EVLA Prototype Correlator Tests: Impact on Observers

Michael Rupen and Gustaaf van Moorsel

The 4-station WIDAR prototype correlator is undergoing extensive testing at the Very Large Array (VLA), leading up to the WIDAR Critical Design Review on 2-3 December 2008. While many of these tests may be carried out during software or maintenance time, some will encroach on dynamically scheduled observations, leading to the loss of 4 antennas. Observers whose science would be severely compromised by this loss should put a note in their OBSERVE files (under Special Instructions), asking that their observations not be scheduled during 4-station WIDAR tests. As with other restrictions on dynamical files, such a request will eliminate some observing time that might otherwise be suitable, making it less likely that those observations will be dynamically scheduled. Currently we are avoiding WIDAR observations during fixed-scheduled observations and observations already involving more than one subarray, such as observations during single-dish VLBI runs. We hope to complete the critical WIDAR tests by the end of November.