OR: Three nights in Glenn County -- Third night -- 10/18/2025
Muriel Dulieu Holzer
Three nights in Glenn County
Third night – 10/18/2025
Our last night in Glenn County. I continue with my list from the Orion DeepMap 600 and some suggestions from Steve. I will be using my Orion 10” Dobsonian and take a few peeks in Steve’s 24” Starstructure.
Comet C/2025 A6 - Lemmon
I talked a lot about the two bright comets in previous ORs so I will keep it short.
Comet C/2025 A6 Lemmon is a long-period comet discovered on January 10, 2025 by the Mount Lemmon Survey in Arizona.
Like most long-period comets, it originally comes from the Oort Cloud. It is moving rapidly southeast at ~4 degrees per day. Its inbound orbital period is ~1350 years, and after perihelion, its outbound orbital period is ~1160 years.
Comet Lemmon is a dust-dominated comet at visual wavelengths. Its magnitude at the time was ~4.8. It has a visible soft diffuse coma and broad bright dust tail 1.6 degrees long. Its fainter ion tail is only visible on pictures.
Looking in my 10”, I search for NGC 5273 in the PiFinder and find the comet nearby. I see a bright center which is likely the inner coma around the nucleus, and a halo around it. The dust tail is visible and goes out of the eyepiece towards the 7 o’clock direction. It has a slight greenish color.
Comet C/2025 R2 - Swan
Comet Swan is also a long-period comet from the Oort Cloud. Because it is a dynamically old comet, meaning a comet that has made multiple passages through the inner Solar System, much of its easily volatile material has already been lost.
In my 10”, I see a fuzzy patch that looks like a galaxy. I do not see a clear tail.
It was currently located near Scutum.
NGC 6888 - The Crescent Nebula in Cygnus
NGC 6888 is an emission nebula created by the violent stellar wind of WR 136, a Wolf-Rayet star. I already described it in yesterday’s OR so I won’t go into too many details.
Looking at it in the 24”, it resembles a cosmic egg and is definitely looking a lot better without the dew!
NGC 6781 - Snowglobe Nebula in Aquila
NGC 6781 is a planetary nebula similar to the Ring Nebula (M 57) but larger, fainter, and more diffuse.
The bipolar dust shell of this nebula is believed to be barrel shaped and viewed from nearly pole-on. The Nebula itself contains cold molecular gas and dust (outer shell) and ionized gas (interior). Its central star is a white dwarf.
In my 10” I see a little grey patch. I am surprised to see it but it looks like I may have gotten the wrong number for its magnitude. I thought at first that its magnitude was 14, but later on I found 11.4. I heard that a long time ago, magnitudes were calculated based on old photographs and those are not accurate.
In the 24”, I can see more details but not the middle star (often listed around magnitude 15 to 17 depending on the source). With a UHC filter, it appears brighter on top, with the brightness decreasing gradually towards the bottom. It has a dark spot in the middle.
A UHC (Ultra High Contrast) filter blocks light from light pollution and natural skyglow while allowing specific wavelengths emitted by nebulae, such as OIII and H-beta, to pass through. This significantly increases contrast, making faint objects more visible and detailed.
UGC 12570 - Galaxy in Aquarius
UGC 12570 is a faint spiral galaxy often listed around 14th magnitude. It is visually close to the Helix Nebula but lies far in the background at a distance of about 230 million light years.
In the 24”, it looks like a little patch of light near a double star. When I can barely see the object, I know we are doing serious astronomy.
NGC 6811 - Open Cluster in Cygnus
NGC 6811 is an intermediate-age (a little less than 1 billion years) open cluster at a distance of 3500 to 4000 light years. The cluster is no longer compact and many original stars have drifted away but it is still clearly identifiable as a physical group.
Its brightest stars are magnitude 10. It contains many pulsating stars (delta scuti, gamma doradus and red giants) and rotating stars that have made it a key target for stellar evolution studies. Two planets Kepler 66b and Kepler 67b have been discovered orbiting sun-like stars by the Kepler Mission.
In the 10” it looks a little bit loose with one long extension.
