SSOC TOHBAN REPORT FOR WEEK 14
                            (4 - 10 April 1994)

                          Prepared on  11 April 1994
                     T. Takano and L. van Driel-Gesztelyi

1 SOLAR ACTIVITY

1.1 The Sun was quiet again last week with only two events exceeding
    the GOES B.20 level. The largest flare was a B2.8 event.


2 STANDARD OPERATIONS

2.1 SXT table uploads

    Date(UT)      Pass            ID
    --------      ----            --
    Apr.05        940405-0824     940405 ARS1 DKCAL
    Apr.06        940406-0515     940406 P2 CCD BAKEOUT
    Apr.07        940407-0619     940407 P3 CCD BAKEOUT2
    Apr.08        940408-0620     940408 P4 ARS1 STD+LONG
    Apr.09        940409-0413     940409 P2 ARS1 STD+LONG

2.2 STT Timer Set - Executed on 9 April.  The eclipse timer was stopped
    on 2 April for the Canopus eclipse, which lasted until 9 April.
    Next STT Timer Set should be executed on 12 April.

2.3 QUIET RATE MEDIUM was inserted in SAA's wherever possible.

3 SPECIAL OPERATIONS - CCD Bakeout was executed starting on 6 April in pass
     2 ending on 8 April in pass 4. During the Bakeout we deleted SXT
     campaign observations.
     Due to the high temperature of the CCD, image quality deteriorated during
     this operation.

4 ERRORS AND PROBLEMS

4.1 Instrument Errors - There was a BCS error during the week.
    It occurred on 8 April during the 5th pass and was corrected on 9 April
    during the 2nd pass.

4.2 On Saturday (9 Apr) a strange filamentary network-like structure appeared
    in the SXT images taken with the Al.1 filter. It was first seen at
    08:08:45 UT and created quite a tension around. A closer examination of
    the event by Hara-san shows that the filamentary structure might be
    connected to some scattered light originating from the pinhole in the thin
    Al filter.
    Greg Slater noted that a similar pattern in the same location occurred
    consistently in thin Aluminum images until very recently.

4.3 Due to the coming Golden Week holiday the new orbital elements will be
    delivered to ISAS slightly later for the period of 25 April - 9 May.
    JPL has been informed about the expected delay.

4.4 The transmission of reformated data was stopped on 8 April due to some
    Sirius problem. Since the error occurred on late Friday afternoon the
    personnel responsible for recovery did not act. Therefore we were not able
    to receive reformated data till Monday for 2.5 days. This unfortunate
    situation should be avoided in the future if possible.

4.5 On Saturday when using op_first_guess for the preparation of the OP table
    for Monday (11 April), the transmission of the file to mainframe which is
    normally done by the program, did not work. Later we successfully ftp-d the 
    file to mainframe2, but there were still some problems with copying the file
    into the proper directory. Eventually we prepared the OP table (#19) 
    manually.

5 DSN COMMUNICATIONS

5.1 We requested 7 additional passes for week15, but the request was turned
    down by the DSN schedulers due to DSS and launch support.

6 HIKITSUGI

6.1 Yohkoh/Asca Pass Conflicts - As the Yohkoh and Asca orbits become
    closer in phase the two satellites will increasingly be competing for
    the same set of passes. On Wednesday (6 Apr) we negotiated with the
    Asuka representatives which passes should we/they use during Week15.
    On Thursday  (7 Apr) the end of Yohkoh's 5th pass occurred 15 minutes
    before the beginning of the Asca 1st pass. To avoid interference we
    finished communications with Yohkoh 3.5 minutes earlier than usual.
    Yohkoh SSOC tohbans should meet every week with Nagase-san (Asca,
    room 1611, ext. 2611) to carry out similar negotiations.

6.2 Tohbans for W15 (Apr 11-17):

    SSOC: Kato_Y and Hanaoka
    KSC:  Shibata and Masuda