Description of EPOCh Earth science data - file nomenclature summary:

MRI: Medium Resolution Visible (Earth) Imaging [750nm filter]

A typical observation name (rad) is:     mv08031900_1000006_001_r.fit

Here:
   mv      = MEDIUM RESOLUTION INSTRUMENT VISIBLE (CCD)
   080319  = observation date (UT) 
   00      = observation midpoint hour (UT)
   1000006 = exposure ID
             "06" is a running observation number. Because the same imaging 
             sequence was executed for each of the three Earth visits, the 
             same exposure IDs were usually repeated.)
   001     = image number (single per exposure)
   rr      = radrev data (calibrated radiance product, reversible to raw)
             level 3 processing
   r       = rad data  (irreversible, (blemish removed) final product,
             level 4 processing

Cadences:

Exposures in pairs, at a cadence of 15 minutes, with exposure times of 
        4.5 millisecs. These exposures are conducted with the same pointing 
        and observing configuration. Observations were conducted at 2 hour 
        intervals.
The MRI red (750nm) filter was used for Earth observations.


COMMENT:  
The MRI was used during the 2008 March visit to Earth only to obtain
"context" (companion imaging) observations for HRII spectra.

HRIV: HIGH RESOLUTION (EARTH) IMAGING   [7 narrow band filters]

A typical Obervation name (rev) is:     hv08031900_1000111_001_r.fit

Here:
 hv       = hi res narrow band imaging
  080319  = observation date (UT)
  00      = observation midpoint hour (UT)
  1000111 = exposure number;
             "111" is a running observation number. Because the same imaging 
             sequence was executed for each of the three Earth visits, the 
             same exposure IDs were usually repeated.)
  001     = image number (single)
            One exposure ID consists of one or more image numbers.  For
            Earth observations, the image number is always 001 (i.e., 
            single).
  rr       = radrev data (calibrated radiance product, reversible to raw)
             level 3 processing
  r      = rad  data (radrev product with blemishes and artifacts removed
             level 4 processing

Filtered images 1-7 are taken at a rate of every ~1.4-2 seconds and
correspond to violet (350nm), blue (450nm), green (550nm), orange (650 nm),
red (750nm), nir (850nm), ir (950nm) in 100nm (1000 Angstroms)-wide bands.

Observations are made at two cadences: 

   o about 15 minutes (blue, green, orange, nir filters)

   o about 1 hour  (violet, red, ir filters).
Exposure times depend on filter responses. These range from 8.5 to 
13.5 milliseconds. Only one exposure time was used for each filter 
during the Earth observations.

The field of view consists of 1024x1024 pixels, at 0.4"/pixel.

Observations were made during three near-Earth visits in 2008 (March 18-19, 
May 28-29, and June 4-5). During the May 28 visit the Moon transited the 
Earth, as seen from the spacecraft. Defocusing degrates spatial resolution 
is to 4-7".

HRII: HIGH RESOLUTION INFRARED (EARTH) SPECTROSCOPY

Field of view consists of frames of 512 (wavelength) x 128 (spatial) 
pixels, at 2 "/pixel (spatial).
Observations were made during three near-Earth visits in 2008
(March 18-19, May 28-29, and June 4-5). Spatial resolution is
degraded to 4-7" due to defocusing. 

A typical obervation name (rev) is: hi08031908_1001020_001_r.fit

Here: 
  hi      = hi res IR spectrometry
  080319  = observation date (UT)
  08      = observation midpoint hour (UT)
  1000120 = exposure number; 
            "20" is a  running number. Since the same imaging sequence 
            was executed for each of the three Earth visits, the same 
            exposure IDs were usually repeated.
  001     = image number, running 1 through 8
  rr       = radrev data (calibrated radiance product, reversible to raw)
             level 3 processing
  r      = rad data (radrev product with blemishes and artifacts removed
             level 4 processing

Consecutive spectra are taken at a rate of every ~1.4-2 seconds.
Except for keywords referring to different times, the observing 
parameters for these images are identical, that is, at the same 
grating setting and pointed to the one of three locations on the 
Earth.

Exposures are grouped in 2 groups of three scans each, e.g. 1001020, 
1001021, 1001022, each pointed to a different location on the Earth. 
Typically, the 2nd and 3rd scan start several minutes after the 
preceding one.  Exposure times are about 1.3 seconds. The first
triplet consists of slow scans, followed by a triplet of fast scans. 

See also the document EPOCh_earth_obs_desc.doc.