Starting at the northern end of the meridian, as usual, (because the apparent motion of the sky is greatest there) we find our friends of last month M31, the Great Andromeda Galaxy and its two companions M32 and M110 have just passed the meridian this month. Take a few moments to look at them again and take in all the detail we mentioned in last month's notes. This is prime stuff!
When you are ready, look to the south-east (up and right), following the stars Mu and Beta Andromedae just across the border of the constellation of Andromeda and into Triangulum, where lies the fabulous spiral galaxy M33, the "Pinwheel Galaxy". Its given brightness of magnitude 6.2 is a little misleading; because the galaxy is so large and diffuse, it seems much dimmer. There is often controversy over whether it is possible to see M33 naked eye. Some of our members claim to have seen it from Wiruna, but it has always eluded me there. However, I have seen it from the deck of a yacht in the Whitsunday Islands, where the skies are extremely dark and steady. That was quite a thrill! When looking for it, use your widest field eyepiece (the one with the largest number on it). It will appear as a soft hazy patch, just a little brighter than the sky background, with the core as the most visible part.
Once you spot it, scan over the whole area. If necessary, direct your vision slightly to the side of the field, thereby using "averted vision", or the more sensitive rods of your eyes to pick up the faint but rich detail that is everywhere. At the centre is the bright oval (or "barred") core. Two huge but faint arms spiral out from either end of the core and can be traced well round the circumference of the galaxy. Larger apertures will show impressive knots and structure throughout the disk and especially along the arms. On a night with steady seeing an O-111 filter can reveal even more structure. This is a magnificent galaxy, but demands patience before it reveals all its rather faint detail. Give it the time it deserves!
Our next target, the spiral galaxy M74, lies almost fifteen degrees south (up) near the eastern border of the constellation Pisces. It can be found about one degree northeast of the 4th magnitude star Eta Piscis. At magnitude 9.4, it is much smaller and dimmer than our earlier objects, but is suitable for most smaller scopes which should show it as a roundish haze. With more aperture we can see some of the detail recorded in my observing notes: "A nearly face-on spiral galaxy, with a large barred core, a long curved pair of arms with many knots and fine structure."
A little higher (south) takes us across the celestial equator and into the galaxy-rich constellation of Cetus. Well to the western side of the constellation lies NGC 157, a 10th magnitude spiral galaxy, which should be visible in many smaller scopes. However it will require some aperture to reveal the detail my observing notes record: "a large almost face-on spiral, seen as an oval haze, almost pear-shaped with a faint core and very extensive, curving arms. These show much structure, including what appear to be tiny stars but are actually small H-11 regions in the arms. Looks much like a smaller M33. An interesting object".
About four degrees southeast we come upon the rather large, magnitude 10.9 planetary nebula, NGC 246. Smaller scopes may have some difficulty seeing detail in this extensive, dim ring, but more aperture reveals much of interest. My notes record: "A large and diffuse ring. There is a very irregularly bright outer ring with several bright segments, especially on the southwest and northeast quadrants. The inner ring shows structure and scalloping. The central disk contains three magnitude 10 and two magnitude 11 stars. The O-111 filter greatly enhances the whole appearance. An excellent object".
Eleven degrees further south and still within the border of Cetus lies another large, nearly edge-on galaxy, NGC 247. At magnitude 9.2 it is a reasonably bright object even for smaller scopes which should show its elongated shape and some mottling of its surface. Larger apertures will show a profusion of detail as my notes record: "A great object when seen on the zenith. It is a large, nearly edge-on, spiral galaxy. The large barred core appears offset from centre to the south. The disk is very irregularly long and chunky with massive H-11 regions, dust and spiral structure. There is a bright star on the northern end of the disk and fainter stars on the south end. A great galaxy."
Due south by four degrees, just over the border of the constellation of Sculptor lies another massive elongated galaxy, NGC 253, the brightest of the Sculptor group. Known in the USA as "The Silver Dollar Galaxy", it is a most impressive sight, especially when seen almost at the zenith. I well remember the first time I saw this galaxy. It was after a long night of chasing faint fuzzies and the impact of coming on this huge, shiny object was stunning, leaving me thinking if there is intelligent life anywhere else in the universe, it is likely to be in this galaxy! NGC 253 can have that sort of effect on one. My observing notes show the same excitement: "A superb, huge object. It has a greatly extended thick disk traceable for three high power fields, either way from the core. The core is complex, appearing to be slightly off centre, with superimposed stars and structure. The remainder of the disk shows bright knots, arms, dust and a dark lane. Just wonderful!"
