//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3235 SUBJECT: GRB 050412: IR Observations DATE: 05/04/12 06:26:39 GMT FROM: Josh Bloom at Harvard/CFA J. S. Bloom (UCB) and C. Blake (CfA) reports on behalf of a larger collaboration: "We begin imaging the field of GRB 050412 (Swift Trigger #114485) with the PAIRITEL 1.3m at Mt. Hopkins at 2005-04-12 05:48:37 UTC, about 2m55sec after the GRB trigger. There are no new sources in the error circle to 2MASS detection levels. Further observations and anaylses are ongoing." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3236 SUBJECT: GRB 050412: IR and Optical observations DATE: 05/04/12 07:05:00 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, S. Piranomonte, P. D'Avanzo, F.M. Zerbi, G. Chincarini, M. Rodono', G. Tosti, L.A. Antonelli, P. Conconi, G. Cutispoto, E. Molinari, L. Nicastro, E. Palazzi, E. Meurs, P. Goldoni, on behalf of the REM/ROSS Team The REM telescope at the La Silla Observatory (ESO) is observing the field of GRB 050412. Observations began 34 sec after the alert (39 sec after the burst). Preliminary analysis of the first frames reveal no new sources in the error circle approximately down to the 2MASS limit in the H band and down to R = 18 in the optical. Observations and further analyses are going on. This message may be cited, //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3237 SUBJECT: Swift-BAT Detection of GRB 050412: A Bright, Long Burst DATE: 05/04/12 07:21:04 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. Cummings (GSFC/NRC), L. Barbier, S. Barthelmy (GSFC), E. Fenimore (LANL), M. Galassi (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), M. Tripicco (GSFC-SSAI), J. Tueller (GSFC), D. Burrows (PSU), J. Kennea (PSU), V. Mangano (IASF-CNR) on behalf of the Swift team: At 05:44:03 UT, Swift-BAT triggered on burst GRB 050412 (trigger=114485) and began to slew 35 seconds after the trigger. The BAT onboard position is RA, Dec = 181.120, -1.252 (J2000) with an estimated error of <4 arcminutes. The lightcurve shows a complex multi-peaked emission from 9 seconds before the trigger to at least 15 seconds after. There was strong flux in all energy bands from 15 to 350 keV. The 1 second peak count rate is 0.8 ph/cm2/s (15-350 keV). We note that this burst is well suited for ground-based followup, being anti-Sunward, far from the Moon, away from the Galactic plane, and equatorial. No object was detected by the XRT on-board software, beginning at about T+100 seconds. However, the XRT counting rate is slightly elevated, indicating a possible weak counterpart. Further information from all 3 Swift instruments will be available when data from the Malindi ground station are received and processed at about 11:00 UT. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3238 SUBJECT: GRB050412: ROTSE-III Optical Limits DATE: 05/04/12 07:37:07 GMT FROM: Robert Quimby at U of Texas/ROTSE R. M. Quimby (UTexas), E. S. Rykoff (UMich) and B. E. Schaefer (LSU) report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas responded automatically to Swift GRB050412 (Trigger #114485), producing images beginning 7.1 seconds after receiving the GCN trigger under excellent conditions. The first image was taken at 05:44:48.0 UT, 45.1 seconds after the burst. We have taken ten 5 second, ten 20 second and forty 60 s exposures and imaging is ongoing. The images are unfiltered and were calibrated relative to USNO A2.0. Individual images have limiting magnitudes ranging from 17.5-19.1. Comparison to DSS (second epoch) reveals no new sources within the 3-sigma BAT error circle to a limiting magnitude of 17.5 for the first 5 second exposure. Coadding the images into sets of 10 revels no new