[AAVSO-HEN] GRB 090118: KPNO 4m Detection of Candidate Afterglow

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8829
SUBJECT: GRB 090118: KPNO 4m Detection of Candidate Afterglow
DATE:    09/01/19 21:29:12 GMT
FROM:    Adria C. Updike at Clemson U  <aupdike at clemson.edu>

Adria C. Updike and Dieter H. Hartmann (Clemson University) report:

Using the KPNO 4m telescope and the NEWFIRM instrument, we observed the
field of GRB 090118 (GCN 8825, Copete et al.) beginning 11.6 hours after
the burst in the J and H bands.  Within the XRT error circle (Rowlinson &
Page, GCN 8828) we detect a faint source at coordinates

RA   03:19:18.6
Dec +18:24:54.3

Variability has not been confirmed.  Further observations are planned.


Time after burst      Band     Magnitude
-------------------------------------------
11.6 hours             J       21.0 +/- 0.5
12.5 hours             H       20.2 +/- 0.4


A total of 40 minutes of exposures were taken in each band and the results
were stacked.  Magnitudes are calibrated to the 2MASS point source catalog
and against a nearby star (RA 03:19:16.7, Dec +18:25:14, J = 14.05).  No
correction has been made for galactic extinction.