//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8361 SUBJECT: GRB 081012: Swift detection of a burst DATE: 08/10/12 13:19:01 GMT FROM: David Palmer at LANL M. C. Stroh (PSU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), P. A. Evans (U Leicester), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), D. M. Palmer (LANL), D. Perez (U Leicester), J. L. Racusin (PSU), T. Sakamoto (NASA/UMBC), T. N. Ukwatta (GSFC/GWU), L. Vetere (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 13:10:23 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081012 (trigger=331475). Swift did not immediately slew due to the Earth limb constraint. The BAT on-board calculated location is RA, Dec 30.217, -17.641 which is RA(J2000) = 02h 00m 52s Dec(J2000) = -17d 38' 28" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 20 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+49.2 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is M. C. Stroh (stroh AT astroh.org). 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: 8362 SUBJECT: GRB 081012: ROTSE-III Optical Limits DATE: 08/10/12 14:54:25 GMT FROM: Fang Yuan at ROTSE F. Yuan (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to GRB 081012 (Swift trigger 331475, GCN 8361, Stroh et al. ), producing images beginning 7.2s after the GCN notice time. An automated response took the first image at 13:11:03.2 UT, 39.3s after the burst. Early observations were affected by proximity to the full moon and the first usable image started at 13:27:03.0 UT, ~1000s after the burst. We took over 100 20s exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 15.8-16.2; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 13:27:03.0 13:27:23.0 20 15.8 999 N 13:28:01.3 13:32:42.9 281 17.4 1057 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8363 SUBJECT: GRB 081012, Swift-BAT refined analysis DATE: 08/10/12 16:34:59 GMT FROM: Scott Barthelmy at NASA/GSFC G. Sato (ISAS), 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/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), M. C. Stroh (PSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-119 to T+183 sec from recent telemetry downlinks, we report further analysis of BAT GRB 081012 (trigger #331475) (Stroh, et al., GCN Circ. 8361). The BAT ground-calculated position is RA, Dec = 30.184, -17.627 deg which is RA(J2000) = 02h 00m 44.1s Dec(J2000) = -17d 37' 36.2" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%. The mask-weighted light curve shows a roughly symmetrical peak starting at ~T-20 sec, peaking at ~T+1 sec, and ending at ~T+20 sec. There is a possibility of earlier emission at ~T-50 sec. T90 (15-350 keV) is 29 +- 4 sec (estimated error including systematics). The time-averaged spectrum from T-23.1 to T+8.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.03 +- 0.18. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.93 sec in the 15-150 keV band is 1.0 +- 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/331475/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8364 SUBJECT: GRB 081012: Swift/XRT detection DATE: 08/10/12 17:06:28 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. A. Kennea and M. Stroh (PSU) report on behalf of the Swift/XRT Team We have analyzed downlinked data from the XRT observations of GRB 081012 (Stroh et al, GCN #8361). The XRT began observing the field at 14:00:09 UT, approximately 49 minutes after the BAT trigger. Data from the first orbit of observations reveal an uncatalogued point source at RA, Dec = 30.20029, -17.63715 which is the equivalent to: RA(J2000) = 02h 00m 48.0s Dec(J2000) = -17d 38m 13.7s with an estimated uncertainty of 8 arcseconds radius (90% confidence). This position is 67 arcseconds from the BAT refined position (Sato et al, GCN #8363). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8365 SUBJECT: GRB 081012: Swift/UVOT analysis of initial observations DATE: 08/10/12 20:33:06 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL/UCL) and M.C. Stroh (PSU) report on behalf of the Swift UVOT team. The Swift UltraViolet/Optical Telescope (UVOT) began observations of GRB081012 (Swift BAT trigger number 331475, Stroh et al., GCN Circ. 8361), on October 12, 2008, at 14:02:28 ,52 minutes after the trigger. We do not detect any new source at the XRT position reported in GCN Circ. 8364 (Kennea et al.). The magnitude upper limits for detecting GRB081012 at the XTR position are given below for the first observations in the UVOT filters: Filter Tstart(s) Tstop(s) Exp(s) Magnitude uvw2 3125 3325 196.6 >20.09 (3-sigma UL) v 3329 3458 125.8 >19.12 (3-sigma UL) uvm2 4876 5076 196.6 >19.72 (3-sigma UL) uvw1 5082 5282 196.6 >19.94 (3-sigma UL) u 5287 5487 196.6 >20.00 (3-sigma UL) b 5492 5692 196.6 >20.33 (3-sigma UL) wh 5697 5713 15.7 >19.42 (3-sigma UL) The values quoted above are on the UVOT Photometric System (Poole et al, 2008, MNRAS 383,627). They are not