dc.contributor.author |
Vishnu, Unni. C |
|
dc.contributor.author |
Sridharan, R |
|
dc.contributor.author |
Ravindra, B |
|
dc.contributor.author |
Prabhu, K |
|
dc.date.accessioned |
2021-07-02T11:03:10Z |
|
dc.date.available |
2021-07-02T11:03:10Z |
|
dc.date.issued |
2021-04 |
|
dc.identifier.citation |
Solar Physics, Vol. 296, No. 4, 65 |
en_US |
dc.identifier.issn |
1573-093X |
|
dc.identifier.uri |
http://hdl.handle.net/2248/7774 |
|
dc.description |
Restricted Access |
en_US |
dc.description |
The original publication is available at springerlink.com |
|
dc.description.abstract |
The parameter-search method (PSM) established by Rengaswamy, Ravindra, and Prabhu (Solar Phys.294, 5, 2019) for measuring the terrestrial atmospheric seeing from long-exposure solar Hα images is further validated - through simulations - to include the effects of i) intermediate exposure-time, exposures that are neither as small as 1 to 20 ms used in solar speckle imaging in the visible nor as long as 1 second; ii) under-sampling of the data (with respect to the telescope's diffraction-limit), and iii) non-ideal telescope point spread function. It is then applied to a large dataset to obtain the statistics of Fried's parameter r0 at Merak: a cold desert in the Himalayas. The bias due to intermediate exposure is well within the error budget. Under-sampling results in an underestimation of r0 only when the seeing-limited point spread function is sampled at a rate worse than two pixels per seeing-limit, implying that r0 estimated in the low-resolution mode is unreliable beyond r0=10 cm. The non-ideal telescope point spread function tends to reduce the estimated r0-values significantly only when the RMS wave-front error of the aberrated pupil is worse than λ /14 . The median seeing at Merak estimated from data spanning over five months is 2.7 arcseconds. |
en_US |
dc.language.iso |
en |
en_US |
dc.publisher |
Springer |
en_US |
dc.relation.uri |
https://doi.org/10.1007/s11207-021-01807-3 |
|
dc.rights |
© Springer |
|
dc.subject |
Atmospheric Seeing |
en_US |
dc.subject |
Chromosphere |
en_US |
dc.title |
Seeing measurements with the Merak Hα Telescope |
en_US |
dc.type |
Article |
en_US |