stefanopesciThis H-alpha and O-III rendition of NGC 6822, with 25h of narrowband integration plus RGB stars, highlights the complex structure of Barnard’s galaxy emission nebulae. These nebulae were thouroughly catalogued in a 1982 science paper available here: https://articles.adsabs.harvard.edu/pdf/1982PASP...94..444K and are shown in the image overlay, with their apparent dimentions (largest ones). In the overlay the nebulae are identified as DN (diffuse nebula).Here is Edwin Hubble 1925 historic paper on Ngc 6822, referred to as a “faint cluster of stars and nebulae”, which provided the first identification for the galaxy emission nebulae labelled as “Hubble” plus a Roman number (from I to X): https://articles.adsabs.harvard.edu/pdf/1925ApJ....62..409HWorth mentioning is that Edwin Hubble correctly identified Ngc 6822 as extra galactic and farther away (correctly) than the Magellanic Clouds, through the analysis of period-luminosity relation of Cepheid variables.In the image, RGB stars were added without overwhelming the nebulae in the galaxy core.
