Galaxies Galore in Grus
27 Aug 2016
During the day the Kalahari is alive with birds and I had a great treat this afternoon – I saw some vultures soaring effortlessly on a thermal, circling around and around, held aloft on their huge wings. Magnificent birds.
Watching them in the binoculars brought to mind another bird that glides through the air on magnificent wings… Grus, the crane.
I think Grus is a constellation close to the hearts of most South African stargazers because the Blue Crane is South Africa’s national bird.
It is a beautiful, graceful bird with its long slender neck, long legs and elegant wing plumes which sweep to the ground.
It is the softest blue-grey colour and stands about one metre high. It is the world’s most range-restricted crane, being almost entirely restricted to South Africa in its distribution.
Grus is also a beautiful, graceful bird flying across our southern night sky with its long slender neck, elegant wing plumes swept back in flight, and its gorgeous tail. (It’s also one of the few constellations whose stars look exactly like what it is… a crane in flight.)
And apart from being a graceful constellation, it is also stuffed with galaxies and as galaxies flourish under dark, dark skies, I spent the evening searching some out.
Observations
10″ f/5 Dobs; magnifications of 90x, 144x and 208x
I began with that well-known grouping –
The Grus Quartet
I was once standing in a queue in a Fruit and Veg shop, when I noticed that the woman ahead of me in the queue had a pair of identical twin girls, I’m guessing around five or six years old. I made some comment on how unusual it is to see two little human beings absolutely identical to each other in every way, and she replied they weren’t twins… and she reached behind her skirt and pulled into view a third little girl – a fraternal triplet to the identical pair. A sort of ‘two plus one’ arrangement.
And that is exactly how I think of the Grus Quartet: ‘a three plus one’ arrangement. A quartet of interacting spiral galaxies – here you have three members of the quartet – NGCs 7582, 7590 and 7599 – all fitting beautifully into a moderately high power field of view… and over there, needing to be pulled from behind the skirt, NGC 7552.
I’ve looked at the quartet many a time, but they were a delight in these dark skies.
NGC 7582 Galaxy
RA 23 18 23.7 Dec -44 22 08 Mag 10.6 Size 5.0′ x 2.1′
It is the brightest and most obvious of the galaxies, appearing as a relatively bright little 3′ oval-spindle, oriented north-northwest to south-southeast, with a bright little nucleus. With higher power the galaxy becomes very slightly patchy, with a very hazy edge, both of which suggest a spiral structure. It appears much larger and a little more patchy with averted vision, a shapely little galaxy.
NGC 7590 Galaxy
RA 23 18 55 Dec -42 14 17 Mag 11.5 Size 2.7′ x 1.0′
NGC 7599 Galaxy
RA 23 19 21.5 Dec -42 15 25 Mag 11.5 Size 4.4′ x 1.3′
NGC 7590 is the smallest of the quartet but it stands out well. It appears as a relatively bright 2′ oval, oriented northeast to southwest, with a slightly brighter little core. A little 11th mag star on its northeastern tip.
NGC7599 appears the dimmest of the three, and displays an even surface brightness without a distinctive nucleus, elongated east-northeast to west-southwest.
NGC 7552 Galaxy
RA 23 16 10.9 Dec -42 35 02 Mag 10.6 Size 3.4′ x 2.7′
This galaxy appears as a bright little 3’ spindle elongated east to west. It has a prominent and bright little stellar nucleus. Higher magnification expanded the hazy edges considerably, and with averted vision I could see an extremely faint outer halo.
Some Other Pavo Galaxies
NGC 7462 Galaxy
RA 23 02 47.1 Dec -40 50 07 Mag 12 Size 4.2′ x 0.7′
This galaxy is a beautiful sight – a strikingly bright narrow sliver of light, elongated east-west. It has a uniform surface brightness, and there is an 11th mag star on its western tip.
NGC 7424 Galaxy
RA 22 57 18.2 Dec -41 04 15 Mag 10.5 Size 9.5′ x 8.1′
This galaxy has a bright stellar nucleus with a small, very faint halo, but which expanded with averted vision, although the inner section didn’t seem to brighten much
NGC 7410 Galaxy
RA 22 55 00.9 Dec -39 39 38 Mag 10.3 Size 5.2′ x 1.6′
This galaxy has a long bright 3′ lens shape, elongated northeast to southwest with a bright nucleus. High power and averted vision revealed the surface brightness is not even – not so much a mottling as more like an unevenness in the glow.
NGC 7412 Galaxy
RA 22 55 46.4 Dec -42 38 24 Mag 11.4 Size 3.9′ x 2.9′
Very faint roundish glow, and a slightly brighter nucleus. Averted vision brightened the glow up a tad, but not by much.
IC 1459 Galaxy
RA 22 57 10.4 Dec -36 37 27 Mag 10 Size 5.2′ x 3.8′
IC 5264 Galaxy
RA 22 56 52.7 Dec -36 33 18 Mag 12.5 Size 2.5′ x 0.5′
IC 1459 is a pretty bright hazy little 2’ envelope of light, elongated northeast to southwest, with a bright little nucleus. Its companion, NGC 5264, about 8’ to the south is only visible with averted vision – a very faint and uniform little wisp of light.
And that was it for Grus’ galaxies; but before departing faint fuzzies, a final stopover at a nice little planetary nebula –
IC 5148/50 Planetary Nebula
RA 21 59 35.2 Dec -39 23 09 Mag 11 Size 132″
This PN is located in the slender neck of Grus, only 1.2° west from mag 4.4 Lambda Gruis. With the OIII filter, it appears as a small, ghostly, and round; a soft, silky, smooth pale grey glow with a just barely perceptible dark central region.