TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3566
SUBJECT: GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
DATE:    05/07/06 18:42:11 GMT
FROM:    Melissa Nysewander at UNC,Chapel Hill  <mnysewan@physics.unc.edu>

M. Nysewander (North Carolina), J. Flasher (Colorado), F. Hearty
(Colorado), G. Stringfellow (Colorado), J. Walawender (Colorado), D. Q.
Lamb (Chicago), J. Dembicky (APO), J. Barentine (APO), R. McMillan (APO),
B. Ketzeback (APO), D. Reichart (North Carolina), and D. G. York (Chicago)
report on behalf of the FUN GRB collaboration:

Using griz all-sky photometry of a 4.8 arcmin x 4.8 arcminute field
centered on the coordinates of the optical afterglow of GRB 0505025a that
was derived from ARC 3.5-meter SPIcam observations made between 4:00 and
7:00 UT on 2005 June 13, we have calculated the griz magnitudes of 103
sources in the field of GRB 050525a:

http://www.physics.unc.edu/~mnysewan/grb050525a.dat

The astrometry in these files is based on the USNO B1.0-catalogue. The
estimated systematic errors in the astrometry are less than 400mas.  The
estimated systematic photometric errors are typically ± 0.05 mag in the gri
bands and ± 0.06 mag in the z band.