Observations of PKS 2155-304 with the Extreme Ultraviolet Explorer
Abstract
We present a high-accuracy light curve for the BL Lac object PKS 2155-304, observed with the Extreme Ultraviolet Explorer. The light curve shows variations of about 10% over a 1.3 day observing period. The observed EUV flux is a factor of 1.7 fainter than when PKS 2155 - 304 was observed by the ROSAT Wide Field Camera (WFC) during the EUV survey. The optical flux during our observations is about a factor of 2 fainter than during the WFC observations, so we conclude that the overall spectral shape is invariant as the flux varies. These observations support the model in which the spectrum from the optical to the X-ray band is given by a synchrotron spectrum. Extrapolating an X-ray power-law spectrum with an energy index of 1.66 into the EUV only slightly over-predicts the observed EUV count rates so that changing any one of several spectral parameters within the uncertainties gives an acceptable model. Subject heading BL Lacertae objects: individual (PKS 2155 - 304)
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1993
- DOI:
- 10.1086/186994
- Bibcode:
- 1993ApJ...414L..53M
- Keywords:
-
- Astronomical Satellites;
- Bl Lacertae Objects;
- Extreme Ultraviolet Explorer Satellite;
- Light Curve;
- Astronomical Models;
- Astronomical Spectroscopy;
- Spaceborne Astronomy;
- X Ray Spectra;
- Astrophysics