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TRMM VIRS Scan Status
Name Format Values Description
Missing 1-byte integer Value and meaning Indicates whether information is contained in the scan.
Validity 1-byte integer Bit and meaning A summary of status modes.
QAC 1-byte integer 0: No decoding error occurred. The Quality and Accounting Capsule of the Science packet as it appears in Level-0 data.
1-byte integer Bit and Meaning A summary of geolocation quality in the scan.
Data Quality[5] 5 x 1-byte integer   The quality of Channel Data for a given channel on given scan line is the percentage of pixels whose value are within the acceptable range listed in the metadata.
Orbital Number
4-byte float   The orbit number and fractional part of the orbit at Scan Time. The orbit fraction part is calculated as:
(Time-Orbit Start Time)/(Orbit End Time-Orbit Start Time)
Current Spacecraft
1-byte integer Value and Meaning Current spacecraft orientation.
Current ACS Mode 1-byte integer Value and Meaning Current ACS mode.
Yaw Update Status 1-byte integer 0: Inaccurate
1: Indeterminate
2: Accurate
Yaw update Status.
VIRS Instrument Status 1-byte integer Bit and Meaning VIRS instrument status.
VIRS mode 1-byte integer Bit and Meaning VIRS mode.
VIRS Abnormal Conditions 1-byte integer Bit and Meaning Bit 0 is the most significant bit.

Value and Meaning of Missing
Value Meaning
0 Scan data elements contain information.
1 Scan was missing in the telemetry data.
2 Scan data contain no elements with rain.

Bit and Meaning of Validity
Bit Meaning if bit=1
0 Spare (always 0)
1 Non routine spacecraft orientation (2 or 3)
2 Non routine RAC mode (other than 4)
3 Non routine yaw update status (0 or 1)
4 Non routine instrument status (other than 1)
5 Non routine QAC (non-zero)
6 VIRS in non-mission mode (non-zero)
7 VIRS condition is abnormal (non-zero)

Bit and Meaning of Geolocation Quality
Bit Meaning if bit=1
0 Grossly bad geolocation results:
* Spacecraft position vector magnitude outside range: pre-boost 6720 to 6740 km, and post-boost 6773 to 6793 km.
* Z component of midpoint of scan outside range -4100 to 4100 km.
* Distance from S/C to midpoint of scan outside range: pre-boost 340 to 360 km, and post-boost 393 to 413 km.
1 Unexpectedly large scan to scan jumps in geolocated positions in along and cross track directions for first, middle, and last pixels in each scan. Allowed duration from nominal jump in along track motion = 0.06 km (first pixel), 0.04 km (middle pixel), and 0.06 km (last pixel). Allowed duration from nominal jump in cross track motion = 0.05 km (first pixel), 0.04 km (middle pixel), and 0.05 km (last pixel). Bit set in normal mode only.
2 Scan to scan jumps in yaw, pitch, and roll exceed maximum values. Values are : yaw = 0.0001 radians; pitch = 0.0001 radians; roll = 0.0001 radians. Bit set in normal control mode only.
3 In normal mode, yaw outside range (-0.003, 0.003) radians; pitch outside range (-0.007, 0.007) radians; roll outside range (-0.007, 0.007).
4 Satellite undergoing maneuvers during which geolocation will be less accurate.
5 Questionable ephemeris quality (including use of predicted Ephemeris for quicklook) or questionable UTCF quality.
6 Geolocation calculations failed (fill values inserted in the per pixel geolocation products, but not in metadata).
7 Missing attitude data. ACS data gap larger than 20 seconds.

Bit and Meaning of Data Quality
Bit Meaning if bit=1
0 Missing
5 Geolocation quality is not normal
6 Validity is not normal
Note: Unless this is 0 (normal), the scan data are
meaningless to higher processing. Bit 0 is the
least significant bit (i.e., if bit i=1 and other
bit = 0, the unsigned integer value is 2**i).

Value and Meaning of
Current Spacecraft Orientation
Value Meaning
0 +x forward
1 -x forward
2 -y forward
3 Inertial -- CERES Calibration
4 Unknown Orientation

Value and Meaning of
Current ACS Mode
Value Meaning
0 Standby
1 Sun Acquire
2 Earth Acquire
3 Yaw Acquire
4 Nominal
5 Yaw Maneuver
6 Delta-H (Thruster)
7 Delta-V (Thruster)
8 CERES Calibration

Value and Meaning of
VIRS Instrument Status
Value Meaning
0 Day (no calibration occurring)
1 Night
2 Monitor Scan Stability
3 Day with Calibration

Value and Meaning of
Value Meaning
0 Missing Mode
1 Safehold Mode
2 Outgas Mode
3 Activation Mode

Value and Meaning of
VIRS Abnormal Conditions

Bit Value Meaning
0 0
Scan phase error
1 0
Selftest error
2 0
Thermal data missing
3 0
Moon in space view
4 0
H/K data drop-out suspected
5 0
SV counts for channel 4 or 5 great than L1B01_MIN_DNSV
6 0 Not used
7 0 Not used
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Last updated: Sep 09, 2009 02:26 PM ET