C/2025 A6 Comet Lemmon on October 31, 2025 using three different focal lengths

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On October 31, 2025, my husband and I returned to Sargent, Texas for another opportunity to view and image Comet C/2025 A6 Lemmon.

I initially set up my camera with a 24 mm lens (very wide field, 53 deg by 35 deg) looking towards the sunset to capture the color gradient (I love these deep colors!).  Then, after it got dark, I took a series of images (about 29.47 minutes worth) to capture the stars and the comet.  By October 31, the comet was moving further away from us, and if you compare the October 31 picture with the October 26 picture, you can see that the comet appears smaller, dimmer, and further to the left (west) relative to the stars.  It also appears to have a hook in its tail.

I took additional data with an 85 mm lens (15 deg by 10 deg field of view), about 7.6 minutes worth.  I cropped this image, so it is an even smaller field of view, and again the tail appears to have a hook in it.

All of the pictures with the camera were taken using just a tripod (no tracking mount), so I had to do a fair bit of processing to remove the star trails in the data (BlurXterminator is a great tool for this), and I had to process the comet separately from the stars to keep it from smearing since is moving relative to the stars.

Finally, while I was taking pictures with the camera on a tripod, I was also taking pictures with my small telescope with a 430 mm focal length and a 1.8 by 1.2 degree field of view, about 42 minutes worth.  Of course the comet and the tail are obvious here, and the field of view is too small to see any further out hook in the tail.  What is not obvious in this integrated image is that there was a knot in the comet’s tail that was obviously moving between frames, which I find amazing.  It’ll take a movie to show that, which is my next project.

Which version do you like the best?

Camera geek info – 24 mm sunset image:

  • Canon EOS 60D in manual mode set 8 second exposure, ISO 800
  • Sigma 24-70 mm f/2.8EX lens, set at f/3.5, 24 mm, manual focus
  • Tripod
  • Intervalometer 

Frames – 24 mm sunset image:

  • October 31, 2025
    • 221 8 second lights
    • 30 1/2500 second flats
    • Matching darks and dark flats from library

Camera geek info – 85 mm night image:

  • Canon EOS 60D in manual mode set at 8 second exposure, ISO 800
  • Canon EF 85 mm f/1.8 lens at f/2.8 manual focus at infinity
  • Tripod
  • Intervalometer 

Frames – 85 mm night image:

  • October 31, 2025
    • 57 8 second lights
    • 31 1/2500 second flats
    • Matching darks and dark flats from library

Camera geek info – telescope:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Sargent, Texas Bortle 4 skies

Frames – telescope:

  • October 31, 2025
    • 14 60 second Gain 150 R lights 
    • 30 0.05 second Gain 150 R flats
    • 14 60 second Gain 150 G lights 
    • 30 0.02 second Gain 150 G flats
    • 14 60 second Gain 150 B lights
    • 30 0.02 second Gain 150 B flats
    • Matching darks and flat darks from library

Abell 7 Planetary Nebula

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When we travel to the glorious dark skies of Dell City, Texas, I try to image objects that I won’t be able to easily image from my light polluted Bortle 8 driveway.  I also try to pick a challenge object – one that needs a lot of time even from the Bortle 2 – 3 skies of Dell City.  In November 2025, my challenge object was Abell 7, a planetary nebula.  Even in 10 minute images with the Ha and Oiii filters, I could not see the nebula.  However, after integrating 10.3 hours of Ha and 8.2 hours of Oiii data, I was able to see and process Abell 7.

Abell 7 is a planetary nebula – the gases expelled from a red giant star before it becomes a white dwarf, lit up by that star.  It’s located in the Milky Way, approximately 1680 light years away, and it has an apparent size of 12.733 arcminutes, making it about 6.2 light years across.  It’s estimated to be 20,841 years old based on the expansion of the nebula, which is “ancient” for a planetary nebula.

I find these small nebulae beautiful and fascinating. Each has its own unique structure.  This one has Hydrogen Ha emissions (mapped to red) and Oxygen Oiii emissions (mapped to blue).  Much of the nebula is purple, so it has both Ha and Oiii emissions.  The strongest Ha regions are on opposite sides of the nebula.  There is a variation in intensity – the center and the outer rim are both dimmer than the brighter middle ring.  It also appears to me to be clumpy or fuzzy, which is not surprising given its age.

