This great starfield shows the central part of Corona Australis and part of its molecular cloud of dust. Between the dust, stars shine in the main star-forming region near NGC 6726-27, some 500 light years away. It features some very interesting objects: reflection nebulae, with the characteristic blue color; the variable R CrA and its associated yellowish variable nebula NGC 6729; several Herbig-Haro objects subject to scientific research, and a lot of very faint dust [1]. “Buried in the dust is a star formation that has given the dark cloud a faint yellow glow and produced a number of small, red nebulae” [2]. The globular cluster NGC 6523, although appearing to be in the same plane as the nebulae, is only juxtaposed from our point of view, lying much further at 28000 light years away [3].

Herbig-Haro objects are bright patches of nebulosity associated with newborn stars, usually found in star-forming regions, formed with the collision of narrow jets of partially ionised gas ejected by stars with nearby clouds of gas and dust at several hundred kilometres per second. In this image they’re tiny bright yellowish-redish nebulae. Interestingly they can evolve visibly in a timescale of a few years. It is quite unusual for us to see astronomical “change”, as our lives are so short in the astronomical timescales, but HH objects present a wonderful challenge: Terry Robison’s image is mesmerizing, showing a 4 year comparison of one of these objects in CrA.

I was pleased to see extremely sharp data (focus was spot on), and the longer integration revealed quite a bit of nebulosity with sufficient SNR! If you want, I further recommend checking the inspirational works by Fabian Neyer, Wei-Hao Wang, Hisayoshi Kato, Terry Robison and Tommy Nawratil on the area.

Constructive criticism, comments and suggestions are more than welcome in the comments section.

Dates: 15, 16, 18 and 19 July 2020

Location: Observatory, MG, Brazil. Rural Skies (Bortle 3, calculated SQM ~21.6)

Camera: Canon EOS 80D (stock) at ISO1600

Optics: 150/750mm ATM Newtonian Telescope (optics by Sandro Coletti) + TS-Optics MaxField 2" Coma Corrector

Mount: Sky-Watcher HEQ5, tracking, guiding

Exposure Detail: 60x240s | Total integration 240min or 4h

[1] APOD 2018/11/29

[2] D.Malin, A View of the Universe, 1st ed. Cambridge University Press, 1993, pp. 112.

[3] NGC 6723, in-the-sky.org. From “Catalog of Parameters for Milky Way Globular Clusters” (Harris 1996).