sources down to 19.1, 19.9 (beginning 05:45:52.1), and 20.3 (beginning 05:50:43.4) magnitude. Analysis is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3239 SUBJECT: GRB 050412: LCO optical observations DATE: 05/04/12 08:29:43 GMT FROM: Edo Berger at Carnegie Obs Edo Berger (Carnegie Observatories), Nidia Morrell (LCO), Brian Schmidt (RSAA, ANU), Derek Fox (Caltech), and Paul Price (IfA, Hawaii) report on behalf of a larger collaboration: "Starting on 2005, April 12.267 UT (41 min after the burst) we imaged the BAT error circle of GRB 050412 (GCN 3237) with the DuPont 100-inch telescope at LCO in the R-band. Two 10-minute images were obtained. A comparison to DSS reveals no new sources to the limit of the survey (R~20.5 mag). Furthermore, no sources exhibit a clear fading behavior between the two images to a limit of R~20.5 mag and delta-R~0.2 mag." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3240 SUBJECT: GRB050412: optical limit before and during GRB DATE: 05/04/12 09:14:19 GMT FROM: Grzegorz Wrochna at Soltan Inst.for Nuclear Studies M.Cwiok, K.Krupska, K.Kwiecinska, L.Mankiewicz, K.Nawrocki, B.Pilecki, L.W.Piotrowski, M.Sokolowski, D.Szczygiel, G.Wrochna, on behalf of "Pi of the Sky" collaboration http://grb.fuw.edu.pl The GRB 050412 (GCN 3237) error box was observed by "Pi of the Sky" apparatus at Las Campanas Observatory for most of the night. No new object has been found within the Swift-BAT error box before, during or after the GRB. The limiting magnitude on single exposures (10s) and sums of 20 images is 11m and 11.5m respectively (unfiltered). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3241 SUBJECT: GRB 050412: Swift XRT Position DATE: 05/04/12 11:38:26 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT F. Tamburelli, P. Giommi, M. Capalbi, M. Perri (ASDC), J. Kennea, D. N. Burrows, J. A. Nousek, M. Chester (PSU), V. Mangano, T. Mineo (IASF/Palermo), A. F. Abbey, P. T. O'Brien (U. Leicester), A. Moretti, G. Tagliaferri (OAB), L. Angelini, F. Marshall, and N. Gehrels (NASA/GSFC) report on behalf of the Swift XRT team: The Swift BAT instrument detected a GRB at 05:44:03 UT on 12th April 2005 (GCN Circ 3237). The observatory executed an automated slew to the BAT position and the XRT began taking data at 05:45:42 UT. The XRT was in Auto state but was not able to centroid on the afterglow due to low source brightness. From downlinked data we find a uncataloged X-ray source located at: RA(J2000) = 12:04:25.3, Dec(J2000) = -1:12:02.2. We estimate an uncertainty of about 5 arcseconds radius (90% containment). This position is 191 arcseconds from the BAT position reported in GCN 3237. [GCN_OPS_NOTE (12apr05): Per author's request, the "050406" in the Subject line was changed to "050412".] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3242 SUBJECT: GRB050412: P60 Observations DATE: 05/04/12 11:59:28 GMT FROM: S. Bradley Cenko at Caltech S. Bradley Cenko and Derek B. Fox (Caltech) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: We have imaged the field of GRB050412 with the automated Palomar 60-inch telescope. Observations began approximately 6 minutes after the burst. Our early time images consist of 3 x 60 second exposures each in the Kron R (mean epoch 5:57 UT, t ~ 13 minutes after the burst) and Gunn i (6:02 UT) and z (6:12 UT) bands. We find no sources in the XRT error circle reported in GCN 3241. Our limiting magnitude, estimated by comparison with several stars from the Guide Star Catalog, is approximately R < 20.0 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3243 SUBJECT: GRB 050412: Optical observations DATE: 05/04/12 12:35:02 GMT FROM: Brian Lindgren Jensen at U.of Copenhagen GRB 050412: Optical