//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10916 SUBJECT: GRB 100702A: Swift detection of a short burst DATE: 10/07/02 01:23:20 GMT FROM: David Palmer at LANL M. H. Siegel (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J. M. Gelbord (PSU), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), D. M. Palmer (LANL) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 01:03:47 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100702A (trigger=426438). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 245.702, -56.538 which is RA(J2000) = 16h 22m 49s Dec(J2000) = -56d 32' 15" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with a duration of about 0.3 sec. The peak count rate was ~11000 counts/sec (15-350 keV), at ~0.2 sec after the trigger. The XRT began observing the field at 01:05:21.1 UT, 93.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 245.6969, -56.5316 which is equivalent to: RA(J2000) = 16h 22m 47.26s Dec(J2000) = -56d 31' 53.8" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 24 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 2.84e+21 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 9.31e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 101 seconds after the BAT trigger. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. A known source from the DSS is within the XRT error circle. However, because of the density of catalogued stars, further analysis is required to determine if this is the GRB host, afterglow or an unrelated background source. The coverage of the XRT error circle by the 8'x8' region for the list of sources generated on-board is uncertain because the large number of sources filled the available telemetry. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the region. No correction has been made for the large, but uncertain extinction expected. Burst Advocate for this burst is M. H. Siegel (siegel AT astro.psu.edu). 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: 10917 SUBJECT: GRB 100702: ROTSE-III Optical Limits DATE: 10/07/02 01:44:13 GMT FROM: Heather Flewelling at IfA/Hawaii H. Flewelling (IfA/Hawaii), W. Zheng (U Mich), S. B. Pandey (U Mich), W. Rujopakarn (Steward), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 100702 (Swift trigger 426438; M. H. Siegel, GCN 10916), producing images beginning 7.7 s after the GCN notice time. An automated response took the first image at 01:04:06.7 UT, 19.5 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 40 60-sec 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 or the XRT error circle, for both single images and coadding into sets of 10; however, we are limited as the field is severely crowded. Individual images have limiting magnitudes ranging from 15.6-15.9; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:04:06.7 01:05:22.8 76 16.1 19.5 Y 01:20:08.4 01:24:48.5 280 16.2 981.2 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10918 SUBJECT: GRB 100702A: VLT optical observations DATE: 10/07/02 04:20:18 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani (DARK/NBI), Andrew J. Levan (Univ. Warwick), Johan P. U. Fynbo (DARK/NBI), report on behalf of the X-shooter GRB collaboration: We observed the field of the short GRB 100702A (Siegel et al., GCN 10916) with the ESO VLT equipped with X-shooter. In the R-band acquisition image, taken starting on 2010 July 2 at 2:05 UT (1 hr after the GRB), we detect two pointlike sources within the XRT error circle (Siegel et al., GCN 10916): A: RA = 16:22:47.05, Dec = -56:31:53.3, R = 15.49 B: RA = 16:22:47.27, Dec = -56:31:55.4, R = 17.20 A third object is located just above the XRT circle: C: RA = 16:22:47.30, Dec = -56:31:50.6, R = 17.25 Photometry was computed against USNO-B1. Sources A and C are clearly visible in the DSS, while source B can be barely spotted, blended with source A. A finding chart is visible at the following URL: http://www.astro.ku.dk/~malesani/GRB/100702A/GRB100702A_finder.jpg A second R-band image was taken 48 minutes after, and none of the above mentioned sources vary by more than 0.05 mag during this time span. For an afterglow decay proportional to t^-1, a variation of ~0.6 mag would be expected. It is thus likely that none of the above sources is related to the GRB. This is not surprising given the moderately crowded field (at Galactic latitude b = -5 deg). We note that the glare from the above mentioned bright objects makes it difficult to identify faint sources within the XRT error circle. We acknowledge excellent and prompt support from the observing staff at Paranal, in particular Christophe Martayan, Andrew Fox, Vincenzo Mainieri, Manuel Olivares, Thomas Szeifert, and the visitor observer, Nick Cox. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10919 SUBJECT: GRB 100702A: Magellan near-IR observations DATE: 10/07/02 04:37:40 GMT FROM: Edo Berger at Harvard W. Fong, E. Berger, and M. Servillat (Harvard) report: "We observed the location of the short GRB 100702A (GCN 10916) with the PANIC infrared imager on the Magellan/Baade 6.5-m telescope starting on 2010 July 2.089 UT (65 min after the burst). A total of 27 min were obtained in the J-band with seeing of about 0.55 arcsec. Within the 2.4-arcsec radius XRT error circle we detect one bright point source and two fainter sources at the following coordinates (J2000; astrometry relative to the 2MASS catalog): S1: RA = 16:22:47.23, DEC = -56:31:55.6 S2: RA = 16:22:47.53, DEC = -56:31:54.6 S3: RA = 16:22:47.24, DEC = -56:31:52.2 Source S1 is the same as source "B" in GCN 10918 (Malesani et al.), while sources S2 and S3 are not detected in their finder. We note that in 2MASS images of the field source S1 is possibly blended with the bright star at RA = 16:22:47.01, DEC = -56:31:53.5 (designated source "A" in GCN 10918), while sources S2 and S3 are below the 2MASS sensitivity threshold. Additional observations are planned to check for variability of sources S2 and S3." