GRB 020406
GCN Circular 1338
Subject
GRB020406(?), optical observations
Date
2002-04-07T22:25:26Z (23 years ago)
From
Arne A. Henden at USNO/USRA <aah@nofs.navy.mil>
D. Durig (ddurig@sewanee.edu) and A. McDermott
report on behalf of the International AAVSO
GRB Network:
We observed the RXTE/ASM error box for the short X-ray
transient 020406 (Smith et al. GCN 1332), that may be related
to a GRB, with the Cordell-Lorenz Observatory 0.3m telescope
and ST-9E/AO-7 CCD system. The western
half of the error box was mosaiced with limiting
magnitude approximately 20. Near the center of
the error box an object was found that does
not appear on either the blue or red POSS-II plate.
At coordinates:
19:00:42.10 +01:27:22.4 J2000
+/- 0.2s +/- 0.4"
this object had an estimated unfiltered magnitude
of 18.9 (USNO-A2.0 red) on a 10-minute exposure with midpoint
UTD 020407.394 (13hrs after the ASM detection);
two subsequent exposures showed fading behavior (19.2 and 19.3mag),
but a constant brightness also fits within the photometric
errors. No known GCVS variable star nor known
asteroid is near this position. As this is a
crowded field with no obvious galaxies on the POSS
plates, this object may just be an unrelated galactic
variable of large amplitude.
GCN Circular 1351
Subject
GRB020406(?), optical observations
Date
2002-04-10T21:40:53Z (23 years ago)
From
Arne A. Henden at USNO/USRA <aah@nofs.navy.mil>
D. Durig and A. McDermott (Cordell-Lorenz)
and B. Gary (Santa Barbara) report on behalf of the
International AAVSO GRB Network:
We observed the RXTE/ASM revised error box for the
possible GRB 020406 (Smith et al. GCN 1332, 1341)
with the Cordell-Lorenz Observatory 30cm telescope
(ST-9E/AO-7 CCD) and Gary 25cm telescope (ST-8E).
coverage lim mag UTD
entire box CR=17 020407.356
western half CR=20 020407.356
central 80% Rc=17.5 020407.500
remaining 20% Rc=17.1 020407.500
entire box CR=20 020410
Where CR = unfiltered, using R-band zeropoint, and Rc = taken
with a standard Cousins R filter. No new objects were
found in the revised error box to the limiting magnitudes
listed above.
In addition, the entire original box was covered to CR=17
on 020407.4 with no new source detected. The candidate
mentioned in Durig and McDermott (GCN 1338) was
reobserved on 020410 and has shown no fading over
the past 72 hours; it can be eliminated as a possible
afterglow candidate.