In addition to the nebula, there are several background galaxies in this image.  I didn’t spend much time collecting RGB data, so there’s not a lot of detail in the galaxies.  The most prominent one in the image is just above and to the left of the nebula.

In this image, the stars and galaxies came from images using red-green-blue filters, and the nebula came from images using Hydrogen alpha (mapped to red) and Oxygen iii (mapped to blue) filters.  The nebula, galaxies, and stars were processed separately to maximally enhance the nebula and galaxies.

Camera geek info:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila HO and RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • ZWO ASiair Plus
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • iOptron CEM40
  • Dell City, Texas Bortle 2-3 dark skies

Frames:

  • November 9, 2025
    • 12 600 second Gain 150 Ha lights
    • 30 1.0 second Gain 150 Ha flats
    • 14 600 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
  • November 10, 2025
    • 60 30 second Gain 150 Red lights
    • 30 0.05 second Gain 150 Red flats
    • 60 30 second Gain 150 Green lights
    • 30 0.02 second Gain 150 Green flats
    • 60 30 second Gain 150 Blue lights
    • 30 0.02 second Gain 150 Blue flats
    • 19 600 second Gain 150 Ha lights
    • 30 1.0 second Gain 150 Ha flats
  • November 11, 2025
    • 20 600 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
  • November 12, 2025
    • 13 600 second Gain 150 Ha lights
    • 30 1.0 second Gain 150 Ha flats
  • November 13, 2025
    • 8 600 second Gain 150 Ha lights
    • 30 1.0 second Gain 150 Ha flats
    • 9 600 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
  • November 14, 2025
    • 10 600 second Gain 150 Ha lights
    • 30 1.0 second Gain 150 Ha flats
    • 6 600 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
  • 30 Flat Darks from library
  • 30 Darks from library

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • NBColourMapper
  • Generalized Hyperbolic Stretch

Sh2-236 IC410 NGC1893 The Tadpole Nebula

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Sharpless Sh2-236 is commonly called the Tadpole Nebula since it appears to contain a tadpole (or two – depending on how you interpret the two white-pink objects near the center of this image).  How many tadpoles do you see? 

This image shows HII region Sharpless Sh2-236 (the whole image) (also cataloged in the Index Catalog of Nebulae as 410 (IC410)), the open cluster NG1893 (stars in the blue region), and the two “cometary globule” tadpole nebulae numbered Simeiz (Sim) 129 and 130.

Sh2-236 is an H II region emission nebula, a region of ionized atomic hydrogen.  The H II regions in the Sharpless 2 catalog were “defined not only in terms of the ionized gas but also in terms of the hot stars which are responsible for the ionization.”

The young open cluster NGC1893 contains five O type stars, short-lived, hot, massive stars that ionize the surrounding molecular cloud.  One of the stars is theorized to be 4 million years old; the others, 2 – 3 million years old.  Between these O-type stars and the two cometary globules are smaller, younger stars that are 1 – 2 million years old that appear to have an age gradient with older stars closer to the O-type stars and younger stars closer to the cometary globules.  The O-type stars are theorized to be causing triggered star formation in the globules – as the ionization and shock wave from the O-type stars hit the initial clumps of material that are the tadpoles, “radiation driven implosion” caused the clumps to form stars.

The tadpoles are believed to be denser clumps of material.  The tails are theorized to be formed from ionized gas from the edge of the tadpole closest to the O-type stars flowing along the magnetic field away from the O-type stars.  The more tadpole-like nebula, Sim 129, is on the far side of the nebula from us and is theorized to contain young stars.  Sim 130 is on the near side of the nebula closer to us and is theorized to contain “incipient stars” – the earliest stage of star formation, so the stellar evolutionary stage in the two tadpoles is different.  I am always amazed when I realize that our galaxy is still under construction!

Sh2-236 is located in the Milky Way, approximately 10500 light years away.  The square “box” of the nebula in the first image is 60 arc minutes across, so the nebula is approximately 183 light years across.  

I collected the frames for this image under the fantastic dark skies of Dell City, Texas.  When we go out there, I generally try for some easier targets and a more difficult target – this was one of the easier targets.  I need far less time than I do for images from my light-polluted driveway, but it was something of a guess to know whether I’d taken enough data to end up with a good image.  In this image, the stars came from images using red-green-blue filters with about 17 minutes of data each, and the nebula came from images using Sulfer ii (4.1 hours of data mapped to red), Hydrogen alpha (4.3 hours of data mapped to green) and Oxygen iii (4.25 hours of data mapped to blue) filters, the standard SHO mapping.  But after doing that mapping, I used Narrowband Normalization to shift the colors so that it wasn’t overly green and to enhance the reds and blues.  The nebula was processed separately from the stars to maximally enhance it.