Slightly over a degree south-east of NGC 253 is a small 8th magnitude globular cluster, NGC 288 which is not very strongly condensed and resolves in larger aperture to hundreds of tiny stars. Another nine and a half degrees east-south-east lies NGC 613, a 10th magnitude spiral galaxy that may be rather dim in smaller scopes, but shows interesting detail in larger apertures. According to my notes: "Shows a very large oval disk with faint arms, and knots. There is a small bright oval bar, off-set from the apparent centre of the disk." There are many more smaller and fainter galaxies in Sculptor, including the bright NGC 7793 off in the far west of the constellation, which those with larger scopes might like to seek out. Meantime, we shall move on to explore the brightest areas in the wonderful Small Magellanic Cloud (SMC).
Some months ago, Universe published a monumental series of articles on the SMC by it's then Observing Officer, Andrew Murrell. I encourage you to read these before starting any programme of observing the Cloud. Andrew describes all the areas of interest, including many objects that are below our brightness limit, so we will have to skip those tonight. However, observers with larger apertures will find Andrew's article a very useful guide for looking into the detailed structure of the SMC.
Last month we examined the magnificent globular cluster NGC 104, located right on the western edge of the SMC It is worth another look tonight and is a good starting point for our tour of the SMC. If we move up to the top (north) of the Cloud, we find another very bright globular cluster, NGC 362. This object is actually in our Milky Way galaxy and only coincidentally appears close to the LMC. I saw the following detail: "It appears round but slightly flattened on the south-east side. There is a very bright, small dense core with spiral patterns of resolved stars going out to the edge like a spiders web over a 5 point star. Very pretty."
Moving due south into the Cloud, we soon encounter NGC 371 of which I noted: "This is a bright stellar association. An O-111 filter greatly enhances several round nebular patches within and to the east of the association. Many stars magnitude 13 and 14 are resolved within the association." Several more NGC and IC numbers have been allocated to details in this area, but are of little real interest to us. A short move to the southwest brings up another bright area of stars and nebulosity, NGC 346. In this area I found: "a bright dense central nebula surrounding a large cluster with several stars of magnitude 11-13 resolved. The shape is a flattened oval, aligned east/west, with more nebulous patches close by to the south. The whole area is much enhanced by an O-111 filter."
Another short move to the southwest brings us to the very bright cluster NGC 330, a landmark almost at the centre of the SMC. According to my observing notes: "A well resolved, very elongated, oval cluster, aligned east/west. Resolved stars of magnitude 13-14 are very densely packed in the centre, with sharply defined, resolved edges to the cluster. A very obvious and spectacular object." If we track down through the Cloud to the southwest, we find a maze of small clusters and nebulae that need careful navigation. Because they are small and rather faint, they are beyond the scope of these articles, but are well worth taking time for a good look in future. For tonight, let us go on to the southeast, where we soon find the small 10th magnitude globular cluster NGC 419. It appears as a small patch of mottled haze in smaller scopes, but larger apertures show an object strikingly like a Milky Way globular, slightly resolved, dense at the centre with a soft edge. Remember that we are seeing this cluster at a distance of about 220,000 light years, so it must be very large.
Further to the southeast we encounter an extensive, complex, chain of clusters and nebulae classified as NGC 456/460/465. This complex spreads over a low-power field, appearing as connected clumps of stars and nebulous haze, aligned roughly east to west. For binoculars and small scopes, they are virtually a single, bright area of interest. Larger apertures reveal much interesting detail as my observing notes record:
"NGC 456 is at the west end of the complex. It is a very bright, oblong, unresolved but intense cluster, about magnitude 11, set in the edge of a large nebula which shows much structure. There are smaller detached nebulae adjacent, containing resolved stars. The nebulae respond well to an O-111 filter. Slightly east is NGC 458, a large, round, centrally condensed haze, about magnitude 11, with a soft edge. Various authorities quote this as a "blue globular cluster" It is an interesting object. Further east again is NGC 460, a small, just resolving, open cluster, about magnitude 12, set within a larger nebula of about magnitude 13.5. An O-111 filter enhances and brightens parts of the nebula, showing some structure and making the whole appear crescent shaped. Three stars about magnitude 14 are just resolved in the cluster. Finally, NGC 465 is a very large open cluster, about magnitude 13 showing four resolved stars about magnitude 12 surrounded by faint haze on which an O-111 filter has no effect. The whole complex 460/465 overflows the low power field, flows west to east and lights up wonderfully well with an O-111 filter."
There we conclude our tour of the brightest objects in the SMC. I hope it whetted your interest and stimulated you to look deeper into the literally dozens of fainter but interesting objects that are to be seen in the fascinating Small Cloud. We are lucky to have such a marvelous area of sky all to ourselves - our northern hemisphere counterparts, who cannot see either Cloud, are desperately envious. Yet how many southern hemisphere observers are really familiar with them? Sadly, too few. Make sure you don't miss out. I'll see you again next month.