TITLE:   GCN CIRCULAR
NUMBER:  5996
SUBJECT: GRB070103: APO SPIcam i' and z' limits
DATE:    07/01/05 02:09:44 GMT
FROM:    Hsiao-Wen Chen at U Chicago  <hchen@oddjob.uchicago.edu>

H.-W. Chen (U Chicago), J. Dembicky (APO), D. York, D. Lamb (U Chicago),
R. McMillan, B. Ketzeback, and G. Saurage (APO) report on behalf of a
larger collaboration:

"We obtained 5x600 sec dithered exposures in each of the SDSS i' and
z' bands of the field of GRB070103 (Sakamoto et al., GCN 5988), using
the SPIcam on the 3.5 m telescope at the Apache Point Observatory.  The
observations started at Jan 04.05 UT (~ 4.5 hrs after the initial
Swift trigger) under photometric conditions with a mean seeing of 1.6-2
arcsec.  Calibrating the final stacks based on a SDSS standard field
observed through these filters gives 5-sigma depths of AB(i')=24.6 and
AB(z')=24.0 over a 2-arcsec diameter aperture at the location of the
x-ray source reported by Mangano et al. (GCN 5992). "