Chandrayaan-1 M3 Reflectance Image (REFIMG)

REFIMG – Reflectance Image

Instrument: M3

PDS Data Set ID: CH1-ORB-L-M3-2-L2-REFLECTANCE-V1.0DOI: 10.17189/1520414Citations of DOI: 10.17189/1520414

For more information about all M3 Image products, see the Data Product SIS.

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:

  1. Descending/forward

  2. Descending/reverse

  3. Ascending/forward

  4. 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.

  • 4 block of 2x and 4x summing

  • 44 lines of summed by 4x and 42 lines of summed by 2x

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