The High-Luminosity BL Lacertae Object PKS 0823-22

Abstract

Simultaneous infrared, optical, and UV observations of the BL Lacertae object PKS 0823-22 are presented. The identification of the observed absorption doublet at λλ5341, 5355 with Mg II λλ2796, 2803 gives an absorption redshift z_abs_ = 0.910. At this redshift, the object is one of the most luminous of its class with M_V_ <~ -29.4. The spectral flux distribution of the source and the properties of intervening absorbing matter are discussed. Analogies with other sources suggest that the object may be gravitationally lensed.