TITLE:   GCN CIRCULAR
NUMBER:  14309
SUBJECT: GRB 130305A: TLS Tautenburg observations
DATE:    13/03/15 00:20:12 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

B. Stecklum, D. A. Kann and C. Hoegner (TLS Tautenburg) report:

Following the announcement of the ground-detection of the bright GRB
130305A by Swift BAT (Cummings & Palmer 2013, GCN 14257), which was also
detected by Fermi LAT (Guiriec et al. 2013, GCN 14260), Fermi GBM (Yu &
Xiong 2013, GCN 14261) and Konus-Wind (Golenetskii et al. 2013, GCN
14262), we initiated observations with the 1.34m Schmidt telescope of the
Thueringer Landessternwarte Tautenburg under excellent weather conditions
at 18:11 UT, 22 minutes after the GCN notice.

We obtained 6 x 600 sec exposures in the Rc band, centered 0.29299 days
after the GRB. At the position of the XRT afterglow (Malesani et al. 2013,
GCN 14263, Zhang et al. 2013, GCN 14276), we detect no source down to a 2
sigma upper limit of Rc > 23.2. Photometric calibration was obtained with
respect to several SDSS stars in the field, using the transformations of
Lupton (2005).

This upper limit is deeper than the one obtained by Kumar & Pandey (2013,
GCN 14274) at a similar time and earlier than several other reported
observations (Cenko 2013, GCN 14265; Butler et al. 2013, GCN 14267;
Breeveld et al. 2013, GCN 14268). We detect all the surrounding sources
seen in the deep Gemini image (Cucchiara et al. 2013, GCN 14272).

A second observation was attempted a day later, but due to inclement
weather conditions only a single 600 sec image could be successfully
obtained. It is significantly shallower than the stack of the first night
and shows no changes.

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