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GCN Circular 56

GRB980326, optical observations
1998-04-22T04:23:19Z (26 years ago)
James Rhoads at KPNO <rhoads@noao.ed>
Frank Valdes, Buell Jannuzi, and James Rhoads (on behalf of the NOAO
Deep Widefield survey team and the KPNO GRB followup team) report:
We observed the location of the GRB 980326 optical transient on 1998
April 7.15 UT using the KPNO 4 meter telescope and the CCD Mosaic
camera.  The total integration time was 3300 seconds.

The final coadded image shows no source at the location of the optical
transient.  The flux obtained in a 5 pixel (1.30 arcsecond) radius aperture
and calibrated by comparison to Groot et al's reference star 1 (IAU Circular
6852) corresponds to -0.44 +- 0.33 microJansky at R band.  The corresponding
3 sigma limiting magnitude is R > 24.3 ; the 2 sigma limit is R > 25.3.  For
a 7 pixel aperture, the flux is -0.52 +- 0.38 microJansky.

We also placed an aperture on the location of Grossan et al's nearby source
(GCNC #35).  The fluxes in 5 and 7 pixel apertures are 0.14 +- 0.32
microJansky and 0.51 +- 0.37 microJansky respectively.  Corresponding 3 sigma
limits are R > 23.6 and 23.2 ; two sigma limits are R > 24.0 and 23.4
respectively.  These results are marginally consistent with Grossan et al's
magnitude measurement of R=24.1 or 24.3 for the neighboring source.

More detail, including a link to a 104 by 91 arcsecond section of the
final image, is available at .
The Mosaic camera has a 36 arcminute field of view, and so covers
the entire BeppoSAX error box (16 arcminute diameter).  We can make
data for this full region available, with the caveat that further data
processing might be required.  Contact one of us if interested.

[GCN Operator's Note:  Due to a programming error this notice
was distributed with a FROM:-line that had incorrect information
(XXXX at XXXX <>)  The correct information
has been included in this archived copy of the notice.]
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