caa a22 4500 445830344 CHVBK 20180317145313.0 cr unu---uuuuu 170323e20110401xx s 000 0 eng 10.1007/s10686-010-9207-0 doi (NATIONALLICENCE)springer-10.1007/s10686-010-9207-0 Issues with external occultation of a coronagraph [Elektronische Daten] [A. Bayanna, Shibu Mathew, K. Sankarasubramanian, P. Venkatakrishnan, J. Singh, B. Prasad] This paper addresses some of the issues related to externally occulted solar coronagraph; vignetting and achievable resolution due to an external occulter. The analytical expression by Evans (J Opt Soc Am 38:1083-1085, 1948) is used to perform the initial calculations. An expression for the vignetting for a given external occulter and field angle is derived. The values obtained with the derived expression are verified with those obtained by ZEMAX an Optical design software. The degradation in angular resolution of the system due to vignetting is also presented and an empirical relation to calculate the normalized resolution for a given amount of vignetting is obtained. Springer Science+Business Media B.V., 2010 Solar coronagraph nationallicence Coronagraph nationallicence Occultation nationallicence Vignetting nationallicence ZEMAX nationallicence Bayanna A. Physical Research Laboratory, Udaipur Solar Observatory, 313004, Udaipur, India aut Mathew Shibu Physical Research Laboratory, Udaipur Solar Observatory, 313004, Udaipur, India aut Sankarasubramanian K. Space Astronomy & Instrumentation Division, ISRO Satellite Center, Airport Road, Vimanapura, 560017, Bangalore, India aut Venkatakrishnan P. Physical Research Laboratory, Udaipur Solar Observatory, 313004, Udaipur, India aut Singh J. Indian Institute of Astrophysics, Koramangala, 560017, Bangalore, India aut Prasad B. Indian Institute of Astrophysics, Koramangala, 560017, Bangalore, India aut Experimental Astronomy Springer Netherlands 29/3(2011-04-01), 145-153 0922-6435 29:3<145 2011 29 10686 https://doi.org/10.1007/s10686-010-9207-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10686-010-9207-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bayanna A. Physical Research Laboratory, Udaipur Solar Observatory, 313004, Udaipur, India aut NATIONALLICENCE 700 1- Mathew Shibu Physical Research Laboratory, Udaipur Solar Observatory, 313004, Udaipur, India aut NATIONALLICENCE 700 1- Sankarasubramanian K. Space Astronomy & Instrumentation Division, ISRO Satellite Center, Airport Road, Vimanapura, 560017, Bangalore, India aut NATIONALLICENCE 700 1- Venkatakrishnan P. Physical Research Laboratory, Udaipur Solar Observatory, 313004, Udaipur, India aut NATIONALLICENCE 700 1- Singh J. Indian Institute of Astrophysics, Koramangala, 560017, Bangalore, India aut NATIONALLICENCE 700 1- Prasad B. Indian Institute of Astrophysics, Koramangala, 560017, Bangalore, India aut NATIONALLICENCE 773 0- Experimental Astronomy Springer Netherlands 29/3(2011-04-01), 145-153 0922-6435 29:3<145 2011 29 10686 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer