TITLE: GCN GRB OBSERVATION REPORT NUMBER: 904 SUBJECT: GRB 001212 Optical Observation DATE: 00/12/16 15:33:29 GMT FROM: Jin Zhu at BAO GRB 001212 Optical Observation J. Zhu, on behalf of the Beijing Astronomical Observatory GRB team, report: "The approximately one degree square field centered with GRB 001212 error box (Hurley et al., GCN 899) was imaged again with the 0.6/0.9-m Schmidt telescope (Zhu et al., GCN 903) during Dec. 15.51-15.54, 15.69-15.76, and Dec. 16.56-59 under good weather condition. Three 1200-s exposures (limiting magnitude for each is about R=21) and nine 600-s exposures were taken in Dec. 15 and three 960-s exposures in Dec. 16. The source mentioned by Mohan et al. (GCN 900) was clearly detected in all images, and there seems to be no obvious variation at the level of photometric accuracy (0.2-0.3 mag). Using the following four USNO-A V1.0 objects (David Monet, et. al.) ================================ No. RA (2000.0) Dec mag. --- ----------------------- ---- 1 06:49:30.03 +36:24:35.5 14.6 2 06:49:31.16 +36:23:30.6 14.9 3 06:49:32.45 +36:22:12.1 14.3 4 06:49:32.63 +36:21:06.1 14.1 ================================ as our magnitude references (the real procedure is to use R=14.475 for the average magnitude of the above 4 stars), the magnitudes derived from each frame are (combined with two previous images mentioned in GCN 903 for completeness; photometric error is one-sigma): ============================= Date mag error notes ---- ----- ----- ----------- 14.63 17.66 1.52 bad weather 14.64 16.91 0.68 bad weather 15.51 18.69 0.14 15.53 18.72 0.14 15.54 18.39 0.13 15.69 18.39 0.18 15.70 18.60 0.22 15.71 18.97 0.28 15.72 18.55 0.19 15.73 18.82 0.26 15.73 18.64 0.22 15.74 19.20 0.37 15.75 18.71 0.24 15.76 18.64 0.23 16.56 18.84 0.16 16.58 18.58 0.14 16.59 18.57 0.17 ============================= We conclude that this object is not optical afterglow for GRB 001212." This message may be cited. -- ======================================================================== Jin Zhu | Tel.: +86-10-62751286 (O) Beijing Astronomical Observatory | +86-314-5054767 (Schmidt dome) Chinese Academy of Sciences | Pager: +86-10-96301682333 P. R. China | Fax : +86-10-62765031 ------------------------------------------------------------------------ Room 2919, No. 2 Science Building, CAS-PKU Beijing Astrophysics Center, Peking University, Beijing 100871, P. R. CHINA. ------------------------------------------------------------------------ email: zj@bac.pku.edu.cn http://vega.bac.pku.edu.cn/~zj ========================================================================