observations Brian L. Jensen (Niels Bohr Institute), Javier Gorosabel (IAA-CSIC (Granada)), Peter Laursen, Pall Jakobsson, Darach Watson, Johan P. U. Fynbo, Jens Hjorth (Niels Bohr Institute) report: "Using DFOSC on the Danish 1.5m Telescope on La Silla we have obtained 2550s R-band imaging of the BAT error circle for GRB 050412 (GCN #3237) starting at 1.2 hr after the GRB trigger. In the XRT error-circle (GCN #3241) we detect a single source. The estimated magnitude of this source at t+1.5h is R ~ 22." [GCN_OPS_NOTE(12apr05): The affiliations were fixed up.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3244 SUBJECT: GRB 050412: LCO Optical Observations DATE: 05/04/12 13:01:48 GMT FROM: Derek Fox at CIT Derek B. Fox (Caltech), S. Bradley Cenko (Caltech), Edo Berger (Carnegie Observatories), and Nidia Morrell (LCO) report on behalf of a larger collaboration: "Examination of our images (GCN 3239) of the GRB 050412 localization region (GCN 3237) reveals a single optical source proximate to the XRT position (GCN 3241). Its coordinates are: RA 12:04:25.0, Dec -01:12:04 (J2000) by reference to USNO B-1.0 catalog astrometry. Due to saturation of bright stars in our images and the faintness of the source, we are not able to perform very accurate photometry at this time; we estimate it to have R >~ 21.5 mag at 55 minutes after the burst. If this source is the one referred to by Jensen et al. (GCN 3243), it is not clear that the source is brighter in our images." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3245 SUBJECT: GRB 050412: Optical limit DATE: 05/04/12 13:17:54 GMT FROM: Ken ichi Torii at RIKEN K. Torii (Osaka U.) reports "The error region of GRB 050412 (Cummings, et al. GCN 3237) was observed with the 0.3-m telescope in the New Mexico Skies observatory. Imaging through clear filter started at 05:48:13 UT (250-s after trigger) and 10 frames of 120-s exposure were obtained. We do not find an optical counterpart to the X-ray source (Tamburelli, et al. GCN 3241) and derive its 3-sigma upper limit relative to USNO-A2.0 (R) mag as follows. MeanEpoch Magnitude Exposure 05:49:13 >18.9 120s 06:00:31 >20.5 10x120s " //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3247 SUBJECT: GRB 050412: UVOT transient not in XRT error circle DATE: 05/04/12 13:53:06 GMT FROM: Josh Bloom at Harvard/CFA D. Pooley (UCB) and J. S. Bloom report: "Inspection of the Swift UVOT Quicklook for GRB 050412 reveals a rapidly fading source at position: 12:04:31.5 -01:11:53.8 (J2000) This is not in the XRT error box. Further astrometric and photometric calibrations are ongoing. For reference, there is a nearby source (with the current astrometric solution from the Quicklook) at: 12:04:27. -01:11:19.2 See http://birrung.mit.edu/dave/GRB050412" This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3248 SUBJECT: GRB 050412: retraction of UVOT transient report DATE: 05/04/12 14:25:22 GMT FROM: Josh Bloom at Harvard/CFA D. Pooley (UCB) and J. S. Bloom report: "Upon further inspection of the Swift UVOT Quicklook for GRB 050412 we cannot confirm the reality of the transient reported in the previous circular (GCN #3247)." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3249 SUBJECT: GRB 050412: Early Optical/Ultraviolet Observations with DATE: 05/04/12 14:41:30 GMT FROM: Pete Roming at PSU P. Roming (PSU), V. Mangano (INAF-IASF/Palermo), S. T. Holland (GSFC-USRA), W. Landsman (GSFC), P. Schady (PSU & MSSL), D. Hinshaw (GSFC-SPSYS), S. Kobayashi (PSU), A. Blustin (MSSL), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), and A. Wells (Leicester) on behalf of the Swift UVOT team report: The Swift Ultraviolet/Optical Telescope (UVOT) observed the field of GRB 050412 (Cummings et al., GCN 3237) starting at 05:45:40 UT on 12 April 2005. We find no evidence for a source in the 5 arcsecond radius XRT error circle (Tamburelli et al., GCN 3241) in the UVOT data. The 3-sigma limiting magnitudes in a 3.5 arcsecond radius circular aperture is V = 19.1 with a systematic uncertainty of 0.1 mag due to uncertainty in the preliminary flight photometric zero point. