GRB140515A

This page lists all entries on GRB140515A in GRBweb

Summary IPN Swift GCN 16267 GCN 16269 GCN 16270 GCN 16271 GCN 16273 GCN 16274 GCN 16275 GCN 16277 GCN 16278 GCN 16279 GCN 16280 GCN 16282 GCN 16283 GCN 16284 GCN 16338

Summary table
Variable Value Source
T0 9:12:36 UTC GCN_circulars,Swift Det
ra 186.0644° Swift
decl 15.1047° Swift
pos_error 1.94e-04° Swift
T90 23.4 s Swift
T90_start 9:12:36 UTC Swift
fluence 5.90e-07 erg/cm² Swift
redshift 6.3200 GCN_circulars,Swift-UVOT Other
T100 23.4 s
GBM_located False
mjd 56792.38375 GCN_circulars,Swift Det
IPN table
GRB_name GRB140515A
ra 186.0375°
decl 15.0833°
pos_error 5.00e-02°
redshift 6.3200
Swift table
GRB_name GRB140515A
t_trigger 9:12:36 UTC
ra 186.0644°
decl 15.1047°
pos_error 1.94e-04°
T90 23.4 s
fluence 5.90e-07 erg/cm²
redshift 6.3200
GCN 16267 table
GRB_name GRB140515A
GCN_number 16267
Detection_method Swift Det
t_trigger 9:12:36 UTC
ra 186.0360°
decl 15.0770°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16267 SUBJECT: GRB 140515A: Swift detection of a burst DATE: 14/05/15 09:30:47 GMT FROM: David Palmer at LANL P. D'Avanzo (INAF-OAB), M. G. Bernardini (INAF-OAB), V. D'Elia (ASDC), P. A. Evans (U Leicester), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 09:12:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140515A (trigger=599037). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 186.036, +15.077 which is RA(J2000) = 12h 24m 09s Dec(J2000) = +15d 04' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 30 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 09:13:52.4 UT, 75.8 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 186.0639, 15.1045 which is equivalent to: RA(J2000) = 12h 24m 15.35s Dec(J2000) = +15d 06' 16.4" with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 138 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 2.54 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 79 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 none of the XRT error circle. 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 P. D'Avanzo (paolo.davanzo AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN 16269 table
GRB_name GRB140515A
GCN_number 16269
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 16269 SUBJECT: GRB 140515A: Gemini-N redshift DATE: 14/05/15 13:55:55 GMT FROM: Ryan Chornock at Harvard R. Chornock (Harvard), D. B. Fox (Penn State), and E. Berger (Harvard) report: We observed the field of GRB 140515A (D'Avanzo et al., GCN 16267) using GMOS on the Gemini-N 8-m telescope, starting at 10:48 UT on 15 May. A faint source was present in the i band acquisition image at a position consistent with the X-ray afterglow. We obtained 2x900s of spectroscopy of this likely afterglow, covering the wavelength range 5900-10150 Angstroms at a resolution of R~1200. The afterglow has a strong continuum at long wavelengths that sharply drops to near zero at wavelengths shortward of lambda~8900 Angs, consistent with the onset of Lyman-alpha absorption at z=6.32. Isolated wavelength intervals of IGM transmission exist between 7500 and 8000 Angs (corresponding to z~5.2-5.6 relative to Ly-alpha). Further analysis is ongoing. We acknowledge excellent support from Gemini observer Lucas Fuhrman.
GCN 16270 table
GRB_name GRB140515A
GCN_number 16270
Detection_method Swift-XRT Det
ra 186.0645°
decl 15.1049°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16270 SUBJECT: GRB 140515A: Enhanced Swift-XRT position DATE: 14/05/15 14:10:01 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 2066 s of XRT Photon Counting mode data and 2 UVOT images for GRB 140515A, 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 = 186.06452, +15.10491 which is equivalent to: RA (J2000): 12h 24m 15.48s Dec (J2000): +15d 06' 17.7" 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.
GCN 16271 table
GRB_name GRB140515A
GCN_number 16271
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 16271 SUBJECT: GRB 140515A: MITSuME Akeno upper limits DATE: 14/05/15 14:19:22 GMT FROM: Taketoshi Yoshii at Tokyo Tech H. Ohuchi, T. Yoshii, Y. Saito, Y. Tachibana, S. Kurita, Y. Ono, T. Fujiwara, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 140515A (P.D'Avanzo et al., GCN Circular #16267) with the optical three color (g, Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2014-05-15 10:32:10 UT ( 1.3h after the burst). We did not find any new point source within the enhanced XRT circle in all the three bands.The measured magnitudes were listed below. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic --------------------------------------------------------------------------------------------------------- 9301 11:47:37 9180 > 20.8 >20.5 >19.4 --------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.
