Ginga Operation Daily Reports (Feb. 1987 - Oct. 1991)
These are the Ginga satellite daily operation reports documented at Kagoshima Space Center (KSC), where the commands were up-linked and the telemetry was down-linked. Usually, two or more scientists were regularly stationed at KSC, in addition to the satellite operating engineers. These scientists (signed on the report) wrote the daily reports showing the observation target (typically one target per day), satellite attitudes (Euler angles), and the commands sent to the satellite, etc.
These operation reports were often helpful in analyzing the Ginga data. A few examples are shown below:
(1) In Ginga, the direct attitude information was obtained only when the star tracker (STT) was occasionally put into the mapping (MAP) mode.
The attitude solution was calculated on-ground based on the STT MAP data. Attitude fine-tuning operation was often made by the scientists during the ground contact at KSC. The observation report tells when the STT MAP data were taken, and the attitude fine-tuning operation was made.
Being a non-imaging detector, Ginga LAC could not tell where the target locates in the collimator FOV.
Knowing when the STT MAP data was acquired and when the attitude was fine-tuned, we can distinguish whether the apparent intensity variation is artificial or intrinsic to the target.
(2) Ginga often performed micro maneuvering operations during the ground contacts to compensate for the above-mentioned attitude shift.
Also, as a non-imaging detector, intentional slew operations were made to determine the location of the celestial objects.
The operational reports tell what kind of maneuver/slew operations were performed for which purposes. Thus, the data analysis will be possible after understanding the intention of these attitude controls.
(3) In Ginga, all the data were quickly looked at KSC by scientists, and various scientific information was recorded in the operation report, such as (unexpected) brightness of the objects, detection of X-ray bursts, etc.
In some cases, there may be a message note by the scientists saying that "the observation mode has been changed", "be careful when analyzing data", etc.
In the Ginga proportional counter, the counts for each energy channel were added by a non-reset counter. When observing a bright object, the counters will turn around, and the counts will seemingly become smaller. If you are not careful, you may not notice, but the operation report is certainly helpful to understand the data.
- (4) If there was a data loss due to such events as an operational error or ground system trouble, they are recorded in the operation report. When data analysts find an unusual data gap, the operation report helps understand its origin.