//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9356 SUBJECT: GRB 090515: Swift detection of a short burst DATE: 09/05/15 04:56:51 GMT FROM: David Palmer at LANL A. P. Beardmore (U Leicester), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), B. A. Rowlinson (U Leicester), M. H. Siegel (PSU), M. Stamatikos (NASA/ORAU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 04:45:09 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090515 (trigger=352108). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 164.171, +14.456 which is RA(J2000) = 10h 56m 41s Dec(J2000) = +14d 27' 22" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single short spike structure with a duration of about 0.1 sec. The peak count rate was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 04:46:13.3 UT, 63.8 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 164.15224, 14.44099 which is equivalent to: RA(J2000) = 10h 56m 36.54s Dec(J2000) = +14d 26' 27.6" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 84 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.94e+20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 5.22e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 72 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 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: 9357 SUBJECT: GRB 090515: ROTSE-III Optical Limits DATE: 09/05/15 05:08:31 GMT FROM: Wiphu Rujopakarn at U AZ/Steward W. Rujopakarn (Steward Observatory), B. E. Schaefer (Louisiana State), and E.S. Rykoff (UCSB), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 090515 (Swift trigger 352108; Beardmore et al., GCN 9356), producing images beginning 6.5 s after the GCN notice time. An automated response took the first image at 04:45:27.5 UT, 18.0 s after the burst, under fair conditions. We took 10 5-sec and 10 20-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 16.4-17.8; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 04:45:27.5 04:45:32.5 5 16.4 18.0 N 04:45:27.5 04:46:34.6 67 18.4 18.0 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9358 SUBJECT: GRB 090515: KAIT optical upper limits DATE: 09/05/15 05:57:53 GMT FROM: Ryan Chornock at UC Berkeley W. Li, R. Chornock, and A. V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory responded to the Swift trigger of GRB 090515 (Beardmore et al., GCN 9356) and began a sequence of filtered and unfiltered 20s images followed by a set of three 180s unfiltered images. We detect no new source within the XRT error circle (Beardmore et al., GCN 9356). Individual unfiltered 20s exposures starting at 04:59:09 UT have 3-sigma limiting magnitudes (calibrated to USNO B1) of about mag 19.1. Our combined set of 3x180s unfiltered images has an upper limit of about mag 20.5 at a midpoint of 05:19:47 UT. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9359 SUBJECT: GRB 090515: PAIRITEL Upper Limits DATE: 09/05/15 06:42:34 GMT FROM: Adam Morgan at PSU/Swift-UVOT A. N. Morgan, B. E. Cobb, C. Klein, and J. S. Bloom (UC Berkeley) report: We observed the field of GRB 090515 (Beardmore et al. 2009, GCN 9356) with the 1.3-m PAIRITEL located at Mt Hopkins, Arizona. Observations began at 2009-05-15 05:11 UT, 26 minutes after the Swift Trigger. We detect no afterglow at the XRT position in a mosaic with an effective exposure time of ~330 seconds. The preliminary photometry (calibrated to 2MASS) yields: post_burst t_mid(min) exp(s) filt U. Limit (3 sig) 30 330 J > 18.0 30 330 H > 17.2 30 330 K > 15.1 All magnitudes are given in the Vega system. No correction for Galactic extinction has been made to the above reported values. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9360 SUBJECT: GRB 090515: Super-LOTIS Upper Limits DATE: 09/05/15 08:00:24 GMT FROM: Grant Williams at Steward Observatory G. G. Williams (MMTO), A. Updike (Clemson), and P. A. Milne (Steward Observatory), on behalf of the Super-LOTIS Collaboration, report: The robotic 0.6-m Super-LOTIS telescope began observing the error box of GRB 090515 (Swift Trigger 352108, Beardmore et al. GCN 9356) at 04:45:52 UT, 43 seconds after the trigger. Our initial observations include 5 x 10s exposures, 5 x 20s exposures, and 30 x 60s exposures, all in the R-band. We do not detect any variable sources or afterglow candidates within the XRT error box in our earliest exposure to the following 3-sigma limiting magnitude determined using nearby USNO-B1.0 stars. We also do not detect any afterglow candidate in later images and sets of combined images: t_start (UT) exp t (s) t_start-t_0 (s) Limit ---------------------------------------------------------------- 04:45:52 10 43 R > 17.7 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9361 SUBJECT: GRB 090515: WIYN NIR Upper Limit DATE: 09/05/15 08:47:58 GMT FROM: Adria C. Updike at Clemson U Adria C. Updike, Ginger Bryngelson (Clemson University) and Peter