Grus the 'Crane'

"The Spaniards call it Flamengo: and it is described with the wings spread abroad, and as it were striking with his bill at the South Fish, in that part where he boweth himselfe. This Asterisme consistith of 13 Starres: of which, that of the second magnitude in his head is called, the Phoenicopters Eye: and it hath two other Stars also of the same magnitude, one in his backe, and the other in his left wing. And those two which are in the middle of his necke, Paulis Merula in his first booke of his Cosmography, calleth his Collar or Chaine"

Chilmead's Treatise

The reference above to Phoenicopterus, the Flamingo, as described by Chilmead in his Treatise is obscure and appears to have been rarely used. It was formerly given the title of Grus the Crane, by Bayer in 1603. In ancient Egypt, a crane was the symbol of a star-observer, so the title seems most appropriate.

The biblicist Caesius saw this group as the "Stork in the Heaven", whilst Julius Schiller entwined it with Phoenix to form "Aaron the High Priest".

There are 13 stars of 5th magnitude, packed within the Crane's 366 square degrees. Unfortunately, because of Grus's position away from the plane of the Galaxy, there are no open or globular clusters. There are therefore, a number of faint galaxies, quite often three or more in the same low power field but needing a dark sky to see at all.

Alpha or Al Nair, the 'Bright One' according to the Arabs, shines at apparent magnitude 1.7. This B type main sequence or sub-giant star lies 101.4 (±1.4) light years away, shining with the light of 256 Suns. Alpha is a possible member of the AB Doradus Group, all having a similar proper motion across the sky.

Just 16'.3 to the south-east lies NGC 7213, an S0 type spiral of reasonable surface brightness. However, nearby alpha's light intrudes so high power must be used to exclude alpha from the field. Then a small, elliptical shaped glow can be seen, brightening toward the middle. Here we have what is called a lenticular galaxy, similar in shape to spirals but containing only the older Population II stars usually seen in elliptical systems.

Moving west of alpha, just 3.4 degrees brings us to the double star Brs0 15. This yellow solar type star lies relatively close to the Sun at 51.0 (±0.44) light years and shines 1.2 (±0.02) times brighter. Well separated from this magnitude 5.7 star to the north is a companion, shining at apparent magnitude 8.7.

Beta is a magnitude 2.1 M5 star that lies 5.9 degrees to the east of alpha. This bright giant or perhaps red giant star lies 170.1 (±5.7) light years away and has a luminosity of 336 (±22) Suns.

Almost midway and north of a line joining alpha and beta lie pi 1 and pi 2, in no way related but forming a nice contrast optical double. Pi 1 is a magnitude 6.4 orange-red carbon star lying 499 (±78) light years distant. The computed luminosity is 53 (±16) that of the Sun. There is a close companion G-type star of magnitude 10.8 about 2".7 in separation.

Pi 2 is a yellow F3 giant or sub-giant star of magnitude 5.6. The distance is closer at 132.5 (±3.3) light years and the luminosity 7.75 (±0.39). It also has a close companion of magnitude 11.3 but with the separation only 4".6 and a brightness difference of nearly 6 magnitudes, high power and a well collimated telescope is needed.

If we now move to the south-eastern corner of Grus and identify epsilon, a sweep of 3 degrees east and slightly north brings us to Dunlop 246. This lovely pair of yellow F5 stars were discovered by J. Dunlop in 1825. Their magnitudes are 6.1 and 6.8 and the separation is 8".6. The measured distance is 129.7 (±4.3) light years and the luminosity 6.24 (±0.41).

Moving to the north-eastern portion of Grus, we can locate theta, a triple system with a combined magnitude 4.3. A companion of magnitude 6.8 lies close and a further family member 160".0 away to the west and slightly north shines at magnitude 7.8.

A line of galaxies run north-east of theta including a lovely triplet of NGC 7552, 7582 and 7590. Starting from theta, we move 32".1 east to NGC 7496, a bright spiral galaxy with a brighter central region. A further 55'.6 to the east brings us to the spiral NGC 7531. It is a lot smaller but shows a brighter central region a well.

A hop of one degree to the north exposes a trio of bright spirals. NGC 7552 is the first of them, pretty small in size and round in shape with a small bright nucleus. NGC 7582 lies 27'.6 to the north-east, larger than the former and showing an extended form and a bright middle region. NGC 7590 lies 9'.8 north-east, also pretty large with an obvious extended shape and a brighter middle. All three show different orientations within a wide field eyepiece.

A fourth galaxy, NGC 7599 lies east of NGC 7590 but is extremely faint and needs a large aperture to see. In fact, Grus is covered with faing galaxies, needing a dark sky and a large telescope to do them justice.

The pick of the others is NGC 7410 lying 4.4 degrees to the north northwest of theta. This bright and large spiral appears edge on with a much brighter central region.

Clear skies and good hunting