TSS Monthly
DSO Challenge – December 2021
This month’s column marks the twelfth edition, of the
TSS Monthly
DSO Challenge, and it has been my privilege to present these to you each month in hopes that it inspires everyone to get out there to observe, sketch and or image some interesting deep sky objects. Though our foot traffic for this past year has been a bit light, I am still committed to its continuation. I hope that with the coming new year we will see an uptick in readership and participation for the challenge. I encourage all to add these monthly targets to your regularly planned observing and/or imaging sessions. While they may not be new to each individual, there is still enjoyment and benefit to returning to previously observed/imaged objects. With that I will wish all the best for the holidays that upon us and that Santa brings you something you want this year. We know the sky will keep bringing us unimaginable beauty and surprises, so partake and enjoy!
Northern Celestial Hemisphere
Messier 45 (Taurus, open cluster, mag=1.2, size=1.7°, SBr=10.9, class=I3rn):
The infamous Pleiades cluster has been known since antiquity and represents the mythological seven daughters of Atlas. Hence they are also known as the Seven Sisters. The cluster is thought to have formed from a complex similar to the Orion Nebula, and lies at a distance of approximately 444 light years. Its age is estimated to be in the 75 to 150 year range and it is slowly moving in the direction of what we see is the feet of the constellation Orion. First observed telescopically by Galileo and a sketch in his Starry Messenger depicts 36 stars in the group. It is generally thought that
Messier added this well known object to his first catalogue (along with M44) to round out his first edition to a nice number (45) of objects.
For a good many of us our first experience with the Pleiades is we notice it with naked eye as a tiny dipper-like
asterism in northwestern Taurus, near its border with Aries. In fact I have been asked a few times if it was the Little Dipper
asterism of Ursa Minor. For those that truly don’t know the sky, it’s not overly difficult to see how they might be confused. After all it is little and it looks like a dipper.
This truly open cluster is best viewed with lower magnification in a wide field. One can get a better grasp of its structural characteristics, plus it is simply a pretty view. A favorite thing to do is to see how many of the Seven Sisters one can spot with the naked eye.
A unique bonus to the cluster is the presence of very delicate reflection nebulae around some of its stars, associated with its birthing complex. To have a chance to glimpse these diaphanous nebulae one should be in dark skies. But one needs to be careful about confusing glaring and scattered light from the bright stars in the cluster with seeing the reflection nebulae. Your optics should be clean and fog-free, or one can get the impression of seeing the nebulae, but in reality are only seeing scattered light within the optical path. One way to confirm its presence is to look at other nearby stars of similar brightness that are not associated with the cluster. If you are indeed seeing the presence of the nebula, then the unassociated stars should be nebula-free. So give this perennial favorite a careful study and see if you can pick up a hint of its elusive bonus.
NGC 1582 (Perseus, open cluster, mag=7.0, size=24.0’, class= IV2p):
A little over 2.5° NNW of the magnitude 4.2 star 58 Persei in eastern Perseus, one can locate this curious cluster. Discovered by William Herschel in 1788, he described it as
"a cluster of coarsely scattered large stars, pretty rich, above 20' diameter." What we will see in our scopes will of course depend on conditions,
aperture and experience. Its field is dominated by a scalene triangle of three 8th magnitude stars in its center. The rest of the field is a scatter of 11th mag and fainter stars. From its center toward the southwestern quadrant of its field there is a noticeable void of very low stellar density. Overall it is a scattered grouping that does not display any areas of significant concentration. Some sources indicate that it is an
asterism rather than a bound cluster, but it seems the jury may still be out on that. Give it a try and see how your mind’s eye interprets its structure.
Messier 1 / NGC 1952 (Taurus, supernova remnant, mag=8.4, size=8.0’x4.0’, SBr=11.9):
For our final northern object we return to the realm of the celestial bull. Discovered by John Bevis in 1731 and was independently rediscovered by Charles
Messier in 1758.
Messier 1 is the only supernova remnant in his list of objects. This object has the reputation of being one of the more difficult of the
Messier objects, particularly from areas of increased sky glow. However, over the decades I’ve found this to more of a result of inexperience and perspective than true difficulty. Often beginners will move too quickly while searching for new objects, and frequently pass over the object without noticing its presence in the field of view. Simply, they lack the perspective of what they should see, and thus struggle to find the object. However, most will find that once they slow down, finally see it and gain that valued perspective of what it is they will see, then subsequent attempts to find
Messier 1 are more successful.
