All images are astrometrically calibrated. For each of the 238 mean fields, there are 3 options to choose from:

  1. Instrumental: fields where the FITS data is in counts. These fields include the MAGZP header keyword, to convert instrument magnitudes to calibrated magnitudes.
  2. Photometrically Calibrated: photometrically calibrated fields, in that the FITS data is offsetted with the above-mentioned zero-point and converted to Janskies.
  3. Photometrically Calibrated & Star-Removed: photometrically calibrated & starless fields, where the FITS data is offsetted with the above-mentioned zero-point and converted to Janskies.

Photometric Calibration

The instrumental images include the MAGZP keyword in their FITS headers. This represents the magnitude zero-point for each field image and can be used to calculate calibrated AB magnitudes, mag(MDW), from measured instrumental flux, as such:

mag(MDW) = -2.5*log10(measured flux [counts]) + MAGZP

The magnitude zero-point for each field is calculated by comparing the instrumental Hα magnitudes of sources in each field with the catalog-matched IGAPS' AB Hα magnitudes. We specifically try to offset our data such that the stellar locus of our color-color plots align with the IGAPS synthetic early-A reddening line.

For the photometrically calibrated and photometrically calibrated star-removed field images, we convert the MAGZP value into a physical flux zero-point and apply it to the FITS data unit. In this way, the measured values (e.g. in aperture photometry) result in a calibrated AB Hα magnitude. Note that the FITS data has the unit of Janskies.

mag(MDW) = -2.5*log10(measured flux [Jy] / 3631 [Jy])

Download Images

The entire data set is also available for download here. (Compressed file size: ~17G)

Mosaics

  • DR0 Mosaic v0.1 download
  • DR0 Mosaic Star-removed v0.1 download

    • This is a preview version of the mosaic that is suitable for large structures. The mosaic has been scaled-down to reduce size.
    A complete version will be released soon.