//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9879 SUBJECT: GRB 090904: Swift detection of a burst DATE: 09/09/04 01:18:05 GMT FROM: Scott Barthelmy at NASA/GSFC M. Perri (ASDC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), V. D'Elia (ASDC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 01:01:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090904 (trigger=361830). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 100.882, +50.206 which is RA(J2000) = 06h 43m 32s Dec(J2000) = +50d 12' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a small peak at T_zero and then two large peaks at T+130 and T+175 sec with a duration of at least 200 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~T+130 sec after the trigger. The XRT began observing the field at 01:05:38.6 UT, 271.7 seconds after the BAT trigger. XRT found a bright, uncatalogued, fading X-ray source located at RA, Dec 100.8816, +50.2040 which is equivalent to: RA(J2000) = 06h 43m 31.58s Dec(J2000) = +50d 12' 14.4" with an uncertainty of 5.2 arcseconds (radius, 90% containment). This location is 7.3 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The XRT prompt light curve shows a large flare peaking about 30s after the start of the XRT observations. The initial flux in the 2.5 s image was 1.71e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 141 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. Because part of the 2.7'x2.7' sub-image was not received, the overlap with the XRT error circle is uncertain. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.10. Burst Advocate for this burst is M. Perri (perri AT asdc.asi.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9880 SUBJECT: GRB 090904A: ROTSE-III Optical Limits DATE: 09/09/04 01:25:32 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey (U Mich), W. Rujopakarn (Steward), W. Zheng (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 090904A (Swift trigger 361830; Perri M., GCN 9879), producing images beginning 9.5 s after the GCN notice time. An automated response took the first image at 01:02:31.6 UT, 84.7 s after the burst, and during the gamma-ray emission, under fair conditions. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle or the XRT error circle, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 15.8-16.6; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:02:31.5 01:02:36.5 5 15.8 84.6 N 01:04:48.1 01:09:27.0 278 17.8 221.2 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9881 SUBJECT: GRB 090904B: Swift detection of a burst DATE: 09/09/04 01:50:16 GMT FROM: Scott Barthelmy at NASA/GSFC V. D'Elia (ASDC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), M. Perri (ASDC), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 01:24:18 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090904B (trigger=361831). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 264.191, -25.212 which is RA(J2000) = 17h 36m 46s Dec(J2000) = -25d 12' 43" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows multiple overlapping peaks starting at T-5 sec with a duration of about 60 sec. The peak count rate was ~1800 counts/sec (15-350 keV), at ~3 sec after the trigger. The XRT began observing the field at 01:26:32.3 UT, 134.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 264.1854, -25.2138 which is equivalent to: RA(J2000) = 17h 36m 44.50s Dec(J2000) = -25d 12' 49.7" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 19 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.28e+21 cm^-2, Kalberla et al. 2005), with an excess column of 4.8 (+5.33/-4.01) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 137 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. Because of the density of catalogued stars,further analysis is required to report an upper limit for any afterglow in the region. We note that this is a separate burst from the "A" burst. But there may be some confusion resulting from overlapping GCN Notices. Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9882 SUBJECT: GRB090904B: REM observations DATE: 09/09/04 03:03:22 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma S. Covino, L.A. Antonelli, P. D'Avanzo, D. Fugazza, S. Campana, G. Chincarini, V. D'Elia, F. D'Alessio, F. Fiore, P. Goldoni, C. Guidorzi, E. Maiorano, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Tagliaferri, G. Tosti, V. Testa, S.D. Vergani, F. Vitali report on behalf of the REM team: The REM 60-cm robotic telescope located at ESO-La Silla reacted promptly after the Swift alert for GRB09094B. Observations began 108 seconds after the GRB time (40 s after the trigger) with the R and H bands and continued with all the available filters (VRIJHK). No transient was singled out in the images, although a not varying 2MASS star with H=11.95 seems to be coincident with the XRT position. The field is located very close to the Galactic Center (LII = 2.12 deg, BII = 3.64 deg) and is heavily reddened and crowded, requiring further analyses to evaluate the chance for this positional coincidence. Further observations are in progress. ------------------------------------------------- This mail sent through IMP: http://horde.org/imp/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9884 SUBJECT: GRB 090904A: NOT observations DATE: 09/09/04 10:50:17 GMT FROM: Pall Jakobsson at U of Iceland D. Malesani (DARK/NBI), P. Jakobsson (U. Iceland), N. Tanvir (U. Leicester) and I. Ilyin (AIP) report on behalf of a larger collaboration: We observed the field of GRB 090904A (Perri et al., GCN 9879) with the Nordic Optical Telescope equipped with StanCam. Observations were carried out on 2009 Sept 4.17 (3.1 hr after the GRB) in the R- and I-bands. No objects are detected inside the XRT error circle to a limit of R > 23. However, just outside the error circle at RA(J2000) = 06:43:32.33 Dec(J2000) = +50:12:12.4 there is an object with R = 22 +/- 0.2 mag (calibrated against several nearby USNO-B1 stars). If weather permits, further observations are planned tonight to estimate whether the object is fading. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9885 SUBJECT: GRB 090904A: Enhanced Swift-XRT position DATE: 09/09/04 12:16:03 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1030 s of XRT Photon Counting mode data and 1 UVOT images for GRB 090904A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 100.88052, +50.20366 which is equivalent to: RA (J2000): 06h 43m 31.33s Dec (J2000): +50d 12' 13.2" with an uncertainty of 2.0 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9886 SUBJECT: GRB090904A: Correction to enhanced XRT position DATE: 09/09/04 12:32:00 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: The automatic enhanced XRT position (GCN 9885) was incorrect and should be disregarded. The position was obtained by averaging all the PC data from the first orbit, however the degree of pile up in this period changes by much more than is normal (see the light curve at: http://www.swift.ac.uk/xrt_curves/00361830/). As a result, the PSF of the image did not match any of our calibrated PSFs. We apologise for any confusion. The best XRT position available is the enhanced SPER position, which was distributed as an XRT Position Update GCN notice about at 01:27 UT. This position is RA, Dec = 100.8858, 50.2038, which corresponds to RA(J2000.0) = 06h 43m 32.59s Dec (J2000.0) = +50d 12' 13.6" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9887 SUBJECT: GRB 090904B: Enhanced Swift-XRT position DATE: 09/09/04 12:55:48 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1190 s of XRT Photon Counting mode data and 1 UVOT images for GRB 090904B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 264.18534, -25.21305 which is equivalent to: RA (J2000): 17h 36m 44.48s Dec (J2000): -25d 12' 47.0" with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9888 SUBJECT: GRB 090904A: Swift-BAT refined analysis DATE: 09/09/04 13:16:39 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), M. Perri (ASDC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090904A (trigger #361830) (Perri, et al., GCN Circ. 9879). The BAT ground-calculated position is RA, Dec = 100.855, 50.235 deg, which is RA(J2000) = 06h 43m 25.2s Dec(J2000) = +50d 14' 06.9" with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%. The mask-weighted light curve shows low level emission starting at ~T-40 sec, with a small peak at ~T+5 sec. Then there was a larger peak at ~T+50 sec, and then the largest peak (FRED-like) starting at ~T+123 sec, peaking at ~T+128 sec. Riding on that tail is a peak ~T+173. The event is over in the BAT energy band at ~T+240 sec. T90 (15-350 keV) is 122 +- 10 sec (estimated error including systematics). The time-averaged spectrum from T+29.3 to T+186.