GCN Circular 148

The faintest GRB host galaxy?

V. Sokolov, S. Zharikov (SAO-RAS), E. Palazzi (ITeSRE-CNR),
L. Nicastro (IFCAI-CNR) and the SAX-GRB team report:

"On 1998 July 23.85 UT and 24.96 UT we obtained a deep Rc band image of
the field of the GRB 980519 optical transient (Jaunsen et al. GCN #78
Not found
 
 
)
with the 6-m BTA telescope of SAO-RAS. The total observing time was 9600 s
with 600 s per exposure.  Conditions were photometric with an average seeing
of 1.20 arcsec. A faint extended source is clearly detected at the position
of the OT. Due to the faintness of the object, we are not able to check
if between the two nights there was any luminosity variation.
The object magnitude was the same within the errors,
and the photometry of the GRB 980519 OT in 2.5 arcsec diameter aperture
was made by two observational nights and gave Rc = 26.05 +/- 0.22.
For photometric calibration we used the secondary standards from
Henden et al. (GCN #96
Not found
 
 
).

From the time of optical observations of GRB980519 OT with Keck and Palomar
(GCN #88
Not found
 
 
) in the R band
the assumed power-law decline slope of -1.98 (GCN #79
Not found
 
 
) would make the OT
undetectable at the epoch of our observations.
So, we conclude that the OT has stopped its power law decay a long time ago,
and the observable now extended object is the host galaxy of GRB 980519 and
it could be the faintest among those known up today.

Images of the field will be posted at
http://www.sao.ru/~zhar/home/GRB/980519.html

This message can be cited."