Measurement of Astronomical Seeing Using Long Exposure Solar Images


We extend our modified parameter search method (Sridharan, Dashora, and Venkatakrishnan, Solar Phys. 222, 35, 2004) of estimating the Fried parameter (\(r_{0}\)) from long exposure images to the images obtained from the H\(\alpha \)-telescope installed at Merak, a cold desert on the Himalayas, with a modified criterion – the contrast ratio of the observed and the deconvolved images – to identify the true \(r_{0}\). We validated our new method by applying it to the solar granulation data and found that it is as accurate as our modified parameter search method. The median seeing at H\(\alpha \) – estimated from the data spanning over 5 months – is ≈ 2 arc-sec and it corresponds to a median \(r_{0}\) of 6 cm. About 30% of the estimated values are above \(r_{0}=7~\mbox{cm}\). The diurnal variation of the seeing is consistent with that expected for a lake-shore site. The significance of our method – extracting the underlying seeing from a single long exposure solar image – lies in the fact that it can be easily adopted to monitor seeing with small H\(\alpha \)-telescopes that are coveted and eagerly possessed by many solar observatories for patrolling solar flares and filament eruptions.

This is a preview of subscription content, log in to check access.

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6


  1. Aime, C.: 1974, Measurement of averaged modulus of atmospheric-lens modulation transfer function. J. Opt. Soc. Am. 64, 1129. ADS .

    ADS  Article  Google Scholar 

  2. Aime, C., Ricort, G., Roddier, C., Lago, G.: 1978, Changes in the atmospheric-lens modulation transfer function used for calibration in solar speckle interferometry. J. Opt. Soc. Am. 68, 1063. ADS .

    ADS  Article  Google Scholar 

  3. Beckers, J.M.: 1989, Some thoughts on the combination of beams in interferometers using telescopes of unequal size. In: Alloin, D.M., Mariotti, J.-M. (eds.) NATO Advanced Science Institutes (ASI) Series C, NATO Advanced Science Institutes (ASI) Series C 274, 365. ADS .

    Google Scholar 

  4. Beckers, J.M.: 2001, A seeing monitor for solar and other extended object observations. Exp. Astron. 12, 1. ADS .

    ADS  Article  Google Scholar 

  5. Beckers, J.M., Liu, Z., Jin, Z.: 2003, ATST seeing monitor: February 2002 observations at Fuxian Lake. In: Keil, S.L., Avakyan, S.V. (eds.) Innovative Telescopes and Instrumentation for Solar Astrophysics, Proc. SPIE 4853, 273. DOI . ADS .

    Google Scholar 

  6. Brandt, P.N., Mauter, H.A., Smartt, R.: 1987, Day-time seeing statistics at Sacramento Peak Observatory. Astron. Astrophys. 188, 163. ADS .

    ADS  Google Scholar 

  7. Fried, D.L.: 1965, Statistics of a geometric representation of wavefront distortion. J. Opt. Soc. Am. 55, 1427. ADS .

    ADS  MathSciNet  Article  Google Scholar 

  8. Fried, D.L.: 1966, Optical resolution through a randomly inhomogeneous medium for very long and very short exposures. J. Opt. Soc. Am. 56, 1372. ADS .

    ADS  Article  Google Scholar 

  9. Gonzalez, R.C., Wintz, P.: 1977, Digital Image Processing. ADS .

    Google Scholar 

  10. Hasan, S.S., Saxena, A.K., Bagare, S.P., Samson, J.P.A., Ismail, M.M., Rajendra, B.S., Aditya, T., Jabilullah, R.I., Tsewang, D.: 2010, Development of Solar Differential Image Motion Monitor at IIA for the NLST Site Characterization Program, IIA Technical Report Series, Indian Institute of Astrophysics, Bengaluru, India.

    Google Scholar 

  11. Irbah, A., Borgnino, J., Djafer, D., Damé, L., Keckhut, P.: 2016, Solar seeing monitor MISOLFA: a new method for estimating atmospheric turbulence parameters. Astron. Astrophys. 591, A150. DOI . ADS .

    ADS  Article  Google Scholar 

  12. Kellerer, A., Gorceix, N., Marino, J., Cao, W., Goode, P.R.: 2012, Profiles of the daytime atmospheric turbulence above Big Bear solar observatory. Astron. Astrophys. 542, A2. DOI . ADS .