Camera geek info:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB and SHO filters
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Dell City, Texas Bortle 2 – 3 skies

Frames:

  • November 12, 2025
    • 17 300 second Gain 150 Ha lights
    • 30 1 second Gain 150 Ha flats
    • 14 300 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
    • 15 300 second Gain 150 Sii lights
    • 30 1 second Gain 150 Sii flats
  • November 13, 2025
    • 17 300 second Gain 150 Ha lights
    • 30 1 second Gain 150 Ha flats
    • 18 300 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
    • 15 300 second Gain 150 Sii lights
    • 30 1 second Gain 150 Sii flats
  • November 10, 2025
    • 18 300 second Gain 150 Ha lights
    • 30 1 second Gain 150 Ha flats
    • 19 300 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
    • 19 300 second Gain 150 Sii lights
    • 30 1 second Gain 150 Sii flats
  • November 11, 2025
    • 34 30 second Gain 150 Red lights
    • 30 0.05 second Gain 150 Red flats
    • 35 30 second Gain 150 Green lights
    • 30 0.02 second Gain 150 Green flats
    • 35 30 second Gain 150 Blue lights
    • 30 0.02 second Gain 150 Blue flats
  • 30 Flat Darks matching flat durations from library
  • 30 Darks matching light durations from library

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • Narrowband Normalization

C/2025 A6 Comet Lemmon on October 26, 2025 Tail Motion Movie

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One of the things that really impressed me when I was imaging Comet C/2025 A6 Lemmon on October 26, 2025 was that the tail changed from frame to frame.  There appeared to be a “knot” that moved along the tail away from the comet head.

It’s taken me a while to figure out how to make a movie of this motion.  One challenge was that since it was just after sunset and the comet was near the horizon, the background level changed from frame to frame.  I realized that I could use Local Normalization and generate normalized files that helped with the varying background a lot.  I also started with separate red, green, blue data that had to be aligned using CometAlignment to make RGB images and then re-aligned with CometAlignment with the original green positions to show the comet motion with respect to the stars.  I ended up making two sets of images: one aligned to the green frames at each time step to show the comet motion relative to the stars, and one with all the frames aligned to the comet to show the comet tail changes. 

This movie was made with 15 frames of data using 1 minute each of red, green, and blue data.  The comet showed this much motion over about 45 minutes!  

Cool!

Camera geek info – telescope:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Sargent, Texas Bortle 4 skies

Frames – telescope:

  • October 26, 2025
    • 16 60 second Gain 150 R lights 
    • 30 0.05 second Gain 150 R flats
    • 15 60 second Gain 150 G lights 
    • 30 0.02 second Gain 150 G flats
    • 17 60 second Gain 150 B lights (16 for stars)
    • 30 0.02 second Gain 150 B flats
    • Matching darks and flat darks from library

C/2025 A6 Comet Lemmon on October 26, 2025 using three different focal lengths

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I finally had some time over my Christmas break to process (some of) my comet data, including the wide field images I took on Sunday, October 26, 2025 from the darker (Bortle 4) skies of Sargent, Texas.  

I miscalculated the direction of the comet motion and initially set up the camera with a 24 mm lens (very wide field, 53 deg by 35 deg) looking towards the sunset to get a lovely gradient of color.  Then, after it got dark, I took a series of images of the stars, about 13 minutes worth.  I didn’t take more data because I decided to move the camera to get a better framing.  The comet is in this image, but I had to circle it because it is so dim and doesn’t have an obvious tail.  You can see that it is below a triangle of stars, the Serpent’s head in the Serpens Caput (Serpent Head) constellation.

I took additional data with the 24 mm lens with a better framing, about 33 minutes worth.  I didn’t take more data because I wanted to switch to a different lens.  Happily, the comet is clearly visible in this image; no circling needed!  And the triangle of stars is still visible as well.

I took additional data with an 85 mm lens (15 deg by 10 deg field of view), about 11 minutes worth.  I cropped this image, so it is an even smaller field of view, again with the comet clearly visible along with the triangle of stars above it.

