GCN Circular 20591

E. Sonbas (Adiyaman Univ.), T. Guver, M. De Pasquale (Istanbul Univ.), E.
Gogus (Sabanci Univ.), O. Erece, M. Kocak, H. Kirbiyik, H. Esenoglu (TUG)
report on behalf of a larger collaboration


We observed the field of Swift GRB 170202A (Racusin et al., GCN#20575) with
the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National Observatory,
Turkey), starting February, 2, 20:12:45.56 UT (~ 1.7 hours after the
trigger). Observations were carried out in the R filter. The afterglow is
detected in the R band images with an exposure time of 300 s.


Using USNO-B1 stars USNO-B1 0950-0184329 (R.A.=152.492, Dec=+5.028) and
USNO-B1 0949-0181744 (R.A.=152.514, Dec=+4.993) in the field, the magnitude
of the OT was estimated as follows;


t-t0 (hr) exp.(s) filt mag err (+/-)

1.75 300 R 18.98 0.07


Analysis of further observations with the same filter is ongoing.


We thank to TUBITAK National Observatory for a partial support in using
T100 telescope with project number 10CT100-95 and technical support.