[vsnet-grb-info 15929] GRB 141215A: further Swift-XRT observations and afterglow detection

Tue Dec 23 01:56:49 JST 2014

TITLE:   GCN CIRCULAR
NUMBER:  17217
SUBJECT: GRB 141215A: further Swift-XRT observations and afterglow detection
DATE:    14/12/22 16:56:41 GMT
FROM:    Valerio D'Elia at ASDC  <delia at asdc.asi.it>

V. D'Elia (ASDC), L. Izzo (URoma/ICRA) & M. M. Chester (PSU) report on  
behalf of the Swift team

Swift-XRT observed again the field of the IPN GRB 141215A (Hurley et  
Â al. GCN 17186). The  observation started on 2014-12-21 at 01:22UT,  
i.e., ~5.5 days after the burst detection. Source #1 (that with a  
2MASS counterpart) and source #3 (which has a DSS counterpart)  
reported by D'Elia & Izzo (GCN 17190) are still detected with a count  
rate comparable to that of the first exposure and are thus not related  
with the GRB. On the other hand, source #2 faded  considerably with  
respect to the first observation. Its decay index is alpha~1, which is  
consistent with a typical afterglow behavior. We thus conclude that  
source #2 is the X-ray counterpart of GRB 141215A.

Swift/UVOT observed the initial two tiled fields for GRB 141215A  
beginning ~100 ks after the IPN trigger. No optical counterpart was  
detected for Swift/XRT Source #2 (D'Elia et al. GCN Circ. 17190).  
Preliminary 3-sigma upper limits using the UVOT photometric system  
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are:

Source #2:
Filter Â Â Â Â Â Â Â Â T_start(s) Â Â T_stop(s) Â Â Â Â Â Exp(s) Â Â Â Â Â UL
white Â Â Â Â Â Â Â Â Â 118715 Â Â Â Â Â Â 125192 Â Â Â Â Â Â Â Â 1026 Â Â Â Â Â > 21.35
v Â Â Â Â Â Â Â Â Â Â Â Â Â 119529 Â Â Â Â Â Â 120370 Â Â Â Â Â Â Â Â Â 824 Â Â Â Â Â > 19.39
u Â Â Â Â Â Â Â Â Â Â Â Â Â 117902 Â Â Â Â Â Â 124472 Â Â Â Â Â Â Â Â 1580 Â Â Â Â Â > 20.85

The magnitudes in the table are not corrected for the Galactic  
extinction due to the reddening of E(B-V) = 0.176 in the direction of  
the burst (Schlegel et al. 1998).

Details on the XRT analysis can be found at:

http://www.swift.ac.uk/xrt_products/TILED_GRB00035/

This is an official product of the Swift team.