All of the pictures with the camera were taken using just a tripod (no tracking mount), so I had to do a fair bit of processing to remove the star trails in the data (BlurXterminator is a great tool for this), and I had to process the comet separately from the stars to keep it from smearing since is moving relative to the stars.

Finally, while I was taking pictures with the camera on a tripod, I was also taking pictures with my small telescope with a 430 mm focal length and a 1.8 by 1.2 degree field of view, about 45 minutes worth.  Of course the comet and its tail is amazingly obvious here, and I could see its tail changing over the course of the evening.  I’m working on making a movie of that, stay tuned!

Which version do you like the best?

Camera geek info – 24 mm sunset image:

  • Canon EOS 60D in manual mode set at f/8, 10 second exposure, ISO 400
  • Sigma 24-70 mm f/2.8EX lens, set at 24 mm, manual focus
  • Tripod
  • Intervalometer 

Frames – 24 mm sunset image:

  • October 26, 2025
    • 80 10 second lights
    • 30 1/2500 second flats
    • Matching darks and dark flats from library

Camera geek info – 24 mm night image:

  • Canon EOS 60D in manual mode set at f/2.8, 20 second exposure, ISO 400
  • Sigma 24-70 mm f/2.8EX lens, set at 24 mm, manual focus
  • Tripod
  • Intervalometer 

Frames – 24 mm night image:

  • October 26, 2025
    • 100 20 second lights
    • 30 1/2500 second flats
    • Matching darks and dark flats from library

Camera geek info – 85 mm night image:

  • Canon EOS 60D in manual mode set at f/2.5, 6 second exposure, ISO 800
  • Canon EF 85 mm f/1.8 lens at f/2.5 manual focus at infinity
  • Tripod
  • Intervalometer 

Frames – 85 mm night image:

  • October 26, 2025
    • 110 6 second lights
    • 30 1/2500 second flats
    • Matching darks and dark flats from library

Camera geek info – telescope:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Sargent, Texas Bortle 4 skies

Frames – telescope:

  • October 26, 2025
    • 16 60 second Gain 150 R lights 
    • 30 0.05 second Gain 150 R flats
    • 15 60 second Gain 150 G lights 
    • 30 0.02 second Gain 150 G flats
    • 17 60 second Gain 150 B lights (16 for stars)
    • 30 0.02 second Gain 150 B flats
    • Matching darks and flat darks from library

Sh2-184 NGC281 The Pac-Man Nebula (or, alternately, the Spouting Whale Nebula)

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Sharpless Sh2-184 NGC281 is commonly called the Pac-Man Nebula for obvious reasons – it looks like the video game character Pac-Man with its round shape and open mouth.  Yet I also see a spouting whale – same big mouth but with a tail and spouting water out of its blowhole.  Can you see it?

I made two versions of this – one “square” with the frame that is missing the stars in the upper right corner, and one “surfing the waves” angled one that has a complete starfield.  Which version do you like better?

This image shows HII region Sharpless Sh2-184 (the whole image) and the open cluster IC1590 (stars in the blue region).  

Sh2-184 is an H II region emission nebula, a region of ionized atomic hydrogen.  The H II regions in the Sharpless 2 catalog were “defined not only in terms of the ionized gas but also in terms of the hot stars which are responsible for the ionization.”

The young open cluster IC1590 is about 3.5 – 4.4 million years old.  Among other stars, it contains four O type stars, short-lived, hot, massive stars that ionize the surrounding molecular cloud. 

The massive stars are believed to be triggering star formation in the surrounding H II region by ionizing, heating, and compressing gas in molecular cloud in which they formed.  In the periphery of the open cluster, Young Stellar Objects (YSOs), young, low-mass stars deeply embedded in parent molecular cloud, are found that are 1 – 2 million years old and 0.5 – 3.5 times the mass of our sun.  I am always amazed when I realize that our galaxy is still under construction!

Sh2-184 is located in the Milky Way, approximately 10110 light years away.  This image is 50 arc minutes across, so the image is approximately 150 light years across. 

I collected the frames for this image under the fantastic dark skies of Dell City, Texas.  When we go out there, I generally try for some easier targets and a more difficult target – this was one of the easier targets.  I need far less time than I do for images from my light-polluted driveway, but it was something of a guess to know whether I’d taken enough data to end up with a good image.  In this image, the stars came from images using red-green-blue filters with 30 minutes of data each, and the nebula came from images using Sulfer ii (3.33 hours of data mapped to red), Hydrogen alpha (3.5 hours of data mapped to green) and Oxygen iii (3 hours of data mapped to blue) filters, the standard SHO mapping.  But after doing that mapping, I used Narrowband Normalization to shift the colors so that it wasn’t overly green and to enhance the reds and blues.  The nebula was processed separately from the stars to maximally enhance it.  As always, I like color, so I leaned into the rich colors.

