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WALOP-South: A wide-field one-shot linear optical polarimeter for PASIPHAE survey

Maharana, Siddharth and Kypriotakis, John A. and Ramaprakash, A. N. and Khodade, Pravin and Rajarshi, Chaitanya and Joshi, Bhushan and Chordia, Pravin and Anche, Ramya M. and Mishra, Shrish and Blinov, Dmitry and Eriksen, Hans Kristian and Ghosh, Tuhin and Gjerløw, Eirik and Mandarakas, Nikolaos and Panopoulou, Georgia V. and Pavlidou, Vasiliki and Pearson, Timothy J. and Pelgrims, Vincent and Potter, Stephen B. and Readhead, Anthony C. S. and Skalidis, Raphail and Tassis, Konstantinos and Wehus, Ingunn K. (2020) WALOP-South: A wide-field one-shot linear optical polarimeter for PASIPHAE survey. In: Ground-based and Airborne Instrumentation for Astronomy VIII. Proceedings of SPIE. No.11447. Society of Photo-Optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 114475E. ISBN 9781510636811.

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WALOP (Wide-Area Linear Optical Polarimeter)-South, to be mounted on the 1m SAAO telescope in South Africa, is first of the two WALOP instruments currently under development for carrying out the PASIPHAE survey. Scheduled for commissioning in the year 2021, the WALOP instruments will be used to measure the linear polarization of around 10⁶ stars in the SDSS-r broadband with 0.1 % polarimetric accuracy, covering 4000 square degrees in the Galactic polar regions. The combined capabilities of one-shot linear polarimetry, high polarimetric accuracy (< 0.1 %) and polarimetric sensitivity (< 0.05 %), and a large field of view (FOV) of 35 35 arcminutes make WALOP-South a unique astronomical instrument. In a single exposure, it is designed to measure the Stokes parameters I, q and u in the SDSS-r broadband and narrowband filters between 500-700 nm. During each measurement, four images of the full field corresponding to the polarization angles of 0°, 45°, 90° and 135° will be imaged on four detectors and carrying out differential photometry on these images will yield the Stokes parameters. Major challenges in designing WALOP-South instrument include- (a) in the optical design, correcting for the spectral dispersion introduced by large split angle Wollaston Prisms used as polarization analyzers as well as aberrations from the wide field, and (b) making an optomechanical design adherent to the tolerances required to obtain good imaging and polarimetric performance under all temperature conditions as well as telescope pointing positions. We present the optical and optomechanical design for WALOP-South which overcomes these challenges.

Item Type:Book Section
Related URLs:
URLURL TypeDescription Paper
Panopoulou, Georgia V.0000-0001-7482-5759
Pavlidou, Vasiliki0000-0002-0870-1368
Pearson, Timothy J.0000-0001-5213-6231
Potter, Stephen B.0000-0002-5956-2249
Readhead, Anthony C. S.0000-0001-9152-961X
Tassis, Konstantinos0000-0002-8831-2038
Additional Information:© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE). The PASIPHAE program is supported by grants from the European Research Council (ERC) under grant agreement No 771282 and No 772253, from the National Science Foundation, under grant number AST-1611547 and the National Research Foundation of South Africa under the National Equipment Programme. This project is also funded by an infrastructure development grant from the Stavros Niarchos Foundation and from the Infosys Foundation.
Group:Astronomy Department
Funding AgencyGrant Number
European Research Council (ERC)771282
European Research Council (ERC)772253
National Research Foundation (South Africa)UNSPECIFIED
Stavros Niarchos FoundationUNSPECIFIED
Infosys FoundationUNSPECIFIED
Series Name:Proceedings of SPIE
Issue or Number:11447
Record Number:CaltechAUTHORS:20201217-093521517
Persistent URL:
Official Citation:Siddharth Maharana, John A. Kypriotakis, A. N. Ramaprakash, Pravin Khodade, Chaitanya Rajarshi, Bhushan S. Joshi, Pravin Chordia, Ramya M. Anche, Shrish Mishra, Dmitry Blinov, Hans Kristian Eriksen, Tuhin Ghosh, Eirik Gjerløw, Nikolaos Mandarakas, Georgia V. Panopoulou, Vasiliki Pavlidou, Timothy J. Pearson, Vincent Pelgrims, Stephen B. Potter, Anthony C. S. Readhead, Raphail Skalidis, Konstantinos Tassis, and Ingunn K. Wehus "WALOP-South: A wide-field one-shot linear optical polarimeter for PASIPHAE survey", Proc. SPIE 11447, Ground-based and Airborne Instrumentation for Astronomy VIII, 114475E (13 December 2020);
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107146
Deposited By: Tony Diaz
Deposited On:17 Dec 2020 19:32
Last Modified:10 Jun 2021 20:59

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