometry of the sources detected by Chandra (GCN #1399) in the field of view of GRB 020531 (GCN #1399, #1402). The observations were done with the WFC on the INT at La Palma. For more details see GCN 1433. Of the 13 sources detected by Chandra, we detect 5 in both epochs: cx00, cx15, cx48, cx55, cx56. Four more sources are detected only in the second epoch: cx05,cx47,cx58 and cx52. We remark that the source cx00 is also visible in the DSS. We have perfomed differential photometry of the first 4 sources by comparing them with 12 stars in the field. The relative accuracy attained is 0.01 mag. The absolute photometry was done via the photometry performed by Henden etal. (GCN #1422). The estimated error in the zero point is higher, 0.4 mag, due to the fact that the observations were performed under non-photometric conditions. Below is a summary of the magnitudes of each object: Id V mag 31 May 2 June ===================================== 5 >24.7 24.5 15 21.73 21.80 --- --------------------------------- 28 >24.7 >25.2 36 >24.7 >25.2 41 >24.7 >25.2 47 >24.7 23.8 48 23.27 23.20 51 >24.7 >25.2 52 >24.7 24.0 55 23.15 23.19 56 21.71 21.60 58 >24.7 ~25.2 The proposed afterglow candidate, cx48 (GCN #1426, #1427 and #1428) is 0.07 +/- 0.01 mag brighter in the second epoch than in the first. This message may be cited. -- Dr. Isabel E. de Salamanca Anton Pannekoek Institute, UvA Amsterdam - The Netherlands. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1461 SUBJECT: Further refinement to IPN error box for GRB020531 DATE: 02/07/25 22:59:37 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses, Mars Odyssey, and HETE GRB teams, I. Mitrofanov, D. Anfimov, A.Kozyrev, M. Litvak and A. Sanin, on behalf of the HEND/Odyssey GRB team, W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS/Odyssey GRB team, and G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew, G. Monnelly, N. Butler, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, report: We have further refined the IPN error box of the short duration, hard spectrum GRB020531 (GCN 1399, 1402, and 1407) using the final Ulysses ephemeris and clock corrections. The error box now has an area of approximately 9 square arcminutes: 15 h 15 m 11.18 s -19 o 24 ' 27.80 " (CENTER) 15 h 15 m 05.61 s -19 o 23 ' 54.43 " (CORNER) 15 h 15 m 20.22 s -19 o 22 ' 00.52 " (CORNER) 15 h 15 m 02.15 s -19 o 26 ' 54.98 " (CORNER) 15 h 15 m 16.75 s -19 o 25 ' 01.16 " (CORNER) A map will be posted shortly at ssl.berkeley.edu/ipn3/020531. In it, "GCN 1407" indicates the previous IPN error box, "C" indicates the Chandra sources reported in GCN 1415 and 1426, and "T" indicates the TAROT sources reported in GCN 1408, 1420, and 1421. We do not expect further improvements to this error box.