This object is the remnant of a supernova recorded by Chinese astronomers in the year 1054, and is commonly known as the Crab Nebula, a term coined by William Parsons because of its resemblance to a crab in a sketch he made using 36 inch telescope. What most amateur astronomers typically see is a mostly evenly illuminated small oval glow. With enough
aperture, and particularly from darker areas, one may glimpse unevenness within its body and even ragged edges indicative of its filamentary structure. Regardless of the visual perception one obtains, it is interesting to consider that you are beholding the results of a cataclysmic event that formed the remnant and left behind a pulsar at its heart.
Southern Celestial Hemisphere
NGC 2070 (Dorado, bright nebula, mag=5.0~, size=30.0’x20.0’:
This amazing nebula is actually an enormous HII region located in the Large Magellanic Cloud (
LMC), a satellite of the Milky Way. In the eastern section of the
LMC, it was discovered in 1751 by Nicolas-Louis de Lacaille using his half-inch 8x telescope while in South Africa. Though the
LMC can all but disappear in light polluted skies, the Tarantula nebula can easily be seen with optical aid. In fact, from darker areas it is an easy naked eye object as a small fuzzy glow. Also known as 30 Doradus and more informally as the Tarantula Nebula, it is the largest known stellar nursery in the sky. Per Astronomy.com, it is roughly 1,000 light years across as compared to the Orion Nebula at 25 light years across. It is also just over 100 times more distant than the Orion Nebula, and per the article on Astronomy.com, if it were at the same distance from us as the Orion Nebula; it would cover an area about the width of 75 full moons. That gives one some perspective on how huge this complex is.
Embedded at the center of the nebula complex is the open cluster designated R136. A second cluster, northwest of R136 carries the designation of Hodge 301. A third major cluster associated with the nebula,
NGC 2060 lies southwest of R136. As one can see, the Tarantula Nebula is indeed a busy neighborhood. If you are fortunate to have this amazing object in your sky, take some time to study it and/or image it. The Tarantula Nebula is a stunning nebula, and amazingly bright at over 160, 000 light years distant in another galaxy.
NGC 1313 (Reticulum, barred spiral galaxy, mag=8.7, size=9.2’x7.2’, SBr=13.0):
In the truly deep southern sky one finds the constellation of Reticulum. Its main stars form a narrow diamond shape in the sky just northwest of the Large Magellanic Cloud. In the very southwest corner of the constellation one finds this bright two-armed barred spiral. Discovered in 1826 by James Dunlop, it is one of the true beauties of the southern sky. Its dominant feature is the thick and bright central bar, which may be what most observers will see in their eyepieces. The spiral arms are rife with HII star forming regions and when seen are heavily mottled in appearance. At only about 22 million light years distance, it is fairly close to us – relatively speaking of course. This galaxy is also an excellent for imagers who live where it gains enough elevation to provide clear access.
NGC 1535 (Eridanus, planetary nebula, mag=9.6, size=48.0”x42.0”, SBr=9.0):
Our final southern object this month is affectionately known as Cleopatra’s Eye because of its appearance in deep images. Located 4° ENE of Gamma Eridani (mag 2.9), it was discovered by William Herschel in 1785, who recorded
“a very curious planetary.” Fairly large angularly for a planetary nebula, it is also relatively bright. It does bring color to the eyepiece for most folks, with some seeing it more greenish, and others more of a bluish tint. Slightly out of round, its central star is magnitude 12.2 and can be glimpsed with enough
aperture. Its internal structure is annular, with a darker ring around the central star ad more diffuse outer ring. It makes an excellent object for imagers, and is within reach for many in the northern hemisphere as well. Turn your scope its way and see how much of its detail you can glimpse and what color your specific eye physiology shows you.
That is the wrap on this year for the challenge. I hope those of you that have participated have enjoyed the ride, and rest assured that we will continue into the coming year full steam ahead. So let’s get out there and enjoy what the night sky has for us. 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!