[AAVSO-HEN] GRB 090715B: Observation of the optical afterglow

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  9675
SUBJECT: GRB 090715B: Observation of the optical afterglow
DATE:    09/07/16 08:27:41 GMT
FROM:    Angelo Antonelli at Obs. Astro. di Roma  <a.antonelli at oa-roma.inaf.it>

L. A. Antonelli (INAF-OAR), S. Marinoni (INAF-TNG), F. Montalvo (UNAM- 
OAN), A. Vazquez (UNAM-IA) report:

We observed the field of GRB 090715B (Vetere et al., GCN 9668) with  
the 1.5 m Telescope in San Pedro Martir (BCN-Mexico) equipped with  
LaRuca, in the B, V, and R filters.

We started observations on 2009 July 16.1729 UT (7.07 hrs after the  
burst) and we detect the object reported by Malesani et al., (GCN  
9671), Smith et al. (GCN 9670) and Vetere et al. (GCN 9668) in all  
filters. The object has a magnitude R = 20.4 +- 0.1 (calibrated  
against USNO B1). The object has faded with respect of the value  
reported by Malesani et al., (GCN 9671) with a decay index of 0.77 
+-0.39. Due to its fading behavior we can confirm that it is the  
optical afterglow of GRB 090715B.

This message can be cited.