GCN 16273 table
GRB_name GRB140515A
GCN_number 16273
Detection_method Swift-UVOT Other
redshift 6.3200
Circular_text TITLE: GCN CIRCULAR NUMBER: 16273 SUBJECT: GRB 140515A: Swift/UVOT Upper Limits DATE: 14/05/15 18:09:41 GMT FROM: Samantha Oates at MSSL S. R. Oates (IAA-CSIC,UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140515A 79 s after the BAT trigger (D'Avanzo et al., GCN Circ. 16267). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 16270) is detected in the initial UVOT exposures. The lack of detection in all UVOT filters is consistent with a redshift of 6.32 (Chornock et al., GCN Circ. 16269). Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 79 229 147 >20.7 u_FC 293 542 246 >20.0 white 79 7407 638 >21.5 v 628 7818 471 >19.7 b 548 7202 456 >20.6 u 293 13671 1398 >20.9 w1 1618 12925 1140 >20.9 m2 6387 12019 1082 >20.6 w2 5977 7612 393 >20.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN 16274 table
GRB_name GRB140515A
GCN_number 16274
Detection_method Swift-BAT Det
ra 186.0646°
decl 15.1046°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16274 SUBJECT: GRB 140515A: Gemini-North imaging DATE: 14/05/15 19:26:23 GMT FROM: Wen-fai Fong at CFA W. Fong (Harvard), R. Chornock (Harvard), D. Fox (PSU), and E. Berger (Harvard) report: "We observed the location of the long-duration GRB 140515A (D'Avanzo et al., GCN 16267) with the Gemini Multi-Object Spectrograph (GMOS) mounted on the Gemini-North 8-meter telescope at a mid-time of 2014 May 15.458 UT (1.78 hr after the BAT trigger). We obtained 480 sec in each of the i- and z-bands in 0.45" seeing. We detect the optical afterglow (Chornock et al., GCN 16269), within the enhanced XRT position (Goad et al., GCN 16270), located at RA(J2000) = 12:24:15.51 Dec(J2000) = +15:06:16.6 with a positional uncertainty of 0.1" in each coordinate. The optical afterglow has a brightness of z = 20.27 +/- 0.11 AB mag, and is at least 3 mag fainter in our i-band observations. Both the astrometry and photometry are calibrated to SDSS. We thank the Gemini staff for their assistance with these observations."
GCN 16275 table
GRB_name GRB140515A
GCN_number 16275
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 16275 SUBJECT: GRB 140515A: KAIT Optical Upper Limit DATE: 14/05/15 19:34:45 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng, Alexei V. Filippenko, Adam Morgan (UC Berkeley), and S. B. Cenko (NASA/Goddard Space Flight Center) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 140515A (D'Avanzo et al., GCN 16267) starting at 09:14:22 UT, 106 s after the burst. Observations were performed with an automatic sequence in the clear (roughly R), V and I filters, and the exposure time was 20 s per image. We do not detect the optical afterglow (Chornock et al., GCN 16269; Fong et al., GCN 16274) in our images within the enhanced XRT error circle (Goad et al., GCN 16270). The typical limiting magnitude of our single clear image is about 17.8, and about 17.1,16.9 mag for the V and I bands respectively. [GCN OPS NOTE(15may14): Per author's request, the Sahu/16272 reference was removed as it refers to a different GRB.]
GCN 16277 table
GRB_name GRB140515A
GCN_number 16277
Detection_method Swift-XRT Other
redshift 6.3200
Circular_text TITLE: GCN CIRCULAR NUMBER: 16277 SUBJECT: GRB 140515A: Swift-XRT refined Analysis DATE: 14/05/15 23:58:11 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo, M. G. Bernardini (INAF-OAB), P. A. Evans (U. Leicester) report on behalf of the Swift-XRT team: We have analysed 7.1 ks of XRT data for GRB 140515A (D'Avanzo et al. GCN Circ. 16267), from 60 s to 13.6 ks after the BAT trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 16270). The light curve can be modelled with a power-law decay with an initial decay index of alpha=2.5 (+0.5, -0.3). Then at T0+1100 s the light curve rises, reaching a count rate ~ 0.3 ct/sec. The remaining two orbits show irregular rate variations likely due to an underlying flaring activity, with a count rate ~ 0.3 ct/sec and ~ 0.1 ct/sec respectively. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.75 (+0.12, -0.11). The best-fitting absorption column is 1.7 (+3.2, -1.7) x 10^22 cm^-2, at a redshift of 6.32 (Chornock et al., GCN Circ. 16269), in addition to the Galactic value of 2.5 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 2.5 x 10^20 cm^-2 Intrinsic column: 1.7 (+3.2, -1.7) x 10^22 cm^-2 at z=6.32 Photon index: 1.75 (+0.12, -0.11) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00599037. This circular is an official product of the Swift-XRT team.
