Space VLBI Observations of Southern Hemisphere Gamma-Ray and Non-Gamma-Ray AGN: First Results for PKS 0637-752

We present the first results from our VSOP proposal, "γ-ray loud and quiet AGN with VSOP and SHEVE at 5 GHz". This project is aimed at determining what, if anything, differentiates γ-ray-identified radio sources from similar strong, flat-spectrum radio sources which have not been identified as sources of greater than 100 MeV γ-rays. Five VSOP observations have been successfully completed as part of this project during VSOP AO1. One observation has been correlated thus far, a 4.970 GHz observation of PKS 0637-752 from 1997 November 21. We present the VSOP image for PKS 0637-752 and make comparisons between the space VLBI image and ground-based VLBI and Australia Telescope Compact Array (ATCA) images, as well as present ATCA flux density monitoring at 4.8 GHz. A brightness temperature for PKS 0637-752 of 0.7×10 12 K has been determined from the VSOP data and a tentative apparent superluminal speed, from comparison to the ground-based VLBI image, of ∼9c. © 2000 COSPAR. Published by Elsevier Science Ltd.