What do you think of the colors?  What do you think of the alternate name?

Camera geek info – Narrowband:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB and SHO filters
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Dell City, Texas Bortle 2 – 3 skies

Frames:

  • November 8, 2025
    • 11 300 second Gain 150 Ha lights
    • 30 1 second Gain 150 Ha flats
    • 11 300 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
    • 11 300 second Gain 150 Sii lights
    • 30 1 second Gain 150 Sii flats
  • November 9, 2025
    • 9 300 second Gain 150 Ha lights
    • 30 1 second Gain 150 Ha flats
    • 9 300 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
    • 8 300 second Gain 150 Sii lights
    • 30 1 second Gain 150 Sii flats
  • November 10, 2025
    • 60 30 second Gain 150 Red lights
    • 30 0.05 second Gain 150 Red flats
    • 60 30 second Gain 150 Green lights
    • 30 0.02 second Gain 150 Green flats
    • 60 30 second Gain 150 Blue lights
    • 30 0.02 second Gain 150 Blue flats
  • November 11, 2025
    • 22 300 second Gain 150 Ha lights
    • 30 1 second Gain 150 Ha flats
    • 16 300 second Gain 150 Oiii lights
    • 30 0.5 second Gain 150 Oiii flats
    • 21 300 second Gain 150 Sii lights
    • 30 1 second Gain 150 Sii flats
  • 30 Flat Darks matching flat durations from library
  • 30 Darks matching light durations from library

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • Narrowband Normalization

Happy New Year 2026!

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We celebrated New Year’s Eve with our traditional time travel movies.  

This year’s first pick was a Filipino film, My Future You, an information time travel plot (two people from different years communicate via, in this case, a matchmaking site) movie.  We found it to be a sweet movie, exactly matching the mood we wanted.

Our second pick was the first two episodes of Doctor Who: The Three Doctors, where the first two doctors are pulled out of their own timestreams to help the Third Doctor, with the classic “I’m the REAL Doctor” banter.

Happy New Year!  I hope you enjoyed your New Year’s celebrations.

Sh2-86 A Lighthouse at Sunset with an Oncoming Storm or, more simply, the Lighthouse Nebula

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Sharpless Sh2-86 does not have a common name, and I think it’s fun to come up with my own names for these objects.  To me, with this framing, the “finger” or “pillar” in the lower center looks like a lighthouse – can you see the beam pointing to the left?  It’s standing on a rocky shore near the blue water (can you see a fish jumping out of water to its right?).  It’s at sunset – the vibrant red to the right – with a storm coming in – the dark spots to the left.  So I call this image “A Lighthouse at Sunset with an Oncoming Storm.” Or, more simply, the Lighthouse Nebula.

This image shows HII region Sharpless Sh2-86 (the whole image), the open cluster NGC6823 (stars in the center of the blue region), and emission nebula NGC6820 (pink spot to the upper left). 

Sh2-86 is an HII region emission nebula, a region of ionized atomic hydrogen.  It is a peak region in a molecular cloud, an interstellar cloud of gas molecules, whose density allows the formation of molecules such as molecular hydrogen (H2) and carbon monoxide (CO).  It is located in the “local spur” region between the “local arm” of the Milky Way where our solar system is located and the “Sagittarius Arm” which is closer to the galactic center.  (There’s a great overhead diagram of our galaxy showing the different arms in A Parallax-Based Distance Estimator for Spiral Arm Sources.)  One theory is that the region is made of three different molecular filaments moving at different velocities, the intersection of which led to the formation of the young open cluster NGC2823.

The young open cluster NGC6823 is about 3 million +/- 1 million years old.  It contains at least 17 OB type stars, short-lived, hot, massive stars that emit UV radiation that ionizes the surrounding molecular cloud.   

Sh2-86 also contains emission nebula NGC6820 which contains an embedded cluster of stars.  

Sh2-86 is located in the Milky Way, approximately 6500 light years away.  This image is 42.2 arc minutes across, so the image is approximately 80 light years across. 

In this image, the stars came from images using red-green-blue filters with a little over 30 minutes of data each, and the nebula came from images using Sulfer ii (4.35 hours of data mapped to red), Hydrogen alpha (3.05 hours of data mapped to green) and Oxygen iii (15.6 hours of data mapped to blue) filters, the standard SHO mapping.  But after doing that mapping, I used Narrowband Normalization to shift the colors so that it wasn’t overly green and to enhance the reds and blues.  The nebula was processed separately from the stars to maximally enhance it.  After making this uber-vibrant version, I tried several rounds of trying to make a more subdued version, but I just didn’t like them as well.  So the vibrant color was an artistic decision.

What do you think of the colors?  What do you think of the name?

Camera geek info – Narrowband:

  • William Optics Pleiades 111 telescope
  • ZWO 2” Electronic Filter Wheel
  • Antila SHO and RGB filters
  • Blue Fireball 360° Camera Angle Adjuster/Rotator
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Friendswood, Texas Bortle 7-8 suburban skies

Frames:

  • August 7, 2025
    • 61 180 second Gain 150 Ha lights
    • 30 0.5 second Gain 150 Ha flats
  • August 8, 2025
    • 86 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • August 9, 2025
    • 45 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • August 14, 2025
    • 77 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • August 16, 2025
    • 86 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • August 24, 2025
    • 7 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
    • 100 20 second Gain 150 Red lights
    • 30 0.02 second Gain 150 Red flats
    • 99 20 second Gain 150 Green lights
    • 30 0.01 second Gain 150 Green flats
    • 96 20 second Gain 150 Blue lights
    • 30 0.01 second Gain 150 Blue flats
  • September 4, 2025
    • 69 180 second Gain 150 Sii lights
    • 30 0.5 second Gain 150 Sii flats
  • November 25, 2025
    • 8 180 second Gain 150 Sii lights
    • 30 0.5 second Gain 150 Sii flats
    • 1 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • November 26, 2025
    • 10 180 second Gain 150 Sii lights
    • 30 0.5 second Gain 150 Sii flats
    • 10 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • 30 Flat Darks matching flat durations from library
  • 30 Darks matching light durations from library

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • Narrowband Normalization

Comet 3I ATLAS on 11 November 2025 – An Interstellar Visitor

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We recently took a trip to enjoy the glorious dark skies in Dell City, Texas.  Imaging Comet Lemmon was on the agenda, but I was delighted when I realized that I could also capture Comet 3I ATLAS, an interstellar visitor to our solar system, with my small telescope!

Comet 3I ATLAS (C/2025 N1 ATLAS) is an interstellar comet.  The designation “3I” means it’s the third interstellar comet to be discovered in our solar system.  The designation C/2025 N1 can be interpreted as follows: “C”: it is a non-periodic comet (comet with an orbital period > 200 years), “2025”: it was discovered in 2025, “N1”: it was the first comet (1) discovered in (N) the thirteenth half-month of the year (the first half of July) (the letter I is skipped due to its visual similarity to the number 1).  The name ATLAS indicates it was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) station.  

Comet 3I ATLAS is considered a comet because it is releasing gas and has formed a visible coma of gas around its nucleus, as you can see in the picture.

Comet 3I ATLAS is the third known interstellar object (object not gravitationally bound to any star) to pass through our solar system, but that’s more likely to be due to improving detection capabilities and not due to the lack of earlier visitors.  We know it’s an interstellar object because of its high velocity and hyperbolic trajectory.  Its trajectory is shown as the purple line in the picture above (image courtesy of TheSkyLive.com TheSkyLive).  As you can see, it did not cross Earth’s orbit (the blue circle).  

One feature of comets is that they are visibly fuzzy, as you can see in the picture and video.  Another is that they are moving relative to the stars, as you can see in the video.    

As 3I ATLAS passes through our solar system, scientists are collecting more data on it and determining more about it.  An early paper from July suggested it might have come from our galaxy’s “thick disk” – the population of older stars above and below the “thin disk” where our solar system is – and so might potentially be over 7.6 billion years old, older than our solar system (there’s a cool image of the orbits of the comet and our sun relative to our galaxy in the news release).  A paper from August suggests it came from our galaxy’s “thin disk” and another paper from August suggests it is 3 – 11 billion years old.  

I think it’s really cool to see science being done in real time, and I look forward to seeing everything that scientists can figure out about this neat object!

