Comet 3I/ATLAS now leaving the Solar System

When Comet 3I/ATLAS streaked into our solar system in 2025, it became only the third confirmed interstellar visitor ever observed. Discovered in 2017, ‘Oumuamua was the first known interstellar object; the second was 2I/Borisov, which was discovered in 2019. Unlike the countless comets born in the Oort Cloud, 3I’s hyperbolic orbit revealed it was just passing through—an icy messenger from another star system. First spotted by the ATLAS survey in Chile, the comet quickly drew attention for its unusual behavior: it brightened far more rapidly than typical comets, driven by volatile gases like carbon dioxide and cyanide that vaporized as it neared the Sun. Its striking bluish glow, dominated by gas emissions rather than dust, set it apart from the more familiar yellow-white comets of our own system.

www.ibtimes.com

For astronomers, 3I/ATLAS is a time capsule billions of years in the making. Observations from Hubble, Webb, and other telescopes suggested a nucleus less than a kilometer wide, cloaked in a vast coma rich in exotic ices and metals. These findings hint that the comet may have formed in the earliest days of its home system, long before our Sun was born. 3I just swung past perihelion two days ago when it came as close as 130 million miles of our star and will make its closest approach to Earth on December 19, 2025, at a safe distance of 270 million kilometers, before fading from view and returning to interstellar space. Comet 3I offered a fleeting but profound reminder: our solar system is not an island. Every so often, the galaxy sends us a visitor carrying whispers of distant worlds, and 3I/ATLAS was one of those rare cosmic emissaries.

Oh, and BTW, it's not an alien spacecraft.

Comet Lemmon still holding it's own

We are just 8 days to perihelion for comet Lemmon. Although the comet's distance from the earth is increasing, Lemmon remains quite bright, maintaining an estimated magnitude of 4.2. Weather prospects for the Maryland area are so-so with this Friday and Tuesday looking good. Lemmon remains about 10-15° above the horizon at 6:30pm EST on November 2nd. After that, the orbit places the comet lower and lower, making it harder to see. And with the moon waxing large, and full on the 4th, these two dates may be the best and last to capture the comet.

Two Comets; My Best Photos of Lemmon and SWAN

Comet Lemmon

Yesterday I posted my best photo of comet Lemmon with hopes that I would be able to image it at least one more time from my home with my larger telescope. As I watched the clouds thickening and moving in from the west and south, prospects for getting a good image of the comet were dwindling. The Windy app was showing the situation to get worse as time draws on. At 5:00pm I decided to power off the telescope and pack things up.

I went out to check on my dogs at 5:40 and wouldn't you know it, the skies over the western horizon were relatively clear - still some very thin high clouds but nothing like it was looking earlier. I checked Windy's satellite feed and yep, a clearing that would last about an hour or so. I went into full gear setting up the equipment at record speed. Making matters even more challenging I decided to configure the telescope in the Hyperstar configuration, allowing me fast optics (f/2) and wide field. This required me to remove the secondary mirror from the front of the scope, add the Hyperstar lens and mount my ASI533 camera. Focus had to be drastically changed, but what could I point to since it was still rather light. The moon of course! Got the focus set pretty good and before I went into the house located a bright star near where the comet would be to get the focus dialed in as best as I could (the autofocuser on my Edge wasn't working so I had to focus by hand).

I think the effort was worth it all as I finally got some pretty good data on the comet's tail. I took 10 second, 30 second and 60 second subs before the comet went behind my tree line. I decided to use only the 30 and 60 second ones.

Processing was a real effort as the CometAlignment tool in PixInsight refuses to lock onto the overexposed comet nucleus. I went with Astro Pixel Processor (APP) which I use almost exclusively for calibrating and stacking comet images. APP worked like a charm and I used PixInsight to finish the process.

