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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/034/02/0175-0192

    • Keywords

       

      Stars; near infra-red magnitudes; adaptive optics.

    • Abstract

       

      The requirements for the production of a near Infra-Red Guide Star Catalog (IRGSC) for Thirty Meter Telescope (TMT) observations are identified and presented. A methodology to compute the expected J band magnitude of stellar sources from their optical (𝑔, 𝑟 , 𝑖 ) magnitudes is developed. The computed and observed J magnitudes of sources in three test fields are compared and the methodology developed is found to be satisfactory for the magnitude range, JVega = 16–22 mag. From this analysis, we found that for the production of final TMT IRGSC (with a limiting magnitude of JVega = 22 mag), we need 𝑔, 𝑟, 𝑖 bands optical data which go up to 𝑖AB ∼ 23 mag. Fine tuning of the methodology developed, such as using Spectral Energy Distribution (SED) template fitting for optimal classification of stars in the fainter end, incorporating spectral libraries in the model, to reduce the scatter, and modification of the existing colour–temperature relation to increase the source density are planned for the subsequent phase of this work.

    • Author Affiliations

       

      Smitha Subramanian1 Annapurni Subramaniam1 Luc Simard2 Kim Gillies3 A. N. Ramaprakash4 G. C. Anupama1 C. S. Stalin1 Swara Ravindranath4 B. Eswar Reddy1

      1. Indian Institute of Astrophysics, Koramangala, Bangalore 560 034, India.
      2. National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia, Canada.
      3. Thirty-Meter Project Office, Pasadena, California, USA.
      4. Inter-University Center for Astronomy & Astrophysics, Pune 411 007, India.
    • Dates

       
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