Instrumental
FITS images in counts, with the MAGZP header keyword included for photometric conversion.
Data Release 0
Image Products
All DR0 images are astrometrically calibrated. For each of the 238 mean fields, the release provides instrumental images, photometrically calibrated images, and photometrically calibrated star-removed images.
Products Included
Photometrically Calibrated
Images converted to Janskies using the field-specific magnitude zero point.
Calibrated and Star-Removed
Starless calibrated fields intended for diffuse-emission and large-scale structure work.
Photometric Calibration
Instrumental images include the MAGZP keyword in the FITS header. This is the
field-specific magnitude zero point used to convert measured flux in counts to calibrated AB magnitudes.
mag(MDW) = -2.5 * log10(measured flux [counts]) + MAGZPThe zero point is determined by comparing instrumental Hα magnitudes to catalog-matched IGAPS AB Hα magnitudes. The calibration is set so that the stellar locus is consistent with the IGAPS synthetic early-A reddening line.
For calibrated and calibrated star-removed products, the FITS values are offset by the physical flux zero point and expressed in Janskies.
mag(MDW) = -2.5 * log10(measured flux [Jy] / 3631 [Jy])