TITLE:   GCN CIRCULAR
NUMBER:  7681
SUBJECT: GRB 080430: TLS imaging one day after the GRB
DATE:    08/05/05 20:00:39 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann, F. Ludwig, R. Filgas and S. Klose (TLS tautenburg) report:

We imaged the afterglow (Klotz et al., GCN 7646) of GRB 080430 (Guidorzi 
et al., GCN 7647) with the TLS Schmidt telescope one day after the GRB. 
Direct RRM observations a day earlier were unobtainable due to persistent 
bad weather. We obtained 22 180 second images starting with twilight under 
good conditions and at airmass 1. The afterglow is visible on all single 
images.

From the SDSS photometry of the field (Cool et al., GCN 7649), we find 
that the bright star southeast of the afterglow, at R.A. = 11:01:16.88, 
Dec. = +51:40:38.6 has g = 17.111, r = 16.539 and i = 16.377. Using the 
transformations of Jester et al. 2005, we find Rc = 16.458 for this star. 
Using it as a comparison star, we derive for the afterglow from a stack of 
all images:

time after burst	Rc	dRc

1.020536 days		21.20	0.06

This is in good agreement with the slightly later measurement of Khamitov 
et al. (GCN 7661) but significantly fainter than the magnitude reported by 
Pandey et al. (GCN 7663) for an observation a few hours earlier.

Data analysis was delayed by access problems.

This message may be cited.