Abstract:
The Ultra Violet Imaging Telescope (UVIT) is one of the payloads on the
first Indian multiwavelength satellite ASTROSAT, which is expected to be launched
by the Indian Space Research Organisation (ISRO) in the year 2015. We have performed simulations of UV studies of old open clusters for the UVIT. The colour magnitude diagrams (CMDs) and spatial appearances have been created using 10 filters
associated with the FUV channel (130–180 nm) and NUV channel (200–300 nm)
that are available for observations on the UVIT, for the three old open clusters M67,
NGC 188 and NGC 6791. The CMDs are simulated for different filter combinations,
and they are used to identify the loci of various evolutionary sequences, white dwarfs,
blue stragglers, red giants, subgiants, turn off stars and the main sequence of the clusters. The present work helps in identifying a potential area of study in the case of
these three old open clusters by considering the availability of filters and the detection
limits of the instrument. We also recommend filter combinations, which can be used
to detect and study the above mentioned evolutionary stages. The simulations and the
results presented here are essential for the optimal use of the UVIT for studies of old
open clusters.
