TSS Monthly DSO Challenge for May 2024

[kt4hx]

Welcome to May and hopefully plentiful clear skies for you wherever you live. This time of year the minds of many start thinking of galaxies and in particular the massive Virgo Galaxy Cluster. This delightful piece of celestial real estate is well positioned for most observers no matter if they live north or south of the equator. However, my intent this month is to diverge from that inclination and go in another direction. Instead, we shall focus our attention on my favorite class of deep sky object after my beloved galaxies, globular clusters. Just as spring (north) and autumn (south) signal galaxy season for many, it also signals the beginning of globular cluster season, when many of these interesting objects start to take center stage in the night sky.

This month I have for you not three, not four, but five globular clusters in each celestial hemisphere to pursue. Whether you be a visual only observer or deep sky imaging is your primary focus, the targets will give you ample opportunity exercise your skills. Some are bright showpiece objects, while some may test your skill level a bit as an observer or imager. As with any class of object, sky quality, aperture and individual skill levels come into play in terms of your success with these targets.

So, let’s dig into this month’s TSS DSO Challenge. As always, please report back to this forum with your results. If you file reports in the normal Reports forum for visual or the AP forum for images it is still okay to make posts here for those objects that are part of the TSS Monthly DSO Challenge. In that case, duplicate posting is warranted and encouraged when it comes to these specific objects. Your participation is very much appreciated and I do hope you enjoy the hunt. So let’s get started and see what I have on tap for you in the month of May. (smiley)


Northern Celestial Hemisphere:


Messier 3 / NGC 5272 (Canes Venatici, globular cluster, mag=6.3, size=18.0’, SBr=12.3, class=6):
Discovered by Charles Messier in 1764, this beautiful cluster is an annual favorite for observers. You can find it almost half way on a line from Arcturus (Alpha Boötis) to Cor Caroli (Alpha Canum Venaticorum). Bright and large it tickles the senses with its intense core. Its outer fringes resolve fairly easily in mid-sized apertures and with careful scrutiny one can discern lanes that flow outward from the core. Because of its brightness it presents a good imaging target as well, even during nights when the Moon dominates the celestial landscape.

Messier 53 / NGC 5024 (Coma Berenices, globular cluster, mag=7.7, size=13.0, SBr-13.0, class=5):
The ancient constellation Coma Berenices was named after Queen Berenices of Egypt, wife of King Ptolemy III Euergestes. Though somewhat faint overall, it is a treasure trove for the deep sky observer/imager. This bright globular cluster was first located by Johann Bode in 1775 and independently discovered by Messier in 1777, earning a spot in his list of objects. It can be found just shy of 1° northeast of magnitude 4.3 Alpha Comae Berenices (Diadem), as a somewhat large round globe. A few of its outer halo stars can be resolved in medium apertures, while large apertures may just begin to resolve additional stars at the fringe of the core area.

NGC 5053 (Coma Berenices, globular cluster, mag=9.0, size=10.0’, SBr=13.7, class=11):
Lurking almost 58’ southeast of Messier 53 and just over 1.5° ENE of Diadem, we now go in search of this challenging object. Discovered in 1784 by William Herschel, who wrote this about the cluster - "an excessively faint cluster of stars intermixed with resolvable nebulosity 8 or 10' diameter. The stars are so small that they cannot be seen without the greatest attention. 240 verified it beyond all doubts." While there is no nebulosity involved, Sir William was not wrong by calling it excessively faint. Because of its class 1l structure on the Shapley-Sawyer Core Concentration Class scale, its light is very evenly distributed without a strong core. This lowers its surface brightness giving it a ghostly appearance in the eyepiece. With darker skies it becomes easier, but still visually weak overall. It presents as a small and dim rounded glow in smaller to medium apertures, while larger apertures can result in some resolution of member stars. Rest assured this is a challenging object that succumbs easily to the increasing sky glow of more populated areas.

NGC 4147 (Coma Berenices, globular cluster, mag=10.4, size=4.4’, SBr-13.4, class=6):
We remain in Coma, but move to its western side, just under 3° inside the Coma-Leo border. This very small globular cluster is a dim little thing and does not yield resolution of member star easily. Larger apertures might just begin to pull out a few of its stars, but doing so is challenging. Officially credited to William Herschel in March 1784, he had observed it a month earlier but his position was off by 20 seconds in R.A. Regardless, his first observation erroneously made it into the record as NGC 4153. However, use of the entry based on his more accurate second observation, NGC 4147, is what one will typically find.