    ADS  Article  Google Scholar 

  13. Pickering, T.E.: 2018, Seeing statistics and characteristics at the MMT Observatory 2003–2018. In: Ground-Based and Airborne Telescopes VII, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 10700, 107005C. DOI . ADS .

    Google Scholar 

  14. Ravindra, B., Kesavan, P., Thulasidharen, K.C., Rajalingam, M., Sagayanathan, K., Kamath, P.U., Dorjey, N., Dorjee, A., Kemkar, P.M.M., Dorjai, T., Banyal, R.K.: 2018, Installation of solar chromospheric telescope at the Indian astronomical observatory, Merak. J. Astrophys. Astron. 39, 60. DOI . ADS .

    ADS  Article  Google Scholar 

  15. Ren, D., Zhao, G., Zhang, X., Dou, J., Chen, R., Zhu, Y., Yang, F.: 2015, Multiple-aperture-based solar seeing profiler. Publ. Astron. Soc. Pac. 127, 870. DOI . ADS .

    ADS  Article  Google Scholar 

  16. Roddier, F.: 1981, The effects of atmospheric turbulence in optical astronomy. Prog. Opt. 19, 281. DOI . ADS .

    ADS  Article  Google Scholar 

  17. Scharmer, G.B., van Werkhoven, T.I.M.: 2010, S-DIMM+ height characterization of day-time seeing using solar granulation. Astron. Astrophys. 513, A25. DOI . ADS .

    Article  Google Scholar 

  18. Seykora, E.J.: 1993, Solar scintillation and the monitoring of solar seeing. Solar Phys. 145, 389. DOI . ADS .

    ADS  Article  Google Scholar 

  19. Sridharan, R., Dashora, N., Venkatakrishnan, P.: 2004, Estimation of Fried’s parameter from long-exposure solar images. Solar Phys. 222, 35. DOI . ADS .

    ADS  Article  Google Scholar 

  20. Sridharan, R., Venkatakrishnan, P., Verma, V.K.: 2002, Estimation of Fried’s parameter from specklegrams of solar features. Solar Phys. 211, 395. DOI . ADS .

    ADS  Article  Google Scholar 

  21. Teare, S.W., Thompson, L.A., Gino, M.C., Palmer, K.A.: 2000, Eight decades of astronomical seeing measurements at Mount Wilson Observatory. Publ. Astron. Soc. Pac. 112, 1496. DOI . ADS .

    ADS  Article  Google Scholar 

  22. von der Luehe, O.: 1984, Estimating Fried’s parameter from a time series of an arbitrary resolved object imaged through atmospheric turbulence. J. Opt. Soc. Am. A 1, 510. DOI . ADS .

    ADS  Article  Google Scholar 

  23. Walker, M.F.: 1984, High quality astronomical sites around the world. In: Ardeberg, A., Woltjer, L. (eds.) European Southern Observatory Conference and Workshop Proceedings, European Southern Observatory Conference and Workshop Proceedings 18, 3. ADS .

    Google Scholar 

  24. Wang, Z., Zhang, L., Kong, L., Bao, H., Guo, Y., Rao, X., Zhong, L., Zhu, L., Rao, C.: 2018, A modified S-DIMM+: applying additional height grids for characterizing daytime seeing profiles. Mon. Not. Roy. Astron. Soc. 478, 1459. DOI . ADS .

    ADS  Article  Google Scholar 

  25. Zhong, L., Beckers, J.M.: 2001, Comparative solar seeing and scintillation studies at the Fuxian Lake solar station. Solar Phys. 198, 197. DOI . ADS .

    ADS  Article  Google Scholar 

Download references


The idea of fitting straight lines to the rms contrast at low and high values \(r_{0}\) emerged during a brainstorming session with Prof. P. Venkatakrishnan and the authors would like to acknowledge him for the same. We thank the DOT team for providing us the speckle reconstructed G-band images that were used in the simulations. We would like to acknowledge the contributions from the engineering division of the institute for their help in establishing the H\(\alpha \) telescope near the NLST site. Also, we thank the observers at Merak for recording the data used in this work. We thank the referee for his insightful comments.

Author information



Corresponding author

Correspondence to Sridharan Rengaswamy.

Ethics declarations

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Rengaswamy, S., Ravindra, B. & Prabhu, K. Measurement of Astronomical Seeing Using Long Exposure Solar Images. Sol Phys 294, 5 (2019).

Download citation


  • High resolution, seeing
  • Imaging, Sun
  • Chromosphere
  • Fried’s parameter