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3250 SUBJECT: GRB 050412: ANU 2.3m observations DATE: 05/04/12 15:00:45 GMT FROM: Brian Schmidt at RSAA, ANU (MSSSO) Brian P Schmidt (Australian National University) and Matthew Whiting (UNSW) report on behalf of a larger collaboration: "We observed a 6' region covering the XRT position of the SWIFT burst GRB 050412 (GCN#3237) using the ANU 2.3m telescope on April 12.27 UT in R band. The object located within the XRT error circle (GCN#3241) located at RA 12:04:25.0, Dec -01:12:04 J2000, (GCN#3241, GCN#3243), in comparison with the images of Berger et al (GCN#3239), is detected at poor SNR at approximately the same brightness. Neither set of images shows the UVOT transient object reported by Pooley and Bloom (GCN#3247) to at least R=21mag." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3251 SUBJECT: GRB 050412: Swift-BAT refined analysis DATE: 05/04/12 16:38:05 GMT FROM: Scott Barthelmy at NASA/GSFC J. Tueller, L. Barbier, S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), M. Tashiro (Saitama U.) on behalf of the Swift/BAT team: At 05:44:03 UT Swift-BAT detected GRB 050412 (trigger=114485) (GCN Circ 3237, Cummings et al.). The refined BAT ground position is (RA,Dec) = 181.089, -1.206, [deg; J2000] +- 3 arcmin, (95% containment). This is 1.0 arc minutes from the position determined by the XRT (GCN Circ 3241, Tamburelli et al.) and the LCO (GCN Circ 3244, Fox et al.) Examination of the mask weighted light curve shows a 16-second main peak, starting ~8 seconds before the trigger and having a roughly symmetrical shape. This is followed by smaller secondary peaks lasting until ~24 seconds after the trigger. The estimated T90 (15-350 keV) is 26 seconds +/- 2 secs (estimated error including systematics). Analysis of the event data shows that this is a very hard burst with significant emission throughout the BAT energy range (15-350 keV). The time-averaged total spectrum is consistent with a simple power-law, with a photon index of -0.62 +/- 0.18 (90% confidence). However, there may be significant systematic uncertainties with such a hard spectrum. The photon index of the 5-s peak spectrum (starting at T0-0.784 s) (also simple power-law) is -0.47 +/- 0.23 (90% confidence). The fluence derived from the event data is 2.1 (+/- 0.5) X 10^-6 erg/cm^2 in the 15-350 keV band and 9.6 (+/- 1.1) X 10^-7 erg/cm^2 in the 15-200 keV band. The 5-s peak flux is 0.7 +/- 0.1 ph/cm^2/s (15-350 keV). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3252 SUBJECT: GRB 050412 : XingLong optical observation DATE: 05/04/12 18:32:27 GMT FROM: Yuji Urata at RIKEN Y. Qiu, C.L Lu (BAO), Y.Q. Lou(THCA), K.Y. Huang, W.H. Ip(NCU), Y. Urata (RIKEN) on EAFON report " We have observed the XRT error region of GRB 050412 (Tamburelli et al. GCN 3241) using 0.8-m telescope at XingLong Observatory, China. Eight R-band images with each 300 exposure times are taken from 15.93 UT to 16.55 UT (~ 10.20 hrs to 10.82 hrs after the burst). Coadding the eight images yields the 3-sigma limiting magnitude of R~20, which was calibrated relative to USNO-B1.0 catalog. No new source was detected in our images. There is no optical emission from the optical candidate reported by Fox et al. (GCCN 3244) down to the limiting magnitude." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3253 SUBJECT: GRB 050412: early Swift XRT analysis results DATE: 05/04/12 19:10:35 GMT FROM: David Burrows at PSU/Swift V. Mangano (IASF/Palermo), M. Capalbi (ASDC), C. Pagani (INAF-OAB), M. Goad (U. Leicester), J. Kennea and D. Burrows (PSU) report on behalf of the Swift XRT team: We have analyzed the Swift XRT data from the first orbit observation of GRB 050412 (Tamburelli et al., GCN3241). The new refined coordinates are: RA(J2000) = 12h 04m 25.5s Dec(J2000) = -01:12:00.2 This position is 65.6 arcseconds from the refined BAT position given in GCN 3251 (Tueller et al. 2005) and 3.6 arcsec from the preliminary XRT position (GCN3241). We estimate an uncertainty of 5 arcseconds radius (90% containment). The [0.2-10] keV light curve in Windowed Timing (WT) and Photon Counting (PC) mode starts ~100 seconds from the BAT trigger (T0). We clearly detect a rapidly fading source. A preliminary spectral fit to the WT data gives a spectral power law photon index of 1.35 +/- 0.2 in the [0.5-10] keV band, assuming Galactic absorption (2.21E20cm^-2). The average (~10000 seconds from trigger) estimated unabsorbed 0.5-10 keV flux is then about 3.9E-12 erg cm^-2 s^-1. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3255 SUBJECT: GRB 050412: optical observations DATE: 05/04/12 23:46:02 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA M. Jelinek, A. de Ugarte Postigo, V. Casanova, J. Gorosabel and A. J. Castro-Tirado (IAA-CSIC, Granada) report: Following the detection by SWIFT of GRB 050412 (Cummings et al. GCN Circ. 3237) we have observed the error box with the 1.5m IAA's telescope at Observatorio de Sierra Nevada in southern Spain. We have obtained 28 x 120s images in the R-band under good seeing conditions (1.3") starting on 12.833 Apr (i.e. 14.55 hr after the event). We confirm the presence of an object mentioned by Jensen et al. (GCN Circ. 3243) and Fox et al. (GCN Circ. 3244) at coordinates: RA: 12:04:25.06 DEC: -01:12:03.6 (J2000). Expected astrometric uncertainty is 0.5". We find a preliminary magnitude of the object to be R = 22.75 +/- 0.14 compared to USNO-A2 stars, implying that the object has not faded in brightness significantly, i.e. it might be unrelated to GRB 050412. We also notice that it is 9" from the SWIFT/XRT error box (5" error radius) provided by Mangano et al.(GCN Circ.3253)." This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3256 SUBJECT: GRB 050412: optical limit DATE: 05/04/13 19:04:59 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li, R. Chornock, S. Jha, and A. V. Filippenko (University of California, Berkeley) report: "The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory robotically observed Swift GRB 050412 (Trigger #114485; Cummings et al., GCN 3237). The first 3x15s grid image started at 05:45:09.0 UT (66s after the burst), but it was not useful due to a technical problem. Subsequent images have varying exposure times from 15s to 360s, and were observed with R, I, V, and z filters. Within the refined XRT error circle (Mangano et al., GCN 3253) we did not detect any sources. Our first useful 15s R-band exposure started at 05:45:53 UT (110s after the burst) has a limiting magnitude of 17.5 when compared to the USNO A2.0 caltalog. A 360s R-band exposure started at 06:12:02 UT has a limiting magnitude of 19.6. One of us (WL) also took two R-band images with the 1.0-m Nickel telescope at Lick Observatory: one 1200s exposure started at 07:56:49 UT and the other 600s exposure started at 08:18:03 UT. The combined image did not detect a source within the XRT error circle to a limiting mag of about 21. " //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3259 SUBJECT: GRB 050412: PROMPT VRcIc Observations DATE: 05/04/13 19:53:06 GMT FROM: Melissa Nysewander at UNC,Chapel Hill M. Nysewander, D. Reichart, J. A. Crain report on behalf of the UNC team of the FUN GRB Collaboration: We observed the BAT localization of GRB 050412 (Cummings et al., GCN 3237) with PROMPT beginning 5m 50s after the burst. We do not detect a source within the XRT localization (Tamburelli et al., GCN 3241; Mangano et al. GCN 3253) nor the source identified by Jensen et al. (GCN 3243). 