Far Ultraviolet Image - 8 degree full width (228 x 200 pixels)

The UVI field of view is circular with an 8 degree full width. The circular image is stored in IMAGE_DATA as a rectangular array of 228 rows and 200 columns. Consequently, the corners of each image contain non-image data. The non-active corner pixel locations are identified by a corner fill value = -128. The image is oriented such that the direction of decreasing row number points along the spacecraft spin axis. The direction of decreasing column number points to the outboard direction (relative to the spin axis). The orientation is the same for both detectors.

Size

228 200

Spectral range

Ultraviolet

Low wavelength

125

High wavelength

190

Units

nanometers

Bins

Bin	Band name	Low wavelength	High wavelength
1	1304 filter	125	135
2	1356 filter	128	142
3	LBHS filter	135	160
4	LBHL filter	160	190
5	SOLR filter	175	190

Image time.

The time in EPOCH and Time_PB5 refer to the center of the image in IMAGE_DATA. There is an offset of up to 8 major frames between the beginning of the image exposure and the ATC telemetry time stamp. The times shown here are corrected for this and describe the actual time of exposure.

Image time.

The time in EPOCH and Time_PB5 refer to the center of the image in IMAGE_DATA. There is an offset of up to 8 major frames between the beginning of the image exposure and the ATC telemetry time stamp. The times shown here are corrected for this and describe the actual time of exposure.

Size

3

Elements

Index	Name	Units	Valid min	Valid max	Fill value
1	Year	year	1990	2020	-2147483648
2	Day of Year (Jan 1 = Day 1)	day	1	366	-2147483648
3	Elapsed millisecond of day	msec	0	86399000	-2147483648

The start of the image, measured from EPOCH/Time_PB5.

The beginning and ending time of the image is specified in msec relative to the time in EPOCH and Time_PB5 by IMG_MINUS_MSEC and IMG_PLUS_MSEC, respectively.

The end of the image, measured from EPOCH/Time_PB5.

The beginning and ending time of the image is specified in msec relative to the time in EPOCH and Time_PB5 by IMG_MINUS_MSEC and IMG_PLUS_MSEC, respectively.

Explanation of preceding gap.

A gap is defined if the time between records is greater than twice the nominal output time (NOMINAL_OUTPUT_PERIOD). The following values are defined for POST_GAP_FLAG: O = No Gap; 1 = Wrong Mode; 2 = Missing Data; 3 = Noisy Data; 4-9 = undefined; 10 = High voltage not enabled; 11 = gain set to zero; 12 =The first minor frame containing UVI housekeeping was zero filled 13 = Unable to sync with telemetry stream; 14 = No background images were present; 15 = Requested filter setting was not present; 16 = Spacecraft was near perigee pass where no kp's are generated; 17 = Despun platform was pointing away from the earth; 18 = Image data lay outside requested process window (Not used for production); 19 = Unknown. Note that long gaps may be caused by multiple events. POST_GAP_FLAG attempts to represent the most severe event contributing to the gap. Also, since each image frame requires a minimum of 4 major frames (36.8 s) very short values of NOMINAL_OUTPUT_PERIOD on the order of 1 minute may always encounter a gap since the desired images may be several minutes apart. This condition is not trapped and will result in an unknown value for the post gap flag.

Bit-mapped quality indicator.

QUALITY_FLAG is a bit-mapped flag in which each bit corresponds to a single quality condition. The most significant bit (minus sign) is not used. Consequently up to 31 different quality conditions can be simultaneously flagged. The flags are ordered in severity with increasing bit position. The following _hexadecimal_ values have been defined for QUALITY_FLAG: 0 = No errors or quality conditions; 1 = an error occurred writing an SFDU comment; 2 = image time was outside of selected processing window; 4 = some level zero minor frames had fill values; 8 = some level zero minor frames had sync errors; 10 = the image single frame integration period could not be determined due to bad telemetry (assumed to be 4 major frames); 20 = the despun platform was in motion or had not settled down from a motion; 40 = the pointing calculations have not been validated or may be unreliable; 80 = the time flags for this image may be unreliable; 100 = there was an error decode star mode data; 200 =some major frames were missing but an image could be partially reconstructed; 400 = calibration data is missing or otherwise invalid; 800 = a background image could not be found; 1000 = the requested output image could not be found.

