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Calculations modeling the effects of stellar evolution on elliptical galaxies (e.g., Bruzual and Kron 1980, Bruzual 1981) suggest that the shape of the spectral flux distribution should remain almost constant in the red and near-infrared out to at least z ~ 2. Thus, it should be possible to derive the redshift of a distant elliptical galaxy by fitting a model galaxy spectrum to broadband near-infrared (RIJHK) photometry.

The purpose of this communication is to update our knowledge of the radio structural properties of quasars and blank field radio sources (blank field ≡ any radio source without an identification on the Palomar Sky Survey prints). The quasar sample consists of all sources (25) with angular sizes greater than 10 arcsec in the list of Jodrell Bank quasars observed by Owen, Porcas and Neff (1978). The blank fields consist of 16 3CR sources also with structures >10 arcsec based on Cambridge 5 km telescope observations. The sources were selected in low-frequency surveys; their emission at v < 1 GHz is dominated by extended components with steep spectra. Thus, both samples should be oriented randomly in space except for a slight bias to be in the plane of the sky.

Observations simultaneously made at visual (B, V, and R) wavelengths, at 1, 1.4, and 3.4 mm and at 1.3, 2, 6, and 20 cm of 9 QSOs and BL Lac objects are reported. The range of the millimeter visual spectral index ɑ_(mv) was only 0.65-0.82, typical of optically thin synchrotron emission. This may indicate that the electrons radiating synchrotron emission in this portion of the spectrum are not subjected to large radiative losses, and therefore relativistic bulk motion with Doppler factors ~10 are required. The visual spectral index is much more broadly distributed and typically larger than ɑ_(mv). The spectral energy distributions have not changed much in the last 2-5 years except for 2251 + 15 and perhaps 0235 + 164. Only 1749 +09 shows a sharp spectral break shortward of 1 mm. Sixteen other sources were observed at 1 mm, of which seven were detected.

In a search for radio emission from bright, optically selected quasars, we detected ∼50% of the quasars at 5 GHz. This radio detection rate is so much higher than that for faint quasars (

Single-epoch multifrequency data are presented for the radio-quiet low-redshift QSO Ton 1542, spanning radio through ultraviolet wavelengths. A 3 Sigma upper limit of 9.2 mJy is obtained for the 20.3 GHz flux density; the first ultraviolet spectrum of this object is presented and discussed. A particularly strong excess of flux density is found at about 3000 A, which is likely to be dominated by Balmer continuum emission. An L-alpha/beta-hydrogen flux ratio of about 17 is also found, which is higher than that usually observed in QSOs.

Photometric observations are presented for outbursts of the quasi-stellar object QSO 1156+295 in 1981 and 1982. High time resolution photometry is included showing variations on time scales of weeks to about half an hour. Data from early plate material show that the object may have been quite bright at the beginning of this century but was quite faint and probably inactive between about 1950 and the beginning of recent activity in 1977-1979. Some results of optical linear polarization are discussed. In examining spectrophotometric results, broadband spectra show very little change in spectral shape during changes in continuum brightness. High resolution spectra (0.1-A FWHM) show no evidence for the Mg II 2798-A absorption sometimes seen in optically violent variables and other QSOs. The radio flux density variations at several frequencies are documented and discussed and compared with the optical light curve. Models for 1156+295 are discussed including variability time scales, and the observed energy output is compared with a magnetic accretion disk model proposed by Shields and Wheeler (1976). Results are summarized and the different sizes of active and inactive regions of the object are compared.

The characteristics of the changes in the shapes of the spectral-flux distributions of variable extragalactic sources have been observed over the wavelength range 0.36..mu..m to 3.5..mu..m. Pronounced activity has been observed in the sources AO 0235+164, 3C 120, PKS 0735+178, OJ 287 (0851+202), and B2 1308+326. The slope of the spectral-flux distribution has been observed to change significantly in some cases during transitions in observed flux. These changes are interpreted in terms of injection and energy loss of high-energy electrons radiating synchrotron radiation.