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The solar zenith, viewing zenith, and relative azimuth values for each pixel are stored in individual arrays within the MOD09A1 HDF file. There is no pre-packaged program or command available in IDL to retrieve these arrays. You have to open the HDF using EOS_GD_OPEN, attach to the specific grid stored inside the HDF using EOS_GD_ATTACH, then retrieve each angle array by calling EOS_GD_READFIELD and pointing it to each specific datafield. Once you have the arrays, you should convert them from their efficiently-packed integer forms to actual angles by recasting each array in floating point and then multiplying it by 0.01. Below is some example code for how to do this with your data.
;Specify input file
input_file = dialog_pickfile(title='Select MOD09A1 File', filter='MOD09A1*.hdf')
;Open the file
file_id = eos_gd_open(input_file)
;Attach to the grid stored in the file
grid_id = eos_gd_attach(file_id, 'MOD_Grid_500m_Surface_Reflectance')
;Retrieve the solar zenith, viewing zenith, and relative azimuth arrays
;Returned arrays are 2400x2400 and contain integerized angle values
solar_read = eos_gd_readfield(grid_id, 'sur_refl_szen', solar_zenith)
view_read = eos_gd_readfield(grid_id, 'sur_refl_vzen', viewing_zenith)
azimuth_read = eos_gd_readfield(grid_id, 'sur_refl_raz', relative_azimuth)
;Convert integerized angles to floating point
solar_zenith = float(solar_zenith)*0.01
viewing_zenith = float(viewing_zenith)*0.01
relative_azimuth = float(relative_azimuth)*0.01
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