PDS_VERSION_ID                 = PDS3
RECORD_TYPE                    = STREAM
RELEASE_ID                     = 0001
REVISION_ID                    = 0000
DATA_SET_ID                    = "VEX-V-VIRTIS-2/3-EXT4-V1.0"
PRODUCT_CREATION_TIME          = 2008-07-18T00:00:00
PRODUCT_ID                     = "CK_HEADER.TXT"

OBJECT                        = TEXT
   PUBLICATION_DATE            = 2008-07-18
   NOTE                        = "VIRTIS CK headers"
END_OBJECT                     = TEXT

END


The camera kernels of the VIRTIS instrument contain the optical angles of the
scanning mirror orientation, which correspond to the actual direction of
pointing of each acquisition with respect to the instrument's  boresight. This
angle is applicable only for the Mapping channel of the instrument (VIRTIS-M),
both for infrared and visible data. The High-Resolution channel (VIRTIS-H) has
different optics and thus the scanning mirror angles are not applicable.

+Y side view:
-------------------------------------

                           VIRTIS-M
                           boresight

                               ^  +Z
      |                         |                         ||
      |  VIRTIS_M_SCAN  ^       |                         ||
      |     boresight    \      |                         ||
Base  |                   \  +  |                         || VIRTIS
Plate |                    \   _|                         || RADIATOR
      |                     \<' |                         ||
      |                      \  |                         ||
Space |                       \ |                         ||  Deep
Craft |                        \|                         ||  Space
      |     +X <----------------o------------------ -X    ||
      |                      \_____/                      ||
      |                   Scanning_mirror                 ||

Reference axis is that of the instrument as defined in the Frames kernel.
 +Z is the VIRTIS_M boresight
 -X is perpendicular to the instrument radiator towards space
 +Y axis goes outside the paper (nominally aligned with the +Y axis of the 
    spacecraft)

The scanning orientation is given in units of radians as the euler angle 
from the VIRTIS-M boresight (+Z axis) to the VIRTIS_M_SCAN  boresight. 
Positive angles imply pointing towards the +X axis.  Scanning of the mirror 
goes nominally from from positive to  negative euler angles, that is, from 
+X to -X.

The information of the mirror orientation is obtained for each science
acquisition inside the corresponding housekeeping telemetry packets
(APID 820), in the form of cosine and sine of the internal electrical
angle. These electrical angle values are converted into optical angle,
expressed in radians, and then written in binary format inside the
camera kernel, together with the corresponding time period given as
Start and Stop SCET (Spacecraft Clock Elapsed Time).

The camera kernels are periodically produced for predefined intervals
of time. The duration of these intervals may vary although it is
generally established for periods of four weeks, which correspond to
the duration of one Medium Term Planning (MTP) cycle.

Filenaming convention: VEX_VIRTIS_YYMMDD_yymmdd_VV.BC, where:

- YYMMDD is the start date
- yymmdd is the stop date
- VV is a version number, starting from 01

The kernels are generated with no time interval tables to reduce file
size. (Spice option INCLUDE_INTERVAL_TABLE = 'NO')

The camera kernels are produced by the VIRTIS-M team, based at the
Istituto Nazionale Astrofisica in Rome, Italy, under the supervision
of Dr. Giuseppe Piccioni (VIRTIS co-PI).

Contact Information
========================================================================

   Giuseppe Piccioni, VIRTIS co-Principal Investigator, IASF-INAF
   +39-0649934445, Giuseppe.Piccioni@iasf-roma.inaf.it

   Alejandro Cardesin, VIRTIS VEX Data Handling Engineer, IASF-INAF
   +39-0649934210, Alejandro.Cardesin@iasf-roma.inaf.it

   Stephane Erard, VIRTIS Data Archive Manager, Obs. Paris Meudon
   +33-145077819, Stephane.Erard@obspm.fr

   Boris Semenov, SPICE support, NAIF/JPL
   +1-818-354-3869, boris.semenov@jpl.nasa.gov

========================================================================