The redshift of the highly variable BL Lac object H0323+022

A. V. Filippenko, S. Djorgovski, H. Spinrad, W. L. W. Sargent
1986 Astronomical Journal  
New optical spectra are used to derive the redshift of H0323 + 022, a bright, highly variable x-ray source whose nature has been the subject of controversy. Most of the spectra are dominated by a featureless nonstellar continuum, as found in BL Lac objects. Photometric variations of ^ 2 mag have been seen over a time interval of only 2 days. The nonstellar light is sometimes faint enough to allow the detection of absorption lines at a redshift z = 0.1471 + 0.0005. These lines are clearly due to
more » ... stars in the host galaxy, which is easily visible in deep images of the object. The galaxy is probably a relatively normal elliptical with M v~ -21 to -22, except that a noticeable extension is evident in one quadrant. On 24.15 February 1985 UT, the nonstellar continuum could be described by a power law of index a-0.6 (wheref v oc v _a ); its relative strength in the nucleus (2" X5.2") was ~62% at 5460 A, while Af K ^ -22 to -23. When the power-law component fades, its slope appears to steepen. There is now no doubt that H0323 + 022 is a BL Lac object, rather than a peculiar Galactic star. As discussed by Feigelson et al. (1986) , its extremely rapid variability (AL^ 1X 10 45 erg s" 1 in Af^30 s) is matched only by that of OJ 287, and the hard x rays must come from a region roughly a factor of 10 4 smaller than that which produces the radio emission.
doi:10.1086/113977 fatcat:cxx5aqi62bdjbgr7oaop466xl4