GCN 16278 table
GRB_name GRB140515A
GCN_number 16278
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 16278 SUBJECT: GRB 140515A: Optical observations from the 2.5 m NOT DATE: 14/05/16 00:30:12 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), J. Gorosabel (IAA-CSIC, UPV-EHU), D. Xu (DARK/NBI), J.P.U. Fynbo (DARK/NBI), P. Jakobsson (U. Iceland), D. Malesani (DARK/NBI), N.R. Tanvir (U. Leicester), E. Gafton (OKC, Stockholm Univ.) and T. Libbrecht (Stockholm Univ.) report on behalf of a larger collaboration: We have observed the afterglow of GRB 140515A (D'Avanzo et al., GCN 16267) with the 2.5m NOT telescope. Observations consisted of 5x300s imaging in the z-band and have an average epoch of 12.10 hr after the burst. The images reveal the optical afterglow detected by Chornock et al. (GCN 16269) and Fong et al. (GCN 16274) at a magnitude of z(AB) = 22.15+/-0.15, as compared with SDSS stars. This indicates a decay with a slope of alpha ~ -0.9 (where F_nu~t^alpha) as compared with the photometry of Fong et al. (GCN 16274). Further observations are ongoing.
GCN 16279 table
GRB_name GRB140515A
GCN_number 16279
Detection_method Other
redshift 6.3200
Circular_text TITLE: GCN CIRCULAR NUMBER: 16279 SUBJECT: GRB 140515A: Spectroscopy from the 10.4m GTC DATE: 14/05/16 02:49:04 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), J. Gorosabel (IAA-CSIC, UPV-EHU), C.C. Thoene (IAA-CSIC), A. Cabrera-Lavers, D. Reverte and C. Alvarez (IAC-ULL) report on behalf of a larger collaboration: We have obtained spectroscopic observations of the afterglow of GRB 140415A (D'Avanzo et al., GCN 16267; Chornock et al. GCN 16269; Fong et al. GCN 16274; de Ugarte Postigo et al. GCN 16278) using the 10.4m GTC telescope (+OSIRIS). Our observation started at 22:37 UT (13.41 hr after the burst), with a seeing of 0.6", and consisted of 3x1800s exposures using grism R2500I, which covers the range between 7330 and 10000 A at a resolution of ~2500. In a preliminary reduction we detect a strong continuum above 8900 A, with no significant absorption features. The sharp decay below 8900 A is consistent with Ly-alpha absorption at the redshift of 6.32 suggested by Chornock et al. (GCN 16269). The transmission of the Ly-forest is low, but some emission is detected down to the blue limit of our spectrum.
GCN 16280 table
GRB_name GRB140515A
GCN_number 16280
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 16280 SUBJECT: GRB 140515A: GROND observation of the afterglow DATE: 14/05/16 12:22:49 GMT FROM: Sebastian Schmidl at TLS Tautenburg J. Graham (MPE Garching), S. Schmidl (TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 140515A (Swift trigger 599037; D'Avanzo et al., GCN 16267) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 22:53 UT on March 15, 2014, 13.7 hrs after the GRB trigger. They were performed at an average seeing of 0.9" and at an average airmass of 1.4. We detect the afterglow reported by Chornock et al. (GCN 16269). Based on a total exposure of 50 min in g'r'i'z' and 40 min in JHK, at a mid-time of 17.0 hrs after the burst, we measure the following preliminary magnitudes (in AB): g' > 24.1 mag, r' > 24.5 mag, i' > 24.2 mag, z' = 22.1 +/- 0.1 mag, J = 20.9 +/- 0.2 mag, H = 20.9 +/- 0.2 mag, and K > 19.1 mag. Based on these data, the photometric redshift is z= 6.5 +/-0.2, which is consistent with the spectroscopic redshift reported by Chornock et al. (GCN 16269). Given magnitudes are calibrated against SDSS (g'r'i'z') as well as 2MASS (JHK) field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.02 mag in the direction of the burst (Schlegel et al. 1998).
