The AstroSat UV Deep Field North: The Far- and Near-ultraviolet Photometric Catalog

February 2023 • 2023ApJS..264...40M

Authors • Mondal, Chayan • Saha, Kanak • Bhattacharya, Souradeep • Borgohain, Anshuman • Tandon, Shyam N. • Rafelski, Marc • Jansen, Rolf A. • Windhorst, Rogier A. • Teplitz, Harry I. • Smith, Brent M.

Abstract • We present deep UV imaging observations of the Great Observatories Origins Survey Northern (GOODS-N) field with AstroSat/UVIT (AstroSat UV Deep Field north-AUDFn), using one far-UV (FUV) (F154W, 34.0 ks) and two near-UV (NUV) filters (N242W, 19.2 ks; N245M, 15.5 ks). The nature of the UV sky background was explored across the UVIT field, and a global mean and rms were estimated for each filter. We reach 3σ detection limits of m _AB ~ 27.35, 27.28, and 27.02 mag for a point source in the F154W, N242W, and N245M bands respectively. The 50% completeness limits of the FUV and NUV images are m _AB = 26.40 and 27.05 mag respectively. We constructed point-spread functions for each band and estimated their FWHM, which were found to be almost the same: 1.″18 in F154W, 1.″11 in N242W, and 1.″24 in N245M. We used SExtractor to separately identify sources in the FUV and NUV filters and produce the UV source catalog of the entire AUDFn field. The source count slope estimated in FUV and NUV is 0.57 dex mag^-1 (between 19 and 25 mag) and 0.44 dex mag^-1 (between 18 and 25 mag), respectively. The catalog contains 6839 and 16,171 sources (brighter than the 50% completeness limit) in the FUV and NUV, respectively. Our FUV and NUV flux measurements of the identified sources complement existing multiband data in the GOODS-N field, and enable us to probe rest-frame FUV properties of galaxies at redshift z < 1 and search for candidate Lyman continuum leakers at redshift z > 0.97.

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Harry Teplitz

Senior Scientist