Calibration of AstroSat/UVIT gratings and spectral responses

AstroSat/UVIT carries two gratings in the FUV channel and a single grating NUV channel. These are useful for low resolution, slitless spectroscopy far near UV bands of variety cosmic sources such as hot stars, interacting binaries, active galactic nuclei, etc. We present calibration these using observations standards NGC40 HZ4. perform wavelength flux derive effective areas different orders. find peak 18.7cm^2 at 2325 Angstrom -1 order NUV-Grating, 4.5cm^2 1390 -2 FUV-Grating1, 4.3cm^2 1500 FUV-Grating2. The FWHM spectral resolution is 14.6 order. has an 33 Angstrom. excellent agreement measurements between FUV/NUV all broadband filters. have generated responses UVIT filters that can directly be used fitting packages XSPEC, Sherpa, ISIS, thus allowing analysis data either separately or jointly with X-ray from AstroSat other missions.