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The lunar global gravity anomaly data
Updated : 2009.01.13
Observation date :

The Relay sub-satellite (Rstar) continues operating for the world-first direct observation of the gravity field of the lunar far side (four-way Doppler measurement) since Nov. 6, 2007 (JST).

RSAT/VRAD team is now analyzing observational data and developing the new lunar gravity field model.

Global gravity anomaly*1 maps of the Moon (the Free-air anomalies*2 and the Bouguer anomalies*3) from the new lunar gravity field model (Selene Gravity Model: SGM 90d) developed from RSAT data taken during the nominal mission (until the end of October, 2008) was published.
The data can be downloaded from the following links. Please carefully read our "Terms of Use" before downlaod the data (please unzip the data file).

(1)Free-air gravity anomaly map
File Name = SGM90d_free_air_gravity_anomaly_map-latitude_longitude_mGal.csv
File Format = CSV
Description = Free air gravity anomaly map from Selene Gravity Model (SGM90d).
Column 1 = latitude in degree
Column 2 = longitude in degree
Column 3 = free-air gravity anomaly in mGal

(2)Bouguer gravity anomaly map
File Name = SGM90d_Bouguer_gravity_anomaly_map-latitude_longitude_mGal.csv
File Format = CSV
Description = Bouguer gravity anomaly map from SELENE Gravity Model (SGM90d) and SELENE Topography Model (STM-359_grid-02).
Column 1 = latitude in degree
Column 2 = longitude in degree
Column 3 = bouguer gravity anomaly in mGal

RSAT PI = Noriyuki Namiki (Kyushu University)
Date = December 25, 2008

*1 gravity anomaly
The lunar gravity field is not homogenous. Any region of the Moon with a higher density than average will produce positive gravity anomalies.

*2 Free-air anomalies
Gravity anomalies which were calculated by subtracting the average gravity from local gravity derived from SGM90d.

*3 Bouguer anomalies
Gravity anomalies which were calculated by removing the attraction of topography from the free-air gravity anomalies assuming the average density of rocks at the surface.

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