Browsing by Author "Srivastava, Mudit K."

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Design and development of an optical-fibre-based Integral Field Unit (IFU) on the IUCAA 2-m telescope
(Mon. Not. R. Astron. Soc., 2011-07-31) Srivastava, Mudit K.; Ramaprakash, A.N.; Das, H.K.
An optical-fibre-based Integral Field Unit (IFU) has been developed for the Inter-University Centre for Astronomy and Astrophysics (IUCAA) Faint Object Spectrometer and Camera (IFOSC), the main back-end instrument on the IUCAA 2-m telescope at Girawali, Pune, India. This IFU enables IFOSC to perform two-dimensional spectroscopy of extended astronomical objects and is being used as one of the modes of IFOSC. Based on the concept of coupling the telescope focal plane with the spectrograph slit using a fibre bundle, the IFU (named the Fibre-based Integral Field Unit for IFOSC, hereafter FIFUI) uses 100 optical fibres, each associated with a tiny lenslet on its tip, to sample the incoming field of view spatially. In addition, FIFUI uses some coupling optics to realize this two-dimensional interface. FIFUI offers three different spatial sampling scales of 0.8, 1.0 and 1.2 arcsec fibre−1. It is optimized for the visible spectrum and for a field of view of ∼13 × 6 arcsec2 on the sky for the nominal 1-arcsec sampling mode. FIFUI was commissioned on the IUCAA 2-m telescope during 2010 February–March after a series of sky tests and science-verification observations and a dataanalysis pipeline was developed to extract the spectra and reconstruct the sky maps. Here we report on the development of FIFUI, including its opto-mechanical design and commissioning observations.
Studying the Imaging Characteristics of Ultra Violet Imaging Telescope (UVIT) through Numerical Simulations
(2009-03-01) Srivastava, Mudit K.; Prabhudesai, Swapnil M.; Tandon, S. N.
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.
TELICS-A Telescope Instrument Control System for Small/Medium Sized Astronomical Observatories
(2009-10-01) Srivastava, Mudit K.; Ramaprakash, A. N.; Burse, Mahesh P.; et al.
For any modem astronomical observatory, it is essential to have an efficient interface between the telescope and its back-end instruments. However, for small and medium-sized observatories, this requirement is often limited by tight financial constraints. Therefore a simple yet versatile and low-cost control system is required for such observatories to minimize cost and effort. Here we report the development of a modem, multipurpose instrument control system TELlCS (Telescope Instrument Control System) to integrate the controls of various instruments and devices mounted on the telescope. TELlCS consists of an embedded hardware unit known as a common control unit (CCU) in combination with Linux-based data acquisition and user interface. The hardware of the CCU is built around the ATmega 128 microcontroller (Atmel Corp.) and is designed with a backplane, master-slave architecture, A Qt-based graphical user interface (GUI) has been developed and the back-end application software is based on C/C++. TELlCS provides feedback mechanisms that give the operator good visibility and a quick-look display of the status and modes of instruments as well as data. TELICS has been used for regular science observations since 2008 March on the 2 m, fllO IUCAA Telescope located at Girawali in Pune, India.