Comet C/2025 A6 (Lemmon) - October 27, 2025
EdgeHD11-Hyperstar / ASI533mc Camera
40x30sec and 8x60sec subs

Comet SWAN

You might recall that back in October I discussed the fact that two comets would be visible in the skies at the same time. Lemmon turned out to be the best by far, but SWAN was visible in small telescopes. On October 23rd I did image comet SWAN. There was only the hint of a very small tail but the halo around the comet's head came out rather nicely.

Comet C/2025 R2 (SWAN) - October 23, 2025
William Optics ZS61 - ASI533mc
48x60sec subs

The next few days look to be cloudy, with clearer skies forecasted for Friday and Saturday. Comet Lemmon will reach perihelion on November 8, 2025.That’s the date when it comes closest to the Sun—about 0.53 astronomical units (AU), or roughly 49.25 million miles away. This marks the peak of its solar proximity and typically coincides with its brightest appearance in the sky. But it will also be sinking lower in the WSW skies making it difficult, if not unlikely, to be seen clearly from my home. I may try at the church property with my portable scope(s).

As shown below, comet Lemmon will still be visible for the next couple of weeks, but it will be losing altitude about 5° every 3 days (about 20° on the 28th to only 5° on Nov 12). The chart shows the position of the comet at 7:30pm EDT from October 28 to Nov 12, 2025, with each horizontal line representing 5° of altitude (Note: comet location against the stars is not accurate in this view).

Comet Lemmon, and other interesting Astro objects

Comet Lemmon

Skies were so-so these past couple of days. I checked to see if I could see Comet Lemmon from my home, and according to Stellarium it should be above my tree line for a short period of time (up until 7:30pm). Although not ideal due to the lightness of the western sky, it's my only option. Checking the situation at 6:00pm, there were numerous clouds in the area. But there were some breaks, and the sky was very clear in those breaks. 

Not to be one who gives up easily I decided to give it a try, especially since my telescope rig was already setup. I mounted my ZS61 wide field telescope with ASI533mc camera on my AP1100 mount. As soon as it was relatively dark (I couldn't wait 'till it was appropriately dark as the comet would be well below the trees by then) I started a sequence of subs: 40x60sec. Clouds interfered throughout most of the sequence (as did some Starlinks and planes!), so I only managed to get 5 good subs. So be it. 

Comet Lemmon - October 26, 2025
William Optics ZS61 - ASI533mc
5x60sec subs

Got my replacement RS232-USB cable to try connecting to my iOptron mount, but the mount still can't see my PC (most likely the motherboard on the mount is damaged). Nevertheless, I am planning on trying again to image from my church property this evening.

The North America Nebula - NGC7000

While testing out the ZS61, prior to my using it on comet Lemmon, I trained the scope on the North America Nebula (NGC7000). I have imaged this object in NB, but I thought it might be interesting to try the OSC camera and capture it in normal color.

The North America Nebula (NGC 7000) is a vast emission nebula in the constellation Cygnus, named for its striking resemblance to the North American continent. Glowing in rich reds from ionized hydrogen gas, it spans over 50 light-years and lies about 2,500 light-years from Earth. This celestial cloud is a stellar nursery, where new stars are born amid intricate filaments and dark dust lanes that sculpt its iconic shape.

North America Nebula (NGC7000) - October 24, 2025
Willilam Optics ZS61 - ASI533mc _L-Quad Filter
40x180sec subs

Double Cluster in Perseus

Nestled between the stars of the constellation Perseus lies a breathtaking celestial pairing known as the Double Cluster—NGC 869 and NGC 884. These two open star clusters, visible to the naked eye under dark skies, dazzle with hundreds of young, blue-white stars that formed roughly 12.8 million years ago. Located about 7,500 light-years from Earth, they offer a stunning example of stellar nurseries in action. Their close proximity and shared origin make them a striking sight through binoculars or telescopes, glowing like twin jewels in the autumn sky.

Double Cluster in Perseus - October 5, 2025
William Optics ZS61 - ASI533mc
40x60sec Subs

I'll report on my attempt of capturing comet Lemmon this evening sometime tomorrow.

