Abstract:
In order to characterize the BSS and YSS populations, we use multiwavelength data, ranging from UV to infrared (IR).
UV data: The fluxes of sources in UV wavelengths are obtained from the Ultraviolet and Optical Telescope (Swift/UVOT) and Galaxy Evolution Explorer (GALEX). The Swift spacecraft is equipped with UVOT, a 30cm telescope sensitive in the optical/UV band in the wavelength range of 170-650nm. We utilize near-UV (NUV) data (Siegel+2019, J/AJ/158/35) from UVOT in this work. Berkeley 39 was observed by Swift/UVOT in three UV filters, UVW2 (180-260nm), UVM2 (200-280nm), and UVW1 (220-400nm), in 2011. In addition to the Swift/UVOT data, we also use data from GALEX, a 50cm aperture space-based telescope which observed Berkeley 39 in its NUV band (1770-2730Å).
Optical data: Gaia data (DR3; Gaia Collab.+2022, I/355) provides proper motions, parallaxes, and three-band photometry (G, GBP, GRP) for over a billion sources observed between 25 July 2014 and 28 May 2017. The wavelength of filter G is centered at 673nm, GBP at 532nm, and GRP at 797nm. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is a ground-based telescope which observed from 2010 to 2015 for its first data release (Chambers+2019, II/349). It utilizes five filters, g, r, i, z, and y, with effective wavelengths 481, 617, 752, 866, and 962nm respectively.