| Description |
deep ccd and near infrared imaging and photometry of flat spectrum radio sources from the 1 jy sample show that nearly all members have an optical or infrared identification with a brightness closely proportional to the radio flux density (in agreement with identification programs for other flat spectrum radio samples). there is one outstanding exception, which is far fainter than expected from this proportionality, and two additional objects which are very faint galaxies but whose nuclei may also be very faint. because the other very faint optical identifications are obscured or have very red continua, it is possible that these three sources are just extreme examples of the same behavior; on the other hand, they might represent an optically (and infrared) quiet type of quasar. because no other flat spectrum sources seem to be truly optical-infrared quiet, the latter possibility would imply discovery of a new emission mechanism or source geometry for quasars. deep iso imaging of these sources at 11.5 microns can tell if they are intrinsically faint in the infrared as well as in the optical. |
| Keywords |
Infrared Space Observatory data, ESA ISO mission dataset, ISO infrared observations, mid-infrared astronomy data, far-infrared spectroscopy dataset, ISOCAM imaging data, ISOPHOT photometry data, SWS short wavelength spectrometer data, LWS long wavelength spectrometer data, infrared spectral line observations, infrared imaging survey data, dust emission infrared observations, star formation infrared dataset, interstellar medium spectroscopy data, polycyclic aromatic hydrocarbons PAH features data, active galactic nuclei infrared observations, circumstellar envelope infrared data, planetary nebula infrared spectroscopy, extragalactic infrared survey data, calibrated ISO data products, FITS files infrared astronomy, spectral energy distribution infrared data, continuum photometry dataset, infrared spectral cubes, flux-calibrated infrared maps, ESA ISO Data Archive, legacy infrared space mission dataset |