Camera geek info:

  • William Optics Zenith Star 73 III APO telescope
  • William Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Dell City, Texas Bortle 2 – 3 skies

Frames:

  • November 11, 2025
    • 15 60 second Gain 150 R lights 
    • 30 0.05 second Gain 150 R flats
    • 16 60 second Gain 150 G lights 
    • 30 0.02 second Gain 150 G flats
    • 16 60 second Gain 150 B lights 
    • 30 0.02 second Gain 150 B flats
    • Matching darks and flat darks from library

NGC7635 The Bubble Nebula

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NGC7635, or the Bubble Nebula, consists of an emission nebula numbered Sharpless Sh2-162 surrounding a bubble surrounding a massive young type O star.  The emission nebula Sh2-162 is part of a molecular cloud, an interstellar cloud of gas molecules, whose density allows the formation of molecules such as molecular hydrogen (H2) and carbon monoxide (CO).  The source of energy creating the bubble and lighting up the emission nebula is the young, hot, type O star BD+60 2522.  The star is about 27 +/- 7 times the mass of the sun and 2 million years old.  The bubble is estimated to only be about 50,000 years old and is striking for appearing nearly spherical and for its star not being near its geometric center (in this image, the star is the bright white circle to the left underneath the bright white arc on the bubble’s surface).  The bubble was created by the solar wind from the star pushing the material around it into a thin, dense shell.  I found a paper from 2019 that argues that because the star is moving at a relatively high velocity and the bubble is relatively young, the star is creating a bow shock.  If the bow shock is the case, the bubble is probably closer to us than the emission nebula and moving towards it.  The bubble and nebula being significantly brighter on one side (the left side in this image) could be explained either by the bow shock or by the interstellar matter on that side being denser.  

The Bubble Nebula is located in the Milky Way, approximately 8155 light years away.  The nebula has an apparent size of 0.69 degrees, so it is approximately 99 light years across.  The bubble itself is about 3 arc-minutes in diameter, so it is approximately 7 light years across.

In this image, the stars came from images using red-green-blue filters with 12 to 33 minutes of data each, and the nebula came from images using Sulfer ii (7.4 hours of data mapped to red), Hydrogen alpha (2.8 hours of data mapped to green) and Oxygen iii (8.1 hours of data mapped to blue) filters, the standard SHO mapping.  But after doing that mapping, I used Narrowband Normalization to shift the colors so that it wasn’t overly green and to enhance the reds and blues.  This tool made getting the colors in this nebula look good a lot easier!  The nebula was processed separately from the stars to maximally enhance it.

I think this nebula is stunning!  We live in a universe filled with wonders.

Camera geek info – Narrowband:

  • William Optics Pleiades 111 telescope
  • ZWO 2” Electronic Filter Wheel
  • Antila SHO and RGB filters
  • Blue Fireball 360° Camera Angle Adjuster/Rotator
  • ZWO ASI183MM-Pro-Mono camera
  • William Optics Uniguide 32MM F/3.75
  • ZWO ASI220MM-mini
  • ZWO ASiair Plus
  • iOptron CEM40
  • Friendswood, Texas Bortle 7-8 suburban skies

Frames:

  • August 7, 2025
    • 56 180 second Gain 150 Ha lights
    • 30 0.5 second Gain 150 Ha flats
  • August 8, 2025
    • 4 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • August 14, 2025
    • 31 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • August 16, 2025
    • 42 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • September 4, 2025
    • 50 180 second Gain 150 Sii lights
    • 30 0.5 second Gain 150 Sii flats
  • September 11, 2025
    • 55 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
  • September 12, 2025
    • 65 180 second Gain 150 Sii lights
    • 30 0.5 second Gain 150 Sii flats
  • September 13, 2025
    • 100 20 second Gain 150 Red lights
    • 30 0.02 second Gain 150 Red flats
    • 35 20 second Gain 150 Green lights
    • 30 0.01 second Gain 150 Green flats
    • 51 20 second Gain 150 Blue lights
    • 30 0.01 second Gain 150 Blue flats
  • October 25, 2025
    • 30 180 second Gain 150 Oiii lights
    • 30 0.2 second Gain 150 Oiii flats
    • 33 180 second Gain 150 Sii lights
    • 30 0.5 second Gain 150 Sii flats
  • 30 Flat Darks matching flat durations from library
  • 30 Darks matching light durations from library

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • Narrowband Normalization