This file contains all 3 bursts: 050509a, 050509b, and 050509c. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3379 SUBJECT: Swift Detection of the Burst GRB050509 DATE: 05/05/09 02:47:54 GMT FROM: Cheryl Pauline Hurkett at Leicester U C. Hurkett, E. Rol, (U Leicester), L. Barbier (GSFC), S. Barthelmy (GSFC), A. Blustin (MSSL), D. Burrows (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), J. Kennea (PSU), C. Markwardt (GSFC/UMD), on behalf of the Swift Team; At 01:46:28 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB050509 (trigger=118707). The BAT on-board calculated location is RA, Dec 310.588, +54.070 (J2000) with an uncertainty of 3 arcmin (radius, 3-sigma, including estimated systematic uncertainty). The BAT light curve shows a single main peak with a small peak on the rising edge (at T-6sec). The total duration is ~13 sec. The BAT peak count rate is ~2300 events/sec at T_zero (15-350 keV). The Swift spacecraft slewed promptly onto the BAT position. The XRT imaged the field at 01:47:22.76 (54.8s after the burst), but did not find any bright source in the field. An XRT position will be determined by analysis of the full data following the next ground station pass. The Swift Ultra Violet/Optical (UVOT) observations began at 01:47:20.5 UT, 52 seconds after the BAT trigger. The first data taken after the spacecraft settled was a 90 sec exposure using the V filter with the midpoint of the observation at 97 sec after the BAT trigger. Based on a preliminary comparison with the DSS and USNO-B, we detect no new source within the BAT error circle down to an approximate five sigma limiting magnitude of 17.3. The observation was truncated by an observing constraint at 01:50:00 UT after approximately 110 sec. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3380 SUBJECT: GRB 050509a: Swift XRT Position DATE: 05/05/09 04:33:55 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. A. Kennea, D. N. Burrows (PSU), C. P. Hurkett, E. Rol (U. Leicester) and N. Gehrels (NASA/GSFC) report on behalf of the Swift XRT team: The Swift BAT instrument detected GRB 050509a at 01:46:28 UT on 9th May 2005 (GCN Circ 3379). The observatory executed an automated slew to the BAT position and the XRT began taking data at 01:47:22 UT. The XRT was in Auto state but was not able to centroid on the afterglow due to low source intensity. From downlinked data we find a uncatalogued X-ray source located at: RA(J2000) = 20:42:19.7, Dec(J2000) = +54:04:16.2 We estimate an uncertainty of about 6 arcseconds radius (90% containment). This position is 13 arcseconds from the BAT position reported in GCN 3379. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3381 SUBJECT: Swift Detection of GRB050509b: A short duration burst DATE: 05/05/09 05:03:23 GMT FROM: Louis M Barbier at NASA/GSFC/Swift C. Hurkett, E. Rol, (U Leicester), L. Barbier (GSFC), S. Barthelmy (GSFC), A. Blustin (MSSL), D. Burrows (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), J. Kennea (PSU), C. Markwardt (GSFC/UMD), S. Holland (GSFC/USRA) on behalf of the Swift Team; At 04:00:19.23 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB050509b (trigger #118749). The BAT on-board calculated location is RA, dec 189.056, +29.000 (12h 36m 13s, +29d 00' 01'') (J2000) with an uncertainty of 4 arcmin (radius, 3-sigma, including estimated systematic uncertainty). The BAT light curve showed a single short spike with a duration of less than 128 milliseconds. The peak count rate measured by BAT was about 2100 counts/sec in the 15 - 350 keV band. The Swift spacecraft slewed promptly onto the BAT position. The XRT imaged the field at 04:01:12 (53.0 s after the burst), but did not find any bright source in the field. An XRT position will be determined by analysis of the full data following the next ground station pass. The Swift Ultra Violet/Optical Telescope (UVOT) observations began at 04:01:09.8 UT, 50 seconds after the BAT trigger. The first data taken after the spacecraft settled was a 100 sec exposure using the V filter with the midpoint of the observation at 100 sec after the BAT trigger. Based on a preliminary comparison with the DSS, there is a possible low significance source at RA=12:36:18, DEC=29:01:24 which is not present in the DSS. It has a V-band magnitude of 18.8. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3382 SUBJECT: GRB 050509B: ROTSE-III Optical Limits DATE: 05/05/09 06:00:23 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), H. Swan (U Mich), B. Schaefer (Louisiana State), R. Quimby (U Texas), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 050509B (Swift trigger 118749), producing images beginning 10.0 s after the GCN notice time. An automated response took the first image at 04:00:43.0 UT, 23.7 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 60+ 60-sec eposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is ongoing. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma error circle, nor do we detect the tentative UVOT source (Hurkett et al, GCN 3381). Individual images have limiting magnitudes ranging from 17.07-18.48. In particular, we set a limit of magnitude 17.25 in a single 5 s exposure, starting 23.7 s after the burst. Coadding the images into sets of 10 reveals no new sources down to limits of 18.63 (77 s effective length (t_end - t_start), beginning 23.7s post-burst), 18.72 (298.5s effective length, beginning 100.6s post-burst), and 19.46 (695.6s effective length, beginning 399.1s post-burst). [GCN OPS NOTE (09may05): Per author's request, the two references to 050509A were changed to the correct value of 050509B.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3383 SUBJECT: GRB 050509b: Swift XRT Position DATE: 05/05/09 06:29:23 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. A. Kennea, D. N. Burrows, J. Nousek (PSU), C. P. Hurkett, E. Rol, J. Osborne, A. Wells (U. Leicester), N. Gehrels (NASA/GSFC), G. Chincarini (INAF-OAB) and P. Giommi (ASDC) report on behalf of the Swift XRT team: The Swift BAT instrument detected GRB 050509b at 04:00:19 UT on 9th May 2005 (GCN Circ 3381). The observatory executed an automated slew to the BAT position and the XRT began taking data at 04:01:12 UT. The XRT was in Auto state but was not able to centroid on the afterglow due to low source intensity. From downlinked data we find a faint uncatalogued X-ray source located at: RA(J2000) = 12:36:13.6, Dec(J2000) = +28:58:58.6 We estimate an uncertainty of about 6 arcseconds radius (90% containment). This position is 61 arcseconds from the BAT position reported in GCN 3381. This source lies 44 arcseconds from the center of the Galaxy Cluster NSC J123610+285901. Note that this source position is 157 arcseconds from the tentative UVOT optical afterglow counterpart reported in GCN 3381, and therefore is not associated with that source. We cannot yet determine whether this X-ray source is fading. Additional observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3384 SUBJECT: GRB 050509b: optical observations DATE: 05/05/09 06:44:52 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA A. de Ugarte Postigo, A.J. Castro-Tirado (IAA-CSIC Granada), A. Eigenbrod (EPF de Lausanne), M. Jelinek, J. Gorosabel and S. Guziy (IAA-CSIC Granada), report: "Following the detection by Swift-BAT of the short gamma-ray burst GRB 050509b (Hurkett et al. GCN 3381), we have obtained two R-band images (300s exposure time each) with the 1.2m Mercator telescope at Roque de los Muchachos Observatory in La Palma, starting at 04:36:02 UT (i.e. 35.88. min after the onset of the burst). The location was observed under poor seeing conditions, at very high airmass. We do not identify any source within the error box provided by Swift-XRT (Kennea et al. GCN 3383) down to magnitude 21." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3385 SUBJECT: GRB 050509b: Swift-BAT refined analysis of the short hard burst DATE: 05/05/09 07:06:49 GMT FROM: Scott Barthelmy at NASA/GSFC S. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC), T. Mitani (ISAS), F. Marshall (GSFC), T. Takahashi (ISAS) on behalf of the Swift/BAT team: At 04:00:19.23 UT Swift-BAT detected GRB 050509b (trigger=118749) (GCN Circ 3381, C. Hurkett et al.). The refined BAT ground position is (RA,Dec) = 189.073,+28.991 {12:36:18,28:59:28} +- 2.8 arcmin [deg; J2000], (95% containment). This is 59 arcsec from the XRT position (Kennea et al., GNC 3383). The burst was in the fully-coded FOV. Using the event-by-event data, the lightcurve shows a single spike with a duration of ~30msec. Further, the hardness ratio S(50-100)/S(25-50) of ~1.5 puts this burst cleanly in the short-hard cluster on the hardness_ratio vs duration scatter-plot. Using a simple power-law model, the photon index of the time-averaged spectrum is 1.5 +- 0.4. The fluence in the 15-350 keV band is (2.3 +- 0.9) x 10^-8 erg/cm2. The 1-s peak photon flux in the 15-350 band is (1.57 +- 0.36) ph/cm2/s. All the quoted errors are at the 90% confidence level. We note that location is consistant with the galaxy cluster NSC J123610+285901 which has a redshift of z=0.22, which roughly translates to a distance of ~1 Gpc. We also note that at this distance and the observed flux, this is is an order of magnitude farther than the 27-Dec-04 SuperFlare event from SGR1806-20 could be seen. