Studying the Imaging Characteristics of Ultra Violet Imaging Telescope (UVIT) through Numerical Simulations

Ultra-Violet Imaging Telescope (UVIT) is one of the five payloads aboard the Indian Space Research Organization (ISRO)'s ASTROSAT space mission. The science objectives of UVIT are broad, extending from individual hot stars, star-forming regions to active galactic nuclei. Imaging performance of UVIT would depend on several factors in addition to the optics, e.g. resolution of the detectors, Satellite Drift and Jitter, image frame acquisition rate, sky background, source intensity etc. The use of intensified CMOS-imager based photon counting detectors in UVIT put their own complexity over reconstruction of the images. All these factors could lead to several systematic effects in the reconstructed images. A study has been done through numerical simulations with artificial point sources and archival image of a galaxy from GALEX data archive, to explore the effects of all the above mentioned parameters on the reconstructed images. In particular the issues of angular resolution, photometric accuracy and photometric-nonlinearity associated with the intensified CMOS-imager based photon counting detectors have been investigated. The photon events in image frames are detected by three different centroid algorithms with some energy thresholds. Our results show that in presence of bright sources, reconstructed images from UVIT would suffer from photometric distortion in a complex way and the presence of overlapping photon events could lead to complex patterns near the bright sources. Further the angular resolution, photometric accuracy and distortion would depend on the values of various thresholds chosen to detect photon events.Comment: Submitted to PASP, 16 Pages, 9 figure

Arabic Stemmer (Spring 2003) EnPRO 356: Arabic Stemmer EnPRO356 Spring2003 Final Presentation

This EnPRO will work on next generation search tools for Arabic processing. You do not have to be a Computer Science major or know anything about programming to be a major contributor to this project. This will be both a regular IPRO and an ENPRO so you will learn about the business side of things as well. Finally, if you are fluent in Arabic, this is really the IPRO for you. Your Arabic language skills will be heavily used. As with all regular courses, ten hours per week outside of class will be requiredSponsorship: IIT Collaboratory for Interprofessional StudiesProject Plan for EnPRO 356: Arabic Stemmer for the Spring 2003 semeste