ISIS 3 Application Documentation
Corrects Voyager 1 Io images from plasma torus irradiation
Description
Removes parabolic (top to bottom) additive error from Voyager
800 x 800 frames.
Calculate the DN offset values for each line to correct additional dark current
buildup on the vidicon detectors on Voyager 1 during a 15 hour passage through
the Io plasma torus. The additive error increased from top to bottom of each
frame and is directly related to the spacecraft event time. Three
two-dimensional [DN offset/Spacecraft event] plots (ICARUS 73,385-426(1988)
Global Color and Albedo Variations on IO, by Alfred S. McEwen) reveal the DN
offset values based on hour by hour event times, one for top of the frame,
middle and bottom.
Full 16 hour points have been identified of each plot and loaded into
three arrays. The event time is given to this routine in GMT hour, minutes
and seconds. The arrays are referenced by the whole integer hour passed.
Two points are identified by x1 = hour and y1 = array(hour); x2 = hour + 1
and y2 = array(hour + 1); where x = event time and y = * DN value. The
hour, minute and seconds of the event time are also converted to a real
value and then all is passed on to a routine which will perform a linear
interpolation between the two points and return the associated DN value
for the real event time.
This program is meant to be run after voycal has been
run on the image, as it provides additional corrections for a specific
time period.
Categories
Applications
History
Mackenzie Boyd | 2010-09-08 |
Original version - Converted from Isis2
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Parameter Groups
Files
Name
|
Description
|
FROM |
Input cube, must be a calibrated Voyager 1 cube
|
TO |
Output cube
|
|
Files:
FROM
Description
The input cube which must be Voyager 1, calibrated, and within the
correct time range, of Io.
Type
| cube |
File Mode
| input |
Filter
|
*.cub
|
Files:
TO
Description
A further calibrated cube corrected for plasma torus irradiation near
the moon Io.
Type
| cube |
File Mode
| output |
Pixel Type
| real |
Filter
|
*.cub
|