Abstract Details
| Name: Ashutosh Bajpai Affiliation: TIFR Mumbai Conference ID: ASI2015_524 Title : Bias estimation technique used for X-ray CCD of Soft X-ray telescope Authors and Co-Authors : Sanket Kotak (TIFR Mumbai) Kallol Mukerjee (TIFR Mumbai) Irfan Mirza (TIFR Mumbai) K P Singh (TIFR Mumbai) Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : There has been a remarkable progress in enhancing the technologies of X-ray charge coupled devices (CCD) over the years and is proven to be efficient and reliable for astronomical applications. The pixel Bias is a constant offset of individual pixel of the CCD dark frames which set-in and vary depending on operational conditions and space environment which is very crucial for accurate measurements. The technique of Bias determination in-flight has been a real challenge for an accurate measurements using X-ray CCD. Significant improvements were made over the period in the bias measurement technique and applied for data correction to several X-ray missions. An application of a Bias determination technique depends also on dynamic conditions of a particular mission and factors such as on-board hardware and data processing capabilities. This paper presents a bias estimation technique suitable for Soft X-ray Telescope (SXT) of Indian Astronomical satellite mission ASTROSAT to be launched in near future. There are many data read out modes in SXT, designed to optimize the astronomical observations. This work presents a comprehensive study and analysis of science data acquired through flight module of the telescope as part of ground calibration, considering individual modes and their limitations and determination of appropriate CCD bias for SXT. This bias estimation technique accounts for spatial, temporal and temperature dependent variation and tested on different modes of data acquired at different temperatures. Results are encouraging and hence this technique is adopted in the data processing chain for extracting scientific data products from the telescope. |