Chandrayaan-1 M3 Reflectance Image (REFIMG)
REFIMG – Reflectance Image
Instrument: M3
PDS Data Set ID: CH1-ORB-L-M3-2-L2-REFLECTANCE-V1.0DOI: 10.17189/1520414
The Moon Mineralogy Mapper (M3) Reflectance Image (REFIMG) data products consist of photometrically calibrated reflectance data (unitless, where a stored value of 1.0 represents 100% reflectance). Processing involves converting the at-sensor radiance data to reflectance (I/F, applying an Apollo 16 normalization factor and a photometric correction, the normalizing by a wavelength-independent scaling factor such that 100% reflectance is stored as the signed integer value 30,000.
In addition to the reflectance data file, the REFIMG products include a supplemental data file. Band 1 provides the 1489-nm channel photometrically-corrected to a sphere to preserve topography (i.e., photometrically-corrected albedo); a stored value of 1.0, unitless, represents 100% reflectance. Band 2 contains the temperature estimated and applied by the thermal correction step of the calibration process; units are Kelvin. Band 3 contains the longest wavelength band that is scientifically useful and has topography from the radiance image; none of the calibration steps has been applied.
All M3 REFIMG products are standardized to remove the different effects of the four possible orbit limb and flight yaw mode combinations:
-
Descending/forward
-
Descending/reverse
-
Ascending/forward
-
Ascending/reverse
In ascending limb data the lines/times are reversed, so all CALIV3 images have the northernmost image line first. In descending/reverse and ascending/forward modes the samples are reversed, so the first sample is on the west side of the image and do not appear left-right mirrored. In descending/forward no changes in lines or samples are performed; this is the only case that matches the Raw Image (RAWIMG) data.
Description of M3 Operating Modes
M3 Mode |
Description |
# Channels |
# Samples |
Format |
Target |
Produces the maximum spectral resolution science data. |
255 |
610 |
32-bit Floating Point |
Global |
Reduces spectral resolution by 3 times.
The spatial data is summed in a 2 by 2 format. |
85 |
304 |
32-bit Floating Point |
Contents of an M3 REFIMG Image Cube File.
M3 REFIMG products have the following file names:
M3xyyyymmddThhmmss_V01_ttt.xxx (with one detached PDS label for all files)
where:
x = imaging mode
G = global mode
T = target mode
yyyy = year of the time stamp from the first image frame of the image cube
mm = month of the time stamp from the first image frame of the image cube
dd = day of the time stamp from the first image frame of the image cube
hh = hour in UTC of the time stamp from the first frame of the image cube
mm = minute within in the hour in UTC of the time stamp from the first frame of the image cube
ss = second within the minute in UTC of the time stamp from the first frame of the image cube
ttt = type of data product
L1B = Level 1B (.LBL)
RDN = Spectral Radiance data (.IMG or .HDR)
LOC = Pixel-located data (.IMG or .HDR)
OBS = Observation geometry data (.IMG or .HDR)
TIM = Observation timing data (.TAB)
xxx = file name extension
IMG = image object
HDR = detached header file
TAB = ASCII data table
In ODE, REFIMG products have the following product IDs:
M3XYYYYMMDDTHHMMSS_V01_RFL