Latest Imaging Session on Comet Lemmon

Well, I tried to image comet Lemmon from my church property in Westminster last evening (Oct 20th). Let's say it didn't go so well.

The weather was great; the skies were clear. It was a bit windy and since the church is on top of a hill the wind can be rather intense. I set up the GT102 with ASI533mc well before dark. My biggest concern, and the issue that ultimately contributed to the failed attempt at imaging, was the mount.

A couple of weeks ago I accidently plugged in the computer cable to the PORT socket on the iOptron iEQ30 mount while prepping for this outing and not the RS232 port. Smoke ensued and the cable plug melted in place. I had to pull the plug out with needle nose pliers. Before I could do anything else with the mount I needed a new RS232 cable. I ordered a replacement from iOptron which arrived a few days ago.

I reconnected the cable but the mount refused to connect. Checking the USB To RS232 DB9 Serial Adapter Cable, I found out that Windows claimed the USB device to be faulty. My guess is that the circuitry in the adapter fried when I attached the cable to the mount's PORT. I think the iOptron motherboard is OK as I could still use the mount with the handset. So, I'm waiting on the new adapter.

That brings me back to the imaging session last night. Without computer control of the mount to do plate solves I was forced to try old school methods of sighting the comet's location with the guide scope. Although the comet was visible in binoculars, it was not a naked eye object, at least not from my location. I was expecting the comet to be much brighter. Homing in on the comet's location was just a nightmare. I just couldn't get it into the FOV of the camera. I guess in retrospect I should have used a wide field eyepiece, located the comet, and then replaced the camera, but I continued to try hit and miss with the camera. After about 90 minutes I gave up. 

I also had my Canon 70D with telephoto lens on a tripod, but the hands-free remote shutter release was also giving me issues. The few photos I got were dim and trailed.

So, I packed up and will try again later in the week when the new adapter arrives. 

Oh, and did I mention I also fried my new ZWO Autofocuser? Yep. The new focuser uses a USB-C connector. My MeLE NUC also uses a USB-C connector for the 12v DC power (instead of the normal barrel type connector everything else uses). You can quess where this is going. When setting up the telescope I plugged in the hot power cable to the focuser thinking I had the computer data USB cable. I'm still evaluating the unit but I think I may need to send it to ZWO for repair.

What a couple of weeks!

Update on Comet Lemmon

Comet Lemmon is still on track to be a naked eye comet in dark skies. It is now getting close to the sun, so is a bit harder to see. I managed to capture it with my GT102 which I setup on it's portable iOptron mount in my front yard where I can get a bit lower in the NNE than from my semi-permanent location. 

Comet Lemmon - October 10, 2025
25x60 sec subs - GT102/ASI533mc

I am praying that I can get a better image later in the month when I'll image both from my church in Westminster with the GT102 and from my home with the Edge11. I'll be imaging in the evening (western skies) where the light pollution is minimized.

Here is the latest data from COBS.

Astronomy Programs: Friday and Saturday this week

Unraveling the Mysteries of the Cosmos

This Friday, October 17, 2025, at 6:30pm I will be giving a special presentation to the Natural History Society of Maryland, hosted at Crosslife Bible Church in Westminster, MD. Whether you’re curious about stars, galaxies, nebulae, supernovae, or black holes, this presentation will guide you through the celestial wonders that have fascinated humanity for centuries. Discover the mesmerizing diversity of galaxies. From majestic spirals adorned with radiant arms to enigmatic irregular shapes, each galaxy tells a cosmic tale. Peer into the heart of the Milky Way, our home galaxy, and unravel its secrets. What lies at the center? How do stars form in its spiral arms? Witness galactic collisions—a cosmic ballet where stars swirl and merge, forever altering their destinies.

