Estimation Of Extinction and Transformation Coefficients of Standard Star

Abstract - Accurate photometric calibration is essential for reliable astronomical observations, particularly in determining stellar magnitudes and colors. In this paper, we use observations of standard stars from Landolt's catalogue to determine atmospheric extinction and transformation coefficients. Using a CCD-equipped telescope and common UBVRI filters, observations were made under photometric circumstances. Whereas transformation coefficients were determined by linear regression between instrumental and standard magnitudes and colour indices, primary extinction coefficients were calculated from the airmass-dependent fluctuations in instrumental magnitudes. Our results show stable extinction behavior consistent with the atmospheric conditions of the observing site, and well-constrained transformation coefficients that allow precise calibration of instrumental data to the standard photometric system. These coefficients are crucial for reducing observational data and ensuring consistency in long-term photometric monitoring programs. Key Words: Extinction Coefficient, Transformation Coefficient, Standard Star