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10921 SUBJECT: GRB 100702A: Second epoch of Magellan near-IR observations and afterglow limits DATE: 10/07/02 13:26:12 GMT FROM: Edo Berger at Harvard E. Berger, W. Fong, and M. Servillat (Harvard) report: "We re-observed the location of the short GRB 100702A (GCN 10916) with the PANIC infrared imager on the Magellan/Baade 6.5-m telescope starting on 2010 July 2.290 UT (4.8 hours after our first observation, which started 65 min after the burst; GCN 10919). A total of 27 min were obtained in the J-band with slightly worse seeing than in our first epoch, 0.75 arcsec. Digital image subtraction of the two epochs using the ISIS package reveals no change in the flux of our previously-identified sources S1 (source "B" of Malesani et al. GCN 100918), S2, or S3. No other variable sources are detected within a 45x45 arcsec region centered on the XRT position to a 5-sigma limit of J>22.1 mag (Vega). We note, however, that the bright star at RA = 16:22:47.01, DEC = -56:31:53.5 (designated source "A" in GCN 10918) strongly contaminates the subtracted image over about 1/4 of the XRT error circle." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10922 SUBJECT: Swift/UVOT observations of GRB100702A DATE: 10/07/02 13:37:35 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL-UCL) and M. H. Siegel (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100621A 101s after the BAT trigger (Siegel et al, GCN 10916). The enhanced XRT error circle appears crowded with sources (Malesani et al., GCN 10918, Fong et al, GCN 10919) which blend together. There is no clear indication of change of optical flux between the first exposures and later ones. The preliminary magnitudes and 3-sigma upper limits for the finding chart exposures (FC) and summed images for the emission in the XRT enhanced error circle are: Filter T_start T_stop Exp(s) Magnitude/3-sigma upper limit ------------------------------------------------------------- white (FC) 101 251 147 17.99 +/- 0.07 white 594 10684 1295 17.84 +/- 0.05 u (FC) 314 564 246 18.85 +/- 0.17 u 5020 5151 131 18.96 +/- 0.26 v 4405 17014 735 16.72 +/- 0.04 b 570 6306 216 17.79 +/- 0.08 uvw1 4815 5015 196 > 19.60 uvm2 4610 4810 197 > 19.40 uvw2 4200 16457 1432 > 20.85 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to E_(B-V) = 0.41 mag. All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10923 SUBJECT: Swift/UVOT observations of GRB100702A - correction DATE: 10/07/02 13:54:36 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL) reports: "In the text of the GCN circular 10922, Swift/UVOT observations of GRB100702A', GRB100621A is erroneously mentioned. All the data quoted in that circular refer to GRB100702A. We apologize for the mistake". //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10924 SUBJECT: GRB 100702A: Swift XRT refined analysis DATE: 10/07/02 15:15:29 GMT FROM: Dirk Grupe at PSU/Swift-XRT D. Grupe and M. Siegel (PSU) report on behalf of the Swift-XRT team: We have analyzed 3770 s of XRT data for GRB 100702A (Siegel et al. GCN Circ. 10916), from 100 s to 9676 s after the BAT trigger. The data comprise 190 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The light curve can be modeled with an initial power-law decay with an index of alpha=0.65 (+0.37, -0.25), followed by a break at T+185 s to an alpha of 4.33 (+0.53, -0.24). The afterglow is not detected after the first orbit. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.92 (+0.11, -0.10). The best-fitting absorption column is 3.6 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 2.8 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 4.45 x 10^-11 (6.94 x 10^-11) erg cm^-2 count^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00426438. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10926 SUBJECT: GRB 100702A, Swift-BAT refined analysis DATE: 10/07/02 15:45:04 GMT FROM: Takanori Sakamoto at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), 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), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. H. Siegel (PSU), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (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 100702A (trigger #426438) (Siegel, et al., GCN Circ. 10916). The BAT ground-calculated position is RA, Dec = 245.693, -56.549 deg which is RA(J2000) = 16h 22m 46.4s Dec(J2000) = -56d 32' 57.4" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 61%. The mask-weighted light curve shows a FRED-like pulse starting at T_zero to ~T+0.25 sec. There is a possible weak pulse emission at T-0.25 sec. T90 (15-350 keV) is 0.16 +- 0.03 sec (estimated error including systematics). The time-averaged spectrum from T+0.036 to T+0.236 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.54 +- 0.15. The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.36 sec in the 15-150 keV band is 2.0 +- 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/426438/BA/