TSS Monthly DSO Challenge - February 2021

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TSS Monthly DSO Challenge - February 2021

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Post by kt4hx »


Here we are with a new month and some new objects for you to pursue. I strive to give you variety so that you can enjoy the beautiful diversity of DSOs in the visible universe. None are excessively difficult, but some may challenge you depending upon your skill level and local conditions. Therefore, I encourage all, regardless of skill level or equipment, to attempt all that are within reach based on your latitude. At the same time, don’t forget your January targets as they remain in play for a bit as well. As always, please report your results back here by starting a thread posting the details. That way we can all share the experience in order to learn and bolster are collective skill levels.


Northern Celestial Hemisphere:

NGC 2420 (Gemini, open cluster, mag=8.3, size=10.0’, class= I2r):
This small, but nice cluster is found just 2° 14’ ENE of the famous planetary nebula NGC 2392 (Eskimo Nebula), which is our second object this month. This cluster was discovered by William Herschel in 1783, who described it as "a beautiful cluster of many large and compressed small stars, about 12' diameter."

The cluster field is compact, but rich. In a 12 inch at 84x I counted around 30 diamonds strewn about the small field. I feel this cluster deserves more attention than it typically receives from observers and imagers. So I encourage you to add this to your observing

NGC 2392 (Gemini, planetary nebula, mag=9.2, size=0.8’x0.7’, SBr=8.2):
Famously known as the Eskimo Nebula because of its appearance in deep images, this bright planetary is a popular visual, sketching and imaging target during the northern winter months. William Herschel discovered this curious object in 1787, but its annular nature was first detected by Lord Rosse’s assistant George Stoney in 1849.

The magnitude 10.5 central star stands out well with direct vision and without a filter. Using an O-III filter (or alternatively a narrow-band nebula filter) tames this star providing more contrast for the nebula’s disk. It is not difficult to see this planetary using an 8x50 optical finder or binoculars as a stellar object where it looks like a wide double with the magnitude 8.2 field star just over 1.5’ to its north. Visual observers should not be afraid to push the magnification, as its high surface brightness will tolerate pushing your limits a bit.

NGC 2419 (Lynx, globular cluster, mag=10.3, size=4.6’, class=2):
The dimmer northern constellation representing a celestial lynx is home to this distant globular cluster. At a distance of around 300,000 light years it was given the erroneous nickname of “Intergalactic Wanderer” by Harlow Shapley in the 1940s when it was thought to have escaped the gravitational grasp of the Milky Way. Eventually that was disproved but the name stuck. This very distant cluster was discovered in 1788 by William Herschel.

It tends to not give up any resolution of its member stars visually, though with enough aperture it may appear slightly granular. It forms a curious conga line of three with two 7th magnitude field stars just to its west. Imagers should be able to obtain some resolution, though its core will likely remain tight. Give it a try and see what your eye or camera reveal to you.


Southern Celestial Hemisphere:

NGC 2516 (Carina, open cluster, mag=3.8, size=30.0’, class=I3r):
This delightful cluster is a bright and pretty grouping of stars that carries the nickname of the Southern Beehive. It very evident along the southern side of a triangle of three 5th magnitude field stars. Discovered by Nicolas-Louis de Lacaille in the 1751 to 1752 timeframe, it can be seen with the naked eye in moderate to low light pollution areas and even an 80mm resolves it well into over 40 stars in a wedge shaped grouping (my experience).

I find it more attractive than more dispersed clusters like Messier 44 because it is more compact and to my eye more dynamic in character. Have a long look at this beauty, and if you image, it should be a wonderful target for you.

NGC 2359 (Canis Major, diffuse nebula, mag=8.0~, size=10.0’x6.0’, SBr=13.3~):
This beautiful emission nebula is known by the nickname of “Thor’s Helmet”, and less often as the “Duck Nebula.” Personally I think it looks more like a snail in images – but that’s just me. Discovered by William Herschle in 1769, it is a beautiful and delicate object exhibiting bubble, bow shock and filamentary structure. Fired by the Wolf-Rayet star WR7 it lies about 12,000 light years away from us.

Visual observers are helped by darker skies, and a narrow-band filter can be utilized to good result. From a dark site I have just glimpsed it in an 8x50 optical finder as a tiny non-stellar glow. Imagers will find this object a very interesting target as they try to draw out the details of its delicate streamers and of course its primary “helmet” structure.

NGC 2298 (Puppis, globular cluster, mag=9.3, size=5.0’, class=6):
This cluster is not particularly large in angular extent, but it is easily discerned as a globular. It definitely gets better as aperture increases. As a class 6 core concentration cluster, if it reveals any visual resolution at all, it will not be significant in amateur scopes.

Puppis is the 20th largest constellation in the sky, but was once part of the vast constellation Argo Navis. This ancient behemoth represented the mythical ship Argo used by Jason and the Argonauts during their search for the golden fleece. According to the book Star Names – Their Lore and Meaning (1963, Richard H. Allen), the constellation contained an outrageous number of naked eye stars – 829. It was this for this reason that Nicolas-Louis de Lacaille was the first to divide the constellation into the three constituents that we know today in his 1755 catalogue. Lacaille named the three components, Puppis (poop deck), Carina (keel) and Vela (sails). These were not officially adopted until 1928 when the IAU finally established boundaries and names for the 88 modern constellations.


So there are your selections for this month. I hope you will use these to supplement your normal observing to add some variety to your routine. Good luck and get on out there! :)
Alan

Scopes: Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob ||
ES AR127 f/6.5 || ES ED80 f/6 || Apertura 6" f/5 Newtonian
Mounts: ES Twilight-II and Twilight-I
EPs: AT 82° 28mm UWA || TV Ethos 100° 21mm and 13mm || Vixen LVW 65° 22mm ||
ES 82° 18mm || Pentax XW 70° 10mm, 7mm and 5mm || barlows
Filters (2 inch): DGM NPB || Orion Ultra Block, O-III and Sky Glow || Baader HaB
Primary Field Atlases: Uranometria All-Sky Edition and Interstellarum Deep Sky Atlas
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