Abstract The Mittelman–di Cicco–Walker (MDW) H α Sky Survey is an autonomously operated and ongoing all-sky imaging survey in the narrowband H α wavelength. The survey was founded by amateur astronomers and is presented here in its first stage of refinement for rigorous scientific use. Each field is exposed through an H α filter with a 3 nm bandwidth for a total of 4 hr, with a pixel scale of 3.″2. Here, we introduce the first Data Release of the MDW H α Survey (Data Release 0, or DR0), spanning 238 fields in the region of Orion (∼3100 deg 2 ). DR0 includes: calibrated mean fields, star-removed mean fields, a point-source catalog matched to Data Release 1 of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) and the Isaac Newton Telescope Galactic Plane Survey (IGAPS), and mosaics. 3 3 DR0 components are available at http://mdw.astro.columbia.edu; the DR0 catalog can also be found on the AAS Journals Zenodo repository: doi: 10.5281/zenodo.12747455 .

The MDW Hα Sky Survey: Data Release 0