TSS Monthly DSO Challenge – October 2021
Posted: Sat Oct 02, 2021 12:03 am
Hey there, it’s a new month! That means that once again it is time for me to share with you a few objects that I hope you will add to your normal observing sessions this month. The objects highlighted this time around are so popular and impressive that I am sure many of you likely already have plans to swing by them over the next couple of months should they grace your sky and even had I not highlighted them.
For the northern folks we will stick with a galaxy trio in Andromeda that is a perennial favorite, and often the first galaxy targets many beginners seek out. You southern folks have a couple of globular clusters, one of which is one of the most glorious objects in the night sky. Plus a bright galaxy that is another one of the night sky’s true treasures.
So get out your scopes and eyepieces, your charts (paper or electronic), your imaging equipment and/or your sketching pad and tools and get busy. Report back here of your results so we can all share in your experiences with this month’s sky treasures. We are all part of one of the greatest hobbies one can have – spending our free time communing with the night sky and all the glorious sights that it spreads out before us.
Northern Celestial Hemisphere
Messier 31 / NGC 224 (Andromeda, spiral galaxy, mag=3.4, size= 3.2ºx1º, SBr=13.3):
The famous Andromeda Galaxy is one of the first galaxies, if not the first, that a great number of beginners pursue and try to observe. It was first mentioned by the Persian astronomer Al-Sûfi as a "nebulous smear" in his "Book of Fixed Stars" (964 AD). The first recorded telescopic observations were made by the German astronomer Simon Marius in 1612. He described its appearance as "resembling the light of a burning candle, at some distance, shining through translucent horn." It eventually found its way into CharlesMessier ’s catalogue of deep sky objects. It was not until 1925 (thanks to Edwin Hubble) that it was recognized to be a distant galaxy, like our own, having been considered a nebula within the Milky Way until that time.
We are blessed to have this beautiful galaxy close enough that we can observe it through our instruments. Those dealing with noticeable light pollution often only glimpse the central portion of its galactic disk in and round the core. The dimmer outer arms may be washed out. From dark skies we can begin to see the outer structure visually as well as some inner details. Its bright visual magnitude can lead to confusion about its visual appearance. Because of its very large angular size, that light is spread out leading to lower surface brightness as seen by the numbers above. That is why it never appears visually to its full angular extent. Regardless, it is a glorious object in our backyard at a mere 2.2 million light years distance. Enjoy it whether you observe visually, do imaging or like to sit at the scope for extended periods to sketch what you see.
Messier 32 / NGC 221 (Andromeda, elliptical galaxy, mag=8.1, size=8.5’x6.5’, SBr=12.2):
This satellite galaxy ofMessier 31 is not difficult to pick up when one is observing M31. It is located just over 24 minutes of arc south of the core of its dominant partner. When one is observing from brighter locations it often appears well separated from M31 visually due to the observer only being able to see the central portion of the larger galaxy. From darker locations, M32 appears very near or slightly involved in the outer edges of M31’s outer extensions. Appearing mostly as a small rounded evenly illuminated glow, it can give the impression of being an unresolved globular cluster.
Discovered by Guillaume Le Gentil in 1749, it was independently discovered byMessier . He was observing M31 in 1757 unaware of Le Gentil’s find and noted the presence of a second nebula, which was added to his list of objects. Of the two main satellite galaxies of M31, this one is the easiest to see in our scopes.
Messier 110 / NGC 205 (Andromeda, elliptical galaxy, mag=8.1, size=19.5’x11.5’, SBr=13.7):
This elliptical galaxy, which is also a satellite of M31, can often be a source of consternation for beginning observers. While it has a comparable visual magnitude to that of M32, its larger angular size reduces its surface brightness noticeably relative to M32. From areas of increased light pollution, in my experience, I can always see M32 but have sometimes not been able to see M110 if transparency happens to be weak. When visible it typically will appear as a small and smooth oval disk, well removed about 36.5 minutes of arc to the northwest of the core of M31.
This galaxy was ostensibly discovered by Caroline Herschel in 1783. Though observed a full decade earlier by CharlesMessier , this fact was not published until 1798, well after the Herschel observations. This fact was ignored by Dryer when compiling the New General Catalogue (NGC ), which continued to give discovery credit to Caroline Herschel. In the below drawing of M31 by Messier and published in 1807, one can clearly see he has depicted both M32 and M110. In 1966 Kenneth Glyn Jones thought is appropriate to add this object to the long posthumous Messier catalogue as object #110. So in the end, with all the facts known, it certainly appears that Messier deserves credit for this object’s discovery.
Southern Celestial Hemisphere
NGC 104 (Tucana, globular cluster, mag=3.8, size=30.9’, class=3):
Known by the stellar designation of 47 Tucannae as designated in Bode’s 1801 catalogue, discovery credit is given to Nicolas-Louis de Lacaille during the 1751-52 timeframe when he was observing from South Africa with his ½ inch telescope that could see its non-stellar character. He described it as looking "like the nucleus of a fairly bright comet."
This globular is one of the grandest showpieces in our visible universe. Slightly dimmer thanNGC 5139 (Omega Centauri), it gives up little in beauty to that amazing cluster. This object, when seen at higher elevations above the horizon puts on a stunning show in most any aperture . Then as aperture increases it fills the field with an unfathomable number of stars at the periphery which continue to compress into a blazing unresolved core. Turn your scope its way and feast your eyes on a spectacular sight.
