ARCHIVAL OBSERVATIONS OF THE ULTRA-SOFT X-RAY TRANSIENT 4U-1630-47

We report on archival observations of the ultra-soft X-ray transient 4 U 1630-47. In 1979 February, 1989 March, and 1994 September, 4U 1630-4 7 was observed in outburst by the Einstein High Resolution Imager (HRI ), the Ginga Large Area Counter (LAC) and the ASCA Gas Imaging Spectro meters, respectively In 1987 October, the Ginga LAC observed the regio n of sky containing 4U 1630-47 and a faint source was detected. While it is possible that this emission originates from another object withi n the LAC field of view, its properties are consistent with an observa tion towards the end of an outburst. The times of the Ginga outbursts are consistent with the known similar to 600 day ephemeris. However, t he ASCA observation and observations of the subsequent outburst by the Rossi X-ray Timing Explorer, indicate that these outbursts started 10 0-150 days later than predicted. This delay confirms the occurrence of more complex outburst behavior from 4U 1630-47. Finally, an observati on by the imaging Einstein HRI in 1980 February, approximately mid-way between expected outburst times, revealed a faint source at a positio n consistent with 4U 1630-47. The measured source intensity is higher than the previous best upper-limit. This implies that (a) the quiescen t intensity is variable by a factor similar to 10, or (b) that the 197 9 outburst had an extremely long duration, or (c) that the emission or iginates from previously undetected inter-outburst activity.