Previous abstract Next abstract
Session 84 - QSOs and BL Lacs.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center
Although the Einstein IPC Slew Survey contains important data on the long-term (c. 1978--1981) behavior of Galactic X-ray binaries (XRBs) and other bright variable sources, the highly nonuniform exposure even on arcminute angular scales has made interpretation uncertain. We have recently tested new, robust measures of the exposure gradients for individual scans in the standard 6^\prime \times 6^\prime detection cell (Elvis et al. 1992, ApJS, 80, 257): the median exposure (\tau_m) of the nonzero--exposure pixels (with robust 16% and 84% sextiles); (2) the median--normalized absolute deviation per pixel (ADev); and (3) the fraction of zero--exposure pixels (f_z). Based on a detailed analysis of exposure maps for individual scans, we find that the most reasonable selection criteria are \tau_m > 0.1 sec, ADev < 1, and f_z < 0.5. Also, we have developed a new IRAF/PROS--based technique to extract Slew Survey photon event lists in 3 ranges of interest: soft (0.15-1.4 keV), hard (1.6-3.4 keV), and broad. We have used the event lists, together with the exposure map selection criteria above to produce improved light curves for all Slew Survey sources with more than 100 detected counts and \ge5 scans. We present fluxes in the 3 bands and hardness ratios as a function of time for the high-mass XRBs Cen X-3, Cyg X-3, LMC X-1, LMC X-3, and 4U1909+048. For high-mass XRBs undetected in the Slew Survey, we use new upper limits for the complete scan data to evaluate the quiescent X-ray luminosities. We also report new long-term light curves for a wide variety of variable X-ray sources, including low-mass XRBs (LMC X-2, 4U1735-44); CVs (EF Eri and V1336 Aql); SS433; active stellar systems (V711 Tau, AB Dor); BL Lacs (3C 66A, OJ 287, Mrk 501, I Zw 187, and PKS 2155-304); and AGN (3C 120, NGC 3783, NGC 4051, NGC 4151, Mkn 205, 3C 273, MCG-6.30.15, NGC 5506, 3C 323.1, and 3C 390.3). Some of these were unobserved, and others looked at only \sim1-2 times in pointed IPC observations. Our work yields \sim 5-10 IPC observations per source.
Program listing for Wednesday