NGC 6891 - Planetary Nebula in Delphinus
NGC 6891 is a bright compact planetary nebula known for its complex, triple-shell structure revealed by the Hubble Space Telescope. A white dwarf in the center is heating the surrounding gas. It appears as a small bluish disk.
I can’t see it in my 10” at first but it is clearly visible in the 24”. It looks small and appears slightly bluish. With averted vision, it appears slightly bigger.
With the 2 inches UHC filter Omega (NPB type), it appears very bright, and did I see it wink?
I look again in the 10” and find it this time, thanks to its proximity to a double star. The nebula is the size of a star when looking straight at it but with averted vision, it looks slightly bigger.
French 1 asterism in Cygnus next to NGC 7025
NGC 7025 is a well-formed barred spiral galaxy with a prominent central bar, a moderately bright bulge, and spiral arms that are smooth and tightly wound. It appears dynamically settled, with no sign of active mergers or starbursts.
But this galaxy was not the object of my search, it was just the means of finding the French 1 asterism that had eluded me before, as it is next to it. The French 1 asterism also called the Toad Stool is an arrangement of stars that looks like a mushroom with a cap and stem.
Abel 72 - Planetary Nebula in Delphinus
Abel 72 is a very faint, large planetary nebula. It is an old highly evolved planetary nebula with extremely low surface brightness. The nebula is faint because the gas has expanded and thinned over tens of thousands of years and the ionizing radiation from the star is weakening.
I use the PiFinder to find it in my 10” as it is a challenging object. Thankfully the PiFinder has the Abell catalog. I see some stars and wonder if one of them might be the planetary nebula but it is more likely that I just don’t see it as it is so faint and I don’t have a filter.
Barnard 142 - Dark Nebula in Cygnus
Barnard 142 is a dense cloud of cold interstellar dust and gas that blocks the light of stars behind it. It appears as a dark void cut into the Milky Way star field. Along with the double-pronged Barnard 143 to its north, Barnard 142 and 143 form “Barnard’s "E" dark nebula.
I can see it in my 10”. It is a dark patch!
NGC 253 - The Sculptor Galaxy or Silver Coin Galaxy in Sculptor
NGC 253 is a barred spiral galaxy, one of the brightest galaxies outside the Local Group, truly beautiful! Caroline Herschel discovered this galaxy in September 1783 with a 4.2” comet sweeper at just 30x.
It is a starburst galaxy, meaning it is undergoing an intense burst of star formation, particularly in its core. It also hosts hundreds of compact super star clusters near its center.
In the 24”, it looks like a nice elongated galaxy, mottled with dust clouds. I can see lots of details.
Looking at it in the 10” for comparison, I am surprised by how well I can still see it.
NGC 288 - Globular Cluster in Sculptor
NGC 288 is a loose low-density globular cluster. It has no strong central concentration, a relatively flat brightness profile and widely spaced stars even near the center. It orbits our galaxy in a retrograde motion compared to most stars. This, and other evidence, suggests NGC 288 was captured from a dwarf galaxy the Milky Way cannibalized - the most likely candidate is the Gaia-Enceladus-Sausage galaxy.
In the 24”, I could distinctly see around 50 stars with a glow behind that has a distinctive shape.
In the 10” at low power, I just saw a ball of fuzz, and at high power, around 10 distinct stars on top of the ball of fuzz.
NGC 7023 (Caldwell 4) - The Iris Nebula in Cepheus
The Iris Nebula is a reflection nebula named so because of its petal-like appearance in photographs. Its dust grains scatter and reflect the light of a nearby binary star (HD 200775). Since shorter wavelengths scatter more efficiently, it appears bluish in images.
NGC 7023 sits inside a larger molecular cloud in Cepheus that contains:
Dense dark lanes of cold dust
Bright reflection regions (NGC 7023 being one of them)
Ongoing low mass star formation at the edges
NGC 7023 is known for its predominant photodissociation region (PDR). The PDR is a transition zone between the ultraviolet radiation from HD 200775 and the surrounding molecular cloud, where UV radiation breaks down molecules and heats the gas, revealing complex organic molecules (PAHs).
