_                   
                                                         |_|                  
      V   V   SSSS   OOO   PPPP                 \__      |_|      __/         
      V   V  S      O   O  P   P                   --____/ \____--            
      V   V   SSS   O   O  PPPP                    _ _ _ --- _ _ _            
       V V       S  O   O  P                      |_|_|_|  @|_|_|_|           
        V    SSSS    OOO   P                             o-o                  
                                                          /                   
      ***  N    E    W    S  ***                        <)                    

THE THIRD VSOP ANNOUNCEMENT OF OPPORTUNITY

The Third VSOP Announcement of Opportunity, with a proposal deadline of October 1, 1999, will be released on September 1. Future calls for VSOP proposals will occur three times per year, coordinated with the calls for proposals by the ground VLBI networks, with subsequent due dates on 1 February, 1 June, etc. This is a departure from the two previous VSOP AOs, which have had durations in excess of a year.

A number of outstanding AO1 and AO2 observations that were postponed while HALCA was out of action at the end of last year have already been scheduled for the first half of next year, but there are gaps left to be filled by sources from successful AO3 proposals. HALCA's orbital elements precess with periods of the order of a year, so AO3 proposals are particularly encouraged for sources in those regions of sky allowing good (u,v) coverage during the first half of next year (see below).

As with the previous AOs, proposals for VSOP observations must be submitted to ISAS and will be ranked by the VSOP Science Review Committee (SRC). The SRC review will occur around December 1 and PI's will be notified of the proposal status shortly thereafter. Observations from this deadline could be observed as early as mid-January, 2000.

Detailed specification of a ground array by the PI is not needed. Each ground array or telescope will allocate a certain amount of observing time to VSOP. Then, as before, the VSOP scheduler will use the allocations from the ground networks/observatories to schedule VSOP experiments following the SRC rankings and instructions. The PI should include relevant information in the proposal regarding special observational or correlation requirements such as spectral line, pulsar, polarization, weak source, or time-critical observations.

The information needed to submit a VSOP proposal for the October 1, 1999 deadline will be available from the VSOP web page (/astro/halca) in early September. This includes the Third VSOP Announcement of Opportunity, AO3 Cover Sheets and Proposer's Guide, a listing of all successfully observed and currently scheduled AO1 and AO2 observations between July 1997 and April 2000, and monthly all-sky (u,v)-coverage plots for 2000 and 2001 using HALCA with illustrative ground arrays. These plots will be helpful in determining when observations of a particular source are most suitable. Details of the Space VLBI Simulation Packages will also be available for more detailed analyses of (u,v) coverages. Those already familiar with VSOP observing may not need to review all of this material. Any questions by proposers can be e-mailed to the VSOP help desk (vsop_help@vsop.isas.ac.jp).

The cover sheets and scientific justification must reach ISAS no later than October 1, 1999. The cover sheets (Latex file) must be submitted by e-mail. The scientific justification can be sent by e-mail in postscript form or by surface mail. Submission one or two days before the deadline is recommended for postscript files to ensure there are no problems with printing the proposal.

                Editors: Phil Edwards and Hirax Hirabayashi