Odyssey GRS Summed Gamma Spectra (SGS)

SGS – Summed Gamma Spectra

Instrument: Odyssey Gamma Ray Spectrometer

PDS Data Set ID: ODY-M-GRS-5-SGS-V1.0DOI: 10.17189/1519441

For more information about GRS CGS products, see the Data Set Catalog File.

For more information about GRS CGS processing, see the Gamma Data Processing document.

For more information about GRS IDR products, see the GRS IDR Product SIS.

The Gamma Ray Spectrometer Intermediate Data Record (GRSIDR) Summed Gamma Spectra (SGS) data products are data tables that contain a gamma spectrum and the associated engineering data that has been summed over 5-degree by 5-degree latitude longitude cells on the surface of Mars and over a time period of 15 degrees of solar longitude (Ls). The data tables are labeled with Mars year, starting Ls, ending Ls, and 5-degree latitude band number (0 centered on 87.5N, 35 centered on -87.5S).

The SGS are produced because the individual gamma spectra collected during an approximately 19.7 second collection interval do not contain enough counts to be statistically significant. The SGS are summed over large enough and long enough spatial and temporal intervals to provide a statistically meaningful spectrum that can be used for scientific data analysis.

The counts in Channel 0 are all the counts that would have been shifted to 0 or less by the spectrum shifting algorithm employed by the correction algorithm. The counts in Channel 16,383 are all the counts with energies greater than 10MeV, and counts in Channel 16,382 are all the counts that belong in either 16,382 or would have been shifted to 16,383 by the correction algorithm. The timing and spatial data provided with the spectra include the time and spatial range over which the sum was generated.

The SGS is intended to be the second intermediate data product available for the gamma portion of the GRS. These data should be useful to those scientists who are experienced in gamma spectroscopy.

GRS SGS products have the following file names:

SGS_yy_nnn_mmm_bb.DAT (with detached PDS label)

where:

yy = Mars Odyssey mapping year field (2 digits)

nnn = starting solar longitude (3 digits)

mmm = ending solar longitude (3 digits)

bb = latitude band number (2 digits, begin with 00 for the 90N to 85N band and end with 35 for the 85S to 90s band)

In ODE, SGS products have the following Product IDs:

SGS_YY_NNN_MMM_BB