//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13357 SUBJECT: GRB 120612A: Swift detection of a burst DATE: 12/06/12 02:18:17 GMT FROM: Scott Barthelmy at NASA/GSFC C. Pagani (U Leicester), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (NASA/UMBC), S. T. Holland (STScI), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 02:05:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120612A (trigger=524128). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 126.726, -17.578 which is RA(J2000) = 08h 26m 54s Dec(J2000) = -17d 34' 39" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows s single broad peak with a duration of about 30 sec. The peak count rate was ~1250 counts/sec (15-350 keV), at ~7 sec after the trigger. The XRT began observing the field at 02:07:38.1 UT, 138.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 126.72350, -17.57649 which is equivalent to: RA(J2000) = 08h 26m 53.64s Dec(J2000) = -17d 34' 35.4" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 10 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 consistent with the Galactic value of 5.49 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 5.98e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 147 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 typical 3-sigma upper limit has been about 19.6 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 0.07. Burst Advocate for this burst is C. Pagani (cp232 AT star.le.ac.uk). 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: 13358 SUBJECT: GRB 120612A: BOOTES-3 optical upper limit DATE: 12/06/12 07:36:14 GMT FROM: Juan Carlos Tello at IAA-CSIC J.C. Tello (IAA-CSIC), A.J. Castro-Tirado (IAA-CSIC), J. Gorosabel (IAA-CSIC), W. Allen (Vintage Lane Obs.), Ph. Yock and Kuan-Yu Lin (Auckland Univ.), P. Kubanek (IP AS CR & IAA-CSIC), report on behalf of a larger collaboration: "We observed the field of GRB 120612A (Pagani et al., GCNC 13357), detected by Swift/BAT, with the 0.6m Yock-Allen robotic telescope (BOOTES-3) located in Blenheim, New Zealand. Unfiltered images were obtained starting 05:58:29UT (3h53m after the burst, limited by sunset). The first 40 images, each of 60 seconds, were combined (with the last exposure ending at 06:39:14 UT). This resulted in a limiting magnitude of 18.0 when calibrated with the R1Mag value of USNO-B1.0 catalogue stars." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13359 SUBJECT: GRB 120612A: Enhanced Swift-XRT position DATE: 12/06/12 11:30:36 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1361 s of XRT Photon Counting mode data and 2 UVOT images for GRB 120612A, 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 = 126.72179, -17.57496 which is equivalent to: RA (J2000): 08h 26m 53.23s Dec (J2000): -17d 34' 29.9" with an uncertainty of 1.6 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: 13360 SUBJECT: GRB 120612A: Swift-BAT refined analysis DATE: 12/06/12 12:28:06 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), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), C. Pagani (U Leicester), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120612A (trigger #524128) (Pagani, et al., GCN Circ. 13357). The BAT ground-calculated position is RA, Dec = 126.723, -17.598 deg which is RA(J2000) = 08h 26m 53.5s Dec(J2000) = -17d 35' 52.9" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curve shows a broad peak starting at ~T+15 sec, peaking at roughtly T+35 sec, and ending around T+150 sec with a long low-level tail out to about T+380 sec. T90 (15-350 keV) is 90 +- 14 sec (estimated error including systematics). The time-averaged spectrum from T+16.9 to T+125.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.36 +- 0.16. The fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+30.20 sec in the 15-150 keV band is 0.5 +- 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/524128/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13361 SUBJECT: GRB 120612A: Swift-XRT refined Analysis DATE: 12/06/12 14:18:04 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), O.M. Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. Mangano (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), J.A. Kennea (PSU), M.C. Stroh (PSU) and C. Pagani report on behalf of the Swift-XRT team: We have analysed 13 ks of XRT data for GRB 120612A (Pagani et al. GCN Circ. 13357), from 144 s to 30.4 ks after the BAT trigger. The data comprise 91 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 13359). The light curve can be modelled with an initial power-law decay with an index of alpha=3.27 (+0.26, -0.22), followed by a break at T+485 s to an alpha of 0.90 (+0.11, -0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.20 (+0.23, -0.22). The best-fitting absorption column is 1.9 (+/-0.6) x 10^21 cm^-2, in excess of the Galactic value of 5.5 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.9 (+/-0.6) x 10^21 cm^-2 Galactic foreground: 5.5 x 10^20 cm^-2 Excess significance: 3.9 sigma Photon index: 2.20 (+0.23, -0.22) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00524128. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13362 SUBJECT: GRB 120612A: Swift/UVOT observations DATE: 12/06/12 18:08:11 GMT FROM: Craig Swenson at PSU/Swift C.A. Swenson (PSU) and C. Pagani (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120612A 148 s after the BAT trigger (Pagani et al., GCN Circ. 13357). No new optical afterglow consistent with the XRT posistion (Evans et al., GCN Circ. 13359) is detected in the initial UVOT exposures. We note that there is a DSS source, which complicates the UVOT analysis, located at RA, DEC = 126.72113, -17.57439. This source lies 3.05 arcsec from the XRT position and may or may not be related to GRB 120612A, though we see no sign of variability in the source in the first 1500 s of UVOT observations. The source is also listed in the USNOB catalog with a color of (B-R) = 0.728, corrected for Galactic reddening. Follow-up observations are encouraged to determine a redshift for the DSS source to determine whether this is potentially the host galaxy. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13363 SUBJECT: GRB 120612A: optical observations DATE: 12/06/13 00:32:25 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), R. Sanchez-Ramirez (IAA-CSIC and DARK/NBI), J. P. U. Fynbo (DARK/NBI), report on behalf of the X-shooter GRB GTO collaboration: We observed the field of GRB 120612A (Pagani et al., GCN 13357) with the ESO VLT equipped with X-shooter. Observations were taken with the acquisition camera in the R and z filters, with an exposure time of 45 s each. The images were obtained around 23:25 UT (about 21.3 hr after the GRB). Within the revised XRT error circle (Evans et al., GCN 13359), we do not detect any object in either filters, down to a limiting magnitude R = 22.5 (3 sigma). We confirm the presence of a bright star just outside the XRT circle (Swenson et al., GCN 13362), which brightness is consistent with the value reported in the USNO catalog. This object is pointlike (with a seeing of 1.3") and is significantly outside the XRT error circle, so it is very likely unrelated to the GRB. We acknowledge excellent support from the observing staff in Paranal, in particular Alain Smette and Claudio Melo.