//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13032 SUBJECT: GRB 120311A: Swift detection of a burst DATE: 12/03/11 05:42:58 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), M. H. Siegel (PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift Team: At 05:33:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120311A (trigger=517469). Swift did not slew because of the Earth limb observing constraint. The BAT on-board calculated location is RA, Dec 273.087, +14.275, which is RA(J2000) = 18h 12m 21s Dec(J2000) = +14d 16' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak structure with a duration of about 6 sec. The peak count rate was ~5100 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+50.1 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13033 SUBJECT: GRB 120311A: Liverpool Telescope optical candidate DATE: 12/03/11 06:49:39 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara), F. Virgili (LJMU), on behalf of a larger collaboration report: "The 2-m Liverpool Telescope robotically followed up GRB 120311A (SWIFT trigger 517469, Markwardt et al., GCN 13032) 14.4 min after the GRB trigger time. The automatic "detection mode" procedure detected an uncatalogued afterglow candidate close to the XRT error circle (7 arcsec from its centroid) at: 18:12:22.166 +14:17:46.3 (J2000) with magnitude R = 19.1 mag (vs USNOB1) 16 min after the burst. Observations and analysis are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13034 SUBJECT: GRB 120311A: Swift-XRT observations DATE: 12/03/11 07:29:52 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), M. Perri (ASDC) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 120311A at 06:26:19.9 UT, 3161.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 273.08966, 14.29709 which is equivalent to: RA(J2000) = 18h 12m 21.52s Dec(J2000) = +14d 17' 49.5" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 80 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 (1.03 x 10^21 cm^-2, Kalberla et al. 2005), with an excess column of 2.5 (+2.12/-1.86) x 10^21 cm^-2 (90% confidence). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13035 SUBJECT: GRB 120311A: Enhanced Swift-XRT position DATE: 12/03/11 12:15:15 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 762 s of XRT Photon Counting mode data and 2 UVOT images for GRB 120311A, 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 = 273.09198, +14.29643 which is equivalent to: RA (J2000): 18h 12m 22.08s Dec (J2000): +14d 17' 47.2" with an uncertainty of 2.6 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13036 SUBJECT: GRB 120311A: CAHA 1.23m I-band early observations DATE: 12/03/11 13:58:08 GMT FROM: Javier Gorosabel at IAA-CSIC P. Kubanek, M. Jelinek, J. Gorosabel (IAA-CSIC), report on behalf of a larger collaboration: "The 1.23m CAHA telescope responded automatically to GRB 120311A (trigger=517469, Markwardt et al. GCN 13032) starting optical observations on March 11.23381 UT (~3.05 minutes after the trigger). The optical afterglow (Melandri et al. GCNC 13033) is clearly detected in two I-band frames taken before dawn at I ~ 17.3." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13037 SUBJECT: GRB 120311A: Swift/UVOT Upper Limits DATE: 12/03/11 15:16:25 GMT FROM: Patricia Schady at MPE/Swift S. R. Oates (MSSL-UCL) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120311A 3164 s after the BAT trigger (Markwardt et al., GCN Circ. 13032). No optical afterglow, consistent with the refined XRT position (Goad et al .,GCN Circ 13035) or optical position reported by the Liverpool Telescope (Melandri et al., GCN Circ 13033), is detected within the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 3164 3314 147 >16.4 white 3164 16486 2114 >16.5 v 3321 20754 1454 >15.8 b 4141 15574 1224 >16.4 u 3936 5571 393 >16.3 w1 3731 5366 393 >17.7 m2 3526 5161 393 >19.0 w2 4552 17272 1850 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.13 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13039 SUBJECT: GRB 120311A, Swift-BAT refined analysis DATE: 12/03/11 16:07:19 GMT FROM: Craig Markwardt at NASA/GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 120311A (trigger #517469) (Markwardt, et al., GCN Circ. 13032). The BAT ground-calculated