corrected for the expected galactic reddening of E(B-V) = 0.023 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8366 SUBJECT: GRB 081012: Observations from NOT DATE: 08/10/13 01:25:26 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (ESO), D. Malesani (DARK/NBI) T. Augusteijn (NOT) report on behalf of a larger collaboration: We have observed the field of GRB 081012 (Stroh et al., GCN 8361) from the 2.5m NOT telescope at Roque de los Muchachos Observatory. A combination of 6x300s R-band observations with mean time 23.79 UT (0.44 days after the burst) did not show any source within the XRT error box (Kennea & Stroh GCN 8364) down to a 3-sigma limiting magnitude of R > 22.0. The images were moderately contaminated by the light of the nearby Moon. We thank the student group from the Mikkeli high school (Finland) for help in carrying out the observations. [GCN OPS NOTE(13oct08): Per author's request, the last paragraph was added.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8370 SUBJECT: GRB 081012: Fermi GBM detection DATE: 08/10/13 18:21:10 GMT FROM: Elisabetta Bissaldi at MPE E. Bissaldi (MPE) reports on behalf of the Fermi GBM Team: "At 13:10:23 UT on 12 October 2008, the Fermi Gamma-ray Burst Monitor triggered and located GRB 081012 (trigger 245509824/081012549), which was also detected by Swift (Stroh et al., GCN 8361). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 30.9, Dec = -19.2 (equivalent to J2000 02h 04m, -19d 12'), with a statistical uncertainty of 6.8 degrees (radius, 1-sigma containment; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). This position is 1.7 deg from the Swift XRT position (Kennea et al., GCN 8364). The angle from the Fermi LAT boresight to the Swift position is 61 degrees. GRB 081012 is single peaked with an estimated T90 (25-900 keV) of about 30 s. The time-averaged spectrum from T0-3.1 s to T0+7.2 s is well fit by a power law function with an exponential high-energy cutoff. The cutoff energy, parameterized as Epeak, is 360 +/- 70 keV with a power law index of -0.31 +/- 0.23. It can also be fit by using a Band function with Epeak = 320 +/- 80 keV and beta = -2.4 +/- 0.7. However alpha is poorly constrained. The fluence (25-900 keV) for the power law model with exponential cutoff is (3.8 +/- 0.4)E-06 erg/cm2. The 1 sec peak photon flux measured starting from T0+4.1 in the 25-900 keV band is 2.0 +/- 0.2 ph/s/cm2. The spectral analysis results presented above are preliminary; the final results will be published in the Fermi GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8373 SUBJECT: GRB 081012: GROND upper limits DATE: 08/10/14 09:44:50 GMT FROM: Robert Filgas at MPI R. Filgas, T. Kruehler, J. Greiner, C. Clemens, A. Yoldas (all MPE Garching), A. Rossi (Tautenburg Obs.), A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile), started observations of the field of GRB 081012 (Stroh et al. 2008, GCN #8361) in g'r'i'z'JHK at 07:43 UT on 13. Oct. 2008, 18.5 hours after the burst. This burst was also detected by the Fermi GBM (Bissaldi 2008, GCN #8370). GROND observations consisted of 20 115-s integrations in g'r'i'z' and 240 10-s integrations in JHK. We do not detect a source in the XRT error circle (Kennea & Stroh 2008, GCN #8364) in the stacked images down to limiting magnitudes (all in Vega system) of g' > 23.2 r' > 23.5 i' > 22.8 z' > 22.8 J > 21.5 H > 20.4 K > 19.4 The given limits are derived based on calibrating the images against USNO and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.023 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8391 SUBJECT: GRB 081012 - Enhanced Swift XRT position DATE: 08/10/20 15:53:53 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 1387 s of XRT Photon Counting mode data and 2 UVOT images, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching to the USNO-B1 catalogue): RA, Dec = 30.2009, -17.6383 which is equivalent to: RA (J2000): 02 00 48.22 Dec (J2000): -17 38 18.0 with an uncertainty of 1.8 arcsec (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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular is an offical product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8394 SUBJECT: GRB 081012: Swift-XRT Refined Analysis DATE: 08/10/21 21:48:38 GMT FROM: Michael Stroh at PSU/Swift M.C. Stroh and C. Pagani (PSU) report on behalf of the Swift-XRT team: We have analyzed the Swift-XRT data obtained for GRB 081012 (Stroh et al., GCN Circ. 8361), totaling 30.4ks of Photon Counting data. The X-ray light-curve can be fit by a simple power law with a decay index of 1.49 +/- 0.07. The spectrum can be fit with an absorbed power-law with absorption consistent with the Galactic nH value (2.37e20 cm-2, Kalberla et al. 2005) and with a photon index of 1.44 (+0.35/-0.34). The average observed (unabsorbed) 0.3-10 keV flux is 6.19e-11 (6.40e-11) ergs/cm^2/ s. This is an official product of the Swift-XRT team.