OR: Calstar Friday 17th of April, Part II
Muriel Dulieu Holzer
Calstar Friday 17th of April 2026, Part II
M101, NGC 5457, the Pinwheel Galaxy in Ursa Major
M101 is one of the largest face-on spiral galaxies in our galactic neighborhood, with a diameter of about 170,000 light-years (roughly twice the diameter of our Milky Way) and an estimated one trillion stars. M101 is the brightest member of the M101 Group, a small group of about nine galaxies in Ursa Major. Its grand-design spiral structure is asymmetric, distorted by the gravitational pull of its smaller companions, particularly NGC 5474, which has been visibly gravitationally disturbed by M101. It lies about 21 million light-years away, has an apparent size of 28.8′ × 26.9′ (almost the diameter of the full Moon), and a magnitude of ~7.9.
In my 18", M101 appeared as a very large galaxy of medium brightness, with a patchy appearance suggesting its spiral arms. The arms appeared to curl clockwise. The galaxy brightened toward the center but showed no obvious core.
M64, NGC 4826, the Black Eye Galaxy in Coma Berenices
M64, also catalogued as NGC 4826, is a spiral galaxy nicknamed the Black Eye Galaxy (sometimes also called the Sleeping Beauty Galaxy or the Evil Eye Galaxy) for the prominent dark band of dust and gas in front of its nucleus. The most likely cause of this band of dust is that M64 absorbed a small gas-rich satellite galaxy in the past, that was orbiting in the opposite direction from M64’s rotation. After the merger, the inner region of M64 ended up rotating in its original direction while its outer disk rotated in the opposite direction. The visible dark band of dust and gas marks the boundary between these two counter-rotating gas streams. The collisions and pressure at the boundary of those two gas streams also created an active star formation region in the shape of a ring. M64 lies about 17 million light-years away, has an apparent size of 10.7′ × 5.1′, and a magnitude of ~8.5.
In my 18", M64 appeared as a medium-bright roundish galaxy with a small medium-bright core that looked slightly off-center. The dust lane was visible.
Castor, Double Star in Gemini
By 11:45 pm, thin high clouds were moving in and the sky started to look fuzzy. It felt a little chilly. I thought maybe this was the time to look at a few double stars. I put on my new SCAC glow-in-the-dark beanie and carried on.
Castor (Alpha Geminorum) is one of the two bright stars marking the heads of the twins in Gemini. While it appears as a single bright point of light to the naked eye, it is in reality six stars arranged in three pairs orbiting each other. The two brightest components, Castor A (magnitude ~1.9) and Castor B (magnitude ~3.0), are the two visible at the eyepiece. Each is itself a spectroscopic binary. A more distant third pair, Castor C (also known as YY Geminorum), orbits the AB pair at a wider separation. The Castor system lies about 51 light-years away.
In my 18", Castor split cleanly into two white-blue stars.
Stargate and the Pistol, Two Asterisms in Corvus
Randy invited us to look through his homemade 20" f/5 at the Stargate and Pistol asterisms.
The Stargate asterism, STF 1659, is an esoteric-looking asterism made up of three stars forming a small inner triangle inside a larger upside-down triangle defined by three other stars. The six stars range in magnitude from ~6.6 to ~10.8. The name came from Texas amateur astronomer John Wagoner, who was inspired by the “Stargate” portal device in the Buck Rogers in the 25th Century TV series (1979-1981).
The Pistol, also called the Jaws or the Hockey Stick, is a four-star asterism with three stars on a line and a fourth at an angle. The two brightest stars form the binary system Struve 1664 (STF 1664). The four stars range from about magnitude 7.8 to 9.2.
Paul Alsing mentioned that the Pistol points to the Sombrero Galaxy on one end and to Stargate on the other.
I was going to go back to my telescope to continue looking at double stars but then I thought I could do that from my backyard. So I spent the rest of the night looking through Randy’s 20” instead, except when otherwise noted.
NGC 4565, the Needle Galaxy in Coma Berenices
NGC 4565, nicknamed the Needle Galaxy, is an edge-on spiral galaxy with hundreds of globular clusters detected. Its thin, elongated profile is crossed by a sharp dark dust lane that splits the disk in two. NGC 4565 has a prominent box-shaped central bulge and a hint of a bar (visible only with high resolution and infrared imaging). It hosts a low-luminosity active galactic nucleus, classified as a LINER (Low Ionization Nuclear Emission-Line Region). LINERs are a type of weak active nucleus that fall between Seyfert galaxies and quiet galaxies in their level of activity. Its central black hole is estimated to be around 80 million solar masses.
