Shibu K. Mathew

Udaipur Solar Observatory
Rajasthan, INDIA
Telephone: +91-0294-2457212

My current research interests include:

Sunspot contrast study is carried out using SoHO/MDI (Solar and Heliospheric Observatory/Michelson Doppler Imager)
continuum images. Dependence of umbral core brightness, the mean umbral brightness and penumbral brightness on
solar cycle is investigated using the above data. In future, multivariate analysis will be carried out to separate the
effects of umbral radius, heliocentric angle, and solar cycle phase on umbral brightness. Hinode SOT/SP data will also be used for
the study of spot size dependence on the minimum umbral contrast.

A new imager is being made at USO to be used as a back-end instrument for MAST telescope. The narrow band filter is constructed
using two tandem solid state Fabry-Perot etalons. The etalons are made of Lithium Niobate electro-optic crystal and can be
tuned to different wavelengths by applying high voltages.

Selected Publications:

  1. Rapid Formation and Disappearance of a Filament Barb
    Joshi, A. D., Srivastava, N., Mathew, S. K., Martin, S. F., 2013, Solar Physics, 288, 191

  2. Formation of a penumbra in a decaying sunspot
    Louis, R. E., Mathew, S. K., Puschmann, K. G., Beck, C., Balthasar, S., 2013, A&A, 552, 7

  3. Analysis of a Fragmenting Sunspot Using Hinode Observations
    Louis, R. E., Ravindra, B., Mathew, S. K., Bellot Rubio R. L., Bayanna, A. R., Venkatakrishnan, P., 2012, ApJ, 755, 16

  4. Properties of Umbral Dots from Stray Light Corrected Hinode Filtergrams
    Louis, R. E., Mathew, S. K., Bellot Rubio R. L., Ichimoto, K., Ravindra, B., Bayanna, A. R., 2011, ApJ, 752, 109

  5. Issues with external occultation of a coronagraph
    Bayanna, A. R., Mathew, S. K., Sankarasubramanian, K., Venkatakrishnan, P., Singh, J., Prasad, B. R., 2011, Expt. Astronomy, 29, 145

  6. Acoustic Power Absorption and its Relation to Vector Magnetic Field of a Sunspot
    Gosain, S., Mathew, S. K., Venkatakrishnan, P., 2011, Solar Physics, 268, 335

  7. Supersonic Downflows at the Umbra-Penumbra Boundary of Sunspots
    Louis, R. E., Bellot Rubio, L, R., Mathew, S. K., Venkatakrishnan, P., 2011, ApJ, 727, 49

  8. Automated Detection of Filaments and Their Disappearance Using Full-Disc H-alpha Images
    Joshi, A. D., Srivastava, N., Mathew, S. K., 2010, Sol. Phys., 262, 425

  9. Supersonic downflows in a sunspot light bridge
    Louis, R. E., Bellot Rubio, L. R., Mathew, S. K., Venkatakrishnan, P., 2009, ApJ, 704, L29

  10. Stray light correction and contrast analysis of Hinode broad-band images
    Mathew, S. K., Zakharov, V., Solanki, S. K., 2009, A&A, 501, L19.

  11. Source region of the 18 November 2003 coronal mass ejection that led to the strongest magnetic storm of cycle 23
    Srivastava, N., Mathew, S. K., Louis, R. E., Wiegelmann, T., 2009, J. Geophys Res., 114, A03107.

  12. Dynamics of sunspot light bridges as revealed by high-resolution images from Hinode
    Louis, R. E., Bayanna, R. A., Mathew, S. K., Venkatakrishnan, P., 2008, Sol. Phys., 252, 43.

  13. Enhanced p-mode absorption seen near the sunspot umbral-penumbral boundary
    Mathew, S. K., 2008, Sol. Phys., 251, 515.

  14. Properties of sunpsots in cycle 23: I. Dependence of brightness on sunspot size and cycle phase
    Mathew, S. K., Martinez Pillet, V., Solanki, S. K., Krivova, N. A., 2007, A&A, 465, 291.

  15. The Imaging MAgnetograph eXperiment for SUNRISE balloon Antarctica project
    Martinez Pillet, V., Bonet, J. A., Collados, M. V., Jochum, L., Mathew, S. K., et al., 2004, SPIE, 5487, 1152.

  16. On the fine structure of sunspot penumbrae. I. A quantitative comparison of two semiempirical models with implications for the Evershed effect
    Borrero, J. M., Solanki, S. K., Bellot Rubio, L. R., Lagg, A., Mathew, S. K., 2004, A&A, 422, 1093.

  17. Thermal-magnetic relation in a sunspot and a map of its Wilson depression
    Mathew, S. K., Solanki, S. K., Lagg, A., Collados, M., Borrero, J. M., Berdyugina, S., 2004, A&A, 422, 693.

  18. Three dimensional structure of a regular sunspot from the inversion of IR Stokes profiles
    Mathew, S. K., Lagg, A., Solanki, S. K., Collados, M., Borrero, J. M., Berdyugina, S., Krupp, N., Woch, J., Frutiger, C. 2003, A&A, 410, 695.

  19. Experimentally Determined r13 Electro-Optic Coefficient for a Lithium Niobate Crystal
    Mathew, S. K., 2003, App. Opt., 42, 3580.

  20. Magnetic field gradient and flare: study of a small flare in NOAA 8038
    Mathew, S. K., Ambastha, A., 2000, Sol. Phys., 197, 75.

  21. A Digital Imaging Multi-Slit Spectrograph for Measurement of Line-of-Sight Velocities on the sun
    Srivastava, N., Mathew, S. K., 1999, Sol. Phys., 185, 61.

  22. Fabry-Perot filter based solar video magnetograph
    Mathew, S. K., Bhatnagar, A., Prasad, C. D., Ambastha, A., 1998, A&AS., 133, 285.

  23. Solar Photospheric and Chromospheric Observations using a Lithium-Niobate Fabry-Perot etalon
    Debi Prasad, C., Mathew, S. K., Bhatnagar, A., Ambastha, A., 1998, Experimental Astronomy, 8, 125.


* A proposal for Solar coronal magnetic field measurement
* Link to MAST back-end instrument page
* Technical Note on Fabry-Perot HV module
* SPW6 Presentation: Update on Mast and Backend instruments
* Udaipur Solar Observatory Local Purchase Page