Below are definitions for the limited selection of keywords from the PDS labels which are shown on each of the browse pages. (A complete listing of the definitions of all the keywords included in the PDS labels is available in Appendix A of the Mars Pathfinder IMP EDR CD-ROM SIS.)

Azimuth Motor Clicks

The number of motor step counts the camera rotated in the horizontal direction from a low hard stop. Since each step count is 0.553 degrees, the approximate azimuthal position of the camera can be derived from this value.

Elevation Motor Clicks

The number of motor step counts the camera rottated in the vertical direction from the low hard stop. Since each step count is 0.553 degrees, the approximate elevational position of the camera can be derived from this value.

Exposure Duration

The time interval between the opening and closing of an instrument aperture. The IMP camera does not have a shutter in the traditional sense, so for MPF this value is the integration time for manual and auto exposure, measured in milliseconds.

Filter Name

The name of the instrument filter through which the image was acquired. The numbers refer to the effective wavelength in nanometers of the filter for the left (L) or right (R) eye.

Filter Number	Filter Name	Application
0	L440_R440	Stereo, Geology
1	L450_R670	Solar
2	L885_R947	Solar
3	L925_R935	Solar
4	L935_R990	Solar
5	L670_R670	Stereo, Geology
6	L800_R750	Geology
7	L860_R-DIOPTER	Geology
8	L900_R600	Geology
9	L930_R530	Stereo, Ranging, Geology
10	L1000_R480	Geology
11	L965_R965	Stereo, Ranging, Geology

Filter Number

The number of the instrument filter through which the image was acquired. (See Filter Name for details.)

Frame ID

Provides an identification for a particular instrument frame. Valid values are LEFT, RIGHT, BOTH, and LEFT_HALF. The IMP camera nominally operates in a mode where both the left and right images are exposed and transferred into the frame buffer simultaneously. Then either the RIGHT, LEFT, or BOTH frames are transmitted. For even shorter shutter times, the left image only may be transferred into the frame buffer (LEFT_HALF). The presence of BOTH in this field indicates that the image should be part of a stereo pair.

Image Time

Date and time at which the image was acquired, recorded in UTC system format. Shown as: "YYYY-MM-DDThh:mm:ss.fffZ".

Instrument Azimuth

One of two angular measurements of the pointing direction of the IMP camera. (Note: this is the boresight pointing, not the pointing of an individiual camera eye.) The azimuth is measured positively in the clockwise direction (as viewed from above). It is measured parallel to the x-y plane of the IMP coordinate frame, with the Y_IMP axis of the frame defining the zero reference direction.

Instrument Compression Ratio

The ratio of the size, in bytes, of the original uncompressed data file to its compressed form.

Instrument Deployment State

Indicates whether or not the IMP camera had been deployed to the end of its 80 cm mast at the time the image was acquired.

Instrument Elevation

One of two angular measurements of the pointing direction of the IMP camera. (Note: this is the boresight pointing, not the pointing of an individual camera eye.) The elevation is measured positively upwards from the plane which is co-planar with the x-y plane of the IMP coordinate frame and which intersects the elevation axis around which the camera rotates.

MPF Local Time

Local time at the lander site on the surface of Mars, meaured in local hours, minutes, and seconds, from midnight. Local hours are defined as one twenty-fourth of a local solar day. Local minutes are one sixtieth of a local hour, and local seconds are one sixtieth of a local minute. Format is "hh:mm:ss".

Observation Name

The purpose of an observation or sequence of commands.

Planet Day Number

The Martian day (ie., sidereal day, equal to a rotation of 360 degrees) on which the image was taken. Starts with 1 as the first day of surface operations, the day the spacecraft landed. Negative values refer to pre-surface images.

Product Id

A permanent, unique identifier assigned to each data product. For the IMP EDRs, this is constructed from the words "IMP_EDR" followed by the spacecraft clock start count, followed by the image observation type, followed by the image id.

Solar Azimuth

One of two angular measurements indicating the position of the Sun as measured from the lander. The azimuth is measured positively in the clockwise direction (as viewed from above) with the meridian passing through the positive spin axis of the planet (ie., the north pole) defining the zero reference.

Solar Elevation

One of two angular measurements indicating the position of the Sun as measured from the lander. The elevation is measured up from the plane which is perpendicular to the line passing between the lander and the center of Mars and which intersects the lander.

Surface Based Instrument Azimuth

One of two angular measurements of the pointing direction of the IMP camera. (Note: this is the boresight pointing, not the pointing of an individual camera eye.) The azimuth is measured positively in the clockwise direction (as viewed from above) with the meridian passing through the positive spin axis ("north pole") defining the zero reference. It is measured in a plane perpendicular to the line between the lander and the center of Mars. The surface based instrument azimuth is derived from the instrument pointing and spacecraft orientation. It is co-linear with the Mars Surface Fixed coordinate system, but the origin is not co-incident with that system.

Note that the surface based instrument azimuth describes the pointing direction of the camera rather than the angular coordinates of the target of an observation. Thus, this parameter cannot be used to uniquely describe the position of a viewed object across changes in the position of the camera (for example, when it went from STOWED to DEPLOYED).

Surface Based Instrument Elevation

One of two angular measurements of the pointing direction of the IMP camera. (Note: this is the boresight pointing, not the pointing of an individual camera eye.) The elevation is measured positively upwards from the plane perpendicular to the line between the lander and the center of Mars. It is derived from the instrument pointing and spacecraft orientation. It is co-linear with the Mars Surface Fixed coordinate system, but the origin is not co-incident with that system.

Note that the surface based instrument elevation describes the pointing direction of the camera rather than the angular coordinates of the target of an observation. Thus, this parameter cannot be used to uniquely describe the position of a viewed object across changes in the position of the camera (for example, when it went from STOWED to DEPLOYED).

Target Name

Identifies the intended target of an observation. Can be either a planetary body or a physical object. Valid values are ALTAIR, APXSSITE, ARCTURUS, CALIMG, DEIMOS, LANDER, MAG(netic targets), MARS, PHOBOS, ROVER, SKY, SUN, VEGA, and WINDSOCK. (Note that ALTAIR, ARCTURUS, and VEGA are all stored in the STAR directory.) This list does not include feature names like "Barnacle Bill" and "Yogi". For details on feature names, please consult the gazetteer on this CD.