GCN Circular 1443
Subject
GRB 020531: optical photometry of Chandra sources
Event
Date
2002-06-27T09:07:40Z (24 years ago)
From
Isabel Salamanca at U. of Amsterdam <isabel@science.uva.nl>
Isabel Salamanca, Evert Rol (University of Amsterdam), Nial Tanvir
(University of Hertfordshire), Lex Kaper (UoA), on behalf of a larger
collaboration, report:
We have performed differential photometry of the sources detected by
Chandra (GCN #1399) in the field of view of GRB 020531
(GCN #1399, #1402). The observations were done with the WFC on the
INT at La Palma. For more details see GCN 1433.
Of the 13 sources detected by Chandra, we detect 5 in both epochs:
cx00, cx15, cx48, cx55, cx56. Four more sources are detected only in
the second epoch: cx05,cx47,cx58 and cx52. We remark that the source
cx00 is also visible in the DSS.
We have perfomed differential photometry of the first 4 sources by
comparing them with 12 stars in the field. The relative accuracy
attained is 0.01 mag. The absolute photometry was done via the
photometry performed by Henden etal. (GCN #1422). The estimated error
in the zero point is higher, 0.4 mag, due to the fact that the
observations were performed under non-photometric conditions.
Below is a summary of the magnitudes of each object:
Id V mag
31 May 2 June
=====================================
5 >24.7 24.5
15 21.73 21.80
--- ---------------------------------
28 >24.7 >25.2
36 >24.7 >25.2
41 >24.7 >25.2
47 >24.7 23.8
48 23.27 23.20
51 >24.7 >25.2
52 >24.7 24.0
55 23.15 23.19
56 21.71 21.60
58 >24.7 ~25.2
The proposed afterglow candidate, cx48 (GCN #1426, #1427 and #1428) is
0.07 +/- 0.01 mag brighter in the second epoch than in the first.
This message may be cited.
--
Dr. Isabel E. de Salamanca
Anton Pannekoek Institute, UvA
Amsterdam - The Netherlands.