First View Through A 22 Inch

FIRST VIEW THROUGH A TWENTY-TWO

The July new moon at Wiruna presented some more clear skies at Wiruna, and the new 56cm scope fitted with a ServoCat goto drive got another chance to inspect some more deep sky objects as part of the initial setup of the ArgoNavis and drive system.

Both Paul Hatchman and Chris Ross had provided me with some technical assistance with the process of ironing out some minor issues, and I was pleased enough with the tracking and performance of the scope to feel confident enough to proceed with some detailed observing. I had intentions of doing some bright Messier objects to get a feel for the tracking controls and the general functionality of the scope and there was nothing better than to start with NGC 6853 the famous "Dumbell Nebula" or Messier 27.

NGC 6853 (M27)

This object was the first planetary nebula to be discovered; by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and its diameter of about 8 arcminutes, it is easily visible in binoculars, and a great observing target in amateur telescopes. This PN appears to be shaped like a prolate spheroid and is viewed from our perspective along the plane of its equator. In the eyepiece of the 56cm dob at 166x mag and the use of an Oxy-III filter this object presents an impressive sight, at some 9.0' x 6.0' in size this objects occupies the centre of the field with its classic "dumbell" shape, though the extra aperture of the 56cm makes the fainter nebulosity much more prominent, hence the dumbbell shape is not as immediately evident as it would be in a smaller scope.

The object is set within a field of rather pretty stars and they frame the object nicely.Steve Gottlieb from the NGC/IC database describes NGC 6853 as follows:"NGC 6853 = M27 = PN G060.8-03.6 = PK 60-3.1= Dumbbell Nebula; 19 59 36.3 +22 43 16; V = 7.1; Size 480"x340""18" (8/23/03): breathtaking view at 215x; with the fainter but larger outer lobes increasing the dimensions to nearly 7.5'x6' and the ends of the major axis seem to open up and bulge out.

With careful viewing, ~10 superimposed stars can be counted including the easy mag 13.8 central star."As you can see in the sketch, NGC 6853 is a magnificent planetary that views well in all sizes of telescopes regardless of whether you use a nebula filter or not, making it a visually satisfying experience.

NGC 6876, NGC 6877, NGC 6880, IC 4981

The next object of interest lies within the southern sky in the form of a group of galaxies in Pavo. This was an interesting group in the 56cm dob at 314x mag, with the brightest member being NGC 6876 as can be seen in the sketch. NGC 6876 is at the very top left of the 15' field followed by NGC 6877 then some 9' further down is the nice edge on galaxy NGC 6880 and then the small IC 4981. All of the galaxies were easily visible in the 56cm at 314x and they spread across the 15' making a pleasant view.

A description from the NC/IC database is as follows:"NGC 6876 = ESO 073-IG035 = LGG 432-001; 20 18 19.1 -70 51 30; V = 11.1; Size 2.8x2.2; SB = 13.0; PA = 80d""18" (7/10/02 - Magellan Observatory, Australia): this is the brightest member of the Pavo Group (mean redshift 3800 km/s). At 171x, it appeared moderately bright and large, slightly elongated ~E-W, 1.5'x1.3', containing a brighter core. A star is at the south edge 0.5' from center. Forms a close pair with N6877 just 1.5' following. Other members of the group which I observed include N6872, N6876, N6880, IC 4970, IC 4972 and IC 4981."

Steve Gottlieb

Stephan's Quintet

The last object in this Post Mortem was observed during the September new moon at Wiruna when the sky provided some superb conditions on the Thursday night into the Friday morning. The constellation Pegasus was noticeable over in the northern sky, so I though it may be an idea to call in on an old favorite in the form of "Stephan’s Quintet" just to see if 15cm of extra aperture can make a major change in perspective on an object. Within the eyepiece at 314x mag this impressive compact group is easily resolved in the 56cm dob with five somewhat small and diffuse galaxies of an average size of some 1' x 1'.

Stephan’s Quintet is perhaps one of the most famous of the Hickson compact groups being number 92 in the list.This unusual system has often been used as proof that the redshift is not truly a distance indicator, which would completely overturn current cosmology, because although four of the galaxies have similar, large redshifts, the fifth (NGC 7320), although apparently a member of the group, shows a much smaller redshift.

Conventional theory states that the low-redshift galaxy is in a nearby group (the NGC 7331 group) and by coincidence appears on the sky projected against a distant background group. Opponents point to debris and tails around the low-redshift galaxy, suggesting that it is interacting with the high-redshift systems, which would require that all five galaxies be at the same physical location in space.The quintet is a challenge object for smaller scopes; however a dark sky site will be essential as the galaxies are of an average mag of 14.0 making them rather faint.

The new 56cm f5 dob was certainly performing to expectations, despite all the irritating little problems. Over the coming months at Wiruna there should be ample occasions were some clear nights should provide some more stunning views of the many and varied range of deep sky objects.

Clear Skies.