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.01 +- 0.10. The fluence in the 15-150 keV band is 3.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+127.07 sec in the 15-150 keV band is 1.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/361830/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9890 SUBJECT: GRB 090904B: Swift-BAT refined analysis DATE: 09/09/04 13:27:29 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-119 to T+303 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090904B (trigger #361831) (D'Elia, et al., GCN Circ. 9881). The BAT ground-calculated position is RA, Dec = 264.194, -25.219 deg, which is RA(J2000) = 17h 36m 46.5s Dec(J2000) = -25d 13' 09.0" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 8%. The mask-weighted light curve shows the burst starting at ~T-30 sec, with several overlapping peaks between T-5 to T+20 sec and another series from T+30 to T+50 sec. The burst is over by ~T+70 sec T90 (15-350 keV) is 47.0 +- 1.7 sec (estimated error including systematics). The time-averaged spectrum from T-2.5 to T+49.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.59 +- 0.07. The fluence in the 15-150 keV band is 1.1 +- 0.0 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+12.42 sec in the 15-150 keV band is 5.3 +- 0.9 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/361831/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9891 SUBJECT: GRB 090904A: Enhanced Swift XRT position DATE: 09/09/04 14:28:45 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team. With 6 ks of XRT data, and 5 UVOT images from recent data downlinks we have generated an enhanced XRT position for GRB 090904A, which does not include the problematic first image and is thus reliable. The enhanced position is RA, Dec = 100.88480, +50.20300 which is equivalent to: RA (J2000): 06h 43m 32.35s Dec (J2000): +50d 12' 10.8" with an uncertainty of 1.6 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. [GCN OPS NOTE(04sep09): Per operator's desire, the Subject-line was changed from "090404A" to "090904A". F.Marshall noticed this.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9892 SUBJECT: GRB 090904B: MOA-II Optical observation DATE: 09/09/04 15:29:08 GMT FROM: Kenta Nishimoto at Nagoya U/MOA-II K. Nishimoto, T. Sako, and D. Suzuki (STE Lab, Nagoya Univ.) on behalf of the MOA Collaboration report: We searched for an optical afterglow of GRB090904B (GCN9881, V. D'Elia et al.) starting from 07:34:56.9 UT on 2009 Sep 4 (6 hours after the burst) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand. In a single image of a 60 sec exposure with a wideband Red filter (center wavelength ~ 750nm and FWHM ~ 250nm), we did not find any object within the error circle of the Swift XRT source position (GCN 9887), except a USNO-B1.0 catalog star, 0647-0516939, which has I mag=15.10 and the separation of 1.8 arcsec from the center of the position. Quick estimation of the limiting magnitude is >20.5 calibrated by using USNO-B1.0 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9893 SUBJECT: GRB 090904B: Swift XRT Refined Analysis DATE: 09/09/04 16:49:07 GMT FROM: Valerio D'Elia at INAF-OAR V. D'Elia, G. Stratta, M. Perri (ASDC) report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 090904B (D'Elia et al. GCN Circ. 9881), from 159 s to 37.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 9987). The light curve, after an initial rise, peaks at T+260 s, while the following decay can be modelled with a power-law with a decay index of alpha=1.20+-0.05 (90% confidence level). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.67 (+0.26, -0.24, 90% confidence level). The best-fitting absorption column is 6.3 (+2.5, -1.1) x 1021 cm-2, in excess with respect to the Galactic value of 3.3 x 1021 cm-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.8 x 10-11 (1.1 x 10-10) erg cm-2 count-1. If the light curve continues to decay with a power-law decay index of 1.20, the count rate at T+24 hours will be 0.0040 count s-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x 10-13 (4.4 x 10-13) erg cm-2 s-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00361831. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9894 SUBJECT: GRB 090904A: Swift-XRT refined analysis DATE: 09/09/04 16:56:03 GMT FROM: Matteo Perri at ISAC/ASDC M. Perri, V. D'Elia, G. Stratta (ASDC) report on behalf of the Swift-XRT team: We have analysed the first 12 ks of XRT data for GRB 090904A (Perri et al., GCN Circ. 9879), from 134 s to 29.6 ks after the BAT trigger. The enhanced XRT position for this burst was given by Evans (GCN. Circ. 9891). During the first Swift orbit, the light-curve shows a steep decay with a large superimposed flare peaking at about T+300 s. Starting from T+1000 s, the curve is well described by a broken power-law model with temporal decay indices alpha1=0.2+/-0.1, alpha2=0.9+/-0.3 and a temporal break at around T+12 ks. A spectrum extracted from the PC mode data from T+460 s to T+29.6 ks can be fitted with an absorbed power-law model with a photon spectral index of 2.46 (+0.16,-0.26) and an absorption column density of 1.03 (+0.66,-0.64)e21 cm-2 in excess of the Galactic value of 9.3e20 cm-2 (Kalberla et al. 2005). The counts-to-observed (-unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3e-11 (6.2e-11) erg cm-2 count-1. Errors are given at the 90% confidence level. If the light curve continues to decay with a power-law index of 0.9, the count rate at T+24 hours will be 6e-3 count s-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0e-13 (3.7e-13) erg cm-2 s-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00361830. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9895 SUBJECT: GRB 090904B: Fermi GBM detection DATE: 09/09/04 22:01:47 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) reports on behalf of the Fermi GBM Team: "At 01:24:13.93 UT on 04 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090904B (trigger 273720255 / 090904058), which was also detected by the SWIFT-BAT (D'Elia et al. 2009, GCN 9881). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 113 degrees. The GBM light curve consists of three bright peaks with a duration (T90) of about 71 s (8-1000 keV). The time-averaged spectrum from T0-9.2 s to T0+65.5 s is well fit by a power law function with an exponential high energy cutoff. The power law index is 1.41 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 149.30 +/- 22.10 keV (chi squared 243.6 for 238 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.44 +/- 0.15)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+21.5 s in the 8-1000 keV band is 9.8 +/- 0.7 ph/s/cm^2. A Band function fits the spectrum equally well (chi squared 239.0 for 237 d.o.f.) with Epeak= 106.30 +/- 24.60 keV, alpha = -1.26 +/- 0.15 and beta = -2.18 +/- 0.18. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9898 SUBJECT: GRB 090904B: Swift/UVOT Refined Analysis DATE: 09/09/05 05:45:47 GMT FROM: Tyler Pritchard at PSU T. A. Pritchard (PSU) and D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 090904B, 138 seconds after the BAT trigger (D'Elia et al., GCN Circ. 9881). We do not detect any source at the UVOT-enhanced XRT position (J.P. Osbourne et al., GCN Circ.9887). The 3-sigma upper limits for the exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white 138 1357 369 > 22.17 v 625 1237 78 > 19.08 b 551 1335 78 > 20.08 u 295 545 246 > 20.41 ------------------------------------------------------------- The quoted upper limits have not been corrected for the highly uncertain extinction corresponding to a reddening along the line of sight of of E_(B-V) = 1.76 mag Schlegel et al., (1998, ApJS, 500, 525). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9899 SUBJECT: GRB 090904A: Swift/UVOT Refined Analysis DATE: 09/09/05 05:46:33 GMT FROM: Tyler Pritchard at PSU T. A. Pritchard (PSU), C. A. Swenson (PSU) and M. Perri (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of GRB 090904A, 141 seconds after the BAT trigger (M. Perri et al., GCN Circ. 9879). We do not detect any source at the UVOT-enhanced XRT position (M.R. Goad, GCN Circ. 9885). The 3-sigma upper limits for the exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white 141 1189 341 > 21.57 v 629 1078 58 > 18.72 b 555 1177 58 > 19.59 u 299 1152 285 > 20.43 uvw1 679 1127 58 > 19.11 uvm2 827 847 19 > 17.61 uvw2 605 1054 58 > 19.17 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction corresponding to a reddeningalong the line of sight of E_(B-V) = 0.1 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9901 SUBJECT: GRB 090904B: GROND detection of the optical afterglow DATE: 09/09/07 12:54:08 GMT FROM: Thomas Kruehler at MPE/MPI F. Olivares, P. Afonso, T. Kruehler, J. Greiner (all MPE Garching), report on behalf of the GROND team: The field of GRB 090904B (Swift trigger 361831, D'Elia et al., GCN #9881, also GBM trigger 273720255/090904058, Goldstein, GCN #9895) was observed simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 01:28 UT, on September 4, 2009, 4 minutes after the GRB trigger. The field was observed during a second epoch, starting at 01:28 UT, on September 5, 2009, 24.07 hours after the GRB trigger. Image subtraction between the two epochs reveals a fading source on the edge of the enhanced Swift/XRT error circle (Osborne et al., GCN #9887). The position of the afterglow is RA (J2000.0) = 17h 36m 44.59s DEC (J2000.0) = -25d 12' 46.5" with an uncertainty of 0.5" in each coordinate. The afterglow is located roughly 1.1" South/East of the 2MASS/USNO star reported by REM (Covino et al., GCN #9882) and MOA-II (Nishimoto et al., GCN #9892), and both sources are strongly blended in the GROND images of 1.0" seeing. At a midtime of 6.5 minutes after the burst, we measure rough preliminary AB magnitudes of the optical afterglow of r' ~ 22.2, i ~ 20.6 and z' ~ 19.7. Calibrations were done against GROND zero points, and given magnitudes are not corrected for the significant Galactic extinction corresponding to a reddening of E(B-V) = 1.76 mag (Schlegel et al. 1998). The object is detected in all bands except g', which, given the large Galactic foreground extinction, does not constrain the redshift. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9931 SUBJECT: GRB090904B : IRSF NIR upper limit DATE: 09/09/25 02:00:32 GMT FROM: Kenta Nishimoto at Nagoya U/MOA-II K. Nishimoto, T. Sako(Nagoya Univ.) on behalf of the MOA Collaboration, M. Kurita on behalf of the IRSF Collabration, T. Yosikawa(Kyoto Univ.), T. Suenaga(Soken Univ.) report: We searched for a NIR afterglow of GRB090904B (GCN9881, V. D'Elia et al.) starting from 17:6:57.7 UT on 2009 Sep 4 (15.71 hours after the burst) with the SIRIUS on the IRSF 1.4m telescope at SAAO in South Africa. In images of a 300sec exposure with J, H and Ks filter, we did not find any object except the reported star (GCN9882, Covino et al and GCN9892, Nishimoto et al.) within the error circle of the Swift XRT source position (GCN9887, J.P. Osborne et al.). Quick estimation of the limiting magnitude calibrated by using 2MASS catalog: J > 17.14 H > 16.57 K > 15.79 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10000 SUBJECT: GRB 090904A: afterglow confirmation DATE: 09/10/08 05:16:08 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani (DARK/NBI), Pall Jakobsson (Univ. Iceland), and Ilya Ilyin (AIP), report on behalf of a larger collaboration: We observed again the field of GRB 090904A (Perri et al., GCN 9879) with the NOT equipped with StanCam. Observations were carried out in the R band, for a total exposure time of 30 min, with a mean time September 6.218 UT (2.176 days after the GRB trigger). The object identified in our previous epoch of imaging (Malesani et al., GCN 9884) has clearly faded and is hardly detectable, if at all. A faint source is visible at its position, with magnitude R = 24.0 +- 0.3. If real, the inferred decay slope is alpha = 0.55 +- 0.12, assuming F(t) propto t^-alpha. The value of alpha is shallower than usually found at late times, and may indicate some host contribution or an unusual light curve. The position of the transient is consistent with the latest available UVOT-enhanced XRT position (Goad et al., GCN 9885; see also http://www.swift.ac.uk/xrt_positions/index.php). We thus identify the object as the optical afterglow of GRB 090904A. A finding chart comparing the two epochs can be found at the following URL: http://www.astro.ku.dk/~malesani/GRB/090904A/GRB090904A_finder_NOT.jpg