TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1416 SUBJECT: GRB020531 Optical Observations DATE: 02/06/07 01:16:18 GMT FROM: Don Lamb at U.Chicago A. Miceli, D. Q. Lamb, D. Zucker, K. Covey, J. Dembicky, and N. C. Hastings report: We have observed the field of GRB020531 (=H2042) (Ricker et al., GCN 1399) using the SPIcam (4.78' x 4.78' field of view) on the ARC 3.5-meter telescope at APO under clear skies and a bright moon on UTC 2002 June 1 from 07:27:53 to 07:43:05 UTC (beginning 1.3 days after the burst), and under mostly clear skies but poor seeing on UTC 2002 June 6 from 04:38:33 to 04:54:22 UTC (beginning 7.2 days after the burst). On both nights we took three 400-second r'-band exposures that cover the entire refined hexagonal IPN error region for GRB020531 (Hurley et al., GCN 1407). We have examined these images in the vicinity of the ten X-ray sources seen in the first Chandra follow-up observation that lie inside the refined IPN error region and the three bright X-ray sources that lie just outside the refined IPN error region (Ricker et al., GCN 1415). The table below lists the approximate r* magnitude or the approximate limiting r* magnitude of any object that lies at the location of these thirteen X-ray sources, based on a preliminary analysis of a single r'-band image taken on each night. SPIcam RMS astrometric errors are 0.2 arcsec or less. --------------------------------------------------------------------------- Nearest X-ray Optical RA Dec r* mag r* mag Comment Source Source (deg) (deg) (June 1) (June 6) --------------------------------------------------------------------------- cxo00 arc00 228.8139 -19.4194 --- 20.6 Outside June 1 FOV cxo05 mag05 ----- ----- > 22.5 > 22.0 Magellan R ~ 23.6 cxo15 arc15 228.7431 -19.3892 20.7 20.7 cxo28 --- ----- ----- > 22.5 > 22.0 cxo36 --- ----- ----- > 22.5 > 22.0 cxo41 --- ----- ----- > 22.5 > 22.0 cxo47 --- ----- ----- > 22.5 > 22.0 cxo48 --- ----- ----- > 22.5 > 22.0 cxo51 --- ----- ----- > 22.5 > 22.0 cxo52 --- ----- ----- > 22.5 > 22.0 cxo55 arc55 228.7374 -19.4107 22.3 --- Outside June 6 FOV cxo56 arc56 228.8091 -19.4073 20.5 20.5 cxo58 --- ----- ----- > 22.5 > 22.0 --------------------------------------------------------------------------- This message is citable.