_          
                                             |_|         
 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  ***               <)               

MISSION UPDATE

The first series of eclipses of the satellite by the Earth finished on the 24th of April, and since then the satellite team have been re-testing all of the on-board systems. Two way Ku-band links to the satellite resumed on the 3rd of May, with the tracking stations having made full use of the eclipse period to test and upgrade their systems in the light of experiences gained during the period before eclipses started. No fringes have been found from the In-Orbit Checkout observations made at the end of March and beginning of April, however a surprisingly large amount of useful information has been gained on the stability of the satellite/tracking station system by cross-correlating the phase calibration tones on the satellite and ground radio telescopes.

The next round of observations has already started. A 1.6 GHz HALCA-Kashima- Usuda fringe-finding run on a strong continuum source was made on the 7th of May, and correlation will start as soon as the reconstructed orbit and tracking station time corrections file are available. A HALCA-VLBA-phased_VLA fringe- finding observation of a strong continuum source will take place on the 15th of May, and the same array will observe an OH maser source the following week.

FIRST AO PERIOD

At its recent meeting, the VSOP International Science Council (VISC) decided that the first Announcement of Opportunity (AO) period will be extended to the end of 1998. This is in part due to delays experienced in the In-Orbit Checkout, and will mean that the AO period will be closer to the originally planned 17 month duration. This extension will allow a number of sources proposed for observations in early 1997 to be covered in the first AO period as their (u,v) coverage improves in late 1998. Furthermore, starting the second AO period in January 1999 coincides with the beginning of a 4-month scheduling block for most ground arrays, with obvious scheduling efficiencies. The nominal date for the release of the second AO is the 1st of December 1997, and nominal proposal deadline the 1st of March 1998.

PROPOSAL UPDATES

As 18 months has elapsed since proposals for the first AO were submitted additional information, such as improved source coordinates, changed contact e-mail addresses, details of coordinated campaigns, or a more appropriate interval for multi-epochs experiments, may now be available. (Note that basic information such as the number of epochs, sources, or observing band(s) cannot be altered!) Any updates should be e-mailed to submit@vsop.isas.ac.jp . In the next VSOP news we plan to include information on incorporating the actual HALCA orbit into the various space VLBI simulation software packages.

 
       Editors: Phil Edwards and Hirax Hirabayashi