Stars, those celestial beacons, ignite our night sky. Learn about their life cycles, from birth in stellar nurseries to fiery supernova finales. Explore the Hertzsprung-Russell diagram, where luminosity and temperature reveal stellar classes. Marvel at blue giants, red dwarfs, and everything in between. Gaze upon constellations—the ancient stories etched in star patterns. Orion, Cassiopeia, and Ursa Major beckon us to connect with the cosmos.

I will also be sharing my setup for astrophotography and showing some of my photographs too. 

Outside viewing with my William Optics GT102 refractor telescope and the larger 11” Edge Cassegrain will be available after the presentation, weather permitting. In case of cloudy weather, we will participate in a class exercise indoors.

Children ages 8 and up who can listen to our presentation are welcome to attend.

Registration is required (click here):   Natural History Society of Maryland - Unraveling the Mysteries of the Cosmos

Our Closest Neighbor - Luna, the Moon

Then, Saturday, October 18, 2025, at 6:30pm, join us at the Soldiers Delight visitor center for a presentation on "Our Closest Neighbor - Luna, the Moon". 

The exploration of the moon has been a fascinating journey, spanning decades and involving numerous countries and space agencies. Overall, the exploration of the Moon has been a testament to human ingenuity, curiosity, and collaboration. As we look to the future, the Moon will likely serve as a steppingstone for further exploration of the solar system and beyond. In this presentation, we will traverse the annals of history, from the early days of lunar observation to the monumental achievements of the Apollo program and beyond. We will delve into the triumphs and tribulations of those intrepid explorers who dared to reach for the stars and touch the lunar surface.

All programs are Rain or Shine. Time machines will be provided by the Westminster Astronomy Club.

Activity: Exploring Moon Phases

Note: Starting this month, through March 2026, time will be 6:30 - 8:30 PM.

Date: Saturday, October 18, 2025
Time: 6:30 p.m. - 8:30 p.m. Eastern

Location: Soldiers Delight Environmental Area

5100 Deer Park Rd.

Owings Mills, MD 21117 

Comet Lemmon continues to brighten

Comet C/2025 A6 (Lemmon) continues to brighten as it approaches perihelion on November 7, 2025. In dark skies with good seeing amateurs have photographed Lemmon showing a lovely, thin, long tail and prominent green coma typical of many comets. 

But in my light polluted skies in Maryland imaging comets tends to be problematic. Adding to the situation is that my tree line prevents viewing anything under 20-25 degrees in altitude. This is generally not an issue with deep sky objects as I just need to wait for them to rise high enough. But comets tend to stay close to the sun and typically low on the horizon. In the east, the sky brightens before they get high enough and, in the west, the opposite is true. Good news is that Lemmon will be better placed when it can be seen in the western skies about 30-60 minutes after sunset towards month's end. My western skies have the minimal amount of light pollution. My latest attempt on imaging Lemmon is shown below. No long tail but showing a well-defined nucleous and coma. In addition, the red giant star Tania Australis makes a nice contribution to the photo, contrasting with the green glow of Lemmon's coma.

Comet C/2025 A6 (Lemmon)
October 6, 2025, 5:40AM EDT - 19 stacked 90sec Subs
William Optics GT102 APO and ZWO ASI533mc camera 

Observational data in the Comet Observation database (COBS) show that the current light curve for Lemmon is holding true and the estimates of maximum brightness (anywhere from magnitude 3.5 to 5.5) are still on track. Let's hope so.

Comet Updates

Comet C/2025 R2 (SWAN) continues to brighten but is still very low in the western sky. It has already passed perihelion and is now on its way out of the solar system. Recent observations put SWAN at magnitude 6.5 to 6.0, probably not visible with the unaided eye, but should be visible in binoculars and small telescopes.

