Overview and Interaction

The objective of the pages in this section is to provide comprehensive explanations of the procedures for spacecraft teams to participate in lunar calibration, including the items of information required and the file formats for communicating that information. Lunar calibration is applicable to any sensor system that has viewed the Moon, even ground-based instruments. To accommodate a wide variety of sensor configurations having different operational objectives, a set of Information Exchange Items [http://www.moon-cal.org/spacecraft/exchange_items.php] with formalized Exchange File Formats [http://www.moon-cal.org/spacecraft/exchange_formats.php] has been developed.

The normal sequence of interaction between a Spacecraft Calibration Team (SCT) and the USGS Lunar Calibration Team (LCT) is:

1. Initial discussion between SCT and LCT about the suitability of lunar calibration for a specific instrument.
2. SCT provides the detailed spectral response for each instrument band.
3. LCT processes the spectral response data, and replies with the effective wavelengths for each band for white, solar, and lunar targets.
4. SCT acquires the lunar observation data exchange specifications and file formats from LCT (see Exchange File Formats [http://www.moon-cal.org/spacecraft/exchange_formats.php]).

For each lunar observation:

5. SCT processes the instrument lunar observation data and computes the necessary items of information, including the down-track dimension of the Moon in the image and the apparent lunar irradiance.
6. SCT prepares the information exchange files for their lunar observations in the standard formats, and provides these to the LCT.
7. LCT computes the detailed geometry for the observation, queries the lunar irradiance model, and replies to the SCT with this geometry and the irradiance comparison.

These steps pertain exclusively to the use of disk-integrated lunar irradiance; procedures for comparison of spatially resolved lunar radiance will be available once a reliable radiance model is operational.

A major objective of the USGS lunar calibration program is to compare the radiance scales that are being used by the various spacecraft instruments. To facilitate this objective, SCTs are asked to provide their irradiance observations in exchange for the lunar irradiance model calculations. Lunar calibration results are communicated only to the SCT unless explicitly approved for release by the SCT.

This website section is intended to aid instrument teams in the lunar calibration processes. Comments and suggestions are welcome, please send correspondence to Tom Stone [tstone@usgs.gov].