VLBA Imaging of Sources at 24 and 43 GHZ
Abstract
We have imaged the sub-milli-arcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high-frequency celestial reference frame. Ten epochs of observations with the Very Long Baseline Array were conducted over the course of 5 years, resulting in a total of 1339 images produced for 274 sources at K-band and 132 sources at Q-band. A detailed analysis of the images allowed us to characterized the effects of intrinsic source structure on the astrometric observations. We find that the average flux densities for the sources imaged at these higher frequencies is tilde 1 Jy, with epoch-to-epoch variations of less than 20%. We also find that the intrinsic structure of the sources is reduced at 24 and 43 GHz relative to typical X-band results. Finally, we find that variations of the flux density contained within the radio core relative to the total source flux density are less than 8% on average at 24 GHz. Our results indicate that there are numerous sources available at high frequencies, and these sources persist over relatively long periods of time. In addition, the sources are more compact at these higher frequencies and should provide high-quality astrometric reference points resulting in an improved celestial reference frame.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2009
- Accession Number
- ADA515365
Entities
People
- A. L. Fey
- D. A. Boboltz
- P. Charlot
Organizations
- United States Naval Observatory