_                    
                                                         |_|                   
      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  ***                        <)                     
 

HALCA OPERATIONS

The last two weeks have seen the continued testing and check-out of HALCA's Attitude Control System and on-board radio-astronomical system. A major component of the former task is the testing of the Star Trackers. HALCA has two star trackers, one mounted on either side of the satellite. Study of the performance of these CCD cameras during passages through the Van Allen radiation belts is important for determining how long the satellite's gyro recalibration will take after slewing to a new source, and thus, how soon observations of the source can begin.

During the week the satellite was oriented so that it would view the Earth during some part of each orbit as part of the on-going calibration process. The first pointing of the satellite to a (celestial!) radio source is scheduled for early next week, when satellite-only observations of W49N are planned for checking the on-board radio-astronomy system.

Ku BAND TELEMETRY

The first tests of the Ku-band telemetry link between the Usuda tracking station and HALCA were an unqualified success! It had been intended simply to test the one-way link from the satellite to the ground tracking station. As this quickly proved to be successful, the two way link, using a constant up-link frequency, and then an approximate doppler-compensated uplink frequency (to correct for the satellite's motion) was successfully tested. The work planned for several tracking passes was successfully completed in one night!

Over the last two days, Ku link tests have been conducted to the Green Bank and Goldstone tracking stations. Reports from both sites indicate that, despite early teething problems, the tests were mostly successful. (After fixing the teething problems, many bytes ensued...) Further tests are scheduled over the next week, with the tests being extended to the Tidbinbilla tracking station also.

OBSERVATIONS

In-Orbit Checkout (IOC) observing starts with fringe-finding observations in early April. The IOC checks will start at 1.6 GHz, progress to 5 GHz, with the 22 GHz check-out occurring last. Once each band has been checked out and a full imaging test successfully completed, General Observing Time (GOT) observations will commence at that band. The current schedule has 1.6 GHz GOT observing slated for late May, though of course the exact date will depend critically on how smoothly things progress between now and then.

 
 
       Editors: Phil Edwards and Hirax Hirabayashi