A0535+26
Abstract
P. C. Joss, Massachusetts Institute of Technology, reports that the SAS-3 Group has detected a new turn-on of the transient, pulsing, x-ray source in Taurus, A0535+26 (IAUC 2774, 2780, 2784, 2787, 2790; see also Rosenberg et al. 1975, Nature 256, 628). The source was undetected (with an upper limit of ~ 0.1 times the 1-10 keV flux of the Crab Nebula) on Nov. 5.5 UT but attained a 1-10 keV flux of ~ 0.2 times that of the Crab by Nov. 7.5 UT. The source is observed to pulse with the 104-s periodicity previously reported. He suggests that the optical candidate for the source, HDE 245770, be monitored for unusual spectral or photometric behavior. Immediate searches for other optical candidates in the x-ray error box (R.A. = 5h35m47s +/- 2s, Decl. = +26o16'52" +/- 45", equinox 1950.0) would also be valuable. The observation of another x-ray turn-on about six months after the original detection probably excludes models involving highly eccentric orbits with periods in excess of ~ 1 year.
- Publication:
-
International Astronomical Union Circular
- Pub Date:
- November 1975
- Bibcode:
- 1975IAUC.2863....1J