//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8661 SUBJECT: GRB 081211B(?): Possible burst detection from Swift-BAT slew data DATE: 08/12/12 04:06:51 GMT FROM: Antonio Copete at Harvard U A. Copete, J. Grindlay (Harvard) S. Barthelmy, C. Markwardt, N. Gehrels (NASA/GSFC) We report the detection of a likely GRB candidate by the BAT Slew Survey (BATSS) in the slew that started on 12/11/08 at 06:15:02 UT and lasted 121 sec. The ground-calculated position is RA, Dec = 168.231, +53.845 deg, which is RA (J2000) = 11h 12m 55s Dec(J2000) = +53d 50' 43" with an uncertainty of 3.04 arcmin (90% confidence, including systematics). The detection was triggered by simultaneous detections of 7.4 sigma and 8.3 sigma from imaging in the overlapping energy bands of 15-50 keV and 15-150 keV, respectively. The burst mask-tagged lightcurve in the 15-150keV band shows two possible broad peaks in its emission profile that span the entire 102 sec that the source remains within the BAT field-of-view, starting at T+18 sec, and peaking T+34 and T+69 sec, suggesting that this is possibly the tail end of the prompt emission of a burst at that location. The time-averaged spectrum over the 102 sec of exposure of the source is best fit by a simple power law with photon index 1.73, and the fluence in the 15-150 keV band is 6.1 x 10^-7 erg/cm^2 A follow-up Swift ToO observation has been scheduled to begin on 12/12/08 at 04:51 UT, 22.6 hours after the burst. Optical/IR observations of this potential GRB are encouraged immediately, as it is well positioned for northern hemisphere observers. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8666 SUBJECT: Possible GRB 081211B - Swift-XRT analysis DATE: 08/12/13 09:19:47 GMT FROM: Kim Page at U.of Leicester K.L. Page, P.A. Evans (U. Leicester) and S.T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift-XRT team: Swift-XRT performed a Target of Opportunity observation of the possible BAT Slew Survey (BATSS) burst GRB 081211B (Copete et al., GCN Circ. 8661), starting 81.6 ks after the slew in which it was detected, and found a single, uncatalogued X-ray source within the BATSS error circle. Using 1878 s of XRT Photon Counting mode data and 4 UVOT images, 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 = 168.2646, 53.8300 which is equivalent to: RA (J2000): 11 13 3.49 Dec (J2000): +53 49 48.1 with an uncertainty of 2.0 arcsec (radius, 90% confidence). During the initial observation (81.6-92 ks), the mean X-ray count rate was 0.035 +/- 0.005 count s^-1. A second observation (126-133 ks) showed a count rate of 0.018 +/- 0.006. The source, therefore, appears to have faded, with a power-law index, alpha = 1.4 +0.8/-0.9. However, we cannot rule out a constant source at this time, so cannot categorically confirm this is an X-ray afterglow. This is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8669 SUBJECT: Possible GRB 081211B: Swift/UVOT Upper Limits DATE: 08/12/15 17:27:44 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA) reports, on the behalf of the Swift UVOT team: The Swift/UVOT observed the field of the possible BAT Slew Survey burst GRB 081211B (Copete et al., GCN Circ. 8661) starting 81.7 ks after the start of the slew that this source was detected in. We find no new source, relative to the DSS, USNO-B1.0, or 2MASS, or a variable source, inside the UVOT-enhanced XRT error circle (Page et al. 2008, GCN Circ. 8666). Preliminary 3-sigma upper limits for detecting a source in the co-added images, using an aperture-corrected 2.5 arcsecond radius circular aperture, are Filter T_start T_stop Exp(s) Mag ------------------------------------------ v 81,651 132,774 2318 >21.4 b 85,687 126,980 1770 >22.5 uvm2 132,780 133,265 478 >20.8 uvw2 87,513 128,664 1426 >21.8 white 86,600 127,893 1770 >23.1 ------------------------------------------ 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} = 0.01 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometry system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8676 SUBJECT: GRB 081211B - possibly a short burst with extended emission DATE: 08/12/16 18:19:57 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and and T. Cline, on behalf of the Konus-Wind team, J. Cummings, S. Barthelmy, N. Gehrels, and H. Krimm, on behalf of the Swift-BAT team, On December 11, Konus-Wind detected in the waiting mode a short spike at 06:12:58 UT, ~120 s before the BATSS GRB 081211B (Copete et al., GCN 8661). The burst was seen as a single 2.9s-long spike in the