If you are browsing this site, chances are you like challenging visual deep-sky targets. One of the most incredible challenge lists I’ve encountered is the Deep Sky Challenge, put together by Alister Ling and Alan Dyer of the Royal Astronomical Society of Canada (RASC). It samples a wide variety of objects, varied both in object type and the nature of the challenge, giving the seeker a broad introduction to several rabbit-holes to go explore for even more challenging objects. In this sense it is an “introduction” to challenging objects whose aftermath may keep you glued to the eyepiece for decades! I clearly put introductory in quotes because this is a very tough list, especially if you try doing it at the minimum aperture listed!
This list has only 45 entries—another reason I love it! Short and diverse lists keep the variety-seeker in me engaged and motivated with the prospect of relatively quick completion. Some of the 45 are star-hopping challenges, like the miniscule planetary nebula Jonckheere 900 which appears stellar even at pretty high power. Others are very low surface brightness, like Barnard’s Loop, requiring the observer to seek transparent, dark nights. Yet others are both tiny and faint, such as Herbig-Haro 1, demanding large aperture or exceptional skill and conditions to compensate.
Whereas the authors of the list challenge observers to try it with a 12-inch telescope (except for the venerable Corona Borealis cluster for which they recommend a 20-inch telescope.), I took the easy route—most of my observations were made with my 18-inch telescope. In my experience though, large aperture does not offer substantial gains on those dim low–surface brightness nebulosities; for those, I had to seek out dark skies and opportune conditions. Below are my experiences tackling this list, and stumbling into a few of the sinkholes the list opens.
NGC 7822
NGC 7822 is a diffuse HII region in Cepheus. Using my 18-inch f/4.5 at the Golden State Star Party 2023, I observed a roughly arc-shaped nebulous region concave towards north, with one prominent star involved. I was using a narrowband filter as is customary when viewing HII regions. Later that year, I had two exceptional nights in the Saline Valley area of Death Valley National Park. This part of Death Valley is at high altitude and avoids some of the extinction and scattering from the desert dust suspended in the air, which plagues the lower elevations. On one of those nights, I looked at the region using my 25×100 binocular without nebula filters and noted an asymmetric, structured halo around a bright star, stronger to the east. The star (of similar brightness) lying to its south also had a tendril of nebulosity going north-east, which connected with this halo enclosing a region rich in dark and bright rifts. The nebula was rather faint.
IC 59 (and IC 63 )
IC 59 is one of two chunks of nebulosity that makes up the “Ghost of Cassiopeia” nebula. They are lit up by both emission and reflection, due to the UV and light from the luminous star gamma Cassiopeiae. IC 63, which probably elicits the “ghost” moniker, is the brighter component; naturally it is the fainter piece that’s on the RASC Challenge.
Perhaps that’s why I missed this fainter strand when I first observed IC 63 in October 2020 from northeastern California. The subsequent year, I made it to the Okie-Tex Star Party and although the conditions weren’t exceptional, I was able to see a wisp of nebulosity roughly 25’ in length. Its faint appearance was reminiscent of the
While we are on the field, don’t ignore the brighter IC 63, which is a very beautiful nebula with a comet-like appearance. I used 207× power on it and was able to see its ghostly shape quite nicely.
NGC 609 (and Trumpler 1 )
Using 147× on my 18-inch telescope at the 2023 Golden State Star Party, I observed NGC 609 as a diffuse overdensity in the milky way with a smattering of a few bright stars in a roundish region. The faint stars comprising the nebulous background were not resolved, but there were many stars of medium brightness.
The spreadsheet for the program also calls out nearby open cluster Trumpler 1, which I first saw in my 25×100 binocular in November 2023. At that low power it presented itself as a “star” that appeared slightly nebulous because of a thin haze that surrounded it. With averted vision, it was reminiscent of a condensed globular cluster, sort of like
IC 1795 (and the Heart and Soul nebulae)
This is the brightest region of nebulosity of the giant “Heart Nebula”. According to Steve Gottlieb’s notes, the bright knot at the western edge of this region is
Using my 18-inch f/4.5 at the 2023 Golden State Star Party, I described this region as a knot (NGC 896) that was reminiscent of a galaxy, embedded in a nebulous background (IC 1795). IC 1795 itself was not all that bright, although NGC 896 was easy.
