GCN Circular 416

GRB 990915, optical observations
---------------------------------

Alberto Castro-Tirado, LAEFF-INTA (Madrid) and IAA-CSIC (Granada) 
on behalf of a large collaboration:
Victor Costa and Jose L. Ortiz, IAA-CSIC
Oliver Cordes, Martin Altmann and Daniel Harbeck, Univ. of Bonn
Javier Gorosabel, LAEFF-INTA 
Mara Salvato and Jochen Greiner, AIP (Potsdam)
Kevin Hurley, UCBerkeley/SSL 

reports:

"Following the detection of the strong burst GRB 990915 
by BATSE and COMPTEL (Batse trigger # 7766) we have obtained:

-150 frames (60-s, no filter, 20' x 13' FOV) at the 0.8-m 
 Schmidt telescope of the German-Spanish Calar Alto Observatory 
 (CAHA) starting 0.5 hr after the burst. The frames covered a 
 significant fraction of the Hunstville/Locburst and COMPTEL 
 error boxes and about a 15 % of the NEAR error box given by 
 Hurley et al. in GCN 412
Not found
 
 
. 

-25 frames (60-s, R-band, 16' x 16' FOV) at the 1.23-m CAHA 
 telescope starting 30 hr after the burst. The frames covered an 
 additional fraction (65 %) of the NEAR error box.

-10 frames (150-s, R-band) at the 1.23-m CAHA telescope starting
 50 hr after the burst. The frames covered the rest (20 %) of
 the NEAR error box.  

After a careful visual comparison with the Digital Sky Survey, 
I have not found any source varying more than 0.3 mag when comparing 
to the DSS-1 charts, i.e. a limit of R > 20.5 can be imposed to the
GRB 990915 optical afterglow."