NGC 5466 (Bootes, globular cluster, mag=9.0, size=9.2, SBr=13.7, class=12):
We now move into Bootes for our last northern object for this month. Another William Herschel discovery, he swept up this fairly dim cluster in 1784, describing it thusly - "a large cluster of exceedingly small and compressed stars, about 6 or 7' in dia; a great many of the stars are visible, the rest so small as to appear nebulous; those that are visible are of one size and are scattered all over equally. The cluster is of an irregularly round form." As with NGC 5053, this one is also very susceptible to sky glow because of its lower surface brightness. Found about 6° southwest of Rho Boötis (mag 3.6) near the border with Canes Venatici, as a class 12 globular it shows no core concentration, thus it presents as a round ghostly glow in the eyepiece. Resolution of some stars at the fringes and possibly across the face of its disk is possible, but the prevailing visual impression will be of a hazy round glow.


Southern Celestial Hemisphere:


NGC 5139 (Centaurus, globular cluster, mag=3.7, size=36.3’, SBr=11.2, class=8
There simply are not enough superlatives to describe the famous Omega Centauri. Of all the globulars I’ve observed, this one is my favorite. Recorded as a star by Ptolemy in 150 AD, it wasn’t until 1677 that Sir Edmund Halley noted its more diffuse nature. Large and showy even in binoculars and small apertures, it is an easy naked eye object for many. Of course city dwellers will likely struggle to see it without optical aid, but it will still be easily found. I have observed it with up to a 5 inch instrument from farther south and it was a stunning beauty, and I described it as an “explosion of stars.” I recall back in the early 1980s scraping the southern horizon with my then Coulter Odyssey II 17.5 inch in search of this gem. Of course it was merely a few degrees above the horizon and more of a blobular than a globular. (smiley) If you can see it with some elevation, it is a sight you will never forget!

NGC 5286 (Centaurus, globular cluster, mag=7.4, size=11.0’, SBr=12.3, class=5):
Though this cluster shares the same constellation with and lies only a mere 5° southeast of Omega Centauri, it is not observed as much as it should be in my opinion. While it in no way compares visually with NGC 5139, it is no slouch either. Discovered in 1826 by James Dunlop, it is found only about 4’ northwest of the magnitude 4.6 star HD 119834, sometimes labeled as M Centauri. When I have observed this cluster during trips nearer the equator I never found the star intrusive in terms of seeing the globular and in fact they present a curious and attractive combination. I’ve only observed it with smaller apertures, but always found it bright and quite compact, with a noticeably condensed core. What do you see?

Messier 68 / NGC 4590 (Hydra, globular cluster, mag=7.3, size=11.0’, SBr=12.2, class=10):
Another Charles Messier discovery, he first spotted it in 1780 and described it as "a beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together.” Found about 3.5° SSE of the Beta Corvi (Kraz), this bright globular show very modest central concentration. Its predominant appearance is of a hazy glow with a few stars being resolved across its disk using medium aperture. Some mottling may be seen in the core, but it may not resolve appreciably, even at larger apertures.

NGC 4372 (Musca, globular cluster, mag=7.2, size=18.6’, SBr=13.3, class=12):
The celestial fly is home to two globulars. Discovered by James Dunlop in 1826, this large and loosely structured cluster is found in a rich Milky Way field. As a class 12 globular, it shows very little if any core brightness and concentration. In small apertures it may appear as a ghostly orb, but as aperture increases, resolution of stars becomes possible. It is found about 43.5’ southwest of Gamma Muscae, while a magnitude 6.6 field star is only about 4’ northwest of the cluster and may impact viewing. An interesting aside is a narrow strand of dark nebula, informally known as the Dark Doodad. This curious object runs southwest from the western side of the main figure of Musca, and turns south. Its southern terminus is just northwest and west of the globular. If your sky is dark enough you might notice its presence.

NGC 4833 (Musca, globular cluster, mag=8.4, size=14.0’, SBr=13.9, class=8):
The second cluster in Musca is found off its eastern side, about 42.5’ NNW of Delta Muscae. This cluster was discovered by Nicholas Lacaille in 1751 using his ½ inch 8x refractor at the Cape of Good Hope. He described it in his 1755 catalogue as a nebula that resembled "a small faint comet." This a bright cluster that will display some internal brightness and one may see some resolution in its outer halo and as aperture increases this resolution increases against a backdrop of central haziness. You may also notice a mag 8.8 field star at its northern edge.


With that, I hope you will go forth and observe! Enjoy the hunt and the reward of success. Even if we struggle to find an object, we can use those difficulties to learn and refine our observing skills. But the main thing here is to have fun, learn and spend time under the night sky. The treasures of the universe are yours to enjoy and ponder every chance you get. Again, good luck and let the rest of us know how you did.