Nominal time between output records.

This is the nominal time between output records. The actual output spacing will vary depending on the nature of the observing sequences being run.

Operating system.

UVI has two independent systems. PRIMARY: +1, SECONDARY: -1

Predefined sequence of observations. Definitions will change over mission.

Instrument operating mode.

(1=Normal, 2=Star, 3=Idle) Normal mode produces one 200 x 228 image every 4 major frames. Star mode produces multiple miniframe images every major frame. Idle mode produces no image output.

Detector gain setting

0=off, 16=highest sensitivity

Aperture door position

(OPEN: +1, CLOSED: -1) MgF2 window in door allows viewing when closed.

Spacecraft Position in GCI, 3 comp.

Copied from S/C orbit file.

Size

3

Elements

Index	Name	Units	Valid min	Valid max	Fill value
1	X (GCI)		-60000.0	60000.0	-1.0E31
2	Y (GCI)		-60000.0	60000.0	-1.0E31
3	Z (GCI)		-60000.0	60000.0	-1.0E31

Spacecraft Attitude in GCI, 3 comp.

Calculated from S/C attitude file.

Size

3

Elements

Index	Name	Units	Valid min	Valid max	Fill value
1	X (GCI)		-1.0	1.0	-1.0E31
2	Y (GCI)		-1.0	1.0	-1.0E31
3	Z (GCI)		-1.0	1.0	-1.0E31

Sun Position in GCI, 3 comp.

Vector pointing to sun.

Size

3

Elements

Index	Name	Units	Valid min	Valid max	Fill value
1	X (GCI)		-1.6E8	1.6E8	-1.0E31
2	Y (GCI)		-1.6E8	1.6E8	-1.0E31
3	Z (GCI)		-1.6E8	1.6E8	-1.0E31

Unit vector along field of view.

GCI_LOOK_DIR is a unit vector in GCI coordinates pointing from the spacecraft along the center of the UVI line of sight. An external utility can be used to calculate latitude and longitude for any pixel of the UVI image.The pointing utility can be found on the UVI WWW home page

Size

3

Elements

Index	Name	Units	Valid min	Valid max	Fill value
1	X (GCI)		-1.0	1.0	-1.0E31
2	Y (GCI)		-1.0	1.0	-1.0E31
3	Z (GCI)		-1.0	1.0	-1.0E31

Offset angle of despun platform from nadir.

Positive in direction opposite of spacecraft rotation.

Filter selection.

1304=2, 1356=3, LBHS=4, LBHL=5, SOLR=6

Geodetic latitude for IMAGE_DATA (23 x 20 pixels)

Sparse matrices (every 10 pixels) of latitude and longitude are given in GEODETIC_LAT and GEODETIC_LONG, respectively. Latitude & longitude are given in geodetic coordinates (determined from the normal to the assumed surface of the earth [assumed to be an ellipsoid of revolution]) and not in geocentric coordinates (determined relative to the center of the earth).

Size

23 20

Geodetic longitude for IMAGE_DATA (23 x 20 pixels)

Sparse matrices (every 10 pixels) of latitude and longitude are given in GEODETIC_LAT and GEODETIC_LONG, respectively. Latitude & longitude are given in geodetic coordinates (determined from the normal to the assumed surface of the earth [assumed to be an ellipsoid of revolution]) and not in geocentric coordinates (determined relative to the center of the earth).

Size

23 20

Row Number

Size

23

Column Number

Size

20

Row Number

Size

228

Column Number

Size

20