Astron. Astrophys. Suppl. Ser. 138, 449-450
A.J. Castro-Tirado1,2 - J. Gorosabel1
Send offprint request: J. Gorosabel (email@example.com)
1 - Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF-INTA), P.O. Box 50727, E-28080 Madrid, Spain
2 - Instituto de Astrofísica de Andalucía (IAA-CSIC), P.O. Box 03004, E-18080 Granada, Spain
Received January 21; accepted March 17, 1999
Since January 1997, we have monitored 15 GRB fields, detecting 6
We have revisited GRB 970508 and GRB 980326. For GRB 970508,
we derive a power-law decay exponent (R-band).
The luminosity of the host galaxy L relative
to the characteristic luminosity is in the range 0.06-0.15,
i.e. a dwarf galaxy.
For GRB 980326, we derive a power-law decay exponent ,
taking into account the new upper limit for the host as
Bloom & Kulkarni (1998).
This implies one of the fastest
GRB optical decays ever measured.
The fact that only about 50% of optical transients have been
found within the /X-ray error boxes, suggest that
either considerable intrinsic absorption is present
or that some optical transients display a very fast decline.
We also propose that the "secondary maximum" detected on 17 Apr. 1998 could be
explained in the context of the "SN-like" light
curves 2-3 weeks after the GRB, as recently suggested by
Key words: methods: observational -- gamma-rays: bursts
Copyright The European Southern Observatory (ESO)