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3386 SUBJECT: GRB 050509b: PAIRITEL and WIYN Observations DATE: 05/05/09 07:21:27 GMT FROM: Josh Bloom at Harvard/CFA J. Bloom (UCB), C. Blake (Harvard), J. X. Prochaska (UCSC), J. Hennawi (UCB), M. Gladders (Carnegie), B. Koester (U Michigan) report: "We find no new point sources at the XRT position (3380) of the GRB 050509b (3381) in RIJHK (WIYN+PAIRITEL). Based I and R imaging and JHK imaging of the XRT position of GRB 050509b, however, there appears (to the West of the XRT) a bright extended galaxy at ra 12:36:12.90, dec +28:58:58.8 (J2000) (=2MASS 2MASX J12361286+2858580), with J=15.25, H=14.46, K=14.09 mag. Although the XRT is ~10 arcsec from this galaxy, at the photometric redshift of the cluster (z=~0.22), this is only 35 kpc h_71^{-1} in projection. Thus, we find a plausible association of this short burst with the outskirts a nearby, potential host galaxy. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3387 SUBJECT: GRB050509b: Radio Observations DATE: 05/05/09 07:38:23 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech) and D. A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie collaboration: "We observed the field of GRB050509b (GCN 3381) with the Very Large Array at 8.5 GHz on May 9.25 UT. We do not detect any radio sources within the XRT error region (GCN 3380). Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3388 SUBJECT: GRB 050509b: Optical Counterpart Candidate DATE: 05/05/09 08:44:13 GMT FROM: Josh Bloom at Harvard/CFA J. Bloom (UCB), C. Blake (Harvard), J. X. Prochaska (UCSC), J. Hennawi (UCB), M. Gladders (Carnegie), B. Koester (U Michigan) and H. W. Chen (MIT) report: We have continued to observe GRB 050509b (GCN #3383) with the imager on the 3.5m WIYN telescope. Under improving conditions, a 600s observation in the sloan r band beggining at 06:05 UT revealed a apparent point source within the XRT error circle (GCN #3383) and within the detectable light of the nearby galaxy (GCN #3386). A finding chart may be found at: http://pairitel.org/grb050509b-candidate.gif This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3389 SUBJECT: GRB 050509A: Optical observations DATE: 05/05/09 09:07:30 GMT FROM: Johan U. Fynbo at U.Copenhagen GRB 050509A: Optical observations J. P. U. Fynbo, B. L. Jensen, J. Hjorth, P. Jakobsson, J. M. Castro Cerón, H. Pedersen, D. Watson (Niels Bohr Institute), J. Näränen (Nordic Optical Telescope) report: "Using ALFOSC on the 2.56m Nordic Optical Telescope we have obtained I-band imaging of the XRT error circle for GRB 050509A (Swift trigger 118707, GCN 3379, 3380) at two epochs starting ~20 min and ~2.5 hr after the GRB trigger. In the XRT error-circle we detect several sources. One source is less than 2" from the centre of the XRT error circle and not seen in the DSS-II (red). The position of this source is: RA(2000) = 20:42:19.60, Dec(2000) = +54:04:17.8 The source is fainter than the sensitivity of the DSS-II red image and has an estimated magnitude of I = 21.7 (not corrected for a galactic extinction of A_I = 1.15 mag). The source does not vary significantly between the two epochs. An image of the field is shown at: http://www.astro.ku.dk/~brian_j/grb/grb050509A/ " //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3390 SUBJECT: Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b DATE: 05/05/09 09:22:11 GMT FROM: Josh Bloom at Harvard/CFA J. X. Prochaska (UCO/Lick), M. Cooper (UCB), J. Newman (LBNL), J. S. Bloom (UCB), K. Hurley, (SSL/UCB), C. Blake (Harvard), B. Gerke (UCB), and H. W. Chen (MIT) report: "We have acquired a DEIMOS longslit spectrum of the galaxy at ra 12:36:12.90, dec +28:58:58.8 (J2000) (=2MASS 2MASX J12361286+2858580) which is tentatively identified as the host of GRB 050509b. We measure a redshift of z=0.226 based on Ca H and K absorption and numerous other absorption features. We do not detect any significant emission at Hbeta, Halpha or [O II]. The spectral features are consistent with an early type galaxy with no ongoing star formation. If the association is confirmed, this would be the first GRB host that is an early-type, hinting that GRBs of short duration may be due to progenitors that are unrelated to current and on-going star formation. This notice may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3391 SUBJECT: GRB 050509b: Possible Optical Counterpart DATE: 05/05/09 09:36:49 GMT FROM: S. Bradley Cenko at Caltech S. Bradley Cenko, B. T. Soifer, Chao Bian, Vandana Desai, S. R. Kulkarni (Caltech), Edo Berger (Carnegie), Arjun Dey and Buell T. Jannuzi (NOAO) report on behalf of a larger collaboration: We have imaged the error circle of the Swift GRB 050509b (GCN 3381) with the Keck Low Resolution Imaging Spectrometer (LRIS) mounted on the Keck I telescope. We have obtained two epochs of simultaneous imaging in the g' and R filters. The first epoch consisted of 4 x 300 s images taken at a mean time of approximately 7:00 UT 9 May (~ 3 hours after the burst). The second epoch consisted of 3 x 300 s images taken approximately 1.5 hours later. Inside the XRT error circle, we find four sources, three of which are marginal detections. The brightest source is located at (J2000.0): RA: 12:36:13.7 Dec: 28:58:57.3 The source appears to brighten slightly from our first to our second epoch. Under close inspection, it also appears to be embedded in an extended nebular galaxy. An image can be found at: http://www.srl.caltech.edu/~cenko/grb050509b/050509.jpg Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3392 SUBJECT: GRB 050509b: Precision Astrometry DATE: 05/05/09 11:12:47 GMT FROM: Josh Bloom at Harvard/CFA J. Bloom (UCB), C. Blake (Harvard), J. X. Prochaska (UCSC), J. Hennawi (UCB), M. Gladders (Carnegie), B. Koester (U Michigan) and H. W. Chen (MIT) report: Connecting a WIYN 600s Sloan r band image to compact astrometric sources in the 2MASS catalogue we find the following refined position for the putative host (Bloom et al. GCN #3386) at redshift z=0.226 (Prochaska et al. GCN #3390) and counterpart (Bloom et al. GCN #3388): galaxy: RA = 12:36:12.87, Dec = 28:58:58.5 counterpart: RA = 12:36:13.67, Dec = 28:58:57.0 (J2000; absolute uncertainty of 200 milliarcsec in each direction). The proposed counterpart is thus 1.51" S, 10.41" E from the galaxy and 1.61" S, 0.88" E of the XRT position (Kenea et al. #3383). This distance of 1.84 arcsec is well within the astrometric uncertainty of the XRT position. The position reported here is consistent with that reported in Cenko et al. GCN #3391. Another zoom in image is now posted at: http://astro.berkeley.edu/~jbloom/grb050509b-zoom.ps http://astro.berkeley.edu/~jbloom/grb050509b-zoom.gif This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3393 SUBJECT: GRB 050509b: Optical observations DATE: 05/05/09 15:30:00 GMT FROM: Ken ichi Torii at RIKEN K. Torii (Osaka U.) reports: "The error region of the Swift short hard GRB 050509b (Hurkett et al. GCN 3381; Barthelmy et al. GCN 3385) was imaged with the 0.3 m telescope in the New Mexico Skies observatory. The observation started at 2005 May 9, 04:08:52 UT (513 s after the trigger) and 120 s integrations in I and V bands were obtained. The optical counterpart candidate (Bloom et al. GCN 3388; Cenko et al. GCN 3391) of the XRT source (Kennea et al. GCN 3383) is not detected in our frames while the candidate host galaxy is detected. The plate scale of our images is 1".41/pixel and the optical counterpart candidate should be readily resolved from the galaxy. We therefore derive the following 3 sigma upper limits for the optical counterpart candidate (GCN 3388; GCN 3391) relative to USNO-B1.0 I magnitude. MidTime(UT) Filter Exposure Mag --------------------------------- 04:09:52 I 1x120s >18.7 04:15:59 I 3x120s >19.2 --------------------------------- " //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3394 SUBJECT: GRB050509a: Swift UVOT observations DATE: 05/05/09 16:04:32 GMT FROM: Katie McGowan at MSSL-UCL T. Poole (MSSL), C. Hurkett (Leicester), S. Hunsberger (PSU), A. Breeveld (MSSL), P. Boyd (GSFC), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of GRB050509a on May 09, 2005 at 01:47:20.5 UT, 52 seconds after the initial Swift BAT trigger (Hurkett et al., GCN 3379). The XRT error circle (Kennea et al., GCN 3380) falls partially on a known source from the DSS. We detect no new sources at the Swift XRT position (Kennea et al, GCN 3380). The limiting magnitudes (in 6" radius apertures) in each of the UVOT filters are as follows: Filter Lim_Mag Lim_mag Total duration