Hello everyone and thanks for stopping by. This month we shall visit the constellations of Perseus, Cassiopeia and Triangulum in the north. For our southern contingent, we shall return to both Sculptor and Tucana for some more interesting objects. Here in the north the weather is starting to get much cooler and this can frequently be accompanied by drier air, resulting in some fine transparency. We begin to say goodbye to the primary plane of the Milky Way and the sky becomes less hindered by the resulting dust, allowing us to peer a bit deeper into the abyss. So good luck with your observing this month and hopefully you will have good opportunities to observe, sketch and/or image the following targets while you go about your normal night time activities.
Northern Celestial Hemisphere
NGC 869 (Perseus, open cluster, mag=5.3, size=30.0’, class=I3r):
NGC 884 (Perseus, open cluster, mag=6.1, size=30.0’, class=I3r):
The infamous “Double Cluster” in Perseus is indeed just that, a rare pairing of open clusters. Additionally they are quite young, at only approximately 12.8 million years of age. First catalogued by Hipparchus around 130 BC, beginners will often question why Charles
Messier did not include this nice cluster(s) in his famous list of objects. After all, he did include other objects that were well known and previously documented such as the Orion Nebula complex (M42/43), the Praesepe (M44) and the Pleiades (M45). In these cases he was only doing so to bring his list to a good stopping point (45) for the purposes of publication.
Ultimately, whether
Messier included this fine duo on his list or not is unimportant. What is important is that they have become an autumn staple for most northern observers. That is easily understood the first time one turns any
aperture upon them. Easily seen with the naked eye even from my typical suburban back yard, with optical aid the pair reveals a mesmerizing double concentration of stars clearly separated by an area of lower stellar density. Both are quite rich in appearance, with several brighter stars within their structure. I’ve observed it countless times over the decades with various apertures and it never ceases to amaze. So spend some time between the familiar patterns of Cassiopeia and Perseus soaking in the splendors of this fine pair of clusters.
NGC 7789 (Cassiopeia, open cluster, mag=6.7, size=25.0’, class=I2r):
This beautiful cluster, known informally as “Caroline’s Rose” was indeed discovered by Caroline Herschel on 30 October 1783 with her 4.2 inch reflecting telescope. She described it as "between Sigma and Rho
Cass, a fine nebula, very strong." It was obvious her scope did not resolve the true nature of the object, but about four and a half months later, her brother William observed the cluster, resolving it as a cluster using his 6.2 inch reflector.
Easily detected with binoculars and finder scopes as a bright concentrated glow, as one increases
aperture its true character takes shape. It presents a supremely rich smooth field of fainter stars. It is a visual treat reveals more of itself as one moves up in
aperture. In smaller apertures I find it resembles a loosely structured globular cluster with a profusion of stars overlaying the haziness of countless unresolved stars. Give this object careful look and I am sure you will agree it is one of the finest open clusters in the sky.
Messier 33 / NGC 598 (Triangulum, spiral galaxy, mag=5.7, size=66.0’x41.41.6’, SBr=14.1):
This spiral galaxy, found opposite of Mirach (Beta Andromedae) from last month’s galaxy trio (M31/32/110) is also part of the local group of galaxies. But it often confounds observers, particularly beginners, who try to observe its large diaphanous disk. Its high visual brightness can trick folks into believing it should be easy to see and they are confused as to why they are unable to – initially. This is a case where we need to pay close attention to its very large angular size and resulting surface brightness. One needs to take their time and allow their eye to adjust to the field in order to pick up its sometimes weak glow. It doesn’t have an intensely bright core like M31, so its general appearance is much more subtle.
Likely first seen prior to 1654 by Gioivanni Hodierna, he described it as a cloud-like nebulosity.