[John Baars]

Thanks for your new challenges. With my moderate aperture and impressive LP I will try the brightest ones. M3 was already observed without knowing it was a candidate for this Monthly Challenge. I'll refresh it and take M53 along with it too.

[kt4hx]

Thank you John. I look forward to your observations and possible sketches.

[Mike Q]

I will have to add these to the hit list for the next time I am out. Hopefully I can get out at least once this month.

[kt4hx]

I will have to add these to the hit list for the next time I am out. Hopefully I can get out at least once this month.

Good luck Mike, glad to have your participation - as time and clear skies allow of course.

[Mike Q]

Its the time part that is the killer for me. When you get up at 0400 staying up much paste 9:30pm isnt much of an option. So for me i need the weather and friday or Saturday nights to line up.

[kt4hx]

Its the time part that is the killer for me. When you get up at 0400 staying up much paste 9:30pm isnt much of an option. So for me i need the weather and friday or Saturday nights to line up.

I get that entirely. Back when I worked for the USG, I commuted into the DC area and it was tough finding time for a lot of things other than sleeping and working.

[John Baars]

Yesterday-evening I did some observations of M3 and M53 with the SCT of the public observatory I belong to. That was an easy job, given the 14 inch mirror. Nothing more, you can't go chasing faint fuzzies while the public is in the dome. I will make some sketches later on with my 120mm refractor.

[Graeme1858]

Nice to have a go at a larger SCT John. Our astronomical society has one but it's out of commission at the moment.

I look forward to seeing your sketches from your refractor viewing.

Graeme

[kt4hx]

Yesterday-evening I did some observations of M3 and M53 with the SCT of the public observatory I belong to. That was an easy job, given the 14 inch mirror. Nothing more, you can't go chasing faint fuzzies while the public is in the dome. I will make some sketches later on with my 120mm refractor.

Excellent John, glad you got a chance to use the larger scope. Look forward to your sketches using the 120mm.

[Lady Fraktor]

If the skies hold I will try tonight

[kt4hx]

If the skies hold I will try tonight

Look forward to your reporting Gabrielle.

[kt4hx]

Thought I'd post my own experiences with these objects. The below observations of the northern objects for this month occurred in May of 2021 using the 17.5 inch at our dark site house. I will post some notes from my observations of the southern objects in a separate post later.


Messier 3 / NGC (Canes Venatici, globular cluster, mag=6.3, size=18.0’, SBr=12.3, class=6):
Already knowing the cluster is located almost halfway between Arcturus (Alpha Bootis) and Cor Caroli (Alpha Canum Venaticorum) I aimed the scope using the Rigel. Moving to the RACI the cluster was easily visible as a tiny diffuse spot not too far off the cross-hairs in the view. So centering it, I moved to the Ethos 21mm (94x) and my eyes were treated to a beautiful sight. Bright and large, the cluster appeared slightly out of round to the eye. A large number of stars were resolved in its halo, as well as across the face of the disk. The core was a bright hazy glow providing a backdrop for the stars that were resolved.

Dropping in the Ethos 13mm (152x) it was a grand visual treat. Not quite symmetrically round in shape, it was a huge glowing ball of stars, with countless resolved at its fringes into the core area. The core itself was an intensely bright glow that underpinned the whole visual experience. I noticed several strings of stars emanating from the cluster’s body. In particular I noticed one curving flow coming off the northern side and turning to the northeast. Another string of stars of which I took note of was one that was thicker closer to the core and thinned out as it strung out to the east. This cluster is a perennial favorite, and it is easy to see why. Give it a try yourself and enjoy the view!


NGC 5466 (Bootes, globular cluster, mag=9.0, size=9.2, SBr=13.7, class=12):
A short 5° star hop to the east of M3 is this more challenging globular. Easily passed over if you are not looking for it, its lack of any significant core concentration means its light is spread out evenly across the disk, reducing its visibility. I easily spotted it at 94x as a large ghostly orb lacking any concentration of brightness across its face. As the weak seeing was changing, various member stars would pop in and out of view across the disk, with a persistent hazy backdrop of the unresolved constituency. Viewed at 152x it presented a large and subtly bright ball that seemed a little ragged around the edges. Countless stars were again popping in and out of view across the disk with the constant backdrop of a hazy glow. I did notice a strand of dim stars flowing from the northeast side and wrapping around to the south. While not a showpiece, its eerie appearance is nonetheless attractive and curious.

