GRB080727A

This page lists all entries on GRB080727A in GRBweb

Summary IPN Swift GCN 8021 GCN 8025 GCN 8027 GCN 8028 GCN 8029 GCN 8039 GCN 8048

Summary table
Variable Value Source
T0 5:57:39 UTC GCN_circulars,Swift Det
ra 208.3909° Swift
decl -18.5446° Swift
pos_error 2.07e-04° Swift
T90 4.9 s Swift
T90_start 5:57:39 UTC Swift
fluence 1.30e-07 erg/cm² Swift
T100 4.9 s
GBM_located False
mjd 54674.24836805555 GCN_circulars,Swift Det
IPN table
GRB_name GRB080727A
ra 208.3875°
decl -18.5500°
pos_error 5.00e-02°
Swift table
GRB_name GRB080727A
t_trigger 5:57:39 UTC
ra 208.3909°
decl -18.5446°
pos_error 2.07e-04°
T90 4.9 s
fluence 1.30e-07 erg/cm²
GCN 8021 table
GRB_name GRB080727A
GCN_number 8021
Detection_method Swift Det
t_trigger 5:57:39 UTC
ra 208.3890°
decl -18.5490°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8021 SUBJECT: GRB 080727: Swift detection of a burst DATE: 08/07/27 06:16:46 GMT FROM: David Palmer at LANL S. Immler (CRESST/GSFC/UMD), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (NASA/GSFC), S. D. Hunsberger (PSU), W.B Landsman (GSFC), C. B. Markwardt (CRESST/GSFC/UMD), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), D. Perez (U Leicester), T. Sakamoto (NASA/UMBC) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 05:57:39 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080727 (trigger=318094). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 208.389, -18.549 which is RA(J2000) = 13h 53m 33s Dec(J2000) = -18d 32' 55" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 5 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 05:59:28.5 UT, 109.2 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 208.39099, -18.54505 which is equivalent to: RA(J2000) = 13h 53m 33.84s Dec(J2000) = -18d 32' 42.2" with an uncertainty of 2.7 arcseconds (radius, 90% containment). This location is 15 arcseconds from the BAT onboard position, within the BAT error circle. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 6.75e+20 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 114 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle and 100% of the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag. 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 0.07. Burst Advocate for this burst is S. Immler (immler AT milkyway.gsfc.nasa.gov). 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 8025 table
GRB_name GRB080727A
GCN_number 8025
Detection_method Swift-XRT Det
ra 208.3905°
decl -18.5448°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8025 SUBJECT: GRB 080727A: Enhanced Swift-XRT position DATE: 08/07/27 10:30:36 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 2786 s of XRT Photon Counting mode data and 1 UVOT images for GRB 080727A, 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 = 208.39050, -18.54479 which is equivalent to: RA (J2000): 13h 53m 33.72s Dec (J2000): -18d 32' 41.2" with an uncertainty of 1.9 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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN 8027 table
GRB_name GRB080727A
GCN_number 8027
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 8027 SUBJECT: GRB080727A: Swift/UVOT Upper Limits DATE: 08/07/27 14:38:23 GMT FROM: Wayne Landsman at GSFC/SSAI W.B. Landsman (NASA/GSFC/Adnet) and S. Immler (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB080727A starting 113s after the BAT trigger (Immler et al., GCN Circ. 8021). We do not find any source, in any of the UVOT observations, at the UVOT-enhanced XRT position of the afterglow (Evans et al. GCN Circ. 8025). The 3-sigma upper limits for detecting a source at this location in the co-added images are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------------------- v 219 7675 1165 >20.6 b 700 7083 471 >20.9 u 675 6878 490 >20.6 uvw1 650 6673 491 >20.5 uvm2 1541 6468 236 >20.0 uvw2 730 7486 471 >20.8 white 113 7284 623 >21.8 ----------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.07 mag. All photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627).
GCN 8028 table
GRB_name GRB080727A
GCN_number 8028