NGC 4565 shows some similarities to our Milky Way. Its size and mass are comparable, which gives observers an idea of what our galaxy would look like edge-on. NGC 4565 lies about 40 million light-years away, has an apparent size of 15.9′ × 1.9′, and a magnitude of ~9.6.
Through Randy's 20", NGC 4565 appeared as a super-thin edge-on galaxy oriented almost vertically from 11:00 to 5:00. It showed increasing brightness towards the middle, a small central bulge, and a star-like core. A dust lane ran along its length, just to the left of the core, and was most visible in the central section.
NGC 5139, Omega Centauri, Globular Cluster in Centaurus
Omega Centauri is the largest and brightest globular cluster in the Milky Way, and one of the few globular clusters that can be glimpsed with the naked eye (from the Southern Hemisphere). It contains about 10 million stars and is roughly 10 times more massive than typical Milky Way globulars. Modern observations suggest that Omega Centauri may not be a true globular cluster at all but rather the surviving stripped core of a former dwarf galaxy that was absorbed by the Milky Way long ago. This hypothesis is supported by the cluster's unusually wide spread in stellar ages and metallicities, and the possible presence of an intermediate-mass black hole at its center. From northern California, Omega Centauri is challenging to observe because of its very low southern declination of about −47°. It rises just above the southern horizon for a brief window in spring evenings. Omega Centauri lies about 17,000 light-years away, has an apparent size of ~36′ (larger than the full Moon), and a magnitude of ~3.7.
Pictures of Omega Centauri here
It was kind of fun to see, all of a sudden, most of the big telescopes aimed almost horizontally towards the southern horizon. It took me a minute to realize what was going on. Looking through Randy's 20", Omega Centauri appeared as a large fuzzy granular cloud with no clearly resolved individual stars. I imagine the lack of resolution is due to atmospheric extinction. At declination -47, in Northern California, Omega Centauri never gets above ~10°, and therefore its light has to cross at least 5-6 air masses. One air mass is the amount of atmosphere at zenith (directly above us).
M60, NGC 4649, Elliptical Galaxy in Virgo
M60 is a giant elliptical galaxy with about 5,000 confirmed globular clusters, a few of them likely former galaxy cores, including the well-studied M60-UCD1. M60 hosts a supermassive black hole of about 4.5 billion solar masses at its center, one of the most massive known.
M60 forms a striking visual pair with the smaller spiral galaxy NGC 4647 just to its northwest. The two appear nearly in contact in deep images, but the consensus is that they are not interacting; they may not even be as physically close as they appear, since their three-dimensional separation is uncertain. M60 lies about 55 million light-years away, has an apparent size of 7.4′ × 6.0′, and a magnitude of ~8.8, making it the third brightest member of the Virgo cluster after M49 and M87.
Through Randy's 20", M60 and NGC 4647 appeared as two round galaxies almost touching. The larger one, M60, showed a brighter and larger core. The smaller companion, NGC 4647, was fainter, with a slight central brightening and a stellar core that became visible with averted vision.
M4, NGC 6121, Globular Cluster in Scorpius
M4 is unusual amongst globular clusters for having a clear central bar of stars running through its core. It is also notable for containing one of the oldest known white dwarfs, with an estimated age of about 13 billion years (close to the age of the universe itself). Its proximity makes it one of the easiest globulars to resolve into individual stars, even in modest telescopes. M4 lies about 7,200 light-years away, contains roughly 100,000 stars, has an apparent size of ~36′, and a magnitude of ~5.6.
Through Randy's 20", M4 showed a sparse concentration of stars in the middle against a fuzzy glow of unresolved stars. At the bottom of the eyepiece, it showed curved star trails going up around the cluster like a closed rose flower viewed from the side. About 100 stars were distinctly visible. I did not notice any red stars. Maybe the stars did not appear bright enough to show their color.
NGC 4361, Planetary Nebula in Corvus
NGC 4361 is a planetary nebula within Spica's Spanker, the trapezoidal asterism formed by the four bright stars of Corvus. NGC 4361’s central star is an unusually hot white dwarf of magnitude ~13, and the surrounding nebula has a roughly elliptical, slightly elongated shape with faint extensions visible in deep imaging. Its bipolar morphology, with two extensions stretching outward in opposite directions, indicates either a binary system of stars or a rotating central star, possibly both. NGC 4361 is unusual in being a planetary nebula in a region of sky dominated by galaxies. It lies about 2,700 light-years away, has an apparent size of ~1.8′, and a magnitude of ~10.3.
Steve invited me to look at NGC 4361 through his 24" with an NPB filter. The nebula appeared as a bright, irregular, roundish shape with the central star still visible despite being dimmed by the filter.
Arp 55, UGC 4881, The Grasshopper, Interacting Galaxies in Lynx
The Grasshopper is a system of two colliding galaxies. The two galaxies are thought to be about halfway through their merger; the cores of the original galaxies are still distinct and visible, while a long, curling tidal tail extends from the system, giving the Grasshopper its name. The tail contains a remarkable number of bright young star clusters, formed from gas and dust compressed by the encounter. The system lies about 500 million light-years away, has an apparent size of about 1.0′ × 0.5′, and a combined magnitude of ~14.7.
Picture of the Grasshopper galaxy here
I really wanted to see this spectacular object, so I looked persistently in Randy’s telescope. But all I could see was two stars, with maybe a faint glow around one of them.
Arp 142, NGC 2936 & NGC 2937, Penguin and Egg, Interacting Galaxies in Hydra
Arp 142, often nicknamed The Penguin and the Egg (sometimes also called the Tadpoles or the Hummingbird and the Egg), is a pair of interacting galaxies. NGC 2936, the larger galaxy, was once a normal spiral but has been distorted by tidal interaction with its companion NGC 2937, a small compact elliptical. NGC 2936 now resembles a penguin in profile, with its disrupted disk forming the body, its tidal tail forming the head and beak, and the core forming its eye; the round, undisturbed elliptical companion below it looks like the egg the penguin is guarding. The two galaxies are connected by a bridge of dim stars and are gradually merging. The pair lies about 326 million light-years away, with a combined apparent size of ~3′ × 1′, and apparent magnitudes of ~13.6 for NGC 2936, and ~14.0 for NGC 2937.
I had great hopes for this one and I really tried but I could not see anything through Randy’s scope.
Arp 266, NGC 4861, The Guppy, Irregular Galaxy in Canes Venatici
The Guppy is the nickname of NGC 4861, a Magellanic-type barred irregular galaxy. It is catalogued as Arp 266 in the "galaxies with irregular clumps" group of Arp's catalog. The galaxy gets its nickname from its shape: a bright, knotted star-forming region at one end forms the head of a small fish, while a fainter, longer extension forms its body. The bright knot was originally catalogued as a separate object before being recognized as part of NGC 4861. The galaxy is undergoing intense star formation, its bright knot being a particularly active H II region. It lies about 28 million light-years away, has an apparent size of 4.0′ × 1.5′, and a magnitude of ~12.3.
Through Randy's 20", the Guppy appeared as a faint glow inside a wide-angle triangle of three “stars”. But it looks like I may have confused the H II region forming the head of the fish with a star at the location of the wide-angle vertex of the triangle of three “stars”.
M5, NGC 5904, Globular Cluster in Serpens Caput
M5 is one of the oldest known globular clusters, with an estimated age of about 13 billion years. It contains around 100,000 stars and resolves into individual stars even in modest telescopes; in larger apertures, it shows a bright concentrated core surrounded by trails of stars. The cluster also contains over 100 known variable stars. M5 lies about 24,500 light-years away, has an apparent size of ~23′, and a magnitude of ~5.7.
Through Randy's 20", M5 appeared as a cotton-ball-like core with bright resolved stars on top of it, surrounded by a fairly regular spread of stars with a few arms of stars extending outward like rays from the sun. About 200 stars were visible.
It was getting late, and we were all tired. My PiFinder and SeeStar decided to go to sleep, I took it as a clue that it was time for me to do the same.
Richard Navarrete
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Jamie Dillon, DDK
Paul Alsing
Richard Navarrete
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