NGC 253 (Sculptor, barred spiral galaxy, mag=7.2, size=29.0’x6.8’, SBr=12.2):
Known colloquially as the “Silver Dollar Galaxy”, the “Silver Coin Galaxy” and even “Caroline’s Galaxy”, it was indeed discovered by Caroline Herschel in 1783. Per her brother William’s notes, she observed it with a "small Newtonian Sweeper of 27 inches focal length, and a power of 30." In theNGC , Dreyer described it as "a most remarkable object, very very bright, very very large, very much extended, gradually brighter middle."
This treasure of the night sky is easy to pick up in binoculars and asaperture increases, so do the visual rewards. Seen from brighter areas one can make out an elongated oval of uneven brightness. From darker areas, this uneven appearance manifests itself into a heavily mottled appearance, with a weak and broadly brighter central region. The higher one can see it above the elevation the better it appears. However, even mid-northern latitude observers can get a decent show from this object, particularly if they can get themselves to a darker location.
NGC 288 (Sculptor, globular cluster, mag=8.1, size=13.8’, class=10):
Less than 2° southeast ofNGC 253 one can find this nice globular. While certainly not in the class of NGC 104 and other bright globulars, it can still present a nice view, particularly for those in darker locations. It is bright enough to pick up in binoculars, but looks better with a bit more aperture . Through mid-sized apertures it can appear granular, just at the edge of resolution. With a little more aperture , some resolution is possible, overlaying a persistent backdrop haziness of unresolved members. The core is not dense, thus its surface brightness is a little lower overall than some more compressed globulars.
Missed by Caroline when she discoveredNGC 253 in 1783, it was discovered by her brother William just two years later. His notes state that “a great many of the stars visible, so that there can remain no doubt but that it is a cluster of vS (very Small) stars." Take a look at this cluster and see how it appears to you. As with most objects, each set of eyes can see things subtly different. It is a quick hop from the beautiful NGC 253 and very worth the time to look it over.
That is it for this month. Nice objects to add your plans, and as I mentioned above, some of them may well already be in your sights over the coming nights anyway. 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 that is.
So have fun and learn which in turn increases the fun aspect!
For the northern folks we will stick with a galaxy trio in Andromeda that is a perennial favorite, and often the first galaxy targets many beginners seek out. You southern folks have a couple of globular clusters, one of which is one of the most glorious objects in the night sky. Plus a bright galaxy that is another one of the night sky’s true treasures.
So get out your scopes and eyepieces, your charts (paper or electronic), your imaging equipment and/or your sketching pad and tools and get busy. Report back here of your results so we can all share in your experiences with this month’s sky treasures. We are all part of one of the greatest hobbies one can have – spending our free time communing with the night sky and all the glorious sights that it spreads out before us.
Northern Celestial Hemisphere
The famous Andromeda Galaxy is one of the first galaxies, if not the first, that a great number of beginners pursue and try to observe. It was first mentioned by the Persian astronomer Al-Sûfi as a "nebulous smear" in his "Book of Fixed Stars" (964 AD). The first recorded telescopic observations were made by the German astronomer Simon Marius in 1612. He described its appearance as "resembling the light of a burning candle, at some distance, shining through translucent horn." It eventually found its way into Charles
We are blessed to have this beautiful galaxy close enough that we can observe it through our instruments. Those dealing with noticeable light pollution often only glimpse the central portion of its galactic disk in and round the core. The dimmer outer arms may be washed out. From dark skies we can begin to see the outer structure visually as well as some inner details. Its bright visual magnitude can lead to confusion about its visual appearance. Because of its very large angular size, that light is spread out leading to lower surface brightness as seen by the numbers above. That is why it never appears visually to its full angular extent. Regardless, it is a glorious object in our backyard at a mere 2.2 million light years distance. Enjoy it whether you observe visually, do imaging or like to sit at the scope for extended periods to sketch what you see.
This satellite galaxy of
Discovered by Guillaume Le Gentil in 1749, it was independently discovered by
This elliptical galaxy, which is also a satellite of M31, can often be a source of consternation for beginning observers. While it has a comparable visual magnitude to that of M32, its larger angular size reduces its surface brightness noticeably relative to M32. From areas of increased light pollution, in my experience, I can always see M32 but have sometimes not been able to see M110 if transparency happens to be weak. When visible it typically will appear as a small and smooth oval disk, well removed about 36.5 minutes of arc to the northwest of the core of M31.
This galaxy was ostensibly discovered by Caroline Herschel in 1783. Though observed a full decade earlier by Charles
Southern Celestial Hemisphere
Known by the stellar designation of 47 Tucannae as designated in Bode’s 1801 catalogue, discovery credit is given to Nicolas-Louis de Lacaille during the 1751-52 timeframe when he was observing from South Africa with his ½ inch telescope that could see its non-stellar character. He described it as looking "like the nucleus of a fairly bright comet."
This globular is one of the grandest showpieces in our visible universe. Slightly dimmer than
Known colloquially as the “Silver Dollar Galaxy”, the “Silver Coin Galaxy” and even “Caroline’s Galaxy”, it was indeed discovered by Caroline Herschel in 1783. Per her brother William’s notes, she observed it with a "small Newtonian Sweeper of 27 inches focal length, and a power of 30." In the
This treasure of the night sky is easy to pick up in binoculars and as
Less than 2° southeast of
Missed by Caroline when she discovered
That is it for this month. Nice objects to add your plans, and as I mentioned above, some of them may well already be in your sights over the coming nights anyway. 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 that is.
So have fun and learn which in turn increases the fun aspect!