Time Parameters:
Each output record is tagged by a time corresponding to the center of the image exposure time. Begin and end of exposure are given relative the center times.
Epoch
Required by ISTP Standard. Number of milliseconds since 01-Jan-0000. Doesn't mean much to people but computers love it. Many utilities can break this down to dd-mmm-yyyy hh:mm:ss.ccc.
Time_PB5
Required by ISTP Standard. Three-element vector containing year, day of year, and millisecond of day. This is for non-computer types who don't want to decode Epoch.
IMG_MINUS_MSEC
IMG_PLUS_MSEC
These define the time of the observation. Epoch and Time_PB5 are as defined by the project and refer to the _middle_ of the image. Image exposure begins at Epoch - IMG_MINUS_MSEC and ends at Epoch + IMG_PLUS_MSEC. IMG_MINUS_MSEC and IMG_PLUS_MSEC are in milliseconds.
NOMINAL_OUTPUT_PERIOD
This is the requested time between output records, in minutes. Note that the actual time between output records will vary as a function of the operating modes and the quality of the telemetry. A gap condition is declared if a period of time equal to twice NOMINAL_OUTPUT_PERIOD passes without an output record. The cause of the gap is indicated by POST_GAP_FLAG.
Instrument Parameters:
SYSTEM
UVI has two independent detector/electronic systems that share a common optical path.
- +1 = primary system
- -1 = secondary system
SEQ
UVI is capable of storing up to 50 predefined observing sequences (numbered 0 to 49). These sequences define filter, gain, and integration settings. The sequence definitions are not fixed and can be expected to change considerably in the early mission lifetime. It is anticipated that the sequence definitions will become more stable as the mission progresses.
MODE
UVI has three operating modes.
- 1 = Normal
- 2 = Miniframe (Star)
- 3 = Idle
Normal mode produces one 200 x 228 image typically every 4 major frames. Star mode produces multiple miniframe images every major frame. Idle mode produces no image output.
GAIN
UVI has 16 gain settings with 16 being the most sensitive. In addition, a gain setting of 0 indicates the high voltage to the detector is off.
DOOR
The entrance aperture is covered by a door which is closed at launch and before thruster firings to prevent contamination of the internal optics and mechanisms. The door is fitted with a MgF2 window to allow observations with the door closed.
FILTER
The UVI KPGS may output one of five intensity images (one for each filter position). This parameter specifies which filter is used.
1 = shutter (not used for KPGS)
- 1 = shutter (not used for KPGS)
- 2 = OI 1304
- 3 = OI 1356
- 4 = LBH short
- 5 = LBH long
- 6 = solar
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