The First Extensive Exploration of UV-bright Stars in the Globular
  Cluster NGC 2808
  In this study, we identified and characterized the hot and luminous UV-bright
stars in the globular cluster NGC 2808. We combined data from the Ultra Violet
Imaging Telescope (UVIT) on-board the Indian space satellite, AstroSat, with
the Hubble Space Telescope UV Globular Cluster Survey (HUGS) data for the
central region (within $\sim$ $\ang[angle-symbol-over-decimal]{;2.7;} \times
\ang[angle-symbol-over-decimal]{;2.7;}$) and Gaia and ground-based optical
photometry for the outer parts of the cluster. We constructed the UV and
UV-optical color-magnitude diagrams, compared the horizontal branch (HB)
members with the theoretical zero-age HB and terminal-age HB models and
identified 34 UV-bright stars. The spectral energy distributions of the
UV-bright stars were fitted with theoretical models to estimate their effective
temperatures (12500 K - 100,000 K), radii (0.13 to 2.2 $R_{\odot}$), and
luminosities ($\sim 40$ to $3000$ $L_{\odot}$) for the first time. These stars
were then placed on the H-R diagram, along with theoretical post-HB (pHB)
evolutionary tracks to assess their evolutionary status. The models suggest
that most of these stars are in the AGB-manqu\'e phase and all, except three,
have evolutionary masses $<$ 0.53 $M_{\odot}$. We also calculated the
theoretically expected number of hot post-(early)-AGB (p(e)AGB) stars in this
cluster and found the range to match our observations. Seven UV-bright stars
located in the outer region of the cluster, identified from the AstroSat/UVIT
images, are ideal candidates for detailed follow-up spectroscopic studies.
