COTM: Telescopium

Steve Crouch

Telescopium is one of the constellations introduced in 1752 by Lacaille and lies between Pavo and Sagittarius. As is normal with these recent constellations, none of the stars are particularly bright but there are a reasonable number of interesting deep-sky objects for observers equipped with moderate to large telescopes. It has to be said, however, that there is virtually nothing for the small telescope or binocular user. As usual, these observations were done from the reasonably dark skies of Theodore with a C11 and (usually) a 22mm Panoptic eyepiece.

Double Stars

My favourite double stars are those where the secondary is much fainter than the primary and ones that exhibit a pleasing colour contrast. Happily, Telescopium has pairs that fit both these categories.

I 113 (RA 18h 58.9m, Dec. -48d 30m) has a 6.7 magnitude primary and a 10.5 magnitude secondary separated by 3". I saw both components without difficulty but you may need a bit of magnification to separate them.

Dunlop 227 (RA 19h 52.6m, Dec. -54d 58m) is a much wider double with magnitude 5.7 and 6.5 components separated by 23". I saw the colour contrast as yellow and bluish-white although Hartung says orange-yellow and white. This probably just illustrates how subjective a process the assessment of double star colours is.

Planetary Nebula

IC 4699 (RA 18h 18.5m, Dec. -45d 59m) is quite small and faint (5" in diameter and 13th magnitude) but is well worth searching out. The best way of finding it is to blink with an OIII filter - the small disk then becomes reasonably obvious.

Globular Cluster

NGC 6584 (RA 18h 18.6m, Dec. -52d 13m, magnitude 8.6) is certainly no Omega Centauri but quite a nice little globular just the same. It is moderately condensed and was just resolved into stars in the fairly poor seeing conditions that I had when I observed it.

Galaxies

Telescopium has quite a few of these. The brightest is NGC 6868 (RA20h 09.9m, Dec.-48d 23m, 10.6). This galaxy is a fairly non-descript circular blur but is easy to see. Another bright one is NGC 6861 about 25' west. The group to which I would particularly like to draw attention for owners of moderate to large telescopes, however, is a 1 degree long north-south chain of galaxies starting at NGC 6708 (18h 55.6m, -53d 43m, 12.7) and NGC 6707 (18h 55.4m, -53d 19m, 12.6). This pair is reasonably challenging but both galaxies were seen fairly easily.

The next galaxy, about half a degree to the south is IC 4796 (18h 56.5m, -54d 13m, 12.3), I found reasonably easily, together with its close companion IC 4797 (18h 56.5, -54d 18m, 11.3). The final member in the chain, ESO 183-30, (18h 57.0m, -54d 33m,11.7) is surprisingly bright to have escaped an NGC/IC designation. It lies just to the west of an eighth magnitude star and is another relatively easy object. There are of course other galaxies but I didn't have time to check them all out. NGC 6758 (19h 13.9m, -11d. 5m) would be a good one for a large telescope as it has many faint companions.