Comet C/2025 A6 (Lemmon) is currently magnitude 6.0, and steadily brightening in the early morning sky. Look for it around 3:00 am in the morning due NE. Follow the three lower stars of the big dipper, and they should direct you to Lemmon, which will be about 10-15 degrees above the horizon. Expectations are still high that Lemmon will reach naked-eye visibility by mid-October. Because of its orbital position Lemmon can be seen both in the early morning hours and early evening hours around 7:00 - 7:30pm.

Comet Lemmon - October 5, 2025 - 3:00 am EDT

Special Presentation - Mysteries of the Cosmos - October 17, 2025

Special Presentation - October 17, 2025

Join us as we explore the universe with local astrophotographer and Westminster Astronomical Society member Michael J. Mangieri. Whether you’re curious about stars, galaxies, nebulae, supernovae, or black holes, this presentation will guide you through the celestial wonders that have fascinated humanity for centuries. Discover the mesmerizing diversity of galaxies. From majestic spirals adorned with radiant arms to enigmatic irregular shapes, each galaxy tells a cosmic tale. Peer into the heart of the Milky Way, our home galaxy, and unravel its secrets. What lies at the center? How do stars form in its spiral arms? Witness galactic collisions—a cosmic ballet where stars swirl and merge, forever altering their destinies.

Stars, those celestial beacons, ignite our night sky. Learn about their life cycles, from birth in stellar nurseries to fiery supernova finales. Explore the Hertzsprung-Russell diagram, where luminosity and temperature reveal stellar classes. Marvel at blue giants, red dwarfs, and everything in between. Gaze upon constellations—the ancient stories etched in star patterns. Orion, Cassiopeia, and Ursa Major beckon us to connect with the cosmos.

Michael will share his setup for astrophotography and his photographs too. Check out his work here: https://mdastro.com/

Outside viewing with a smaller refractor telescope and a larger 11” Edge Cassegrain will be available after the presentation, weather permitting. In case of cloudy weather, we will participate in a class exercise indoors.

Children ages 8 and up who can listen to our presentation are welcome to attend.

Registration is required (click here):   Natural History Society of Maryland - Unraveling the Mysteries of the Cosmos

Two Comets in the Same Sky! - October 2025

During the month of October, there will be not one, but two comets in the western sky. Although not unheard of, it is very rare for more than one bright comet to be visible in the same section of the sky at the same time. But next month, comets C/2025 A6 (Lemmon) and C/2025 R2 (SWAN) will be visible in the western sky about 30 minutes to an hour after sunset. Lemmon is expected to be the brighter of the two.

As seen in the diagram below, Lemmon (yellow path) moves from very low in the NW on Oct 11 to a more favorable position (20 degrees above the horizon) on the 21st. While comet SWAN (blue path) rises steeply from Oct 6 to Oct 21 and into November. 

SWAN will continue to rise high in the sky over the weeks to come, and although it will be decreasing in brightness a little bit (as it moves farther from the sun) it will be in dark skies and will remain visible with optical aid through November. Lemmon is in an orbit that limits its continued view for the northern hemisphere as it will start to sink lower in the sky soon after Oct 30. 

How bright will these be? That's a good question, and difficult to answer. Best estimates are looking good, however, especially for Lemmon.

On October 21st, comet Lemmon will be closest to Earth, very well placed in the sky and may reach magnitude 3.0, a very bright comet indeed! Anything under magnitude 6.0 is visible with the naked eye in good dark locations (brightness goes up as the magnitude number decreases). If it actually reaches that brightness it will be very easy to see with the unaided eye. On November 8th it reaches perihelion (closest to sun) and will be a little brighter but also lower in the sky. You'll need to view it 30 minutes after sunset (6:30pm). 

Comet Lemmon - October 21, 2025 - 7:20pm

Comet SWAN on the other hand remains at about magnitude 7.0 throughout its appearance. But it is a newly discovered comet, and the jury is still out on the magnitude estimates.

Comet SWAN - October 21, 2025 - 7:20pm

Binoculars will enhance the view for both of these and may be required to see comet SWAN. I'll post updates on or around October 5 when more data comes becomes available.