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 8028 SUBJECT: GRB 080727A: Swift-XRT refined analysis DATE: 08/07/27 15:30:20 GMT FROM: Kim Page at U.of Leicester K.L. Page, J.P. Osborne (U. Leicester) and S. Immler (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team: We have analysed the first three orbits of data obtained for GRB 080727A (Immler et al., GCN Circ. 8021), covering 7 ks of Photon Counting mode data. The UVOT-enhanced position has been given by Evans et al. (GCM Circ. 8025). During the first orbit (117s - 1.9 ks after the trigger), the light-curve shows a number of small flares, superimposed on a power-law decay of alpha= 2.01 +0.18/-0.17. The source is no longer detected in the combined second and third orbits of data (5.3 ks of exposure time, starting 5 ks after the trigger). Although the upper limit is consistent with the continued decay of alpha = 2.01, it is not possible to determine whether a break has occurred. The spectrum from the first orbit of data can be fitted with a power-law of Gamma = 1.43 +0.20/-0.19, absorbed by the Galactic column in this direction (6.75x10^20 cm^-2). The average observed (unabsorbed) flux over this time is 5.56 (6.02) x 10^-12 erg cm^-2 s^-1. The counts to observed flux conversion is 5.3 x 10^-11 erg cm^-2 count^-1. With the limited information available from a detection only in the first orbit, we are unable confidently to predict the flux at 24 hours. This is an official product of the Swift-XRT team.
GCN 8029 table
GRB_name GRB080727A
GCN_number 8029
Detection_method Swift-BAT Det
ra 208.4160°
decl -18.5720°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8029 SUBJECT: GRB 080727A, Swift-BAT refined analysis DATE: 08/07/27 16:47:32 GMT FROM: Takanori Sakamoto at NASA/GSFC K. McLean (GSFC/UMD), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080727A (trigger #318094) (Immler, et al., GCN Circ. 8021). The BAT ground-calculated position is RA, Dec = 208.416, -18.572 deg which is RA(J2000) = 13h 53m 39.9s Dec(J2000) = -18d 34' 18.6" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%. The mask-weighted light curve shows a single weak pulse starting at T+~0 and ending a T+~5 sec. T90 (15-350 keV) is 4.9 +- 1.0 sec (estimated error including systematics). The time-averaged spectrum from T-0.1 to T+5.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.25 +- 0.34. The fluence in the 15-150 keV band is 1.3 +- 0.3 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+1.20 sec in the 15-150 keV band is 0.3 +- 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/318094/BA/
GCN 8039 table
GRB_name GRB080727A
GCN_number 8039
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 8039 SUBJECT: GRB 080727A: VLT upper limits DATE: 08/07/28 08:05:37 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK), P. Jakobsson (Univ. Hertfordshire), A. J. Levan (Univ. Warwick), E. Rol (Univ. Leicester), J. P. U. Fynbo (DARK), report on behalf of a larger collaboration. We observed the field of GRB 080727A (Immler et al., GCN 8021) with the ESO VLT equipped with FORS1. Observations started on 2008 Jul 27.979 UT, 17.5 hr after the burst, for a total exposure time of 900 s in the R filter. Inside the refined XRT error circle (Evans et al., GCN 8025), we detect no new source down to a limiting magnitude R~26. Calibration was based on tabulated zeropoints and is in rough agreement with USNO-B1 stars. We acknowledge kind support from the observing staff at Paranal, particularly Suzanna Randall, Karla Aubel, and Alain Smette.
GCN 8048 table
GRB_name GRB080727A
GCN_number 8048
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 8048 SUBJECT: GRB 080727A: Early IR observations DATE: 08/07/29 15:12:05 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick) and K. Wiersema (U. Leicester) report for a larger collaboration: We observed the location of GRB 080727A (Immler et al. GCN 8021) using UKIRT. A series of K-band exposures were taken beginning at 06:24:51 UT, roughly 30 minutes after the burst, a total of 720s of observtions were taken (36x20s). We find no evidence for any source within the XRT error circle (Evans et al. GCN 8025) for GRB 080727A, down to a limit of K=19.8 mag (3-sigma). Comparing this limit to the extrapolated X-ray flux 30 minutes post-burst implies that the observed X-ray to optical/IR spectral slope was beta_KX < ~0.8, thus the non-detection in the IR is likely down to the rapid fading of the afterglow, rather than suppression of the optical/IR flux. We thank the staff of UKIRT for their rapid response to these alerts.