"We present further R-band observations of the IPN errorbox of GRB 000630 (Hurley et al. GCN #736) obtained with the NOT 2.56-m and the USNOFS 1.0-m. Comparison of three new epochs with our June 30.9 NOT observations (GCN #739) reveals a single transient object (less than an arcmin from the center of the IPN error box) which has faded monotonicly from 21 hours to 94 hours after the burst. The position of the point-like object, which we identify as the likely optical afterglow of GRB 000630, is RA(J2000) = 14:47:13.49, Dec(J2000) = +41:13:53.3, with an astrometric uncertainty of 0.7" relative to the USNO-A2.0 catalog. Based on the photometric calibration of Henden (GCN #746) we find the following magnitudes for the optical afterglow using PSF photometry:
Date 2000 UT Telescope Exp. time FWHM t_burst+ R (mag)
June 30.9 NOT 2.56-m 3x300 s 0.9" 21 h 23.04+-0.08
July 1.3 USNO 1.0-m 18x600 s 2.1" 31 h 23.13+-0.25
July 1.9 NOT 2.56-m 3x600 s 1.2" 46 h 24.05+-0.16
July 3.9 NOT 2.56-m 5x600 s 0.8" 94 h 24.70+-0.16
The lightcurve resulting from these data points is consistent with a power-law decay with an index of -1.1 +- 0.3, assuming no contribution from an underlying host galaxy. We note that the burst occurred in a region with an apparent overdensity of galaxies. Sections of the images and a lightcurve are posted at http://www.astro.ku.dk/~brian_j/grb/grb000630/ ."
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TITLE: GCN GRB OBSERVATION REPORT NUMBER: 739 SUBJECT: GRB 000630: Optical observations DATE: 00/07/01 12:33:48 GMTB. L. Jensen, H. Pedersen, J. Hjorth, J.P.U. Fynbo (U. of Copenhagen)
"We have obtained images covering about 95% of the error box reported by Hurley et al. (GCN #736) with the 2.56-m Nordic Optical Telescope (+ALFOSC) on La Palma on 2000 June 30.90 UT (about 21 h after the burst). We obtained 3 x 300 sec R band exposures in seeing of 0.9". Comparing with DSS-2 (red) exposure no convincing candidates down to the limit of DSS (R~21.3) are found. We find no object at the position of the proposed counterpart by Bartolini et al. (GCN #737), but detect a star-like object (R = 21.0+-0.1) 3.5" to the south of it at RA(J2000) = 14:47:25.37, Dec(J2000) = +41:12:24.1. This object may be present on the DSS-2 (red) exposure. We find no optical counterpart to the radio source of Berger et al. (GCN #738) down to R = 24. The nearest optical source (R = 24.5+-0.4) is located at RA(J2000) = 14:46.58.9, Dec(J2000) = +41:17:00, ie. 1.5"+-0.5" from the radio source. The photometry and astrometry reported here was based on the USNO-A2.0 catalog. Images of the field are posted at:
