Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/7454
Title: Estimation of asymmetries in point spread function for the echelle spectrograph operating at Vainu Bappu Telescope for high precision radial velocity studies
Authors: Sireesha, C
Banyal, R. K
Sriram, S
Keywords: Echelle Spectrograph;Asymmetries in PSF;Zemax;Iodine absorption cell;Radial Velocity;Vainu Bappu Telescope
Issue Date: Jul-2018
Publisher: SPIE--The International Society for Optical Engineering
Citation: Proceedings of the SPIE, Vol. 10702, 1070275-1- 1070275-10
Abstract: Precision in the Radial Velocity (RV) measurements depends upon the efficiency of the technique to remove instrumental artifacts from stellar measurements. Iodine absorption cell technique is being implemented for high precision studies with the Echelle spectrograph operating at Vainu Bappu Telescope (VBT), Kavalur, India. Since the star spectrum is convolved with the PSF of the spectrograph, the asymmetries in the PSF are imposed on the stellar spectral lines. The fiber fed Echelle spectrograph is a general purpose instrument, designed for high resolution (R = 60,000) spectroscopic observations. The asymmetries in the Point Spread Function (PSF) arise due to the off-axis launching of the stellar beam into the collimator and vignetting across the field. Apart from this, due to usage constraints, the grating of the spectrograph is a movable component. The impact on the Doppler shift calculations due to the movable components in the spectrograph is to be estimated. For upgrading the spectrograph for precision studies, the component level sensitivity for RV is to be analyzed. Thus, instrument design asymmetries and component induced PSF variations are analyzed to estimate the limitations of the spectrograph for precision studies. We have developed Zemax based optical design of the spectrograph to estimate the PSF variations and design limitations on the RV studies. Here, we present a model developed in Zemax and a preliminary analysis on RV sensitivity and the PSF asymmetries of the spectrograph. These instrument variations are to be taken as input during RV data reduction for precision measurements.
Description: Restricted Access
URI: http://hdl.handle.net/2248/7454
ISSN: 1996-756X
???metadata.dc.rights???: © SPIE--The International Society for Optical Engineering
???metadata.dc.relation.uri???: https://doi.org/10.1117/12.2312508
Appears in Collections:IIAP Publications



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