H. Pedersen, M. Tarenghi, P. Grosbol and J. Danziger, European Southern Observatory; G. Pizzichini, Bologna; and W. H. G. Lewin, Massachusetts Institute of Technology, communicate: "We have made four observations during 1981-1982 of two optical sources in the error box for the optical flash which may have been associated with the source of the 1978 Nov. 19 gamma-ray burst (Schaefer 1981, Nature 294, 722). The observations were made with a CCD-camera and the 1.54-m Danish telescope at the European Southern Observatory. Source A is a possibly-extended object within 2" of the center of the error box. Observing in a wide, red band (665-1000 nm), we found the average magnitude to be 8.1 (+/- 0.3) fainter than star No. 11 of Fishman et al. (1981, Astrophys. Space Sci. 75, 135); this was determined from 20-, 45-, 60- and 30-min exposures on 1981 July 10 (B = 24.3 +/- 0.6, B-V = 0.5 +/- 1.0), 1982 July 3, 4 and 6, respectively. No definite claim can be made as to variability, although the source appears to have been faint on 1982 July 3 and 4. Source B is a starlike object ~ 3" west and 1" south of source A, and in the red band it is ~ 0.7 mag fainter than A; it is invisible on the B and V exposures. Either A or B may be identical with a faint stellar image found by M. Liller (Schaefer, op. cit.). The optical identification of the gamma-ray burst source will probably have to be based on studies of variability. Other observers are therefore encouraged to monitor the above-mentioned two candidates."
International Astronomical Union Circular
- Pub Date:
- July 1982