Spherical harmonic models of the shape of (433) Eros

This archive contains two spherical harmonic models of the shape of asteroid 433 Eros. One model is based on laser altimetry from the instrument NLR and the other is based on a stereo photoclinometry shape.

The data used to generate the model based on laser altimetery were taken from the file nlr125ar.img on NASA's PDS website. This image file was first converted to netcdf format using the generic-mapping-tools function xyz2grd, and the resulting pixel registed map was then converted to a gridline registration using the function grdsample. Following this, the resulting netcdf file was read into the pyshtools software and expanded into spherical harmonics using the function SHCoeffs.expand(). The spherical harmonic functions were chosen to be "4pi" normalized and to exclude the Condon-Shortley phase factor of (-1)m. The units of the coefficients are meters.

The data used to generate the model based on the stereo photoclinometric shape model were taken from the file quad512q.tab on NASA's PDS website. The vertices from the ICQ shape model with Q=512 were first converted from Cartesian to spherical coordinates, from which a regular gridline registered netcdf file was created using the generic-mapping-tools function surface with a tension of 0.6 and with a grid spacing of 0.17578125 degrees. This file was then read into the pyshtools software and expanded into spherical harmonics in the same manner as the NLA based model.

The two files in this archive are

Eros_NLR_shape_719.bshc.gz

Eros_SPC_shape_511.bshc.gz

The numbers 719 and 511 in the filename refer to the maximum spherical harmonic degree of file, which corresponds to effective spatial resolutions of 8 and ~5.7 pixels per degree, respectively. The files are stored in the binary "bshc" format as described in the pyshtools documentation and are furthermore compressed using gzip.