3-sigma limiting magnitudes are based on 10 USNO-B1.0 stars for Rc and Ic observations, and 10 NOMAD stars for V observations: Start Time Integration Filter Limiting Telescope Since GRB Time Magnitude 5m 50s 10 x 10s Rc 18.5 PROMPT-5 8m 48s 10 x 10s Ic 18.0 PROMPT-5 + 1 x 20s 14m 30s 1 x 30s Rc 17.9 PROMPT-5 15m 46s 3 x 30s V 20.0 PROMPT-5 + 10 x 60s 39m 44s 10 x 60s Rc 20.3 PROMPT-5 50m 42s 10 x 60s Ic 18.9 PROMPT-5 61m 46s 10 x 60s V 19.2 PROMPT-5 73m 22s 10 x 60s Rc 20.0 PROMPT-5 84m 29s 10 x 60s Ic 18.3 PROMPT-5 95m 24s 30 x 60s Rc 17.6 PROMPT-5 PROMPT is still being built and commissioned. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3263 SUBJECT: GRB 050412: Subaru observations DATE: 05/04/15 05:13:27 GMT FROM: Nobuyuki Kawai at Tokyo Tech G. Kosugi, N. Kawai, K. Aoki, T. Hattori, K. Ohta, and T. Yamada report on behalf of the Subaru GRB team: "We have observed the Swift/XRT position of GRB 050412 reported by Mangano et al.(GCN #3253) in Rc-band with FOCAS on the Subaru 8.2m telescope atop Mauna Kea on the night of Apr.12. We obtained one 60s image at 08:03 UT (2.3 hr after the event) and three 600s images at 12:55 UT (7.2 hr after the event). Our first image shows no afterglow candidates inside the XRT error circle (5" in radius) down to Rc=24.9 (3-sigma). A galaxy 9" SW from the XRT position first mentioned by Jensen et al. (GCN #3243) is found to be Rc=22.6 +/- 0.1. Our second data set revealed an object almost at the center of the XRT error circle with the magnitude of Rc=26.0 +/- 0.5. Due to the marginal detection, we cannot determine whether it is a point source or a galaxy." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3277 SUBJECT: GRB050412: Radio Observations DATE: 05/04/16 20:25:10 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech) reports on behalf of the Caltech-NRAO-Carnegie GRB collaboration: "Using the Very Large Array at 8.5 GHz, we observed the field of GRB050412 (GCN 3237) on 2005 Apr 16.12 UT. We do not detect a radio source coincident with the Swift XRT position (GCN 3253). We place a 2-sigma upper limit of 38 uJy on the XRT error region. Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3291 SUBJECT: GRB 050412: Chandra observations DATE: 05/04/18 20:30:54 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie Observatories) and D. B. Fox (Caltech) report: "We observed the position of GRB 050412 (GCN 3237) with the Chandra X-ray Observatory + ACIS for 20 ksec beginning on 2005 April 17.392 UT. A comprehensive "wavdetect" analysis reveals no X-ray sources in the XRT 5-arcsec error circle (GCN 3253). The 90%-confidence upper limit is 5 counts, or 2.5e-4 counts/sec. Assuming a photon index of 1.35 as inferred from the XRT data, and a Galactic column density of 2.2e20 cm^-2, we estimate that the upper limit on the unabsorbed 0.5-10 keV flux is 3.6e-15 erg/cm^2/sec. A comparison to the 0.5-10 keV flux measured by the XRT at 0.116 days after the burst indicates an average fading rate steeper than alpha=-1.8, suggestive of a jet break between the two observations." We are grateful to the Chandra Science Data Center for providing rapid data processsing of this observation, and we thank Harvey Tananbaum for his allocation of Director's Discretion Time.