• Development of a Code to Analyze the Solar White-Light Images from the Kodaikanal Observatory: Detection of Sunspots, Computation of Heliographic Coordinates and Area

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    • Keywords


      Sun; sunspots; Kodaikanal digitized data; sunspot area; heliographic coordinates

    • Abstract


      Sunspots are the most conspicuous aspects of the Sun. They have a lower temperature, as compared to the surrounding photosphere; hence, sunspots appear as dark regions on a brighter background. Sunspots cyclically appear and disappear with a 11-year periodicity and are associated with a strong magnetic field $(\sim 10^3$ G) structure. Sunspots consist of a dark umbra, surrounded by a lighter penumbra. Study of umbra–penumbra area ratio can be used to give a rough idea as to how the convective energy of the Sun is transported from the interior, as the sunspot’s thermal structure is related to this convective medium. An algorithm to extract sunspots from the white-light solar images obtained from the Kodaikanal Observatory is proposed. This algorithm computes the radius and center of the solar disk uniquely and removes the limb darkening from the image. It also separates the umbra and computes the position as well as the area of the sunspots. The estimated results are compared with the Debrecen photoheliographic results. It is shown that both area and position measurements are in quite good agreement.

    • Author Affiliations


      Ragadeepika Pucha1 K. M. Hiremath2 Shashanka R. Gurumath3

      1. Integrated Science Education and Research Center (ISERC), Visva-Bharati University, Santiniketan 731 235, India
      2. Indian Institute of Astrophysics, Bangalore 560 034, India
      3. VIT University, Vellore 632 014, India
    • Dates

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