T_start T_mid 5sigma 3sigma (s) (s) (s) V 18.23 18.79 191 52 1853 UVW1 18.97 19.52 210 5722 5827 UVM2 20.29 20.84 921 3763 4739 UVOT only observed GRB050509b in V, UVW1 and UVM2 because it's run of observations were interrupted by GRB050509b. The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3395 SUBJECT: GRB 050509B: Swift/XRT refined analysis DATE: 05/05/09 17:10:13 GMT FROM: David Burrows at PSU/Swift E. Rol, K. Page (Univ. of Leicester) D. N. Burrows (Penn State), N. Gehrels (GSFC), M. Goad, C. Hurkett (Univ. of Leicester), J. Kennea (Penn State), P O'Brien (Univ. of Leicester) report on behalf of the Swift XRT team: We have analyzed the Swift XRT data from the short/hard burst 050509B (Hurkett et al. 2005, GCN 3381) using 3 orbits with a total exposure time of 6648 seconds in Photon Counting (PC) mode, starting 62 seconds after the trigger. The refined coordinates of the X-ray afterglow are: RA(J2000) = 12:36:13.9 Dec = +28:59:01 with an estimated error of 8 arcseconds (90% containment). Note that we have increased the estimate of the error circle radius to account for systematic variations in the centroid position for this source, which has very few counts. The source is detected in the first 400 seconds of PC mode at a count rate of 0.03 counts/sec, after which it disappears below background level, and is not seen in the data from later orbits, with an estimated decay slope steeper than -1. Assuming a Crab-like spectrum, we estimate an average flux level of 1e-12 erg/cm^2/s (0.3 - 10 keV), between 62 and 262 seconds after the burst trigger. This is the faintest X-ray afterglow yet detected by Swift/XRT at such an early time. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3396 SUBJECT: GRB 050509B, Optical Observations DATE: 05/05/09 18:02:14 GMT FROM: Kuntal Mishra at ARIES,Nainital,India Kuntal Misra and S. B. Pandey (ARIES Naini Tal), on behalf of larger Indian GRB collaboration Afterglow candidate (GCN 3388) of the short duration GRB 050509B, localized by SWIFT (GCN 3381), was monitored from ARIES Naini Tal, India using 1-m telescope. The total exposure given in R_c band was 900sec*4 in good sky conditions, around 11 hours after the burst. Photometry of the stacked frame poses an upper limit of ~ 22 mag at the location of OT in comparison to nearby USNO-A2.0 stars. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3397 SUBJECT: Swift UVOT Follow-up Observations of GRB 050509B DATE: 05/05/09 18:30:50 GMT FROM: Pete Roming at PSU A. Breeveld, S. Rosen (MSSL), C. Hurkett (LU), E. Rol(LU), S. Holland (GSFC), P. Roming (PSU), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team Further to the initial Swift UVOT results (C. Hurkett et al. GCN 3381) we report the results of co-added, deeper exposures of GRB 050509b with the Swift Ultra-Violet/Optical Telescope (UVOT) on May 09, 2005. We detect no source at the XRT determined location (Kennea et al., GCN 3383) in any of the UVOT filters with the following 5 sigma limits in 6" radius apertures. Because of the proximity of this position to the galaxy cluster NSC J123610+285901 the measurements were repeated with a smaller (3.5") aperture. The measurements are listed in the following table. Filter Lim_Mag Lim_mag Total duration (s) T_range (s) 5sigma (6") 5sigma (3.5") V 19.0 19.6 345 51 - 1670 B 19.7 20.3 197.4 196 - 1502 U 19.41 19.44 752.88 182 - 7642 T_range values are start and stop times between which UVOT exposures were made, measured w.r.t the BAT trigger time (Barthelmy et al. GCN 3385). The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3399 SUBJECT: GRB 050509b: Physical Properties of the Candidate Host galaxy DATE: 05/05/10 00:53:14 GMT FROM: Hsiao-Wen Chen at MIT/CSR Jason X. Prochaska (UCO/Lick Obs.), J. S. Bloom (UCB), H.-W. Chen (MIT), & K. Hurley (UCB) report on behalf of the GRAASP collaboration: "We have further analyzed the longslit spectrum obtained for the candidate host galaxy of GRB 050509b Bloom et al. GCN 3386) by Prochaska et al. (GCN 3390), using Keck/DEIMOS. We estimate a more precise redshift of the galaxy at z = 0.2249 +/- 0.0008 by cross-correlating the spectrum with galaxy templates from SDSS. At this redshift, the host has an intrinsic K-band luminosity of ~ 1.6 x 10^11 L_sun as derived based on its 2MASS photometry of K = 14.1 mag. We attempt to constrain the underlying dark matter halo mass of the galaxy based on the observed absorption line profiles. Using the Ca H&K doublet, we estimate a velocity dispersion of ~ 340 km/sec. This corresponds to an enclosed dynamical mass of 7.2 x 10^11 h^{-1} M_sun at the radius of the OT r = 26.6 h^-1 kpc. The spectrum of the galaxy is presented at http://www.graasp.org/Data/050509b. This message can be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3400 SUBJECT: GRB050509c: REM NIR and Optical observations DATE: 05/05/10 02:59:38 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma P. D'Avanzo, S. Piranomonte, L.A. Antonelli, S. Covino, F.M. Zerbi, G. Chincarini, M. Rodono', G. Tosti, P. Conconi, G. Cutispoto, E. Molinari, L. Nicastro, E. Palazzi, V. Testa, F. Vitali, E. Meurs, P. Goldoni, on behalf of the REM/ROSS Team report: "We imaged the central part of the field of GRB050509 with the robotic 60-cm REM telescope located at La Silla, Chile. REM is equipped with the REMIR near infrared camera (10x10 sq arcmin FoV, JHK filters) and the ROSS optical spectrograph/imager (10x10 sq arcmin FoV, VRI filters and AMICI prism). Observations of GRB 050509 were performed in fully automated mode simultaneously in the near infrared and in the optical starting approximately 56 seconds after the burst (32 seconds after the reception of the burst alert). Then, 2 hrs after the burst, REM performed automatically a further observation of the refined position of GRB 050509 few seconds after the new trigger delivered by the HETE Team. A preliminary analysis of both the H and R band images does not reveal any new object down to the 2MASS and DSS limits respectively." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3401 SUBJECT: GRB 050509b: Further Analysis of Keck LRIS Images DATE: 05/05/10 03:13:47 GMT FROM: S. Bradley Cenko at Caltech S. Bradley Cenko, B. T. Soifer, Chao Bian, Vandana Desai, S. R. Kulkarni (Caltech), Edo Berger (Carnegie), Arjun Dey and Buell T. Jannuzi (NOAO) report on behalf of a larger collaboration: Further to our GCN 3391 we obtained an additional LRIS image in g and R band. The sum of these three epochs centered on the fading X-ray source (GCN 3395) is shown at http://www.srl.caltech.edu/~cenko/grb050509b/050509b_zoom.jpg In addition to the elliptical galaxy discussed in GCN 3386, there are four sources listed below. ------------------------------------------------------------------------ Source RA (J2000.0) Dec (J2000.0) Dist from X-ray source ------------------------------------------------------------------------ S1 12:36:13.7 28:58:57.3 4.5" S2 12:36:14.1 28:58:59.6 3.0" S3 12:36:14.0 28:59:01.5 1.4" S4 12:36:13.7 28:59:02.5 3.0" Source S1 was proposed as a candidate by its proximity to the elliptical galaxy (GCN 3388) and by its possible variability (GCN 3391). However, as noted earlier and now confirmed with more data, source S1 is clearly extended. The color and a low resolution (LRIS) spectrum of S1 show it to be a blue object. A simple interpretation of the data is that source S1 a high redshift star-forming galaxy. The optical counterpart of the fading X-ray source has not yet been securely identified. To this end we are undertaking detailed analysis of the LRIS images." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3402 SUBJECT: GRB050509c (=H3751): An X-Ray Flash Localized By HETE DATE: 05/05/10 03:51:45 GMT FROM: Don Lamb at U.Chicago GRB050509c (=H3751): An X-Ray Flash Localized By HETE G. Prigozhin, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki, T. Tamagawa, K. Tanaka, Y. Yamamoto, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: The HETE FREGATE, WXM, and SXC instruments detected GRB 050509c at 22:45:54 UT (81953.95 SOD) on 9 May 2005. This was a weak burst consisting of a single pulse ~25 s long, with almost no emission above 18 keV in the WXM. The WXM flight localization can be expressed as a circle of radius 14 arcminutes (90% confidence) that is centered at WXM-Flight: RA = 12h 52m 39s, Dec =-44d 17' 50" (J2000). The first flight localization was distributed in a GCN Notice issued at 22:46:13 UT, 19 s after the burst trigger. Ground analysis of the WXM data produced a refined WXM localization that was in a GCN Notice issued 10 May 05 at 00:43:29 UT. This ground WXM localization can be expressed as a rectangle with corners: R.A. = 12 52 15.4 ; Dec. = -44 23 06 R.A. = 12 54 05.0 ; Dec. = -44 23 46 R.A. = 12 54 01.7 ; Dec. = -45 10 01 R.A. = 12 52 11.3 ; Dec. = -45 09 18 (J2000). The burst was also detected by the SXC Y camera. Ground analysis of the SXC data produced a long thin rectangle. Truncating the rectangle by the WXM ground localization results in a rectangle with corners: R.A. = 12 54 02.9 ; Dec. = -44 52 23 R.A. = 12 52 12.7 ; Dec. = -44 51 43 R.A. = 12 52 13.2 ; Dec. = -44 48 43 R.A. = 12 54 03.1 ; Dec. = -44 49 23 (J2000). A preliminary spectral analysis indicates that Epk < 19 keV. The preliminary fluences are: S(2-30 keV) = 6E-07 erg cm^-2, S(30-400) = 3E-07 erg cm^-2. Therefore GRB 050509c is an X-ray flash. A light curve, skymap, and spectral information for GRB 050509c are provided at the following URL: http://space.mit.edu/HETE/Bursts/GRB050509C/ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3404 SUBJECT: GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400) DATE: 05/05/10 10:43:13 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L.A. Antonelli on behalf of the REM/ROSS Team report: Please, note that GCN 3400 (D'Avanzo et al.) having subject "GRB050509: REM NIR and Optical observations" is referring to GRB 050509c. Thanks to Alberto Castro-Tirado and Nicola Masetti to point out the misleading subject. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3405 SUBJECT: GRB 050509B: WSRT Radio Observations DATE: 05/05/10 14:50:54 GMT FROM: Alexander van der Horst at U of Amsterdam A.J. van der Horst, K. Wiersema and R.A.M.J. Wijers (University of Amsterdam) report on behalf of a larger collaboration: "We observed the position of the GRB 050509B afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at May 9 14.59 UT to May 10 2.59 UT, i.e. 10.98 - 22.98 hours after the burst (GCN 3381). We do not detect a radio source within the SWIFT/XRT error circle (GCN 3395), in particular at the position of the four optical sources mentioned in GCN 3401. The rms noise in het map within the SWIFT/XRT error circle is 22 microJy per beam. The formal flux measurement for a point source at the center of the SWIFT/XRT error circle is 3 +/- 22 microJy. We detect a point source coincident with the position of the center of the galaxy observed in the optical (GCN 3390), with a peak flux of 324 +/- 22 microJy." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3406 SUBJECT: GRB 050509c: ROTSE-III Optical Limits DATE: 05/05/10 15:19:36 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), H. Swan (U Mich), R. Quimby (U Texas), T.A. McKay (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 050509c (HETE trigger 3751), producing images beginning 6.4 s after the GCN notice time. An automated response took the first image at 22:46:19.6 UT, 25.7 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 120 60-sec eposures. These unfiltered images are calibrated relative to USNO A2.0 (R). The final error box reported by Prigozhin et al. (GCN 3402) was entirely contained within the ROTSE-IIIc field of view of the initial response. Comparison to the DSS (second epoch) reveals no new sources within the SXC/WFC error box reported in GCN 3402; however, we are limited as the field is somewhat crowded. Individual images have limiting magnitudes ranging from 15.8-17.1. In particular, we set a limit of magnitude 15.9 in a single 5 s exposure, starting 25.7 s after the burst. Coadding the images into sets of 10 reveals no new sources down to limits of 17.0 (136 s effective length (t_end-t_start), beginning 25.7 s post-burst), 17.5 (295.4 s effective length, beginning 170.7 s post-burst), and 17.7 (695 s effective length, beginning 466.1 s post-burst). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3407 SUBJECT: GRB 050509a: Swift-BAT refined analysis DATE: 05/05/10 16:36:13 GMT FROM: Louis M Barbier at NASA/GSFC/Swift 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), T. Mitani (ISAS) D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC), W. Voges (MPE) on behalf of the Swift/BAT team: At 01:46:28 UT Swift-BAT detected GRB 050509a (trigger=118707) (GCN Circ 3379, C. Hurkett, et al.). The refined BAT ground position is (RA,Dec) = 310.608,+54.059, [deg; J2000] {20:42:24; +54:00:14} +- 0.45 arcmin, (95% containment). XRT found an uncatalogued x-ray source 13 arcseconds from the BAT position (GCN Circ 3380, J. Kennea, et al.) The coding was 100% in the FOV. The 1-s maskweighted lightcurve shows two distinct peaks. T90 (15-350 keV) is (11.6 +- 1.0) seconds (estimated error including systematics). The photon index of the time-averaged spectrum is 2.1 +- 0.2. The fluence in the 15-350 keV band is (4.6 +- 0.7) x 10^-7 erg/cm2. The 1-s peak photon flux measured from T0+0.388 second in the 15-350 keV band is (0.98 +- 0.13) ph/cm2/s. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3409 SUBJECT: GRB 050509b: No Optical Variability in XRT Error Circle DATE: 05/05/11 06:45:45 GMT FROM: S. Bradley Cenko at Caltech S. Bradley Cenko, B. T. Soifer, Chao Bian, Vandana Desai, S. R. Kulkarni (Caltech), Brian P. Schmidt (ANU), Arjun Dey and Buell T. Jannuzi (NOAO) report on behalf of the Caltech-NRAO-Carnegie GRB collaboration: We have continued to image the field of GRB 050509b with the Low Resolution Imaging Spectrometer mounted on the 10-m Keck I telescope. Our latest observations consisted of 3 x 300 s images simultaneously in the g' and R filters. The mean epoch of these observations was approximately 5:56 UT 10 May (25.8, 25.9, and 26.0 hours after the burst, respectively). We stacked all the R-band images obtained on 9 May (GCNs 3391, 3401) and differenced this from the stack obtained on 10 May. Adopting the value of R = 18.5 for the USNO-A2 star located at RA 12:36:19.970, Dec +29:00:36.31 (J2000.0), we find no variation within the revised XRT error circle (GCN 3395) to a limiting magnitude of R = 25.6. Specifically for the extended source in the XRT error circle (S1 in GCN 3401), we find this object has not varied by more than +/- 0.18 magnitudes from 9 May to 10 May. It is therefore unlikely that any of the 4 sources identified in GCN 3401 is the optical afterglow of GRB 050509b. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3410 SUBJECT: GRB050509B: Optical observations at the Very Large Telescope DATE: 05/05/11 13:41:19 GMT FROM: Brian Lindgren Jensen at U.of Copenhagen GRB 050509B: Optical observations at the Very Large Telescope J. Hjorth, J. Sollerman, B. L. Jensen, J. P. U. Fynbo, P. Jakobsson, J. M. Castro Cerón, K. Pedersen, H. Pedersen, D. Watson (Niels Bohr Institute), R. Starling (Amsterdam), J. Gorosabel (IAA-CSIC Granada), E. Ramirez-Ruiz (IAS, Princeton), C. Kouveliotou (NASA/MSFC) on behalf of GRACE, report : "Using FORS2 on the 8.2m Antu Telescope at ESO/Paranal we have obtained 45 min R-band imaging (FWHM~0.7") of the XRT error circle for GRB 050509B (Swift trigger 118749, GCN 3381) at a mean epoch of May 11.0 UT. In the revised XRT error-circle (GCN 3395) we detect the four sources (S1-S4) mentioned in GCN 3401. None of these sources show pronounced variability with respect to the image posted in GCN 3401. The source previously designated S3 seems to be resolved into two sources separated by 1.8", or a new source is apparent in the centre of the error circle. The position of this source is: S5: RA(2000) = 12:36:13.88, Dec(2000) = +28:59:01.0 Another object is included just within the revised 90% XRT error-circle. The coordinates of this object is: S6: RA(2000) = 12:36.13.63, Dec(2000) = +28:59:07.7 An image of the field is shown at: http://www.astro.ku.dk/~brian_j/grb/grb050509B/ We plan to monitor the field with the VLT in the following weeks. We thank the Paranal Observatory staff, in particular Chris Lidman and Jura Borissova, for efficiently conducting the reported service-mode observations. " [GCN OPS NOTE(11may05): Per author's request, the RA value in source S6 was changed from "12:33.13.63" to "12:36.13.63".] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3411 SUBJECT: GRB 050509b Milagro GeV/TeV Observations DATE: 05/05/11 16:11:11 GMT FROM: Pablo Saz Parkinson at UCSC/Milagro Pablo Saz Parkinson (UC Santa Cruz) on behalf of the Milagro collaboration reports: We have searched Milagro data for emission at GeV/TeV energies from GRB 050509b (GCN Circ 3381, C. Hurkett et al.), during the burst duration (30 ms) reported by the Swift team (GCN Circ 3385, S. Barthelmy et al.). No evidence for prompt GeV/TeV emission was found. A preliminary analysis, assuming a differential photon spectral index of -2.4, gives an upper limit on E^2dN/dE at 99% confidence of: E^2dN/dE at 2.5 TeV < 5.4 * 10^(-8) erg cm^(-2) (No EBL absorption assumed) The spectrum of the host galaxy of the proposed afterglow of GRB 050509b implies a redshift of 0.225 (GCN Circ 3386, J. Bloom et al., GCN Circ 3392, J. Bloom et al.). We expect that TeV photons will be attenuated by pair production with infrared photons in intergalactic space so we also calculate upper limits assuming different extragalactic infrared background light (EBL) absorption models, a "fast evolution" model by Stecker & de Jager 1988 (A&A, 334, L85) and a model by Primack et al. 2004 (AIP Conf. Proc. 745, p. 23). We find 99% confidence level upper limits on E^2dN/dE of: E^2dN/dE at 150 GeV < 5.5 * 10^(-7) erg cm^(-2) (Stecker et al. EBL model) E^2dN/dE at 300 GeV < 2.0 * 10^(-7) erg cm^(-2) (Primack et al. EBL model) The energies quoted represent the median energy of the events that would be detected assuming a power law spectrum with differential index -2.4 convolved with each of the absorption models. These upper limits are preliminary and will be refined with further analysis. ___________________________________________________________ Santa Cruz Institute for Particle Physics (SCIPP) University of California, Santa Cruz Natural Sciences II, Room 313 1156 High Street, Santa Cruz, CA 95064 Phone: (831) 459-4870 Fax: (831) 459-5777 ___________________________________________________________ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3412 SUBJECT: GRB 050509b: Swift/UVOT follow-up measurements DATE: 05/05/11 17:25:42 GMT FROM: Alexander Blustin at MSSL-UCL A. Breeveld (MSSL), T. Poole (MSSL), E. Rol(LU), M. Ivanushkina (PSU), S. Rosen (MSSL), M. Still (GSFC), P. Roming (PSU), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team Further to the initial Swift UVOT results (C. Hurkett et al. GCN 3381 and A. Breeveld et al. GCN 3397) we report the results of co-added, deeper exposures of GRB 050509b with the Swift Ultra-Violet/Optical Telescope (UVOT) in the 21 hours following the burst on May 09-10, 2005. We detect no source at the refined XRT determined location (12:36:13.9,28:59:01; E. Rol et al., GCN 3395) nor in the location of the extended source S1 (12:36:13.7, 28:58:57.3; S. Bradley Cenko et al. GCN 3391) in any of the UVOT filters. The 3-sigma limiting magnitudes are listed in the following table for the XRT position (XRT_Lim_Mag) and the S1 position (S1_Lim_Mag). A 6" aperture was used in all cases. Filter XRT_Lim_Mag S1_Lim_Mag Total Exp (s) T_range (s) V 21.1 21.1 5213 50 - 71553 B 21.8 21.8 4696 196 - 69818 U 21.8 21.8 5070 182 - 76713 UVW1 22.3 22.2 6491 169 - 76511 UVM2 22.2 22.2 6493 154 - 75603 UVW2 22.7 22.6 5596 212 - 70726 T_range values are start and stop times between which UVOT exposures were made, measured w.r.t the BAT trigger time (Barthelmy et al. GCN 3385). The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3413 SUBJECT: GRB050509B: Optical/Infared observations DATE: 05/05/11 17:39:30 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma S. Covino, G.L. Israel, L.A. Antonelli, D. Malesani, A. Melandri, N. Masetti, G. Tagliaferri, on behalf of the MISTICI and CIBO collaborations report "On May 11, we observed the revised error circle of SWIFT-XRT (GCN 3395) of the short GRB 050509B (Hurkett et al. GCN 3381) with DOLORES at the TNG (La Palma) and with=A0 FORS2 and NACO at the VLT (Chile). We collected R band photometry with FORS2 (a total of 45 minutes of exposure with ~0.8 seeing), R band photometry with DOLORES ( a total of 3600 s with ~1.5" seeing) and H band photometry with NACO (a total of 1800 s with ~0.7" seeing). All sources mentioned in GCN 3401 (Bradley et al.) and GCN 3410 (Hjorth et al.) are detected with no clear sign of variability. Further observations in the nexts days are planned." This message may be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3414 SUBJECT: GRB 050509b: RAPTOR deep, early limits. DATE: 05/05/11 22:18:35 GMT FROM: Przemyslaw R. Wozniak at LANL P. Wozniak, W.T. Vestrand, J. Wren, S. Evans, and R. White, on behalf the RAPTOR team at Los Alamos National Laboratory The RAPTOR-S telescope at Los Alamos National Laboratory responded to Swift trigger 118749 (Hurkett et al. GCN 3381) and collected a series of 113 unfiltered images starting at 26.57 s and continuing for the first 90 minutes after the trigger. The exposure durations are 10 s for the first 10 images, 30 s for the next 10 images and 60 s for the remaining 93 images. Using difference imaging techniques, comparing individual images as well as stacks of images, we have placed limits on early time variability at the locations of sources S1-S4 (Cenko et al. GCN 3401) within the XRT error circle (Rol et al. GCN 3395). We find no evidence for transient emission at the four candidate locations with the following 5 sigma limits. time of mid limiting # of effective t-t_trig t-t_trig UT exp. (s) mag (R) images duration start (s) end (s) start (5 sigma) 31.6 18.8 1 10.0 26.6 36.6 04:00:45.8 193.9 20.0 10 100.0 26.6 220.4 04:00:45.8 395.3 20.8 10 300.0 234.0 629.3 04:04:13.3 1399.5 21.7 20 1200.0 642.9 2042.4 04:11:02.1 1402.7 21.8 19 1140.0 2052.9 3455.6 04:34:32.1 1399.8 21.6 19 1140.0 3466.0 4865.8 04:58:05.2 The conversion of our unfiltered PSF fluxes to R-band magnitudes was performed using measurements of 10 nearby comparison stars from the USNO B1.0 catalog. Sample RAPTOR-S images will be posted at http://www.raptor.lanl.gov/images/GRB050509/grb050509_raptorS.gif. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3415 SUBJECT: Chandra observation of GRB 050509b DATE: 05/05/12 07:21:02 GMT FROM: David Burrows at PSU/Swift D. N. Burrows, D. Grupe (PSU), C. Kouvelioutou, S. Patel (MSFC), N. Gehrels (GSFC), P. Meszaros (PSU), B. Zhang (UNLV), and R. Wijers (U. Amsterdam) report: We have observed the field of the short burst GRB 050509b (Hurkett et al. 2005, GCN 3381) with the Chandra ACIS instrument. The 50 ks observation was centered at the Swift XRT afterglow position reported by Kennea et al. (2005; GCN 3383). Within the ACIS S3 detector 20 point sources are found by XIMAGE in our preliminary analysis. Two of these sources fall within the revised 8 arcsecond radius error circle reported by Rol et al. (2005; GCN 3395). The coordinates and count rates of these sources are: #5: 12 36 14.0 +28 59 02.5 2.46E-04+/-8.6E-05 #8: 12 36 13.9 +28 59 07.9 1.94E-04+/-7.8E-05 Source #5 is 2.0 arcseconds from the revised XRT position and is tentatively identified as the X-ray afterglow. However, the source intensity is too low for us to to verify whether this source is fading during our observation. Assuming a Crab-like spectrum absorbed by galactic NH (1.5E20), this count rate corresponds to a flux of 1.6E-15 cgs (0.2-10 keV). Combined with the Swift XRT flux measurement at early times, we estimate a power-law decay index of approximately -1.0 over the 200 ks interval between the two observations. Confirmation of this afterglow candidate will require additional Chandra observations to see whether any of these sources are fading. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3416 SUBJECT: GRB 050509b: Keck/Chandra Cross-Correlation DATE: 05/05/12 08:48:39 GMT FROM: Josh Bloom at Harvard/CFA J. S. Bloom, R. J. Foley, D. Pooley, A. V. Filippenko, R. Chornock (UCB), C. Blake (Harvard), J. X. Prochaska (UCSC), J. Hennawi (UCB), M. Gladders (Carnegie), B. Koester (U Michigan) and H. W. Chen (MIT) report: We observed the field of GRB 050509b (#3383,#3385) with Keck I (+LRIS) with g' and R filters. Starting at 20050511.25 UT, we took 5 dithered images in each band for a total of 1660 and 1620 sec exposures in g and R, respectively. At the location of the two reported Chandra sources we find no significantly-detected flux in either band, however there are indications of an R counterpart (at the few sigma level) to Chandra#8. Moreover, these images do reveal a number of sources in the XRT fainter than reported deep imaging with the VLT (3410) and Keck II (3401), which we label J1-J4: J1 12:36:13.56 +28:59:03.4 J2 13.44 04.7 J3 13.41 58:56.3 J4 13.47 59:06.2 (J2000; estimated errors of 0.3 arcsec in each direction). We note that S5, which is less than 2 arcsec from the Chandra source #5, appears bluer than neighboring S3 and S2. The finding chart can be found at: http://astro.berkeley.edu/~jbloom/grb050509b-chandra-keck-combo.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3417 SUBJECT: GRB 050509b: Keck/Chandra Cross-Correlation DATE: 05/05/12 09:40:53 GMT FROM: Josh Bloom at Harvard/CFA Correction: in GCN circular #3416 we inadvertently left out reference to the Chandra observations (Burrows et al. #3415). Below is the corrected circular. We apologize for the reference omission. --------------------------- J. S. Bloom, R. J. Foley, D. Pooley, A. V. Filippenko, R. Chornock (UCB), C. Blake (Harvard), J. X. Prochaska (UCSC), J. Hennawi (UCB), M. Gladders (Carnegie), B. Koester (U Michigan) and H. W. Chen (MIT) report: We observed the field of GRB 050509b (#3383,#3385) with Keck I (+LRIS) with g' and R filters. Starting at 20050511.25 UT, we took 5 dithered images in each band for a total of 1660 and 1620 sec exposures in g and R, respectively. At the location of the two reported Chandra sources (Burrows et al. GCN #3415) we find no significantly-detected flux in either band, however there are indications of an R counterpart (at the few sigma level) to Chandra #8. Moreover, these images do reveal a number of sources in the XRT error circle fainter than in reported deep imaging with the VLT (#3410) and Keck I (#3401), which we label J1-J4: J1 12:36:13.56 +28:59:03.4 J2 13.44 04.7 J3 13.41 58:56.3 J4 13.47 59:06.2 (J2000; estimated errors of 0.3 arcsec in each direction). We note that S5, which is less than 2 arcsec from the Chandra source #5, appears bluer than neighboring S3 and S2. The finding chart can be found at: http://astro.berkeley.edu/~jbloom/grb050509b-chandra-keck-combo.