THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1998

2.4. Transient Sources

UKIRT has long been used to react quickly to targets of opportunity, and the 1998 semesters were no exception. Two highlight programmes are identified here, one of which is a genuine override programme, and the other of which was given a more normal PATT allocation.

In a continuing, well-supported programme of overrides, Tanvir (now Hertfordshire) et al. undertook J, H and K band monitoring (using IRCAM3) of the gamma-ray burster GRB980703 for 2.5 weeks in July, during which it declined by nearly an order of magnitude. Several observers cooperated by sacrificing some hours of their observing time to make the requested observations. Most of those observers recovered their lost time from time originally designated for commissioning of UFTI. The data were used in conjunction with monitoring at other wavelengths to tie down the power-law decline of the optical transient, and to determine the physical parameters of the burst afterglow, including its prodigious energy output - greater than 10⁵² erg.

Late-time observations of SN1998s were carried out by Miekle, Fassia and Geballe using CGS4; this programme produced clear detections of cobalt lines in decay, and verifies this decay as the main power source of such supernovae in their late stages.