The final COS-B database - In-flight calibration of sensitivity and instrumental background behaviour
Publication date: 15 January 1987
Authors: Strong, A.W., et al.
Journal: Astronomy and Astrophysics Supplement Series
Copyright: European Southern Observatory
This is one in a series of papers prepared in association with the release of the final COS-B database. Various aspects of the performance of the COS-B gamma-ray telescope are studied using in-flight data. First, the time-variation of the sensitivity and background over the 6.7 years of the mission is investigated. COS-B observed many regions of the sky repeatedly over the mission lifetime, allowing the study of the temporal behavior of the instrument. Using a multivariate optimization algorithm, the relative sensitivity for the 65 observation periods is determined to an accuracy generally better than 10 percent. The temporal variations of the instrumental background, assumed to be related to a cosmic-ray scaler aboard the satellite, are simultaneously determined. Second, the dependence of the instrumental background on the inclination to the telescope axis is analyzed using observations of high galactic latitude areas. The resulting corrections to the instrumental parameters are a necessary prerequisite for the combination of the data into large-scale maps for scientific analysis. The implementation of the corrections to give such maps is outlined.Link to publication