//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7209 SUBJECT: GRB 080121: Swift-BAT detection of a very weak, short burst DATE: 08/01/23 20:39:09 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings and D. M. Palmer for the Swift-BAT team At 21:29:55 on Jan 21, 2008, BAT detected a weak short GRB (trigger #301491) at a ground-calculated location RA, Dec 137.235, +41.841, error radius 3 arcmin (90% confidence), which is: RA(J2000) = 09h 08m 56s Dec(J2000) = +41d 50' 29" The significance of the source in the detection image was just below the alert threshold, so Swift did not slew immediately to the burst. In addition, the source location was in Moon constraint, so no late observation was made. As seen in BAT, the burst was a single peak with T90 0.7 +- 0.2 seconds. Because of the weakness of the burst, a power-law fit to the spectrum from T-0.4 to T+0.4 sec is not well constrained. The power-law index is 2.6 +- 0.8. The fluence was (3 +- 2) x 10^-8 erg/cm2/sec. Quoted uncertainties are 90% confidence including estimated systematic error. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7210 SUBJECT: GRB 080121: Nearby SDSS galaxies DATE: 08/01/23 22:51:25 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, R. J. Foley, and J. S. Bloom (UC Berkeley) report: Two SDSS spectroscopically-catalogued galaxies are present in NED* within the Swift-BAT error circle of GRB 080121 (Cummings et al., GCN 7209): SDSS J090858.15+414926.5 09:08:58.1 +41:49:27 z=0.045322 SDSS J090904.12+415033.2 09:09:04.1 +41:50:33 z=0.046041 Several other, fainter extended sources are also present in the field, possibly indicating that this GRB may have occurred within a group or small cluster. At a redshift of z=0.046, the isotropic energy release would be ~10^47 erg, several orders of magnitude less than typical short-hard bursts. * The NASA/IPAC Extragalactic Database (NED) is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7214 SUBJECT: GRB 080121: Enhanced Swift-XRT position DATE: 08/01/25 09:07:23 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 1003 s of overlapping XRT Photon Counting mode and UVOT V-band data for GRB 080121, 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 = 137.15169, +41.84639 which is equivalent to: RA (J2000): 09h 08m 36.41s Dec (J2000): +41d 50' 47.0" with an uncertainty of 3.5 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, astro-ph/0708.0986 http://www.swift.ac.uk/xrt_positions/Goad.pdf). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7215 SUBJECT: GRB 080121 position was incorrect DATE: 08/01/25 09:22:19 GMT FROM: Phil Evans at U of Leicester P. A. Evans reports, The enhanced XRT position for GRB 081021 just reported (GCN Circ. 7124) was not the position of the GRB afterglow. This source is a serendipitous source. We apologise for any confusion. We are implementing further checks to ensure that circulars are only issued for GRB afterglow candidates. Details of the XRT enhancement process are provided at http://www.swift.ac.uk/team/xrt_positions/docs.php //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7217 SUBJECT: GRB 080121: Swift/UVOT upper limits DATE: 08/01/25 14:06:29 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara (PSU), P. Schady (MSSL) report on behalf of the Swift-UVOT team: The Swift/UVOT observed the field of GRB080121 (trigger #301491) starting 2.3 days after the BAT detection (J. R. Cummings et al. 2008, GCN Circ. 7209). We do not find any new source in any of the UVOT coadded observations inside the BAT error circle. The 3-sigma upper limits (in the UVOT photometric system, Breeveld et al., GCN Circ. 6614) are listed. Filter Tstart Exp Magnitude (s) white 2.3 days 2015 >22.25 v 2.3 days 2268 >20.73 uvm2 3.4 days 1491 >21.13 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E_{B-V} = 0.02 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7224 SUBJECT: GRB 080121: Upper limit on X-ray afterglow DATE: 08/01/28 15:43:03 GMT FROM: Eleonora Troja at INAF-IASFPA E. Troja (INAF/IASFPA), and D. N. Burrows (PSU) report on behalf of the Swift XRT team: We have analysed 21 ks of XRT/PC data for the short GRB 080121 (trigger 301491; Cummings & Palmer, GCN 7209), starting 2.3 d after the burst. No X-ray afterglow candidate is found within the BAT error circle (GCN 7209). A faint source is detected within the BAT error circle at RA(2000) = 09h 08m 46.36s, Dec(J2000) = +41d 51' 21.1'' with an error radius 5 arcsec (90% containment). This source has a count rate of ~2E-03 cts/s, and displays no fading behaviour. We place a 3 sigma upper limit of 1E-03 cts/s on the X-ray afterglow count rate, which corresponds to an unabsorbed flux of 3.7E-14 erg/cm^2/s (over 0.3-10 keV), assuming a Crab-like spectrum and a Galactic absorption of 1.23E+20 cm^-2 (Kalberla et al. 2005). This circular is an official product of the Swift XRT Team.