G1 (20-70 keV) and G2 (70-300 keV) bands. The BAT also detected this burst at 06:12:55.1 UT as a weak single pulse that did not produce a significant on-board image. The BATSS position of GRB 081211B was 1.3% coded in the BAT at the time of this burst. The measured propagation time delay from Swift to Wind as well as the K-W ecliptic latitude response for a short spike are consistent with the position of GRB 081211B. Hence, taking in account that the BATSS GRB081211B light curve shape suggests that it is possibly the tail end of the prompt emission of a burst (Copete et al., GCN 8661), we believe that the short spike detected by Konus-Wind and BAT is the main burst (likely short), followed by a long tail (extended emission) seen as the BATSS GRB081211B. There is a hint of the extended emission in the K-W G1 and G2 bands. The K-W light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB081211B/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8683 SUBJECT: GRB 081211B: Further Swift-XRT analysis DATE: 08/12/19 16:21:47 GMT FROM: Kim Page at U.of Leicester K.L. Page, J.P. Osborne (U. Leicester) and S.T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift-XRT team: The possible BAT Slew Survey burst GRB 081211B has been observed again by Swift, 8 days after it was first located. The source mentioned by Page et al. in GCN Circ. 8666 is not detected in 2.3 ks of XRT data, with an upper limit of 4.3x10^-3 count s^-1 (equivalent to a 0.3-10 keV observed flux of ~1.6x10^-13 erg cm^-2 s^-1). The decay slope is 1.6 +0.9/-0.6, incorporating the limit placed by this non-detection. We therefore confirm that the source has faded. This is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8727 SUBJECT: GRB 081211B: optical observations DATE: 08/12/25 18:09:36 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), Ju. Babina (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of GRB 081211B (Copete et al., GCN 8661) with Zeiss-600 telescope of Mt. Terskol observatory on Dec.13 in R-band. In the XRT error box (Page et al., GCN 8666) we do not detect any optical source. A photometry of the combined image is following: Mid time (UT) Exposure R_mag (3 sigma) s 08-12-13 02:10:40 85x60 >21.1 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8914 SUBJECT: GRB 081211B: Nearby cluster DATE: 09/02/23 05:25:22 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, J. S. Bloom, and N. R. Butler (UC Berkeley) report: GRB 081211B was discovered in the Swift-BAT slew survey (Copete et al, GCN 8661) and, based on observations by Konus-Wind (Golenetskii et al., GCN 8676), was classified as a possible short burst with an extended emission component. We note that the GRB localization lies within a visual galaxy overdensity in SDSS archival imaging, and near the centers of several reported clusters in the literature, which likely correspond to the same physically extended structure: ZW 3893, Abell 1196, and MaxBCG J168.22310+53.83028. Redshifts from the Sloan Digital Sky Survey of the brightest two apparent cluster members place this cluster at a probable redshift of z=0.216. On the night of 2009-02-19 (UT) we observed the field with Keck I (+ LRIS) for an exposure time of 990 sec (g-band) and 870 sec (R-band) simultaneously through thin cloud cover. No host galaxy underlying the XRT position (Page et al., GCN 8666) is detected to approximately R > 25, g > 26 mag. The nearest catalogued objects are: SDSS J111303.09+534953.8 g=21.26 r=20.26 i=20.03 (7" = 24 kpc) SDSS J111304.73+534959.5 g=20.56 r=19.25 i=18.84 (16" = 56 kpc) An additional very faint extended object is located 3" west of the center of the XRT position, outside the 90% confidence error circle. Images of the field (from our observations and from SDSS) are posted to: http://lyra.berkeley.edu/~dperley/081211b/081211b_keck.png http://lyra.berkeley.edu/~dperley/081211b/081211b_sdss.png If the BAT detection represents extended emission from this event and no fainter host galaxy is found, this would constitute an additional case of a short GRB event with detected extended emission occurring without a coincident host galaxy (after GRB 080503 - arXiv:0811.1044), as well as an additional example of a short burst occurring within a galaxy cluster (see also e.g. GRBs 050509B, 050813, 051210, 061201). The isotropic gamma-ray energy release at the cluster redshift would be 7 x 10^49 erg in the BAT bandpass, comparable to values measured for other short GRBs. We encourage deeper observations of the field.