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GCN Circular 6926

Subject
GRB 071013: TLS 2nd epoch - Kornienko candidate constant
Date
2007-10-16T19:51:44Z (17 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann, C. Hoegner, U. Laux & R. Filgas (TLS Tautenburg) report:

We observed the field of GRB 071013 (Marshall et al., GCN 6907) with the 
Tautenburg 1.34m Schmidt telescope under good conditions, obtaining 6 300 
second images in the Rc band at 3.2 days after the GRB. We use the same 
comparison star as given in Kann, Hoegner & Filgas (GCN 6917), and find 
the following magnitudes of the possible variable source discovered by 
Kornienko et al. (GCN 6925):

Date		Mid-Time	Rc	dRc

13.74086	0.23439		19.537	0.027
13.75231	0.24584		19.506	0.028
13.76103	0.25456		19.634	0.040
13.76977	0.26330		19.566	0.032
13.77850	0.27203		19.704	0.036
13.78723	0.28076		19.629	0.038
13.79596	0.28950		19.683	0.045
13.80469	0.29822		19.593	0.044
13.81342	0.30695		19.589	0.038
13.82216	0.31569		19.635	0.028
13.83088	0.32441		19.598	0.044
13.83961	0.33314		19.572	0.040
13.84834	0.34187		19.762	0.054

Thus, we see no significant variability in the source over the span from 
0.23 to 0.34 days after the GRB.

For the second epoch, we combine the 6 300 second images and find, using 
the same comparison star:

Date		Mid-Time	Rc	dRc

16.75845	3.25198		19.583	0.015

Thus, we also see no variability between 0.3 and 3.3 days after the GRB. 
If this source is at low redshift and possibly associated with a 
supernova, there is no evidence for it yet. Further photometric follow-up 
and spectroscopy of the USNO/DSS source is encouraged.

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