//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3734 SUBJECT: GRB 050802: Swift Gamma-ray Burst DATE: 05/08/02 11:53:01 GMT FROM: David L. Band at NASA/GSFC D. Band (GSFC-UMBC), C. Markwardt (GSFC-UMD), M. Perri (ASDC), K. McGowan (MSSL), C. Gronwall (PSU), K. Page (U. Leicester), J. Racusin (PSU), D. Burrows (PSU), N. Gehrels (GSFC), J. Kennea (PSU), report on behalf of the Swift Team: At 10:08:02 UT, Swift-BAT triggered and located GRB050802 (trigger=148646). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec 219.287, +27.806 {+14h 37m 09s, +27d 48' 23"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve has a total duration of ~20 sec. The peak count rate was ~2000 counts/sec (15-350 keV). The XRT began observing at 10:12:51 UT, 289 seconds after the BAT trigger. XRT was unable to centroid on any source, however the downlinked lightcurve and raw spectrum show a bright variable source is present in the XRT field of view. There are no catalogued X-ray sources in the field, suggesting that this bright source is the GRB afterglow. Swift-UVOT began observations after the slew, however, the UVOT dark burst image did not come down via TDRSS so no information is available at this time. Detailed analysis will be performed when data is available after the next Malindi pass. [GCN OPS NOTE(02aug05): Per author's request, The "05080" in the Subject-line was changed "050802".] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3735 SUBJECT: GRB 050802: XRT position DATE: 05/08/02 13:21:55 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J.A. Kennea, D.N. Burrows (PSU) report on behalf of the Swift/XRT Team: We have analysed the downlinked data on GRB 050802 (GCN 3734) and have found a fading uncatalogued X-ray source at the following coordinates: RA (J2000): 14:37:05.8, Dec(J2000): 27:47:05.6, with an error radius of 8 arcseconds (90% containment). This source is 87 arcseconds from the BAT position reported in GCN 3734. Further detailed analysis of XRT data will be reported in a later GCN. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3737 SUBJECT: GRB 050802: Swift-BAT refined analysis DATE: 05/08/02 15:16:08 GMT FROM: Takanori Sakamoto at NASA/GSFC D. Palmer (LANL), L. Barbier (GSFC), S. Barthelmy (GSFC), P. Boyd (GSFC-UMBC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC), W. Voges (MPE), on behalf of the Swift-BAT team: At 10:08:02 UT Swift-BAT detected GRB 050802 (trigger=148646) (GCN Circ 3734, Band, et al.). The refined BAT ground position is (RA,Dec) = 219.287, +27.806 {14h37m08.9s, 27d48'21.6"} [deg; J2000] +-3 arcmin, (95% containment). The partial coding was 27%. The light curve has a 5 second rise time to the first and largest of 3 symmetrical peaks in the interval T-5 to T+13 seconds. There is a hint of a small peak at T+30 seconds. T90 (15-350 keV) is (13 +- 2) seconds (estimated error including systematics). The power law index of the time-averaged spectrum is 1.6 +- 0.1. The fluence in the 15-350 keV band is (2.8 +- 0.3) x 10^-6 erg/cm2. The 1-s peak photon flux measured from T0-0.4 second in the 15-350 keV band is (3.3 +- 0.5) ph/cm2/s. All the quoted errors are at the 90% confidence level. There was no BAT Position GCN Notice on this burst, because none was transmitted from the spacecraft. The cause is being investigated. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3738 SUBJECT: GRB 050802 : Lulin Optical follow-up observation DATE: 05/08/02 15:31:06 GMT FROM: Yuji Urata at RIKEN Y. Sato (Tokyo Univ.), N. Awajiya (Tokyo Gakugei Univ.), D. Kinoshita, K-Y. Huang, W-H. Ip(NCU), Y. Urata (RIKEN) on behalf of EAFON report: " We have imaged the entire error region of GRB 050802 (Band et al. #3734) using the imaging polarimeter PICO with Lulin One-meter Telescope. After end of twilight, the observation was started at 12:42 (0.107 days after the burst). We have obtained 12 x 300 sec i'-band images. These images show no optical counterpart brighter than i'=17.2. These 3-sigma limiting magnitudes are derived from the USNO-B1.0 catalog. This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3739 SUBJECT: GRB 050802: Swift/UVOT observations DATE: 05/08/02 17:34:24 GMT FROM: Katie McGowan at MSSL-UCL K. McGowan (MSSL), D. Band (GSFC-UMBC), P. Brown, C. Gronwall (PSU), H. Huckle, B. Hancock (MSSL) report on behalf of the Swift/UVOT team: The Swift/UVOT began observing the afterglow of GRB 050802 at 2005-08-02T10:15:14, 286 s after the BAT trigger (Band et al., GCN 3734). We detect the afterglow in the V-band data at a position (J2000, corrected to the DSS coordinates) of: RA 14:37:5.69 (+/- 1 arcsec) Dec +27:47:12.2 (+/- 1 arcsec) The data are extracted using a 6 arcsec radius aperture centered on the source position. If the significance of the source detection was less than 2 sigma we determined a 3-sigma limiting magnitude. Filter Exposure (s) T_mid (s) Magnitude Notes V 100 336 17.07+/-0.09 detection V 10 466 17.32+/-0.20 detection V 10 550 17.10 3-sig limit V 10 634 17.17 3-sig limit V 10 718.5 16.77+/-0.20 detection V 10 803 17.34 3-sig limit V 10 887.5 17.04+/-0.20 detection V 10 972 17.46 3-sig limit V 100 1463 18.35+/-0.09 detection V 100 2088 18.81+/-0.09 detection where T_mid is the midpoint of the exposure post-trigger in seconds. Analysis of the data from the other filters is ongoing. The magnitudes are based on preliminary zero points, measured in orbit, and will require refinement with further calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3740 SUBJECT: GRB 050802: early Swift XRT analysis results DATE: 05/08/02 20:34:15 GMT FROM: Milvia Capalbi at ISAC/ASDC M. Capalbi, M. Perri, P. Giommi (ASDC), J. Kennea, D.N. Burrows, M.Chester (PSU), R. Fink (GSFC) report on behalf of the Swift XRT team: We have analyzed the Swift XRT data from the first orbit observation of GRB 050802 (Band et al., GCN 3734). The refined coordinates of the X-ray afterglow are: RA(J2000) = 14h 37m 06.1s Dec(J2000) = +27d 47' 11" This position is 80 arcseconds from the BAT refined position given in GCN 3737 (Palmer et al.), 6.7 arcseconds from the early XRT position reported in GCN 3735 (Kennea et al.) and 5.4 arcseconds from the UVOT position (McGowan et al., GCN 3739). We estimate an uncertainty of 6 arcseconds radius in the derived position. Data in Photon Counting (PC) mode starts at 10:15:57 UT, 475 seconds from the BAT trigger. The 0.3-10 keV afterglow light curve shows a fading which can be fitted with a power law of slope alpha=-0.7+/-0.1 up to T+2875 s, when the first orbit ends. A preliminary spectral fit in the 0.3-10.0 keV energy band to the first orbit gives a spectral power law photon index of 1.9+/-0.1 with nH=(6.6+/-2.5)E20 cm^-2. The Galactic nH along the line of sight is 1.8E20 cm^-2. The unabsorbed 0.5-10.0 keV flux at 24 hours after the burst is estimated to be 3.6E-12 erg cm^-2 s^-1. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3742 SUBJECT: GRB050802 radio non-detection DATE: 05/08/03 09:07:09 GMT FROM: Guy Pooley at MRAO, Cambridge, UK Guy Pooley (Cavendish Laboratory, University of Cambridge) reports: An observation of the field of GRB050802 (GCN 3734) was made with the Ryle Telescope (Cambridge, UK) at 15 GHz from 18:54 to 22:53 UT on 2005 Aug 02 (mid-observation 10h46m from the trigger), using the Swift/UVOT position reported in GCN3739. No source was detected - the formal flux density was -0.02 mJy with an rms noise of 0.3 mJy. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3744 SUBJECT: GRB050802: CrAO optical observations DATE: 05/08/03 11:02:17 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Pavlenko, Yu. Efimov, A. Shlyapnikov, A. Baklanov(CrAO), A.Pozanenko (IKI), M. Ibrahimov (MAO) on behalf of larger GRB follow up collaboration report: We observed the error box of GRB050802 (Band et al., GCN 3734) with 2.6m Shain telescope (CrAO) on August 2 between (UT) 18:46 - 20:40. OT found by McGowan et al. (GCN 3739) is clearly detected. Preliminary VRI photometry is following: Mean time Exposure Filter Magnitude (UT) s 18:54 60 V 20.6 20:27 2x60 V 21.1 18:48 60 R 20.6 20:36 2x60 R 21.0 18:56 60 I 20.2 20:39 2x60 I 20.6 with a typical error of 0.1m. Comparing decay index of fading light curve in V between magnitudes obtained in UVOT observation (McGowan et al. GCN 3739) and our first observation in 18:54, and decay index obtained based on our observations we suggest that the break of OT light curve occurs between (UT) 19:00 - 20:40. Detailed analysis is underway. Finding chart of the OT in V band can be found in http://grb.rssi.ru/GRB050902. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3745 SUBJECT: GRB 050802: Swift/UVOT optical and UV detections DATE: 05/08/03 15:37:09 GMT FROM: Katie McGowan at MSSL-UCL K. McGowan (UCL-MSSL), A. Morgan (PSU), K. Mason (PPARC), T. Kennedy (UCL-MSSL) report on behalf of the Swift/UVOT team: The Swift/UVOT began observing the afterglow of GRB 050802 at 2005-08-02T10:15:14, 286 s after the BAT trigger (Band et al., GCN 3734). In addition to our reported detection from the initial V filter observations (McGowan et al., GCN 3739), we now report that we detect the afterglow in all six filters. We extracted data using a 6 arcsec radius aperture centered on the source position (McGowan et al., GCN 3739) for the optical filters, a 12 arcsec radius for the W1 and M2 filters, and 4 arcsec for the W2 filter. If the significance of the source detection was less than 2 sigma we determined a 3-sigma limiting magnitude. The detection in UVW2 implies that the Lyman Limit must be blueward of 2000 A, and we estimate that the burst is at redshift z < 1.2. We obtain the following photometry of the afterglow candidate: Filter Exposure (s) T_mid (s) Magnitude Notes V 100 336 17.07+/-0.09 detection V 900 12566 20.35+/-0.09 detection B 10 437 17.66+/-0.20 detection B 900 36405 21.10+/-0.08 detection U 10 423 16.82+/-0.24 detection U 899.79 35498 20.22+/-0.16 detection W1 10 409 17.08+/-0.29 detection W1 100 2296 19.22+/-0.23 detection M2 278 1316 18.79+/-0.26 detection M2 3753 28197 21.30+/-0.26 detection W2 268 1240.5 20.73+/-0.27 detection W2 3481 25890.5 >22.64 3-sig limit where T_mid is the midpoint of the exposure post-trigger in seconds. The magnitudes are based on preliminary zero points, measured in orbit, and will require refinement with further calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3749 SUBJECT: GRB050802: Tentative absorption redshift DATE: 05/08/03 20:25:25 GMT FROM: Johan U. Fynbo at U.Copenhagen Johan P. U. Fynbo, Jesper Sollerman, Brian L. Jensen, Jens Hjorth, Darach Watson, José María Castro Cerón (DARK cosmology centre/Niels Bohr Institute), Palle Moller (ESO), Thomas Augusteijn (Nordic Optical Telescope), Javier Gorosabel (IAA-CSIC), Klaas Wiersema (Amsterdam) report: "Using ALFOSC on the Nordic Optical Telescope we have obtained spectra of the afterglow of GRB 050802 (GCN 3734, 3739) on 2005, August 2.9 UT. We detect several absorption features which we tentatively identify as CIV and FeII lines, corresponding to a redshift of z=1.71. This tentative redshift is at odds with the interpretation of the UVOT results (GCN 3745). We encourage further observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3756 SUBJECT: GRB 050802.422: Fading of the afterglow and detection of the host DATE: 05/08/04 