GCN Circular 709
Subject
GRB000615, further R-band photometry
Event
Date
2000-06-16T22:02:26Z (26 years ago)
From
Krzysztof Z. Stanek at CfA <kstanek@cfa.harvard.edu>
K. Z. Stanek (CfA), P. M. Garnavich (Notre Dame), S. Jha (CfA) and
P. Berlind (FLWO) report:
We have obtained additional images of the BeppoSAX error-box of
GRB000615 (GCNs 703, 705) using the FLWO 1.2-meter telescope on
Mt. Hopkins. We obtained two 4x300 sec R-band image sequences, with
the first sequence starting at UT June 16 04:19, and the second
starting at UT June 16 10:19. As was the case with our first night
images (GCN 706), visual comparison of these new images with the
POSS-II red plate, which reaches about R~20.0 mag, reveals no obvious
new objects.
In addition, by comparing our images from the two nights we are able
to place much stronger limit on any variable optical afterglow of
GRB000615. Employing the image subtraction code ISIS-2 (Alard 1999)
between the two nights reveals no variable objects brighter than about
R~21.5. Using DAOPHOT-II (Stetson 1992) we detect about 350 objects
with R<21.5 mag in 11x11 arcmin field.
Our FLWO R-band fits images from both nights can be accessed from
ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB000615/.
We find one possible variable object detected in the first night
images, which is not present in the second night images. It is located
near at RA=15:33:06.04, DEC=+73:49:46.4 (J2000.0; uncertainty +/-
0.3"; x=431.7, y=614.5 in the "ff1003" image), and its brightness is
about R~21.6 (calibrated using the USNO R-band magnitudes). However,
as the object seems to move slightly in the first night images, we DO
NOT think it is the GRB afterglow.
Further observations are planned at FLWO.
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