V0332+53

J. Terrell and W. C. Priedhorsky, Los Alamos National Laboratory, inform us that the TENMA x-ray transient mentioned on IAUC 3891 is apparently identical with V0332+53 (Terrell et al. 1982, B.A.A.S. 14, 619), for which their analysis of the 1973 data gives the position R.A. = 3h32m, Decl. = +53deg0 (equinox 1950.0, uncertainty 0.2 deg). The hard x-ray source was first observed from the satellite Vela 5B in the 10-day interval centered on 1973 June 1, rose to an intensity of ~ 1.4 Crab in July and was last observed around Aug. 30. The slow rise and symmetric fall of intensity are unusual. Rapid fluctuations took the source to peak intensities > 2 Crab. J. Davelaar, R. Blissett, L. Stella and M. McKay, EXOSAT Observatory, Darmstadt; N. White, E.S.T.E.C., Noordwijk; and J. Bleeker, Space Research Laboratory, Utrecht, report that observations by EXOSAT during Nov. 20.2-20.4 and 21.6-21.8 UT yield the following position: R.A. = 3h31m14s5, Decl. = +53deg00'17" (equinox 1950.0) error radius 10"). No change in the overall flux level was observed between these two EXOSAT observations, the source strength being 0.10 Crab. Autocorrelation analysis reveals the presence of short noise fluctuations with typical decay and rise times of ~ 1 s and provides evidence also for fast time variability below 10 ms. A complex, though featureless, spectrum was measured, and it is best described by a 4.8-keV blackbody with a soft excess below 4 keV modeled by a power law of photon index 1.0. A hydrogen column density of ~ 10**26 m**-2 is suggested. Ground-based observations at optical, infrared and radio wavelengths are strongly urged. EXOSAT will continue to monitor the source periodically. Specific EXOSAT observations are scheduled for Nov. 28.8-29.0 and Dec. 1.4-1.6 UT. For information about future observations contact McKay (telephone 49-6151-886-707, telex West Germany 419453 or 419441 ESOC D). P. W. J. L. Brand, T. R. Geballe, M. P. Toner, A. S. Webster and P. M. Williams, U.K. Infrared Telescope, Edinburgh University, and Royal Observatory, Edinburgh, telex that an infrared candidate has been found with the U.K.I.R.T. 5" east and 4" north (both +/- 5") of the EXOSAT position. It lies within a few arcsec of a faint stellar image on the Palomar Sky Survey and was estimated to be at R ~ 13-14 on the television guider. The infrared magnitudes on Nov. 23.31 UT were measured to be J = 12.10, H = 10.70, K = 10.31 and L' = 9.65 (uncertainty 5 percent).