is GALEX data calibrated?
Details of GALEX calibration may be found in the GALEX In-Flight Calibration Plan. Calibration steps are summarized below. The initial calibration was done on the ground, before flight. Data acquired in-flight are being used to improve and refine calibration parameters. The ERO data were calibrated using the pre-flight ground calibration. DR1 will be calibrated with in-flight parameters. Ground calibration: Galex was calibrated on the ground during the spring of 2002, in thermal vacuum, using a Roper Scientific Acton Research VM-502 0.2-m vacuum monochromator with a deuterium lamp to provid UV illumination. Top priority calibration items were relative sensitivity versus wavelength, flat field, imaging-to-spectroscopic differential sensitivity versus wavelength, and spatial nonlinearity. Middle priority were absolute sensitivity (measured at 3 pencil beam locations in the aperture), grism dispersion function compared to imaging, high count rate tests (local and global), and a sky-simula