Messier 53 / NGC 5024 (Coma Berenices, globular cluster, mag=7.7, size=13.0, SBr-13.0, class=5):
Next up was this nice cluster about 57’ northeast of Alpha Comae (Diadem). The cluster was just picked up in the RACI finder and of course quickly found using 94x. It presented a large and bright round glow with a very intense core blazing at its center. The core was tight, but numerous stars were resolved in its outer halo and across the face. Viewed with 152x it was a real showpiece. Large and bright within the field, its core was exceedingly strong, with its well resolved halo extending outward. I noticed about three or four short chains of stars trickling outward from the core into the halo. While not the rival of M3, it still holds up well visually and is well placed near a bright star.

NGC 5053 (Coma Berenices, globular cluster, mag=9.0, size=10.0’, SBr=13.7, class=11):
As NGC 5466 was the antithesis to M3, so too is this globular to M53. Nearly 58’ southeast of M53, it is another one that must be specifically targeted or it will be easily passed over. As a class 11 cluster, it lacks any significant core concentration, which lowers its surface brightness. Thus it suffers greatly from the impact of light pollution, struggling to push through the sky glow. But from our dark site, it was easily seen at 94x, though admittedly it was merely a smallish diffuse dusting against the black sky. Perhaps 10 stars were resolved across its disk. Moving up to 152x, it remained a low surface brightness round glow. I picked up about 20 stars that drifted in and out of view across its disk, but its dominant characteristic was its low surface brightness hazy glow. This one presents a ghostly ethereal personality in the eyepiece, diaphanous and delicate.

NGC 4147 (Coma Berenices, globular cluster, mag=10.4, size=4.4’, SBr-13.4, class=6):
The final of three globulars in this constellation, is a small little thing. Found almost 6.5° northwest of Denebola (Beta Leonis), using 94x it displayed a tiny concentrated brightness in the core, with perhaps four or five stars resolved in its outer fringes. When viewing with 152x and even 199x, it was bright but quite small visually. Upwards of 10 stars were being seen in its outer halo and across its face. Interestingly, my last observation was from our typical suburban backyard about eight years ago with my 10 inch. In that case, it did not appear clearly as a globular cluster, but brought to mind a small elliptical galaxy as no stars were resolved. This one is challenging because of the combination of its visual magnitude and its small angular size.

[Graeme1858]

Thought I'd post my own experiences with these objects.

You have a lovely way with words Alan! That was a pleasure to read.

I look forward to imaging these five Globulars. To date I've only imaged Messiers 5, 10, 13 and 14 from the Globular Cluster list. But I've seen M3 and M53 through my 10" Dob. After I saw M13 for the first time I was wow'd into a bit of a glob hunt!

A globular cluster is a thing of beauty, thanks for putting this list together.

Graeme

[John Baars]

Last night I was able to fulfill my promise in the “Monthly DSO Callenge” subforum of M3 and M53, the sketches.
See here:
viewtopic.php?t=34473

[kt4hx]

Thought I'd post my own experiences with these objects.

You have a lovely way with words Alan! That was a pleasure to read.

I look forward to imaging these five Globulars. To date I've only imaged Messiers 5, 10, 13 and 14 from the Globular Cluster list. But I've seen M3 and M53 through my 10" Dob. After I saw M13 for the first time I was wow'd into a bit of a glob hunt!

A globular cluster is a thing of beauty, thanks for putting this list together.

Graeme

Thank you Graeme, your kind words are much appreciated. Globulars are intriguing objects indeed. Some can reveal an amazing number of stars and core details, whereas some may appear as nothing more than a dim fuzzy object more akin to an elliptical galaxy.

I look forward to your images my friend.

[kt4hx]

Last night I was able to fulfill my promise in the “Monthly DSO Callenge” subforum of M3 and M53, the sketches.
See here:
viewtopic.php?t=34473

Thank you John, you sketches are great, as expected. The contrast between apertures is quite evident as one would expect. Thanks for adding in NGC 5866 (M102), and well done on pulling it in with your 120mm under your very bright skies.

[Lady Fraktor]

A possibility for viewing on Thursday night if the weather holds.

[Graeme1858]

I've been away this week to a Dark Sky Camp and managed to capture the May Challenge Northern Targets with a single Luminance subframe on each one. It's a buzz putting the work in to capture a wall hanger but I have to say it was great fun hunting down each target, plate solving it into the centre of the screen and capturing its photons.

M3, an old favourite, the biggest and brightest of the bunch.

M53, almost twice as far away, so a bit smaller but just as lovely.

NGC 5053, quite faint and diffuse, looks more like an open cluster.

NGC 4147, a tiny Globular Cluster compared to the others, zoomed in the core looks like a tulip!

NGC 5466, again, almost open cluster in appearance but somewhat more dense at the core.

An excellent list of targets Alan, cheers.

Graeme

[kt4hx]

Outstanding Graeme! Your fine images truly capture the uniqueness of those globulars, and I truly appreciate your effort to share them with everyone here.