Messier independently discovered it in 1764. This galaxy has very distinct, but visually fragile, spiral arms that can be discerned in darker locations by an experienced observing eye. Its primary structural feature is the bright H-II region,
NGC 604, located about 12’ northeast of the core and discovered by William Herschel in 1784. Because of its weak surface brightness, it is generally thought of as one of the more difficult
Messier objects. It nonetheless can be spotted with binoculars, even under a typical suburban sky. That said, take your time in hunting it, because it is not the bright easy object one may think it is based on its visual magnitude alone.
Southern Celestial Hemisphere
Blanco 1 (Sculptor, open cluster, mag=4.5, size=90.0’, class= IV3m):
This large nearby open cluster is also known as the Zeta Sculptoris Cluster, as this mag 5.0 lies in the western section of the cluster field. It is fairly close and young, lying only about 850 light years distant and being only about 100 to 150 million years old. This cluster was not recognized until 1949 when the Puerto Rico astronomer Victor Blanco noticed a disproportionate number of A-type stars within the 1.5° field.
This is not an overly rich cluster, and though Zeta Sculptoris is not thought to be a true member, it does contain over 20 stars brighter than 11th magnitude, with numerous dimmer ones strewn about the field. While it is not significantly detached from the general stellar field, it is not difficult to discern. It makes a good binocular object, but applying a little more
aperture will dig deeper into its stellar population.
NGC 362 (Tucana, globular cluster, mag=6.8 , size=14.0’, class=III):
We return to the southeast corner of Tucana for this bright globular cluster. Unfortunately it is overshadowed by the great
NGC 104 (47 Tuc) just over 4’ to the southwest. While it is nowhere near the level of 47 Tuc, it still is a beauty in its own right. Under excellent skies it can be glimpsed with the naked eye, but it comes into its own when one applies optical aid. It displays a very bright and dense core that yields some very modest resolution in its outer halo with small to medium apertures.
James Dunlop discovered this beautiful object in 1826, and in his notes compared it to the object we now know as
Messier 2 in Aquarius. Try putting this object near the northeastern edge of your field of view and pull
NGC 104 into the same field. You can then enjoy the wonder of having two bright, though radically different, clusters in the same eyepiece field.
NGC 292 (Tucana, barred spiral galaxy, mag=2.3, size=5.3°x3.4°, class=14.1):
While you are looking at the two globulars (
NGC 362/104), you will also find this deep southern object very nearby. Immediately south of
NGC 362 and east of
NGC 104, the Small Magellanic Cloud provides an interesting counterpoise to these fine globulars. This satellite galaxy of our own Milky Way is a very large angular target, and though it has a bright visual magnitude, this light is spread over a large area reducing its suface brightness. This makes it vulnerable to localized sky glow or poor transparency conditions. It makes a fine binocular target because of its large size, but may appear as nothing more than a subtle brightening against the backdrop of the night sky. From darker areas it is a very easy naked eye object, but a telescope will begin to reveal some interior structure, such as nebulae and star clusters. This object was undoubtedly seen by numerous explorers and indigenous peoples because of its brightness, but the first record we have of it is from 1501 by Amerigo Vespucci
That is it for this month. I hope that you find this month’s objects worthy of your time and effort, whether you are strictly a visual observer, like to dabble in sketching or are a dyed in the wool imager. Regardless, I hope you will add them to your plans as you make your way around the universe in search of deep sky treasure. I would like to thank team member John Baars for suggesting
NGC 7789 for this month’s challenge. While I had a different Cassiopeia open cluster in mind, I didn’t mind swapping it for John’s suggestion, as Caroline’s Rose is a beautiful cluster indeed. I also wish to apologize for being tardy this month. I was feeling a big sluggish and off my normal game lately, and simply was slow to get around to compiling this month’s targets for your enjoyment. I plan to be right on time for December and beyond however.
So let’s get out there and enjoy what the night sky has for us to enjoy. It’s a show with free admission – well other than the equipment needed to see the show in detail.
So have fun and learn which in turn increases the fun aspect!