Looking in my 10”, I see a glow around one star. I don’t really see the dust lanes. According to SkySafari, the nebula is on top of a cluster but I don’t see that either.
Night Vision device on 24”
We are getting close to the end of the evening. It is time to blow out our night vision with Steve’s night vision device on the 24”. The model is a PVS-14 Gen 3 (white phosphor). It was used with a low-power eyepiece that gave 34x, along with a H-alpha filter. It is also really fun to use across the sky handheld. It makes all the nebulae appear in the sky!
With the night vision device on the 24”, we look at a large number of nebulae. They are all shaped by massive stars, either glowing under intense ultraviolet radiation or torn apart by supernova shocks. They all look fantastic in the night vision device. I list them in 2 categories below.
Nebulae ionized by massive stars (H II regions and wind bubbles)
These nebulae glow because ultraviolet radiation from hot stars strip electrons from hydrogen, making the gas emit light.
California Nebula (NGC 1499)
Pacman Nebula (NGC 281)
Wizard Nebula (NGC 7380)
Bubble Nebula (NGC 7635)
Flaming Star Nebula (IC 405)
They have in common that they are powered by O and early B stars, they emit strong H alpha emission, and in some cases O III emissions, and they are regions of active or recent star formation within larger molecular clouds.
Supernova remnants
These nebulae glow because supersonic shock waves heat and ionize the gas.
Jellyfish Nebula (IC 443)
Crab Nebula (M1)
Veil Nebula (NGC 6960, NGC 6992, NGC 6995, IC 1340, NGC 6974, NGC 6979)
Their common features are that they have expanding shock fronts, strong O III emission, filamentary lace structures, and are no longer forming stars.
They are regions where a massive star has died.
The bat
Finally going to sleep, I am met with an unexpected surprise. There is a bat flying in circles just below the ceiling of my bedroom! It is late, I am tired, I am not quite sure what to do. I remember that bats sometimes have rabies so I am hesitant to try to get it out. On the other hand if I wait until the morning, the bat might be asleep and it might be harder to get it out. In the end the fatigue wins and I go to sleep in the third bedroom that was thankfully unoccupied, leaving my bedroom to the bat.
In the morning, the bat is nowhere to be found. We check all possible hiding places: curtains, bed covers, … nothing. In retrospect, it was not a very safe thing to look for the bat considering the risk of rabies, but apparently daytime gave me some imprudent and unwarranted courage. Thankfully we were protected by the bat’s sleeping schedule and uncanny hiding abilities.
At some point, I wondered if the bat was gone in the vent. It was a small bat after all.
But it was time to leave, I got my things out of the room quickly and we notified the owner. I am not quite sure what happened after. I heard the bat was still there later on welcoming the new guests…
Richard Navarrete
--
Observing Sites, Observing Reports, About TAC linked at top of:
https://groups.google.com/forum/#!forum/sf-bay-tac
Subscribers post to the mailing list at:
sf-ba...@googlegroups.com,
---
You received this message because you are subscribed to the Google Groups "The Astronomy Connection (TAC)" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sf-bay-tac+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/sf-bay-tac/CAMZ69tx3vN5LVtv9m8UOzzmRD5kzfO0Q63REX1PtJvwcjeqPgw%40mail.gmail.com.
David Kirjassoff
--
Observing Sites, Observing Reports, About TAC linked at top of:
https://groups.google.com/forum/#!forum/sf-bay-tac
Subscribers post to the mailing list at:
sf-ba...@googlegroups.com,
---
You received this message because you are subscribed to the Google Groups "The Astronomy Connection (TAC)" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sf-bay-tac+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/sf-bay-tac/CAMZ69tx3vN5LVtv9m8UOzzmRD5kzfO0Q63REX1PtJvwcjeqPgw%40mail.gmail.com.
<C-2025 A6.jpg><NGC 7023.jpg><C-2025 R2.jpg><NGC 6888.jpg><NGC 1499.jpg><NGC 281.jpg>
