Extinction maps with UVIT and related work
Abstract
The Ultraviolet Imaging Telescope (UVIT) is scheduled to be launched as a part of the ASTROSAT satellite. As part of the mission planning for the instrument we have studied the efficacy of UVIT observations for interstellar extinction measurements. We find that in the best case scenario, the UVIT can measure the reddening to an accuracy of about 0.02 magnitudes, which combined with the derived distances to the stars, will enable us to model the three-dimensional distribution of extinction in our Galaxy. The knowledge of the distribution of the ISM will then be used to study distant objects, affected by it. This work points the way to further refining the UVIT mission plan to best satisfy different science studies. In this work, we have created the model SEDs for stars of different spectral types reddened by interstellar dust. The stellar SEDs are based on the model spectra of Castelli and Kurucz (2004), provided as fluxes as a function of temperature. Each spectrum was reddened by an extinction curve, based on the standard Milky Way curve of Draine (2003), and then convolved with the all filter curves to produce a magnitude for each of the 16 bands. We have performed Monte Carlo simulations to estimate the uncertainty expected from the UVIT observations. Each simulation consisted of a series of 100 independent runs for a 20th magnitude star, with different combinations of temperature and E(B-V) with an assumed error of 0.1 magnitudes in each of the bands. We have begun the process of observational mission planning for the UVIT instrument by calculating the flux in each of the UVIT bands to maximize the science. In this work, we describe our plans to make a three-dimensional dust map over the sky using the UVIT point source catalog, combined with GALEX and SDSS observations. We have determined the best filter combination for this extinction work as NUVB5 filter with any of the FUV filter, but since observations are generally serendipitous in nature, we will use all the UVIT data for our purpose. The process of observational mission planning for UVIT will include the optimization of filters combinations for all scientific objectives. For example, we will calculate SEDs for different scientific programs (such as, for eg., stellar astrophysics, observations of globular clusters, AGN, etc.) and select the optimal filters.
- Publication:
-
Astronomical Society of India Conference Series
- Pub Date:
- 2013
- Bibcode:
- 2013ASInC...9..123R