During the next year, approximately 30% of the VLBA's scientific observing time has been allocated for co-observations with the first dedicated space VLBI mission, VSOP/HALCA. Proposals for co-observations with VSOP are submitted directly to the VSOP mission rather than to the NRAO; proposal information can be found in the ``Announcement of Opportunity'' (AO) page, available on the WWW from the VSOP home page via URL
The AO itself, proposal cover sheets, a proposer's guide describing (among other things) the sensitivity of observations using the VLBA and VSOP, and simulation software packages are available via the AO page.
VLBA projects using VSOP have some different characteristics from other VLBA projects. First, the observing schedules for the VLBA are prepared by the VSOP Science Operations Group in order to take account of the constraints on the spacecraft observations, and need not be generated by the investigators. Second, the spacecraft frequency reference is provided in series by several of a total of five tracking stations, and the wideband spacecraft data are recorded separately on tapes at each of these tracking stations. This makes the process of correlation, which requires multiple wideband recordings for the spacecraft, as well as multiple clock corrections and the spacecraft ephemeris, considerably more complex. Finally, although the standard VLBA calibration data are available as discussed in Sections 14 and 15, the spacecraft data calibration and fringe-fitting is considerably more complex, owing to (1) the inability to observe fringe-finders for each project; (2) the rapid change in projected baseline length during the spacecraft orbit; and (3) the clock jumps that will occur at each tracking-station handoff. For further information about processing of VLBA data taken together with an orbiting element, investigators should contact one of the ``space VLBIers'' identified in Section 26.4.