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3418 SUBJECT: GRB050509b, SDSS pre-burst observations DATE: 05/05/12 16:38:13 GMT FROM: Daniel Eisenstein at U of Arizona Daniel J. Eisenstein (Arizona), David W. Hogg (NYU), and Nikhil Padmanabhan (Princeton) report on behalf of the Sloan Digital Sky Survey (SDSS) Collaboration: The Sloan Digital Sky Survey imaged the region of GRB 050509b on Dec 15, 2004 (MJD 53354.48, 145 days before the burst trigger). These data will be part of a future SDSS data release, but as they should be useful as a pre-burst comparison image and for calibrating photometry, we are supplying the images and photometry measurements for this GRB field. SDSS spectroscopy has not yet been performed here. Data from the SDSS is being placed at http://www.sdss.org/dr3/products/value_added/grb050509b/ These include 5 FITS images, 3 JPGs, and 2 files of photometry and astrometry. We supply FITS images in each of the 5 SDSS bands of a 8'x8' region centered on the BAT position (ra=189.073, dec=28.991; Barthelmy et al. GCN 3385), as well as 3 gri color-composite JPGs (with different stretches). The units in the FITS images are nanomaggies per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is a flux unit equal to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS images have WCS astrometric information. The cluster NSC J123610+285901 (Gal et al., AJ, 125, 2064, 2003) is clearly visible in the JPGs. The bright galaxy close to the XRT error circle (ra=189.0537, dec=28.9830) has SDSS photometry of r_Petrosian = 17.18 +- 0.02 mag and model colors of u-g = 1.78 +- 0.13 mag, g-r = 1.42 +- 0.02 mag, r-i = 0.52 +- 0.01, i-z = 0.35 +- 0.02 mag. The galaxy is selected by both the Luminous Red Galaxy and Main galaxy sample targeting algorithms, and at z=0.225 (Prochaska et al. GCN 3390 & 3399), this is a rather luminous galaxy. Using the r-band Petrosian magnitude, we compute a rest-frame g-band luminosity M_g = -21.90, applying evolution corrections to z=0.3 (not z=0! see Zehavi et al. ApJ, 621, 22, 2005 for an explanation). This is about 1.5 magnitudes brighter than L* (Blanton et al., ApJ, 582, 819, 2003). The comoving number density of galaxies more luminous than this is only about 2x10^-5 h^3 Mpc^-3. This is all in keeping with the large velocity dispersion reported by Prochaska et al. (GCN 3399). A posteriori statistics are always suspicious, but we note that the sky density of galaxies this bright is about 40 per square degree, while that of galaxies this luminous at z<0.3 is about 1 per square degree. These are far smaller than 40,000 deg^-2, the inverse of the area of a 10 arcsecond circle. Hence, the chance association with a low-redshift galaxy is unlikely (at the 10^-3 level), although unless additional evidence for the association is found, it will be hard to draw a firm conclusion from this one object. In the file grb050509b.sdss_objects.dat, we report photometry of 335 objects detected by SDSS within 4' radius of the Swift BAT position. We have removed saturated objects and objects fainter than 23.0 in the r-band model magnitude. All quantities are standard SDSS photometry, meaning that they are very close to AB zeropoints and are quoted in asinh magnitudes. Photometric zeropoints are known to about 2% rms; photon noise can be much worse, of course. See documentation for details. None of this photometry is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis (1998) predictions for this region are A_u = 0.098 mag, A_g = 0.072 mag, A_r = 0.052 mag, A_i = 0.040 mag, and A_z = 0.028 mag. SDSS astrometry is generally better than 0.1 arcsecond per coordinate. Users requiring high precision astrometry should take note that the SDSS astrometric system can differ from the 2MASS system used in GCN 3392; we have not checked the offsets in this region. See the SDSS DR3 documentation for more details: http://www.sdss.org/dr3. These data have been reduced with the DR3 data pipelines; however, they are not part of that data release. We cannot guarantee that the values here will exactly match those of the data release in which these data are included. Moreover, the calibration of the FITS image may differ by a small amount (~1%) from the calibration of the quoted photometry; these came from different pipelines. To aid with calibration of other data sets, we also report the photometry of 90 brighter stars (r<20.5) in a wider region (0.3 by 0.2 degrees) around the burst. These data are in the file grb050509b.sdss_calibstars.dat. Beware that some of these stars are not well-detected in the u-band; use the errors to monitor this. This note can be cited, but please also cite the SDSS data release paper, Abazajian et al. (AJ, 129, 1755, 2005), when using the data or refering to the technical documentation. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3419 SUBJECT: Refined Chandra analysis of GRB 050509b DATE: 05/05/12 22:43:26 GMT FROM: David Burrows at PSU/Swift S. Patel, C. Kouveliotou (MSFC), D. N. Burrows, D. Grupe (PSU), N. Gehrels (GSFC), P. Meszaros (PSU), B. Zhang (UNLV), and R. Wijers (U. Amsterdam) report: Further analysis of our 50 ks Chandra observation of GRB 050509b (Burrows et al. 2005; GCN 3415) has shown that the XRT error circle is embedded in the diffuse X-ray emission from the cluster NSC J123610+285901. We find that the two X-ray sources reported in GCN 3415 are due to fluctuations in the counts from the cluster emission and are spurious. Our refined analysis finds no Chandra point sources within the XRT error circle down to an estimated 99% unabsorbed flux upper limit of about 1.2 x 10e-15 ergs s^-1 cm^-2 (0.5-10.0 keV; assuming galactic column density 1.52e20 cm^-2 and spectral photon index of -2). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3420 SUBJECT: GRB050509b, Bok telescope B-band imaging DATE: 05/05/13 00:34:33 GMT FROM: Daniel Eisenstein at U of Arizona Charles W. Engelbracht and Daniel J. Eisenstein (Arizona) report: We acquired B-band imaging of the field of GRB050509b using the 90-prime 1-degree camera on the 2.3-m Bok telescope. The time of the observation was 0500 UT May 10 (25 hours after the burst). The exposure time was 20 minutes, and the seeing was 1.7" due to wind shake. We clearly detect the source S1 (GCN 3388, 3401) at a B-band magnitude of 23.9. We do not find any sources in our B-band image that are not in the Hjorth et al. JPG image (GCN 3410). We are making the calibrated data for a 30' square region centered on the burst available at http://cmb.as.arizona.edu/~eisenste/grb050509b/grb050509b_B.fits.gz The header contains WCS astrometric information, good to 0.5". We estimate the photometric calibration at 5%. If you are using the B band image, please send an email to deisenstein@as.arizona.edu so that we can inform you of any revisions. While this image is surely not as deep as the nearly contemporaneous Keck LRIS imaging (GCN 3409), it may be useful for photometric redshifts. The B band lies blueward of but close to the 4000A break for the cluster at z=0.225 (Gal et al., AJ, 125, 2064, 2003; Prochaska et al., GCN 3399). Combined with slightly redder filters (V or g), one should be able to efficiently distinguish cluster members from higher redshift galaxies. We remark that if the GRB is at a much higher redshift than the cluster, then mapping of the cluster may be important for assessing the impact of gravitational lensing on the interpretation the burst. The velocity dispersion of 340 km/s (Prochaska et al., GCN 3399) for the large galaxy near the XRT position (Rol et al., GCN 3395) would predict an Einstein radius of 3.3" with a singular isothermal sphere model and an infinitely distant source. The embedding of the galaxy in the cluster may increase this value. Although multiple imaging remains unlikely, there should be non-negligible magnification. This note can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3422 SUBJECT: GRB 050509B: Subaru Optical Observations DATE: 05/05/13 16:52:43 GMT FROM: Nobuyuki Kawai at Tokyo Tech G. Kosugi, H. Furusawa (Subaru/NAOJ), M. Takada (Tohoku U) and N. Kawai (Tokyo Tech) report: "We have observed the Swift/XRT position of GRB 050509B (GCN 3381) in V-band with SuprimeCam on the Subaru 8.2m telescope atop Mauna Kea on the night of May 9. We obtained 600s exposure images at 08:08 UT (4.1 hr after the event) and 11:33 UT (7.5 hr after the event), respectively. We detect the four sources (S1-S4) mentioned in GCN 3401 along with other two sources (S5, S6) in