NGC 6744

Deep in the southern sky lurks a Milky Way analog, seen from a distance. It's called NGC 6744.

NGC 6744

NGC 6744 and surroundings shine in this 4°x3° vista, which also includes 21 other, fainter IC- & NGC-galaxies.

One of the nice things about using a short and fast refractor is the ability to capture a whole blob of the sky at once, while at the same time retaining some fine resolution which is normally lost when you use plain medium telephoto lens. This is instantly apparent from the above picture of the region around NGC 6744, a large barred spiral galaxy. Fine detail in the disk are visible, while the large areal span of the image shows multitudes of fainter and obscure galaxies. Despite the relatively short exposure time, slightly less than 1 hour, extremely faint stars down to magnitude 18.9 are visible, 100,000x fainter than the faintest star visible to the eye.

NGC 6744 and environment

This 100% crop shows NGC 6744 and its immediate surroundings. The spiral arms can be traced (very faintly) to a span of 22', which at a distance of 9.5MPc translates to a visible disk spanning an incredible 200kly, 2 times larger than the Milky Way. The subtle color shading is also quite obvious, with the yellowish central barred region containing the older, sun-like population of stars, while the spiral arm regions are currently undergoing significant star formation. This is probably due to the perturbations in gas induced by NGC 6744A, a satellite visible near the end of a spiral arm about 10' to the north-west, magnitude 14.2. which is a Magellanic cloud type of irregular galaxy, probably in the process of being gobbled up. It is visible about 10' NW, at mag 14.2. Some notable field galaxies dotting the area are IC 4820, 24' N at mag 14.0, ESO 104-44 24' S-SE (a special class of galaxies dubbed "Low Surface Brightness" galaxies), and IC 4823, 17.4' to the east, at magnitude 13.1. This last one is actually an interacting trio, of which some hint is visible in this image. Other, very faint galaxies are smeared throughout, like the 17.9 magnitude galaxy 7.2' north of IC 4823.

A selection of interesting field galaxies is shown below:

IC 4799, a compact but photographically bright barred galaxy. J.L.E. Dreyer observed this galaxy in the 19th century with the remarks 'very faint, small, round, stellar nucleus, ring, 2 wisps'. Coincidentally, Dreyer is also the author behind the famous NGC and IC catalogs, compiled from a time when the only sky surveys were visual.

NGC 6722

NGC 6722, a face-on spiral galaxy similar to NGC 891, but much further away, at 65MPc.

IC 4831 group

Located about 2° north of NGC 6744 lies a group of 3 nearly colinear galaxies, the brightest one being IC 4831, and fainter members IC4828,IC4824, and IC4833. These are all irregular galaxies with low surface brightness

Image information

Galaxies, Tivoli 2016