//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9585 SUBJECT: GRB 090628: Swift detection of a burst DATE: 09/06/28 21:42:02 GMT FROM: Scott Barthelmy at NASA/GSFC V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), D. M. Palmer (LANL), B. Sbarufatti (INAF-IASFPA), M. Stamatikos (NASA/ORAU) and M. A. Stark (PSU) report on behalf of the Swift Team: At 21:20:12 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090628 (trigger=355942). Swift could not immediately slew to the burst. The BAT on-board calculated location is RA, Dec 237.050, -15.977 which is RA(J2000) = 15h 48m 12s Dec(J2000) = -15d 58' 36" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 5 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an Earth limb constraint, a prompt slew was not possible. Swift will execute a delayed slew after 2656 s. No XRT or UVOT data will be available until the slew occurs. The series GCN Notices for this burst are corrupted with many (but not all) bogus values. For the moment, please disregard the original series of notices. We may issue Updated position notices when the information becomes available. Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). 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: 9586 SUBJECT: GRB 090628: Swift XRT position DATE: 09/06/28 23:04:34 GMT FROM: Vanessa Mangano at INAF-IASFPA B. Sbarufatti, V. Mangano (INAF-IASF PA) report on behalf the Swift XRT team: Analysis of preliminary data from the BAT trigger 355942 (GRB090628, Mangano, et al., GCN Circ 9585) reveals an uncatalogued point source at RA, Dec = 237.05355, -15.98577 which is equivalent to: RA(J2000) = 15h48m12.85s Dec(J2000) = -15:59:08.79 with an estimated uncertainty of 6.5 arcseconds radius (90% confidence). Analysis is ongoing and an improved analysis will be reported as soon as more data will be available. This is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9587 SUBJECT: GRB 090628: Swift/UVOT Finding Chart Observation DATE: 09/06/28 23:55:02 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten and V. Mangano (INAF-IASFPA) report on behalf of the Swift UVOT team: UVOT took a finding chart exposure of 150 seconds with the White filter starting 2790 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 0.18. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9589 SUBJECT: GRB 090628: 1.23m CAHA optical observations DATE: 09/06/29 03:56:33 GMT FROM: Javier Gorosabel at IAA-CSIC P. Kubanek (IAA-CSIC & GACE), N. Morales (IAA-CSIC), J.L. Ortiz (IAA-CSIC), A. de Ugarte Postigo (ESO, INAF/OAB), J. Gorosabel (IAA-CSIC), A.J. Castro-Tirado (IAA-CSIC), M. Jelinek (IAA-CSIC), report on behalf of a larger collaboration: We carried out R-band observations of the GRB 090628 XRT position (Sbarufatti et al., GCN 9586) with the 1.23m Calar Alto telescope. The observations were done on June 28.9486-29.0225 UT (1.43-3.20 hours post GRB) with an exposure time of 3120s. A quick inspection of the XRT error box reveals no object brighter than R ~ 22. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9590 SUBJECT: GRB 090628: Enhanced Swift-XRT position DATE: 09/06/29 08:00:55 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 3973 s of XRT Photon Counting mode data and 2 UVOT images for GRB 090628, 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 = 237.05272, -15.98489 which is equivalent to: RA (J2000): 15h 48m 12.65s Dec (J2000): -15d 59' 05.6" with an uncertainty of 1.9 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, arXiv:0812.3662). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9591 SUBJECT: GRB 090628: GROND upper limits DATE: 09/06/29 09:05:28 GMT FROM: Thomas Kruehler at MPE/MPI T. Kruehler (MPE Garching), S. Klose (Tautenburg) and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 090628 (Swift trigger #355942; Mangano et al., GCN #9585) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 02:06 UT on June 29th, 2009, 4.8 hr after the burst and were performed under poor seeing conditions. In stacked images of 75 min total integration time in griz and 60 min in JHK, we do not detect any object within the enhanced XRT error circle (Goad et al., GCN #9590), down to the following limiting magnitudes (all in the AB system): g' > 23.7 r' > 24.0 i' > 23.0 z' > 22.8 J > 21.8 H > 21.1 K > 20.5 These upper limits were derived using the GROND zeropoints and 2MASS field stars as reference and are not corrected for the Galactic foreground extinction corresponding to a reddening of E(B-V)=0.18 mag (Schlegel et al., 1998). We note the presence of a r'~23.5 mag source ~5 arcsec north east of the center of the enhanced XRT error circle, which given the large offset is very unlikely to be related to the GRB. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9593 SUBJECT: GRB 090628: Swift-BAT refined analysis DATE: 09/06/29 12:43:06 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (GSFC/UMD), 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), V. Mangano (INAF-IASFPA), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+649 sec from recent telemetry downlinks, we report further analysis of BAT GRB 090628 (trigger #355942) (Mangano, et al., GCN Circ. 9585). The BAT ground-calculated position is RA, Dec = 237.038, -15.969 deg, which is RA(J2000) = 15h 48m 09.0s Dec(J2000) = -15d 58' 09.0" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 63%. The mask-weighted light curve shows a weak 1-sec wide precursor peak at ~T-7.5 sec that then returns almost to background levels, and the main peak starting at ~T-0.3 sec, peaking at ~T+1 sec, and ending at ~T+6 sec. T90 (15-350 keV) is 20.1 +- 4.6 sec (estimated error including systematics). The time-averaged spectrum from T-25.0 to T+4.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.36 +- 0.20. The fluence in the 15-150 keV band is 7.0 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.05 sec in the 15-150 keV band is 1.5 +- 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/355942/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9596 SUBJECT: GRB 090628: Swift/UVOT Upper Limits DATE: 09/06/29 22:59:56 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and V. Mangano (INAF-IASFPA) report on behalf of the Swift/UVOT team. The Swift/UVOT began observing the field of GRB 090628 2790s after the BAT trigger (Mangano et al., GCN Circ. 9585). Data summed from the first orbit does not reveal a source at the refined position of the X-ray afterglow (Goad et al., GCN Circ. 9590). The 3-sigma upper limits for the finding chart (fc) and summed exposures are reported below: FILTER T_start(s) T_stop Exposure Mag/3UL ============================================================= white fc 2791 2941 147 > 20.26 white 3361 3560 196 > 20.72 v 3771 3971 196 > 19.23 b 3155 3355 196 > 20.16 b 4591 4672 79 > 19.64 u 2950 3149 196 > 19.63 u 4386 4586 196 > 19.82 uvw1 4181 4381 196 > 19.65 uvm2 3976 4176 196 > 19.33 uvw2 3566 3766 196 > 19.62 ================================================================= The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.05 (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9599 SUBJECT: GRB 090628: Swift XRT refined analysis DATE: 09/06/30 15:35:22 GMT FROM: Vanessa Mangano at INAF-IASFPA V. Mangano, B. Sbarufatti (INAF-IASF PA) report on behalf the Swift XRT Team: We have analyzed 19 ks of PC data of the candidate X-ray afterglow of GRB 090628 (Mangano et al, GCN Circ. 9585) spanning the time interval from T+2796 s to T+101.7 ks. The best position available for the source is the enhanced Swift-XRT position from Goad et al. (GCN Circ. 9590): RA, Dec = 237.05272, -15.98489 which is equivalent to RA (J2000): 15h 48m 12.65s Dec (J2000): -15d 59' 05.6" with an uncertainty of 1.9 arcsec (radius, 90% confidence). The 0.3-10 keV XRT light curve shows an initial flat or rising phase followed by a steep decay. The best fit with a broken power-law model is insensitive to the initial rise slope, of the order of 0.4, possibly consistent with zero, and provides a break at 14+/-4 ks after the trigger and a post-break decay slope of -1.3+/-0.3. The source is rather faint, and at this rate it will reach a level of 8.0e-4 counts/s at T+48 hours. All quoted errors are at the 90% confidence level. The average spectrum can be fitted by an absorbed power-law model with Cash statistics. Best fit spectral parameters are NH < 2.0e21 cm^-2 (consistent with Galactic absorption of 8.7e20 cm^-2, Kalberla et al. 2005) and photon index = 1.4 +/- 0.3 (Cstat(dof): 87.6(113)). The 0.3-10 keV observed(unabsorbed) average flux is 5.0e-13(5.5e-13) erg cm^-2 s^-1. The rate to flux conversion factor is 8.0e-11. The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00355942 This circular is an official product of the Swift-XRT team.