Odyssey THEMIS VIS Calibrated Data Record (VISRDR)
VISRDR – Visible Calibrated Data Record
Instrument: Thermal Emission Imaging System
PDS Data Set ID: ODY-M-THM-3-VISRDR-V1.0 (in data directories odtvr1_****) DOI: 10.17189/1520384
For more information about THEMIS VISRDR products, see the Data Set Catalog File.
For more information about all THEMIS products, see the THEMIS Product SIS.
The Thermal Emission Imaging System (THEMIS) Calibrated Visible Record (VISRDR) data products contain the calibrated visible observations. Calibration includes 8-bit to 11-bit decoding, removal of instrumental effects, and conversion to spectral radiance (Wcm2str-1μm-1). The instrumental effects considered are detector bias, register stray light, phososite stray light, and variations in pixel sensitivity (i.e., “flatfield” effects). Spectral radiance is calculated from the exposure time and from the decoded, instrumentally corrected Digital Number (DN) levels of the raw image, using conversion factors derived from pre-flight tests.
For VIS data, the DN values represent relative radiance values which are converted to scene radiance by: (1) correcting for the CCD dark current with nighttime Mars images; and (2) converting signal to radiance using the instrument response function determined prior to launch. Both of the above VIS calibration steps are functions of the exposure setting of the camera, which is one of the defined image parameters available in the image label.
THEMIS VIS images are acquired in framelets of size 1024 pixels crosstrack by 192 lines downtrack. The number of framelets is determined by the number of bands selected (five available, enumerated in the table below) and the spatial resolution selected (three summing modes available). If spatial summing is not applied, either a single-band, 19-framelet (65.6 km) image or a 5-band, 3-framelet (10.3 km) image can be collected.
THEMIS available visible bands:
|
Band Numbers |
Center (μm) |
FWHM* (μm) |
|
V-1 |
0.425 |
0.049 |
|
V-2 |
0.540 |
0.051 |
|
V-3 |
0.654 |
0.053 |
|
V-4 |
0.749 |
0.053 |
|
V-5 |
0.860 |
0.045 |
*Full-width, Half-maximum
THEMIS VISRDR products have the following file names:
VnnnnnsssRDR.QUB
where:
nnnnn = 5-digit mission orbit when the image was collected
sss = 3-digit image sequence number indicating the order that images were collected each orbit (001 = first image collected in the nnnnn orbit)
In ODE, VISRDR products have the following Product IDs:
VNNNNNSSSRDR