Nearby in the main body of the heart nebula lies the cluster
In October 2023, a bunch of us (Patty and Steve Gottlieb, Connie and Jimi Lowrey, Debbie and Paul Alsing) had congregated in Bluff, UT for the Annular Solar Eclipse. I was carrying my 6-inch f/8 for eclipse projection and 25×100 binocular; no 18-inch. The sky conditions were spectacular in Bluff. Although tired after the eclipse, Steve and I spent some time with our binoculars, observing the excellent skies right from the front yard of our host. The nebulosity NGC 896/IC 1795 was pretty distinct in that excellent sky in my unfiltered 25×100 binocular, even without a filter. It was detected as an asymmetric glow around a star in an otherwise blank region. The glow fanned out from the star in the direction away from IC 1805. That night I also looked at the Soul Nebula,
Although I had seen bits and pieces of the heart nebula several times over the years, the entirity of the heart structure had eluded me; that was until October 2023. Two nights later, I found myself at a rest area off highway UT-95, a few miles west of Natural Bridges National Monument. This area is high in the ranks amongst the regions with pristine skies left in the USA. Not only is it away from sources of light pollution, it is also at high altitude. The Milky Way stretched almost from horizon-to-horizon, save for perhaps some 10°. The winter milky way was thick and rifty. M 33 could be held continuously with the naked eye in averted vision. The Gegenschein was bright and elongated, and the Zodiacal band emerging from its either end stretched about a total of 4 Zodiacal constellations. I definitely want to go back here during a solar minimum year! Anyway, wanting to make the best of the excellent skies I was under, I quietly set up my 25×100 and got to work. After grinding my eyes out to see the Sculptor dwarf (successfully), I casually pointed to the Heart Nebula region curious to see what the skies will deliver. I was shocked to see the entire heart shape present itself without much difficulty! I started by noting a band of light connecting from near NGC 896 to the main body of the heart, then the top edge, and then the bottom edge, culminating in the “tricuspid valve” near cluster IC 1805. I wish I had nebula filters on – that takes work with binoculars because one needs to shield the stray light falling on the filter. I had a long, beautiful drive ahead of me through the Glen Canyon area, so I forced myself to quit shortly after, but this is a night I will fondly remember for a long time to come.
Rough sketch of the Heart Nebula through my 25x100 binocular
Steve Gottlieb explores this region in detail in the 2012 January issue of Sky & Telescope magazine.
Maffei 1 (and the Maffei group)
Next on the RASC DSC list is a tough galaxy in Cassiopeia, of all places. That’s why it’s dim. I read somewhere that Maffei I and
The dust renders this extremely bright galaxy into a challenging target. I’ve looked at Maffei I multiple times though, using various apertures. Of course, dark and transparent skies are key. On a frosty winter November 2013 winter night, my friend Hemant and I were at the Texas Astronomical Society’s site near Atoka, OK. Surprisingly, I was able to detect Maffei I in his 5-inch Takahashi refractor. It looked like the glow from an asterism, but repeated checking confirmed it wasn’t. Anyway, with my 18-inch, it wasn’t as difficult. At the 2015 Okie-Tex Star Party, I was able to see an unusual glow behind an asterism at 103×. Upping the power to 200×, I nailed down the brightest part of the glow and later confirmed it against a POSSII image.
That was also the night I finally claimed Maffei II with my 18-inch. The object was at the edge of visibility. Only knowing the rough position of the glow, I managed to pin-point its exact position. I carefully isolated various confounding stars to rule out the possibility that my averted vision was catching on a star instead. I checked it in multiple eyepieces, the best view at 295×. I must have spent anywhere between 30 to 45 minutes on this very difficult observation. This successful observation of Maffei II in my 18-inch was made after many many failed attempts, but it wasn’t my first observation…
Thanks to Jimi Lowrey’s 48-inch. In his telescope, Maffei II appeared as a large diffuse glow, just like a faint nebulosity. It was faint but distinct nevertheless. Maffei I in his telescope sported a very distinct core between two stars, but I couldn’t nail down its elongation.
This is where the wise stop, but I made the mistake of going down this rabbit-hole. The Maffei / IC 342 group has many nearly-invisible galaxies. Wolfgang Steinicke and Rich Jakiel’s excellent book not only lists a bunch of members of this group, but also a bunch of positive observing reports by various experienced observers. Of course IC 342 is not very difficult and even shows spiral structure in my 18-inch. Some of the other galaxies listed in the IC for example are not too difficult either. However, falling prey to the more obscure ones, I have tried hard to see anything of
The galaxy
NGC 1049 (and the globulars of the Fornax Dwarf)
NGC 1049 is a globular cluster discovered by John Herschel in 1835. Little did he know he’d seen a globular in another galaxy, 630kly away. In 1938, Harlow Shapley reported on “Two Stellar Systems of a New Kind”. He had just discovered the first dwarf spheroidal galaxies (save for the M 31 satellites) – the
NGC 1049 is not “too difficult” with large aperture. I first saw it back in 2009 through my (then) 17.5-inch f/5 telescope from Coorg in southern India – my observing buddy Amar Sharma had culled it out of one of the hallowed pages of this very website. In January 2015, I took up the task of observing all five then known globulars of the Fornax system in January 2015, and my observations are detailed here.