A. Milne (Steward Observatory) report: We observed the field of GRB 090515 (GCN 9356, Beardmore et al.) with the 3.5m WIYN telescope and the NIR imager WHIRC located at Kitt Peak National Observatory beginning 1 hour after the trigger. Observations consisted of J-band exposures at high airmass. In a stacked image consisting of 20 x 2min J-band exposures (T_0 = 1.4 hours after trigger), we detect no new objects down to a limiting magnitude of J > 19.0 mag (upon comparison to the 2MASS catalog). No further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9362 SUBJECT: GRB 090515: Gemini-N upper limit DATE: 09/05/15 09:00:11 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara, D. B. Fox (PSU), N. Tanvir (U. Leicester), E. Berger (Harvard U.), John Graham (STScI / JHU) and A. Levan (U. Warwick) report: On May 15.28 UT we observed the field of the short GRB 090515 (Beardmore at al, GCN 9356) with Gemini GMOS-N. We took a sequence of 6 images of 300 sec each in R band. No clear afterglow candidate has been found in the XRT error circle (GCN 9356) at the limiting magnitude of R ~ 25.4. We also note the presence of a galaxy on the north edge of the XRT error circle, at the following position: RA: 10:56:36.46 Dec: +14:26:31.91 with a 0.3 arcsecond error in both coordinates. The magnitude of this galaxy is R = 22.90 +- 0.18 (calibrated using the SDSS star at RA = 10:56:35.74 , Dec = 14:26:49.6). We thank the Gemini staff for performing these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9364 SUBJECT: GRB 090515: Swift-BAT refined analysis DATE: 09/05/15 12:44:58 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), 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 sets from T-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 090515 (trigger #352108) (Beardmore, et al., GCN Circ. 9356). The BAT ground-calculated position is RA, Dec = 164.166, 14.469 deg, which is RA(J2000) = 10h 56m 39.8s Dec(J2000) = +14d 28' 09.5" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 86%. The mask-weighted light curve shows a single peak with a slightly longer fall time than rise time. The total width is about 0.075 sec. T90 (15-350 keV) is 0.036 +- 0.016 sec (estimated error including systematics). The time-averaged spectrum from T+0.008 to T+0.056 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.6 +- 0.2. The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band is 5.7 +- 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/352108/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9365 SUBJECT: GRB 090515: Swift-BAT refined spectral analysis DATE: 09/05/15 15:29:10 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (GSFC/UMBC), A. P. Beardmore (U Leicester) on behalf of the Swift-BAT team Based on a further analysis of the BAT spectrum of GRB 090515 (Barthelmy, et al. , GCN Circ. 9364), we found that the spectrum shows a significant improvement of chi2 by a power-law with an exponential cutoff (chi squared 52.55 for 56 d.o.f.) over a simple power-law (chi squared 58.63 for 57 d.o.f.). This fit gives a photon index -0.05 +- 1.36, and Epeak of 64 +- 23 keV. For this model the total fluence in the 15-150 keV band is 2.0 +- 0.3 x 10^-8 erg/cm2. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9367 SUBJECT: GRB 090515: Enhanced Swift-XRT position DATE: 09/05/15 16:44:21 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 2254 s of XRT Photon Counting mode data and 1 UVOT images for GRB 090515, 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 = 164.15047, +14.44174 which is equivalent to: RA (J2000): 10h 56m 36.11s Dec (J2000): +14d 26' 30.3" with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, arXiv:0812.3662). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9368 SUBJECT: GRB 090515: Swift-XRT refined analysis DATE: 09/05/15 18:58:27 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team : We have analysed 4.5 ks of XRT data for GRB 090515 (Beardmore et al. GCN Circ. 9356), from 70 s to 11.5 ks after the BAT trigger. The data comprise 132 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 9367). Initially, the light curve follows a shallow decay from a rate of 30 count s^-1 (at T+70 s), with a decay index of 0.59, out to approximately T+245 s. The count rate then drops by a factor of ~250 in the next ~70 s (i.e. suggesting a decay index in excess of 10 at this time). The burst is no longer detected beyond the first orbit to a 3 sigma count rate upper limit of 0.0058 count s^-1 (from T+5.7 to T+11.5 ks). A spectrum formed from the WT mode data (from T+70 to T+195 s) can be fitted with an absorbed power-law with a photon spectral index of 1.88 +/- 0.14. The best-fitting absorption column is (6.1 +3.0 -2.8) x 10^20 cm^-2, in excess of the Galactic value of 1.9 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00352108. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9369 SUBJECT: GRB 090515: Swift/UVOT Observations DATE: 09/05/15 20:10:18 GMT FROM: Michael Siegal at Swift/PSU M. H. Siegel (PSU) and A. P. Beardmore (Leicester) report on behalf of the Swift/UVOT team. The Swift/UVOT began observing the field of GRB 090515 67s after the BAT trigger (Beardmore et al., GCN Circ. 9356). Data summed from the first and second orbits does not reveal a source at the refined position of the X-ray afterglow (Osborne et al., GCN Circ. 9367). The 3-sigma upper limits for the finding chart (fc) and summed exposures are reported below: FILTER T_start(s) T_stop Exposure Mag/3UL ============================================================= white fc 67 216 146 > 20.35 white 67 2389 488 > 21.24 white 5901 13321 401 > 21.12 v 608 2439 213 > 19.27 v 6311 7947 393 > 19.62 b 534 2365 194 > 20.15 b 5696 13291 688 > 20.70 u 278 528 245 > 19.83 u 6926 12386 491 > 20.40 uvw1 657 2488 214 > 19.83 uvw1 6722 8290 327 > 20.01 uvm2 805 2291 97 > 19.07 uvm2 6516 8151 393 > 20.16 uvw2 583 2414 213 > 20.11 uvw2 6107 7742 393 > 20.48 ================================================================= The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.02 (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9370 SUBJECT: GRB 090515: MMT/MMIRS NIR Upper Limit DATE: 09/05/15 22:59:17 GMT FROM: Grant Williams at Steward Observatory B. McLeod (CfA), G. Williams (MMTO) on behalf of the MMIRS commissioning team report: We observed the field of GRB 090515 (Beardmore et al. 2009, GCN 9356) with the MMIRS instrument on the 6.5-m MMT telescope.  Observations began at 06:44 UT, approximately 119 minutes after the Swift trigger. We obtained 27 x 30 second exposures in the K-band.  We do not detect any afterglow candidate in the XRT error circle in the combined image to the following 5-sigma limiting magnitude determined using nearby 2MASS stars: t_start (UT)     exp t (s)     t_start-t_0     Limit ----------------------------------------------------------- 06:44        27x30              119 min      K > 19.3 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9371 SUBJECT: GRB 090515: ROVOR Upper Limit DATE: 09/05/15 23:34:03 GMT FROM: J. Ward Moody at BYU Cameron J. Pace, Richard L. Pearson, and J. Ward Moody report for Brigham Young University’s ROVOR team: We report our observations in the field of GRB 090515 (Swift trigger 352108, Beardmore et al., GCN 9356) beginning 37.73 minutes post-burst at 05:22:53.376 UT. Using the 0.41m ROVOR telescope in Delta, Utah, we combined 70 x 60 second exposures in the R-band. No detection of an afterglow was obtained after stacking the images. An upper limit of 21.4 ± 0.1 mag was found by calibrating the frames using stars in the MRK 501 field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9372 SUBJECT: GRB 090515: Lick Upper Limits DATE: 09/05/15 23:42:40 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, M. Kislak, and M. Ganeshalingam (UC Berkeley) report: We imaged the field of short GRB 090515 (Beardmore et al., GCN 9356) with the Nickel 40-inch telescope at Lick Observatory starting at 04:52:57 UT (7.8 minutes after the trigger) in BVRI filters. No object is detected within the XRT error circle (Osborne et al., GCN 9367) in any exposure or in stacked frames. Approximate upper limits (relative to SDSS): tmid(min) exp(sec) filt lim(mag) 8.3 60 B > 19.9 10.0 60 V > 20.5 22.5 720 I > 20.3 38.1 600 R > 21.3 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9373 SUBJECT: GRB 090515: VLA observations DATE: 09/05/16 04:32:00 GMT FROM: Edo Berger at Harvard E. Berger and W.-f. Fong (Harvard) report: "We observed the field centered on the XRT error circle of the short GRB 090515 (GCNs #9356,9367) with the VLA at a frequency of 8.46 GHz starting on 2009 May 16.066 UT (20.8 hours post burst). We do not detect any sources within the XRT error circle to a 3-sigma limit of 60 microJy." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9385 SUBJECT: GRB 090515: Swift/BAT spectral lag results DATE: 09/05/17 19:35:45 GMT FROM: Tilan Ukwatta at GSFC/GWU T. N. Ukwatta (GWU/GSFC), J. Norris (U. Denver), N. Gehrels (GSFC), S. D. Barthelmy (GSFC) (for the Swift-BAT team): For GRB 090515 (Beardmore et al. GCN 9356), the BAT team has analyzed spectral lags for the data from T-0.05 sec to T+0.1 sec using non-mask weighted light curves with 1 msec time binning. The spectral lags were measured between standard canonical BAT energy bands: channel 1 (15-25 keV), 2 (25-50 keV), 3 (50-100 keV) and 4 (100-350 keV) are given below. Lag Ch3-Ch1 : 3.9 (+2.4, -2.1) msec Lag Ch3-Ch2 : 3.0 (+1.0, -1.0) msec Lag Ch4-Ch2 : 2.8 (+1.1, -1.4) msec Lag Ch4-Ch3 : 1.0 (+1.0, -1.0) msec Furthermore, Bayesian block analysis, on the light curve time range from T+10 sec to T+230, yields that there is no apparent extended emission for this burst.