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    24-Jul-2014
EO Data Access
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Index
  Acknowledgements and contact
List of figures and tables
List of tables
 Additional information on the GOMOS measurements
Periods of data unavailabilities
Evolution of the IPF
Glossary
List of abbreviations and acronyms
Product types and structure
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Secondary products
Scintillation and turbulence
Aerosols and PSC
Product validation
NO2 and NO3 measurements
O3 measurements
CAL/VAL activities
Retrieval and processing issues
Assimilation of GOMOS products
Mesosphere
Specific events
GOMOS-related theses
Other technical reports by members of GOMOS SAG, ESL and QWG
Level2 processing
How to
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Access tools
GOMOS products toolbox
EnviView
Data selection
PCD summary in the Level2 products
Obliquity
Star properties
Data availability
Presentation of the GOMOS products
Description of the products
Product content
Product structure
Time availability
Data size
Presentation of the instrument and the measurements
Scientific achievements
Validation results
Measurement characteristics
Accuracy
Occultation obliquity
Geographical and time coverage
Star characteristics
Mission planning
Modified mission scenario since August 2005
Instrument description and measurement principle
Calibration phase and monitoring activities
Measurement technique
GOMOS Product Handbook
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1.4 Star characteristics

The list of the 300 brightest stars selected for use by GOMOS measurements is provided in the Appendix B of this document. Over 2003, 177 different stars were used for the occultation measurements.

The star characteristics impact the quality and the accuracy of the measurements and of the retrieved products. The visual magnitude of the star gives an indication of the star brightness. It ranges from -1.44 for the brightest one (Sirius) to 4.5 for the faintest ones. A star is usually considered as being strong if its visual magnitude is lower than 0.8 and as being faint if it is higher than 2. Only stars with a visual magnitude lower than 3.553 are used for the GOMOS measurements.

The spectral type of the star (the shape of its spectrum) is approximated by its effective temperature. It ranges from 2800 K to 39000 K. A star is usually considered as being cold if its effective temperature is lower than 6000 K and as being hot if it is higher than 10000 K.

The signal-to-noise ratio of the measurement depends on both the visual magnitude of the star and its effective temperature.