The spreadsheet on the RASC website notes, “galaxy itself invisible?”. I would say perhaps, from Canadian latitudes. This nearly invisible galaxy eluded me for years. After many futile attempts, I finally bagged it in my 25×100 binocular at the 2021 Okie-Tex Star Party and later also in my 18-inch scope. Steve Gottlieb wrote about this and also his own observation from “down under” in his article titled “The Milky Way and the Seven Dwarfs” which appeared in Sky & Telescope magazine, 2023 October issue.
The Sculptor Dwarf is yet another nightmare, which I eventually confirmed just before I saw the Heart Nebula on that exceptional October 2023 night.
Abell 426 , the Perseus Cluster
This beautiful cluster in Perseus sprawls around the galaxy
I revisited it in January 2024 using Jagan Mohan Gorti’s newly purchased 16-inch Hubble Optics telescope. We were observing at a BAS star party in southern India. I logged NGC 1275 as the brightest; roundish NGC 1272 the second brightest; NGC 1278 is the third brightest. These three galaxies were held continuously with averted vision, although difficult to find in the humid conditions. They also yielded to direct vision individually. NGC 1273 was next in difficulty and formed a nice parallelogram with the remaining three. This was continuously visible to averted vision. PGC 12405 was vaguely detected with averted vision before we were interrupted.
You can find Steve Gottlieb’s logs on this page and a finder chart here. Also worthy of mention are late Albert Highe’s notes.
NGC 1432 and NGC 1435 (also, Barnard’s Merope Nebula)
These are the reflection nebulae around the stars Maia (NGC 1432) and Merope (NGC 1435) in the Pleiades. Both of them require dark and transparent skies, but at least Merope nebula is not too challenging under those conditions.
I had a memorable view of NGC 1435 through my 25×100 binocular at the 2021 Okie-Tex Star Party. I arrived during the wee hours of October 3rd and parked outside the closed gate of the star party, so I set up only my binocular. That was one of the finest nights of that star party; although there was heavy dew, the transparency was really good. As Pleiades rose, I pointed my binocular to it and Merope nebula appeared as a distinct asymmetric glow around Merope, extended to the south of the star.
Merope nebula is easy to confirm because it is rather asymmetric. Maia nebula, I find more troublesome. On my drive back from Okie-Tex on Interstate Highway 40, I stopped by near Amboy Crater. Even though the light pollution map indicates it as very dark, I found the conditions unimpressive, with a huge light dome from the Los Angeles metro area. However, with Pleiades slightly higher in the sky and a little more time investment, I was able to detect Maia nebula as a weak glow showing slight north-eastern elongation in my 25×100 binocular.
More recently, through the Bangalore Astronomical Society’s 16-inch Dobsonian, Maia appeared to have a slight asymmetric glow of a different nature from the glare around other stars, headed in the eastern direction for a short distance. In fellow observer Ranjit Neelakandan’s 5-inch refractor, the Maia nebula “leaked” into the region between Maia and the stars flanking it, indicating that it may after all not simply be the glare of stars.
Every time I point my binocular to Pleiades at a decently dark location, I can see nebulosity around all the stars. Some of this is real nebulosity, but I can’t help wonder if a substantial component is simply scattering in the optics. Maybe, maybe not. I really would like to see some asymmetric structure to confirm it, and whereas it is obvious with Merope, I have also been able to invest efforts confirming the Maia nebula. I have not invested efforts into the rest of the nebulosity yet.
Before departing this region, I must mention
IC 342 and its spiral features
I mentioned IC 342 earlier in the context of the Maffei group. This is a beautiful face-on spiral galaxy rendered challenging by the Milky Way’s dust. This low surface brightness galaxy needs dark skies, and aperture is secondary. I remember seeing it in the finder scope of my friend Hemant Hariyani’s 5-inch Takahashi refractor, and was surprised to see it was not much brighter in my 18-inch!
At the 2015 Okie-Tex Star Party, I spent some time tracing out the spiral arms of IC 342 in my 18-inch. I used a DSS2 image as a finder chart. Using various magnifications ranging from 80× to 130×, I picked up on three spiral arms and three brighter knots embedded in the arms. It was hard to observe these arms because of superposed stars.
Features of IC 342 detected through my 18-inch; image is from DSS2, north up