position is RA, Dec = 273.075, 14.297 deg which is RA(J2000) = 18h 12m 18.1s Dec(J2000) = +14d 17' 49.0" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 71%. The mask-weighted light curve shows a single gradual-rise exponential-decay peak. T90 (15-350 keV) is 3.5 +- 0.8 sec (estimated error including systematics). The time-averaged spectrum from T-1.38 to T+3.22 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.30 +- 0.15. The fluence in the 15-150 keV band is 3.0 +- 0.3 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.07 sec in the 15-150 keV band is 3.2 +- 0.2 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/517469/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13043 SUBJECT: GRB 120311A: Swift-XRT refined Analysis DATE: 12/03/11 22:58:04 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF/OAB), P. D'Avanzo (INAF/OAB) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed 15 ks of XRT data for GRB 120311A (Markwardt et al. GCN Circ. 13032), from 3.2 ks to 34.5 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 13035). The late-time light curve (from T0+3.2 ks) can be modelled with a single power-law decay with a decay index of alpha=1.09 (+0.13,-0.12). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.03 (+0.27, -0.25). The best-fitting absorption column is 2.6 (+0.9, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 1.0 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.6 (+0.9, -0.8) x 10^21 cm^-2 Galactic foreground: 1.0 x 10^21 cm^-2 Excess significance: 3.2 sigma Photon index: 2.03 (+0.27, -0.25) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00517469. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13048 SUBJECT: GROND observations of GRB 120311A DATE: 12/03/12 15:19:16 GMT FROM: Vladimir Sudilovsky at MPE V. Sudilovsky, T. Prinz, and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 120311A (Markwardt et al., GCN #13032) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP, 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations centered on the BAT position started on March 11, 2012, at 08:02 UT, 2.5h after the GRB trigger. They were performed at an average seeing of 1.0", and average airmass of 1.8. Based on a 20 minute exposure centered at 09:09 UT, the afterglow candidate reported by Melandri et al. (GCN 13033) is measured as follows (all in the AB system and calibrated against GROND zeropoints (g'r'i'z') and 2MASS (JHK)): g' = 22.9 +/- 0.3 r' = 22.5 +/- 0.1 i' = 22.4 +/- 0.1 z' = 22.0 +/- 0.1 J > 20.5 H > 19.6 K > 18.0 These above magnitudes have not been corrected for the Galactic extinction of E(B-V) = 0.13 towards the direction of the burst (Schlegel et al. 1998). These magnitudes imply a fading of more than two magnitudes relative to the observations reported by Melandri et al. (GCN 13033), and thus confirm the afterglow nature of this object. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13051 SUBJECT: GRB 120311A: VLT/X-shooter observations DATE: 12/03/12 19:24:15 GMT FROM: Paul Vreeswijk at U of Iceland Paolo D'Avanzo (INAF/OAB), Bo Milvang-Jensen (DARK/NBI), Paul Vreeswijk (U. Iceland), Nial Tanvir (U. Leicester), Daniele Malesani (DARK/NBI), Paolo Goldoni (APC/U. Paris 7 and SAp/CEA), Lex Kaper (U. Amsterdam), Stefano Covino (INAF/OAB) and Johan Fynbo (DARK/NBI) report on behalf of a larger collaboration: The optical afterglow (Melandri et al., GCN 13033) of the Swift GRB 120311A (Markwardt et al., GCN 13032; Evans et al., GCN 13034) was observed spectroscopically with VLT/X-shooter, starting on 2012 March 11.384 UT (3.65 hours after the GRB trigger). An exposure of 2400 seconds was secured, which ran well into morning twilight. The approximate X-shooter wavelength range is 0.3-2.5 micron. The seeing during the observations was about 0.8" in the optical, and the spectrum has a resulting resolving power of 5000 in the ultraviolet and near-infrared arms, and around 9000 in the optical. The reduced spectrum shows a very weak continuum in all three arms. The very low signal-to-noise ratio prevents us from identifying any significant absorption or emission lines. From the detection of continuum flux down to roughly 3700 Angstrom we set an upper limit to the GRB 120311A redshift of approximately z < 3. Using acquisition images preceding the spectrum, with a mid-exposure time of March 11.373 UT (3.40 hours after the GRB), we measure R = 21.57 +- 0.05 for the afterglow, assuming R=18.30 for the USNO-B1.0 star 1042-0333539 at RA = 18:12:21.82, Dec = +14:17:24.6. We are grateful for the support of the ESO staff at Paranal, in particular that of Gabriel Brammer and Stan Stefl. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13058 SUBJECT: GRB 120311A: C88 optical limits DATE: 12/03/13 12:45:03 GMT FROM: Simone Leonini at Monarrenti Obs Simone Leonini and Paolo Rosi (Montarrenti Observatory, Siena, Italy) report: We observed the field of GRB 120311A (Swift trigger 517469, Markwardt et al., GCN 13032) with 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88). The observations were performed in four sessions (~22 hours after the trigger): from 2012-03-12 03:22:33 UT to 2012-03-12 03:23:15 UT from 2012-03-12 04:16:03 UT to 2012-03-12 04:16:46 UT from 2012-03-12 04:18:09 UT to 2012-03-12 04:18:52 UT from 2012-03-12 04:20:16 UT to 2012-03-12 04:20:59 UT Eight unfiltered images of 40s exposure were obtained. We do not detect any new point source in the coadded images (limit R~19.1, USNO-B1 catalogue) within the refined XRT error circle (Goad et al.,GCN Circ 13035) or in the afterglow candidate position reported by Melandri et al. (GCN Circ 13033). Observations were made on the twilight. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13060 SUBJECT: GRB 120311A: Optical follow-up DATE: 12/03/13 14:09:33 GMT FROM: Shashi Bhushan Pandey at ROTSE Vijay Kumar Bhatt, Brajesh Kumar and S.B. Pandey (ARIES, Nainital, India, on behalf of larger Indian GRB collaboration) We imaged the field of GRB120311A (Swift trigger 517469, Markwardt et al., GCN 13032) using 1.04m and 1.3m telescopes at ARIES Nainital starting ~16 hours after the burst. Several sets of 300s exposures were taken in R_c and I_c pass-bands. We do not detect the optical afterglow candidate (Melandri et al., GCN 13033) in our stacked images to following limits. The photometry was performed in comparison to nearby USNO-B1 stars. Filter Exposure Limiting mag ---------------------------------- R_c 5x300s 20.0 mag I_c 5x300s 19.5 mag ---------------------------------- This massage could be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13063 SUBJECT: GRB 120311A, the review of the sky area in plate archives DATE: 12/03/13 20:44:54 GMT FROM: Valentyna Golovnya at Main Astro Obs,Kyiv V.V.Golovnya (Main Astro Obs, Kyiv) report: We have undertaken the review of the sky area in vicinity of GRB 120311A (M.R. Goad et al. GCN Circ.13035) on astronegatives, collected in Ukrainian NAS Main astronomical observatory plate archive (1976-1996). All the plates with the possible object appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed scanners and have been placed into Golosiiv Plate Archive database DBGPA with open access to them. The list of plates is given in the table: YYYYMMDD/TimeUT --Plates-- Exp. LimMag Star USNOA2 19840817/191914 GUA040C002619 40.1 14.50 0975-10768885 19840817/191917 GUA040D002620 40.1 14.50 0975-10768885 19860613/221841 GUA040C002948 41.7 16.20 0975-10753116 19860613/221846 GUA040D002949 41.7 15.95 0975-10751623 19870630/215915 GUA040C003102 50.5 16.20 0975-10753116 19900627/221058 GUA040C001669 19.0 16.20 0975-10753116 19900628/215100 GUA040C001976 18.0 16.20 0975-10753116 19910619/224921 GUA040C001815 18.0 14.75 0975-10758776 19910704/210331 GUA040C001818A 25.0 15.95 0975-10751623 Plates: –the plates archive identifier of DWA (D/F=400/2000, GUA040C, M=103"/mm) of the Ukrainian NAS Main Astro obs. GUA040D (Marsden's number - 83) the plate number [1]. Exp. - Duration of the maximum exposure (minutes). LimM - Limited V mag, derived in the 25 minutes area around the location given in M.R. Goad et al. GCN Circ.13035: RA(J2000)= 18h 12m 22.08s, Dec(J2000)= +14d 17' 47.2" Star USNOA2 - Comparison star. The preview images of 9 areas together with the 25x25 min.of arc area from SkyMap can be found in http://gua.db.ukr-vo.org/img/grb/120311A/index.html The images with full resolution are available via e-mail on demand. References: 1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0), http://gua.db.ukr-vo.org