GCN 3410. In addition, another source is detected (S7) within the XRT error circle. No apparent variability could be observed for these sources during the two epochs. Our first epoch image is shown at: http://www.naoj.org/staff/george/Distribute/GRB050509B/GRB050509B.html" This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3423 SUBJECT: GRB 050509B and short GRB-SN association? DATE: 05/05/15 08:56:20 GMT FROM: Arnon Dar at Technion-Israel Inst. of Tech S. Dado (Technion) and A. Dar (Technion) report: The leading scenarios for the production of short-duration GRBs involve (a) neutron-star mergers [1] (b) super flares from SGRs (GCN 2942 and [2]) (c) gravitational collapse of neutron-stars to strange-quark stars [3] (d) gravitational collapse of C/O white dwarfs to neutron stars (GCN 2174) and [3]). While scenarios (a),(b) are not associated with standard optical SNe, scenarios (c),(d) are expected to produce a standard optical SN. In particular, in scenario (d), a bright SNIa is expected at the GRB location with a standard rest frame optical light curves which peak around 20 days after burst with un-reddened absolute rest frame magnitudes, Bmax~-19.47, Vmax~-19.42, Rmax~-19.42 and Imax~-19.06 (+\-0.15 magnitude). GRB050509B (GCN 3381) is the first well localized short-duration (~30 ms) GRB. It allows a late time search of an SN associated with a short duration GRB. In the observer frame the expected un-reddened spectral energy density at a frequency nu and a time t after burst is: F(nu,t)=((1+z) [D_L(z')]^2 / (1+z')[D_L(z)]^2) Ftsn(nu',t') where z' is the redshift of the template SNIa whose spectral energy density is Ftsn and nu'=[(1+z)/(1+z')] nu, t'=[(1+z')/(1+z)] t. If GRB050509B was produced in an SNIa in the galaxy cluster NSC J123610+285901 at a redshift z~0.225 (GCN 3390), its observed V-band light curve should peak near t=25 days after burst with Vmax~20.43+/- 0.15 (extinction in the host galaxy is not included, but Galactic extinction in the direction of GRB 050509B, Av~0.06 [5] is included). Despite the failures so far to detect an optical afterglow within/near the refined XRT error circle (GCN 3395) of GRB 050509B, an SN search within/near the burst XRT error circle, with the most powerful telescopes such as Keck, VLT, Subaru and HST, is highly encouraged. [1] Goodman, J, Dar, A, & Nussinov, S. 1987, ApJ, 314, L7 [2] Hurley, K., et al. 2005, astro-ph/0502329 [2] Dar, A. 1999, A&AS, 138, 505 [3] Dar, A. & De Rujula, A. 2004, Physics Reports, 405, 203 [4] Germany, L. M., et al. 2004, A&A 415, 863 [5] Schlegel, D. J.; Finkbeiner, D. P. & Davis, M. 1998, ApJ, 500, 525 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3424 SUBJECT: GRB 050509B and short GRB-SN association? (corrected) DATE: 05/05/15 11:13:06 GMT FROM: Arnon Dar at Technion-Israel Inst. of Tech S. Dado (Technion), A. Dar (Technion) and A. De Rujula (CERN) report: The leading scenarios for the production of short-duration GRBs involve (a) neutron-star mergers [1] (b) super flares from SGRs (GCN 2942 and [2]) (c) gravitational collapse of neutron stars to strange-quark stars [3] (d) gravitational collapse of C/O white dwarfs to neutron stars (GCN 2174 and [4]). While scenarios (a), (b) are not associated with standard optical supernovae (SNe), scenarios (c),(d) are expected to produce a standard optical SN. In particular, in scenario (d), a Type Ia SN is expected at the GRB location with standard rest-frame optical light curves peaking around 20 days after burst with un-reddened absolute magnitudes [5] Bmax ~ -19.47, Vmax ~ - 19.42, Rmax ~ - 19.42 and Imax ~ - 19.06 (+\-0.15). GRB050509B (GCN 3381) is the first well-localized short-duration (~ 30 ms) GRB. A SN associated with a short GRB has never been looked for in such favorable conditions. In the observer's frame the associated-SN expected un-reddened spectral energy density at a frequency nu and a time t after burst is: F(nu,t) = F'(nu',t') [1+z] [D(z')]^2 / ( [1+z'] [D(z)]^2] ) where z' is the redshift of a template Type Ia SN with spectral energy density F'; D(z) and D(z') are luminosity distances, nu'=[(1+z)/(1+z')] nu and t'=[(1+z')/(1+z)] t. If GRB050509B was produced in association with a Type Ia SN in the galaxy cluster NSC J123610+28590, at redshift z = 0.225 (GCN 3390), its rising optical light curve should be observable well before its peak around t = 25 days after burst with Vmax ~ 20.43 +/- 0.15 (extinction in the host galaxy is not included, but Galactic extinction in the direction of GRB 050509B, Av~0.06 [6] is included). In spite of the non-detections of an optical afterglow near the refined XRT error circle (GCN 3395) of GRB 050509B, a SN search in this direction, perhaps with telescopes such as Keck, VLT, Subaru and HST, may prove very fruitful. [1] Goodman, J., Dar, A., & Nussinov, S. 1987, ApJ, 314, L7 [2] Hurley, K., et al. 2005, astro-ph/0502329 [3] Dar, A. 1999, A&AS, 138, 505 [4] Dar, A. & De Rujula, A. 2004, Physics Reports, 405, 203 [5] Germany, L. M., et al. 2004, A&A 415, 863 [6] Schlegel, D. J.; Finkbeiner, D. P. & Davis, M. 1998, ApJ, 500, 525 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3425 SUBJECT: XRF 050509c optical afterglow DATE: 05/05/16 10:55:28 GMT FROM: Jens Hjorth at U.Copenhagen J. Gorosabel (IAA-CSIC), B. L. Jensen (NBI), G. Galaz (Pont. Uni. de Chile), R. Salinas (Uni. de Concepcion), J. Hjorth, J. P. U. Fynbo, H. Pedersen, D. Watson, P. Jakobsson, J. M. Castro Cerón (NBI), report: "We have carried out R-band observations of XRF 050509c (HETE trigger #3751; GCN 3402) error box with the 1.54m Danish telescope (+DFOSC) on La Silla, as follows: ====================================== Date UT t-to Texp Seeing May 2005 (hr) (s) (") -------------------------------------- 10.1545-10.1703 5.1 2x600 1.2 14.0490-14.0829 98.8 4x600 1.3 ====================================== Both observations are centred in the SXC error box covering ~80% of it. Comparison of the two epoch images reveals, well centred in the SXC error box, a fading point-like object with coordinates: RA(J2000) = 12:52:53.94 Dec(J2000) = -44:50:04.1 (internal astrometric error of 1") which we propose as the XRF 050509c optical afterglow. Assuming R = 17.9 for the USNO star placed at (12:52:52.34, -44:49:23.1) we estimate a decay from R~20.1 to R~24.0 between the two epochs. This would imply a power-law decay index of -1.2 typical of GRB afterglows. Finding charts can be found at: http://www.dsri.dk/~jgu/grb050509c/FCs/grb050509c.1.54dk.epoch1.gif http://www.dsri.dk/~jgu/grb050509c/FCs/grb050509c.1.54dk.epoch2.gif Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3427 SUBJECT: XRF 050509C: REM NIR and Optical refined analysis DATE: 05/05/16 22:12:22 GMT FROM: Paolo D'Avanzo at INAF-OAB S. Piranomonte, P. D'Avanzo, L.A. Antonelli, S. Covino, D. Malesani, F.M. Zerbi, G. Chincarini, M. Rodono', G. Tosti, P. Conconi, G. Cutispoto, E. Molinari, L. Nicastro, E. Palazzi, V. Testa, F. Vitali, E. Meurs, P. Goldoni, on behalf of the REM/ROSS Team report: Following the detection of a candidate optical counterpart for XRF 050509c (HETE trigger #3751; GCN 3402), by Gorosabel et al. (GCN 3425) we re-analyzed our optical and NIR REM data (D'Avanzo et al GCN 3400). At 2.5 hours after the burst no object is found at the position of the candidate down to a limiting magnitude of R=19 and H=15.5 (3-sigma level). We note that our R limit is consistent with a power-law decay index of -1.2 (Gorosabel et al. GCN 3425). This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3440 SUBJECT: XRF050509c: Radio Observations DATE: 05/05/20 15:55:48 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech) and D. A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie collaboration: "We observed the field of XRF050509c (GCN 3402) with the Very Large Array at 8.5 GHz on May 20.17 UT. We do not detect a radio source coincident with the OT position (GCN 3425). We place a 2-sigma upper limit of 104 uJy." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3441 SUBJECT: XRF 050509c: Swift XRT Upper Limit DATE: 05/05/20 16:45:22 GMT FROM: Sergio Campana at INAF-OAB S. Campana (INAF-OAB), C. Pagani (INAF-OAB, PSU), D.N. Burrows (PSU) and N. Gehrels (NASA/GSFC) report on behalf of the Swift XRT team: The Swift XRT observed the HETE II burst XRF 050509c for ~4ks from 07:00 UT to 21:35 UT on 18 May 2005 and for ~19 ks from 00:18 UT to 23:25 UT on 19 May 2005. We did not detect any source in either observation in a 20 arcsec radius circle centred at the position of the optical counterpart identified by Gorosabel et al 2005 (GCN 3425). Combining data from the two observations, we obtain 23.1 ks of good data after normal data screening. The 3 sigma upper limit on the count rate is of 8.4e-4 counts/s (0.2-10.0 keV). Assuming a Crab-like spectrum and a Galactic column of 7.1e20 cm-2, this corresponds to an upper limit on the unabsorbed flux of ~3e-14 ergs/cm2/s (0.5-10.0 keV). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3442 SUBJECT: XRF050509C: Chandra Afterglow Detection DATE: 05/05/20 18:09:04 GMT FROM: Derek Fox at CIT Derek B. Fox (Caltech) reports on behalf of a larger collaboration: "We have observed the afterglow (Gorosabel et al, GCN 3425) of XRF 050509C (Prigozhin et al., GCN 3402) with the Chandra X-ray Observatory and ACIS-S detector, in a single 20-ks pointing beginning at 09:54 UT on May 19, and detect the X-ray afterglow at a count rate of 0.7(2) counts per ksec. This count rate corresponds to a 0.5-10 keV flux of 9E-15 erg cm-2 s-1, assuming a spectrum with power-law photon index alpha=1.5 and Galactic N_H=5.5E+20 cm-2. We note that this flux is consistent with the upper limit from Swift XRT at a similar epoch (Campana et al., GCN 3441)." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3455 SUBJECT: GRB050509b: optical observations DATE: 05/05/22 21:31:42 GMT FROM: Vasilij Rumjantsev at CrAO V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), B. Kahharov, M. Ibrahimov, D. Sharapov (MAO), A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the refined XRT error circle (Rol et al, GCN3395) of GRB050509b (Hurkett et al, GCN3381) with 2.6m F/3.85 Shajn telescope (ZTSh, CrAO) equipped with FLI IMG1001E CCD camera and 1.5m telescope (Maidanak Astronomical Observatory) on May 9 and 10. Maidanak observation took place on May 9 (16:48 - 18:31 UT) and May 10 (16:15 - 18:20 UT) in R-band with total exposure of 3600 sec in each date. ZTsh observation starts on May 9, 18:26 (UT) with total exposure of 3360 sec in R- and 1680 sec in I-band. The source S1 (S. Bradley Cenko et al, GCN3391, 3401) is visible in R and I. USNO B1.0 catalog is used for calibration and photometry of S1 source in R and I band: UT Telescope Exp. Band magnitude May 9 16:48-18:31 1.5m 3600 R 22.88 +/-0.13 May 9 18:51-20:02 2.6m 1680 I 22.72 +/-0.23 May 9 18:26-21:16 2.6m 3360 R 22.79 +/-0.08 May 10 16:15-18:20 1.5m 3600 R 22.93 +/-0.18 May 9+10 1.5m 7200 R 22.92 +/-0.07 (Magnitude of the S1 may be biased due to highlighting of bright galaxy.) Stacked images and stars used for calibration can be found in http://grb.rssi.ru/GRB050509b. While no variable optical source was found till now (G. Kosugi et al, GCN3422) the data obtained may be useful for long term monitoring of S1. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3460 SUBJECT: GRB 050509A: Further I-band imaging DATE: 05/05/23 12:48:28 GMT FROM: Brian Lindgren Jensen at U.of Copenhagen GRB 050509.074: Further I-band imaging Johan P. U. Fynbo, Brian L. Jensen, Jens Hjorth, Pall Jakobsson, J. M. Castro Cerón, H. Pedersen, Darach Watson (Niels Bohr Institute), Tapio Pursimo, Raine Karjalainen, John Telting (Nordic Optical Telescope), Björn Voss (University of Kiel) report: "Using StanCAM on the 2.56m Nordic Optical Telescope we have obtained further I-band imaging of the XRT error circle for GRB 050509.074 (Swift trigger 118707, GCN 3379, 3380) on May 19.17. All sources detected in our early I-band images from 20 min and 2.5 hr after the burst (GCN 3389) are also detected in the image from May 19. Our 3-sigma upper limit on the magnitude of any transient source in the XRT error circle (except in the eastern part covered by the bright star) is I=22.5. Images of the field are shown at: http://www.astro.ku.dk/~brian_j/grb/grb050509.074/ " //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3494 SUBJECT: GRB 050509b: refined XRT/Chandra afterglow position analysis DATE: 05/05/28 00:46:58 GMT FROM: David Burrows at PSU/Swift D. N. Burrows (PSU), S. Patel (MSFC), C. Sarazin (U. Virginia), E. Rol, M. R. Goad, P. T. O'Brien, R. Willingale (U. Leicester), and N. Gehrels (GSFC) report: Motivated by Bloom et al. (astro-ph 0505480), the Swift XRT team has reviewed our analysis of the XRT position for GRB 050509b (Rol et al., GCN 3395). We have taken into account the low counting statistics, cluster emission in the field and astrometric corrections. In order to evaluate possible cluster contributions, we have tested a variety of aperture sizes and time intervals. We find that the cluster emission contributes no more than 1 photon (on average) to the counts detected within any of our temporal and spatial regions, and is therefore unlikely to bias the results. We use the entire first orbit of data to maximize the signal to noise, and detect 11 photons in a 15 arcsecond (radius) source region. The xrtcentroid tool in the XRTDAS software package calculates the following position for these photons: RA(J2000) = 12:36:13.80, Dec(J2000) = 28:59:01.0 in the Swift frame of reference (shifted by 0.1 second in RA from the position reported in Rol et al.). We have corrected the Swift position to the 2MASS system astrometry by registering our 50 ks Chandra image to 2MASS coordinates using sources appearing in both, and then registering the 30 ks XRT observation to the Chandra image. This astrometric correction gives a shift of -2.9 arcseconds in RA and +0.3 arcseconds in declination, for a final XRT afterglow position of: RA(J2000) = 12h 36m 13.58s, Dec(J2000) = 28d 59' 01.3". This position is 9.8 arcseconds from the center of the E1 galaxy. Combining pre-launch calibration data with the uncertainties in the astrometric correction, we estimate an error circle radius of about 9.3 arcseconds (90% containment). This error circle is dominated by the Poisson statistics associated with the low number of source counts. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3521 SUBJECT: Limits on a SN in the field of GRB 050509b DATE: 05/06/06 03:45:40 GMT FROM: David Bersier at STScI D. Bersier, A. Fruchter, J. Rhoads, (STScI), A. Levan (U. of Leicester), N. Tanvir (Hertsfordshire) report on behalf of a larger collaboration: We have observed the field of GRB 050509b (Hurkett et al, GCN 3379) with the Gemini Multi-Object Spectrograph on the Gemini-North telescope. We obtained imaging data (Sloan filters) on May 13, May 17 and May 28. PSF-matched image subtraction of the May 13 and May 17 data from the May 28 image reveals no variable sources down to 26.5 on May 14 and 26.4 on May 17 (3-sigma limits). At the redshift of the cluster this would imply that any unextincted SN would be more than 4 magnitude fainter than SN 1998bw. Furthermore, our detection limit on May 28 is ~27.4. At that epoch, a supernova like SN 1998bw would be 6 mag brighter than this. There is no such bright source in the XRT error circle. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3543 SUBJECT: XRF050509c: Radio Detection DATE: 05/06/10 16:21:34 GMT FROM: Patrick B. Cameron at Caltech P. B. Cameron and A. M. Soderberg (Caltech) report on behalf of the Caltech-NRAO-Carnegie collaboration: "We observed the field of XRF050509c (GCN 3402) with the Very Large Array at 8.5 GHz on Jun 8.13 UT. At the position of the optical afterglow (GCN 3425) we detect a radio source with flux density 310 +- 49 uJy. Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3546 SUBJECT: XRF 050509c: Optical monitoring DATE: 05/06/14 09:43:49 GMT FROM: Javier Gorosabel at IAA-CSIC J. Gorosabel (IAA-CSIC), J. Hjorth, B. L. Jensen, U. G. Jørgensen (NBI), J.-P. Beaulieu, A. Cassan (IAP), M. I. Andersen (AIP), J. Donatowicz (Tech. Uni. of Vienna), D. Watson, J. P. U. Fynbo, P. Jakobsson, J. M. Castro Cerón, H. Pedersen (NBI), report: "We have performed almost daily R-band monitoring of the XRF 050509c field (GCN Circ. 3402, HETE-2 trigger #3751) from May 15 to June 8. No significant rebrightening brighter than R ~ 22.5 has been detected at the afterglow position (GCN Circ. 3425) during the mentioned period. If XRF 050509c was related to a supernova similar to SN 1998bw, our observations would impose a lower redshift limit of z > 0.4. A combination of all late images (www.astro.ku.dk/~brian_j/grb/grb050509.95/) reveals a faint (R ~ 24) object coincident with the afterglow position, which we tentatively identify as the host galaxy of XRF 050509c." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3861 SUBJECT: XRF050509c: Radio upper limits from GMRT DATE: 05/08/23 10:47:38 GMT FROM: Atish Kamble at Raman Research Inst Atish Kamble (Raman Research Institute [RRI], Bangalore, India), C. H. Ishwara Chandra (NCRA, Pune, India) and D. Bhattacharya (RRI) report on behalf of a larger GRB collaboration : We observed the field of XRF 050509c (GCN 3402, GCN 3425, GCN 3543) on Jul. 6.56 (UT) and on Aug 4.48 (UT) with the Giant Meterwave Radio Telescope (GMRT), India at 1280 MHz using a bandwidth of 32 MHz. We do not detect any source coincident with the position of radio afterglow reported by Cameron and Soderberg (GCN 3543). The two sigma upper limits are as follows: Jul. 6.56 (UT) : 0.22 mJy Aug 4.48 (UT) : 0.12 mJy We thank GMRT and the National Centre for Radio Astrophysics (NCRA) staff. This TOO was done under the GMRT Director's Discretionary Time. GMRT is run by NCRA-TIFR, Pune (INDIA). This messege may be cited.