LP ER Electron Reflection Data (DATAL2, Level 2)

DATAL2 – LP ER Electron Reflection Data Collection, Level 2 Data

Instrument: Electron Reflectometer

PDS3 Data Set ID: LP-L-ER-4-ELECTRON-DATA-V1.0DOI: 10.17189/1519721

PDS4 Bundle: urn:nasa:pds:lp-er-derivedDOI: 10.17189/1134-zy26

For more information about DATAL2 products, see the Lunar Prospector ER Electron Reflection Document Description.

The Lunar Prospector Electron Reflectometer (LP-ER) Level 2 Data (DATAL2) data products are a time ordered values of derived quantities from electron reflection, including calculated effective electron reflection coefficient. Each data file contains data from a single energy channel: 200 eV, 220 eV, 340 eV, 520 eV, or 590 eV.

Each record consists of a time tag followed by 7 scalar values. The first two columns after the time tag provide the selenographic (body-fixed) longitude and latitude of the LP-ER measurement footprint, which is obtained by extrapolating the magnetic field vector measured at the spacecraft along a straight line until it intersects the Moon. The next column gives the average magnetic field amplitude in nanoTeslas, measured at the spacecraft (|Bsc|), during the time interval of each LP-ER measurement. The next two columns give the cutoff pitch angle (A) and its uncertainty (in degrees) for electrons reflected from the lunar surface at the energy channel of the file. The last two columns give the effective electron reflection coefficient (R) and its uncertainty. The effective reflection coefficient is the ratio of the reflected flux to the incident flux for an ideal uniform pitch angle distribution, and is an indicator of surface magnetic field strength. This is calculated from the loss cone angle: R = |cos(A)|. From this, an estimate of the surface magnetic field, uncorrected for electrostatic reflection, can be calculated:

|Bsurf| > |Bsc|*[R2/(1-R2)]

ER DATAL2 products have the following file names:

yyyymm.TAB

where:

yyyy = year of data collection

mm = month of data collection

In ODE, DATAL2 products have the following product IDs:

ER_XXXEV_YYYYMM

where:

xxx = energy channel