The MDW H <i>α</i> Sky Survey: Data Release 1

Abstract The Mittelman–di Cicco–Walker (MDW) H α Sky Survey is an autonomously operated all-sky narrowband (3 nm) H α imaging survey. The survey was founded by amateur astronomers, and the northern sky (decl. ≥ 0°) is presented here in its second stage of refinement for academic use. Each 3.6 deg 2 MDW field has 12 20 minutes individual exposures with a pixel scale of 3 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 2, a typical point-spread function of 6″, and a stack point-source depth of 16–17 mag. The northern MDW Survey Data Release 1 (DR1) includes calibrated mean and individual images, star-removed mean fields, and point-source catalogs for all images matched to Data Release 1 of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) and the INT Galactic Plane Survey. (All DR1 components are available at https://mdw.astro.columbia.edu . The catalogs are also made available in the AAS Journals Zenodo repository: doi: 10.5281/zenodo.17307324 .) Our initial study of H α filament widths finds a typical FWHM of 30″–45″ in the Lyra region. The matched catalogs (with a median match distance of ∼0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 5), combined with our distinctive narrowband photometry, are also used to identify H α variable and excess sources. These initial studies highlight some of the many scientific uses of the MDW H α survey.