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Data Set Overview:
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The data from the Rosetta Navigation Camera (NavCam) was extracted by
Bernhard Geiger; the data set was constructed and submitted by Maud
Barthelemy on behalf of the Planetary Science Archives (PSA).

The data have been observed and measured from 28th July 2015 to 25th
Aug 2015. The frequency of the navigation slots was of one image
every five hours, with interruption by manoeuvres. 131 navigation
images, 303 context images and 5 calibration images were taken. This
makes a total of 439 images.

One navigation image was lost due to bad weather. One navigation image
was taken with lost rows.
One context image was not acquired due to the recovery of an anomaly.
Three context images were taken with lost rows.

The orbiter was executing far fly-by arcs in the terminator plane. The
distance increased from 180km to 330km due to Star tracker issues.
A further increase of the distance to 420km was done at the transition
to lower phase angles.

All images in this data set are raw and uncalibrated data taken using
the imaging mode. The data set contains images resolved using both
NavCams onboard the Rosetta S/C and the DATA directory is organised
to reflect this with two sub directories:
 - CAM1
 - CAM2
CAM2 directory is only present if CAM2 observations are done.
After hibernation exit CAM2 was only switched on to confirm its health
status in a check-out. During the comet escort phase CAM2 will only be
used in the case of a failure of the nominal camera CAM1.

For each image, the user can also find the FITS format of the
observation.

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Filename Convention:
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The filenaming convention for all data levels is given by:

           __.
              ROS     CAM1    YYYYMMDDThhmmss       IMG
                      CAM2                          LBL
                                                   (JPG)

Examples:
        ROS_CAM1_20140223T081016.IMG
        ROS_CAM1_20140223T081016.LBL
        ROS_CAM1_20140223T081016F.FIT
        ROS_CAM1_20140223T081016F.LBL
       (ROS_CAM1_20140223T081016.JPG)
        ROS_CAM2_20140223T094017.IMG
        ROS_CAM2_20140223T094017.LBL
        ROS_CAM2_20140223T094017F.FIT
        ROS_CAM2_20140223T094017F.LBL
       (ROS_CAM2_20140223T094017.JPG)

(In the case of the BROWSE directory)

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Geometry Information - Coordinate System:
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The label files include the following geometric variables:
- SC SUN POSITION VECTOR: The vector from the spacecraft to the Sun
  in equatorial J2000 inertial frame.
- SC TARGET POSITION VECTOR: The vector from the spacecraft to the
  centre of the comet nucleus in equatorial J2000 inertial frame.
- SC TARGET VELOCITY VECTOR: The spacecraft to comet nucleus velocity
  vector in in equatorial J2000 inertial frame.
- TARGET CENTER DISTANCE: The distance between the spacecraft and the
  comet nucleus centre. (Note that also for checkout and stellar
  calibration images the comet nucleus distance is given here.)
- SUB SPACECRAFT LATITUDE and SUB SPACECRAFT LONGITUDE: The latitude
and longitude of the sub-spacecraft point derived from the Flight
Dynamics body-fixed reference frame implicitly specified by the
information provided in the comet attitude file CATT.
- RIGHT ASCENSION and DECLINATION: Right Ascension and Declination of
the camera boresight direction in equatorial J2000 inertial frame.
- CELESTIAL NORTH CLOCK ANGLE: The direction of celestial north at the
  center of the image - measured from the upward direction,
  clockwise to the direction toward celestial north.
- SOLAR ELONGATION: The angle between the line of sight of observation
  and the direction of the Sun.
All geometric values are calculated for the time t = IMAGE TIME
(and not START TIME).

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All data have been validated by
                ESA and found as expected. Any exceptions are noted by
                the DATA_QUALITY field in the label files.