14:51:16 GMT FROM: Johan U. Fynbo at U.Copenhagen Johan P. U. Fynbo, Brian L. Jensen, Jens Hjorth, Jesper Sollerman, Darach Watson, José María Castro Cerón (DARK Cosmology Centre/NBI), Javier Gorosabel (IAA-CSIC), Magnus Galfalk (Stockholm), Amanda Kaas (Nordic Optical Telescope) report: "Using ALFOSC on the Nordic Optical Telescope we have obtained further imaging of the field of GRB 050802.422 (Band et al. GCN 3734, McGowan et al. GCN 3739) on 2005, August 3.9 UT. From Aug 2.9 UT to Aug 3.9 UT the object has faded from about R=20.5 to R=22.5 (based on preliminary photometry), indicating a fairly steep early decay. In the image from Aug 3.9 there is contamination from an extended source, presumably the host galaxy. This fairly bright host galaxy makes it feasible to make an independent measurement of the redshift of the burst and hence confirm or reject the tentative measurement reported by Fynbo et al. GCN 3749. An image can be seen here: http://www.astro.ku.dk/~brian_j/grb/grb050802.422/" //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3765 SUBJECT: GRB050802: TNG optical observations DATE: 05/08/05 09:57:55 GMT FROM: Vincenzo Testa at INAF/Astro. Obs. of Rome V. Testa (INAF-OAR), A.Melandri , L.A. Antonelli, L. Stella (INAF-OAR), S. Covino, D. Fugazza, G. Tagliaferri (INAF-OAB), G. Chincarini (Univ. Milano-Bicocca), N. Masetti (INAF-IASF-Bologna), G. Andreuzzi, M. Pedani (INAF-TNG), on behalf of the CIBO collaboration report We imaged the field of GRB050802 (GCN 3734, Band et al.) with the 3.5 m Italian National Telescope (TNG) (Canary Islands). Observations were carried out with the optical spectrograph Dolores on August 2.9 UT in 5 filters (U, B, V, R, I) and on August 3.9 UT in 2 filters (V, I). In all images we detect an object at the position reported by McGowen et al. (GCN 3739). Therefore, the detected object is identified as the afterglow candidate reported in GCN 3739. Preliminary photometry shows the object fading from V~21.1 to V~22.8 and from I~20.5 to I~21.9 between the two epochs. We note also an extended fainter object near the afterglow in the V frame obtained on August 3. This object is at the same position as can be seen in the image linked in GCN 3756, that Fynbo et al. propose as suspected host galaxy. Further refined analysis is ongoing. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3855 SUBJECT: GRB050525, GRB050607, GRB050802 BVRcIc field photometry DATE: 05/08/22 15:26:26 GMT FROM: Arne A. Henden at AAVSO A. Henden (AAVSO/USNO) reports on behalf of the USNO GRB Team: We have acquired BVRcIc all-sky photometry for 23x23arcmin fields centered on the coordinates of recent GRB localizations with the USNOFS 1.0-m telescope on 1 or 2 photometric nights but with bright moonlight and variable seeing. Stars brighter than V=12.0 are saturated and should be used with care. We have placed the photometric data on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050525.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050607.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050802.dat The astrometry in these files is based on linear plate solutions with respect to UCAC2 or USNO-A2.0. The external errors are usually 200mas or better. The estimated external photometric error is about 0.03mag. Some fields are relatively crowded, and the large apertures required to handle the variable seeing also blended some measurements, so choose comparison stars wisely. We have one additional night for GRB050525 that will be added when reductions are complete. As always, you should check the dates on the .dat file prior to final publication to get the latest photometry. There is a README file on the ftp directory to give you information about the procedures used to calibrate these fields.