GCN 16282 table
GRB_name GRB140515A
GCN_number 16282
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 16282 SUBJECT: GRB 140515A : TNG near-infrared observations DATE: 14/05/16 15:51:49 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri, P. D'Avanzo (INAF/OAB), A. Fiorenzano and G. Mainella (INAF/TNG) report on behalf of the CIBO collaboration:. We observed the field of GRB 140515A (D'Avanzo et al., GCN 16267) using the NICS near-Infrared camera on the 3.6m TNG Telescope (La Palma, Canary Islands). We obtained a series of imaging observations in the J and H bands for a total exposure time of 30 and 60 minutes respectively. The GRB afterglow is clearly detected in both bands at a level of Dt Exposure Filter Mag (err) [hr from GRB] [min] 14.54 60 H 19.35 (0.12) 15.60 30 J 19.52 (0.18) Magnitudes are in the Vega system, calibrated against the 2MASS catalogue. We thank the TNG staff for the support.
GCN 16283 table
GRB_name GRB140515A
GCN_number 16283
Detection_method VLA Det
ra 186.0646°
decl 15.1046°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16283 SUBJECT: GRB 140515A: VLA Detection DATE: 14/05/16 17:06:52 GMT FROM: Tanmoy Laskar at Harvard U T. Laskar, A. Zauderer, and E. Berger (Harvard) report: "We observed the position of GRB 140515A (D'Avanzo et al; GCN 16267) at multiple frequencies with the VLA beginning 2014 May 16.00 UT (0.62 days after the burst). At a mean frequency of 21.8 GHz, we detect a radio source with a preliminary flux density of ~ 0.1 mJy at RA = 12:24:15.5055 +/- 0.0005 Dec = +15:06:16.609 +/- 0.005 consistent with the enhanced Swft/XRT position (D'Avanzo et al.; GCN 16277) and the optical position (Fong et al.; GCN 16274). Follow-up observations are planned."
GCN 16284 table
GRB_name GRB140515A
GCN_number 16284
Detection_method Swift-BAT Det
ra 186.0710°
decl 15.0990°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16284 SUBJECT: GRB 140515A: Swift-BAT refined analysis DATE: 14/05/16 20:03:00 GMT FROM: Amy Lien at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), P. D'Avanzo (INAF-OAB), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-288 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 140515A (trigger #599037) (D'Avanzo, et al., GCN Circ. 16267). The BAT ground-calculated position is RA, Dec = 186.071, 15.099 deg which is RA(J2000) = 12h 24m 17.0s Dec(J2000) = +15d 05' 55.8" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%. The mask-weighted light curve shows a double-peaked structure. The first pulse starts at ~T-22 s and peaks at ~T-18 s. The second pulse starts at ~T-10 s, peaks at ~T+2 s, and ends at ~T+4 s. T90 (15-350 keV) is 23.4 +- 2.1 sec (estimated error including systematics). The time-averaged spectrum from T-22.0 to T+3.8 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.98 +- 0.64, and Epeak of 51.3 +- 14.7 keV (chi squared 54.37 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 5.9 +- 0.6 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+1.51 sec in the 15-150 keV band is 0.9 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.85 +- 0.13 (chi squared 61.03 for 57 d.o.f.). 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/599037/BA/
GCN 16338 table
GRB_name GRB140515A
GCN_number 16338
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 16338 SUBJECT: Chandra late-time observations of GRB140515A DATE: 14/05/28 19:03:45 GMT FROM: Raffaella Margutti at Harvard R. Margutti, E. Berger, R. Chornock, W. Fong, T. Laskar and A. Zauderer (Harvard U.) report: "We observed the location of GRB 140515A (D'Avanzo et al., GCN 16267) at z=6.32 (Chornock et al., GCN 16269) with the Chandra X-ray Observatory (Program 15508477, PI Margutti). Our observations started on May 25th, 07:38:38 UT, 858.6 ks after the BAT trigger. No X-ray source is detected at the position of the optical and radio afterglow (Fong et al., GCN 16274, Laskar et al., GCN 16283), with a 3-sigma count-rate limit of 1.5E-4 c/s (0.3-10 keV energy range, total exposure time of 19.8 ks). Adopting the best fitting parameters from the total PC-mode spectrum (photon index Gamma=1.8, intrinsic neutral hydrogen column density NHint=2.3E+22 cm-2 at z=6.32), we compute an observed flux limit of 1.5E-15 erg/s/cm2 (0.3-10 keV). The Galactic hydrogen column density in the direction of the burst is NHgal=2.5E+20 cm-2 (Kalberla et al., 2005). Our observations constrain the late-time (t> 100 ks) X-ray afterglow decay to be steeper than t^-2.6. We thank Belinda Wilkes and the entire Chandra team for making these observations possible."