Study of aerosol content based on spectrophotometric observations: A comparison with long-term extinction profile from photometric observations

Abstract

Spectroscopic observations of standard stars (spectrophotometric) have been carried out at Bosscha Observatory ITB (latitude= 6°49′28″ S, longitude= 107°36′56″ E, altitude=1310 m) using the Celestron C-11 reflector (D=11 inches, F/10.0), equipped with NEO R-1000 spectrograph (Resolution of 1000), and ST-8XME CCD camera to deduce total atmospheric extinction curve. Spectrograms were reduced with the long-slit task in the Image Reduction and Analysis Facility (IRAF). The total extinction curve obtained from observation is decomposed into three main components, i.e. Rayleigh scattering, Ozone and water vapor absorptions, and extinction by aerosol. The extinction profile by Aerosol serves as an important indication on size and distribution of particulates as the main constituent of atmospheric pollutant. This pollutant can be resulted from natural process or anthropogenic activities. The behavior of atmospheric extinction over Bosscha Observatory based on long-term astronomical photometric database (1982-1993) was previously studied by one of us in 1993. In this study we analyze new data and study the dynamics of atmosphere by comparing our recent result with that from long-term photometric observations to indicate variation of degree of atmospheric turbidity, particulate size and its distribution over the atmosphere. We recommend that long-term regular based spectrophotometry at an Observatory is imperative as an effective means to gain our insight on atmospheric dynamic.