Tag Archives: Comet

Capturing Comet C/2025 F2 SWAN

Posted on by
Reply

In late March 2025, a new comet, C/2025 F2, was found in imagery from the Solar Wind Anisotropies (SWAN) camera on the Solar and Heliospheric Observatory (SOHO). 

Orbit images Courtesy NASA/JPL-Caltech.

The Jet Propulsion Laboratory (JPL) has a great orbital dynamics viewer where you can see its orbit relative to the planets.  It’s quite fun to play with!  C/2025 F2’s orbit is very parabolic and nearly 90 degrees out of the ecliptic plane.  It is coming in from north of the ecliptic plane, will loop around the sun near Mercury’s orbit on May 1, 2025, and then head back out to the outer solar system south of the ecliptic plane.  So it’s visible from the Northern Hemisphere in the early morning now, but as it approaches the sun, it will get more and more difficult to spot, and it will be more visible from the Southern Hemisphere on its outgoing trajectory.

“Now” was the best time to see it from the Northern Hemisphere, and we have had a nice string of days with clear skies, so last weekend, it was time to go comet hunting!  

I used the JPL Horizons System to predict the comet location and motion so that I knew where to point my telescope and I knew how long the images could be without “smearing” the comet – 15 seconds for my telescope and camera combo.

I loaded up my gear, and my husband and I drove to our favorite early morning comet viewing site in Bacliff, Texas.  By the time I had everything set up, the comet was above the horizon.  My preprogrammed location contained a small, fuzzy object which looked like a comet on the first try!  I was really delighted that everything worked on the first try; this has not always been the case in the past.  I spent some (probably too much) time trying to get it positioned better in the frame and started imaging.  It was brighter in green than in red and blue which, with its fuzziness, confirmed to me that it was likely a comet.  I couldn’t see a tail in my single images.

I set up my regular camera to see if I could get some wider field images.  Given what I ended up with in the telescope images, I do not think the comet will be visible in the wider field images.

Both my husband and I tried to find the comet with binoculars, with no luck at all.  

We finished the morning with a lovely sunrise and breakfast.

Processing comets is still a big challenge for me, with more steps than processing a nebula.  I mostly follow the excellent process outlined by Adam Block in his Comet Academy.  Blinking through my frames, I could see the comet moving across the sky, another sure indicator that I had captured the right object!  After aligning, integrating, and stretching the comet images, I could see a faint tail that stretched all the way across the field of view (about 2 degrees with this telescope and camera combination), but the background noise was brighter than it was.  I tried several methods to make the tail visible, and the one that worked the best was to “murder the background” as Adam says in one of his videos.

I’m probably not going to get another chance to capture this one, but I enjoyed getting to see it at least once.  Has anyone else tried to go out and capture this one?

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
  • Bacliff, Texas Bortle 6 suburban skies

Frames:

  • April 12, 2025
    • 47 15 second Gain 150 Green lights
    • 30 0.02 second Gain 150 Green flats
    • 45 15 second Gain 150 Blue lights
    • 30 0.02 second Gain 150 Blue flats
    • 50 15 second Gain 150 Red lights
    • 30 0.05 second Gain 150 Red flats
  • 30 Flat Darks from library
  • 30 Darks 

Processing geek info:

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

Post-Solar-Swing Comet C/2023 A3 Tsuchinshan ATLAS 

Posted on by
3

Comet C/2023 Tsuchinshan ATLAS looped around the sun on September 27, 2024 and started on its path back towards the outer solar system.  For a few days, it was not visible because it was too close to the sun.  But it was predicted to become visible again around October 11, and it would be the closest to the Earth on October 12, 2024. 

We were in Dell City at the time and staked out a sunset viewing spot with a long view to the west. 

We made our first attempt to see the comet on October 10, 2024.  The comet should have been barely above the horizon at sunset, and unless it was truly extraordinary, we were unlikely to be able to see it.  We were treated to a lovely sunset, but we could not spot the comet.  I had told myself this was a dry run, so I wasn’t too disappointed.  And, when we returned back to our B&B, we were treated to a rare viewing of the northern lights from Texas.

We made a second attempt to see the comet on October 11, 2024.  The comet was supposed to be higher above the horizon at sunset than the day before.  There were low clouds in the sky.  We saw a lot of “fake comets” – bright airplane contrails.  Eventually my husband found the comet with his binoculars – success!  I started taking pictures, but I hadn’t used the right settings, and when I discovered that later, I suspected that the data would not be usable.  I was right – I can see a moving smudge in the images, but it’s not good enough for PixInsight to comet align the images (and there aren’t enough stars in the images for it to star align them).

We made a third attempt – third time is the charm! – on October 12, 2024.  The comet was supposed to be more than 10 degrees above the horizon at sunset, and it had been the closest it would be to the Earth, 0.47239 AU or 70668538.14 km, just nine hours earlier.  This time there weren’t any clouds.  And this time we could easily find the comet and see that it had a huge tail!  Given my experience the night before, I made sure I was using good camera settings, and I could see the comet and its tail in single images.

I used PixInsight to stack 50 images (8.3 minutes of data) to make this final image – my first post-solar-swing image of C2023 A3.  Isn’t it beautiful?

Today, on this day of Thanksgiving, I am most thankful for my family and friends, near and far.  But I’m also thankful for all the wonder to be found in this universe we live in, and particularly for this comet.  Happy Thanksgiving!

Camera geek info:

  • Canon EOS 60D in manual mode, 4 second exposures, ISO 800
  • Canon EF 85 mm f/1.8 lens at f/11 manual focus at infinity
  • Intervalometer
  • Tripod
  • Dell City, Texas Bortle 2-3 dark skies

Frames:

  • October 12, 2024 
    • 50 10 second lights 
    • 31 0.01 second flats
    • 31 0.01 second flat darks
    • 30 10 second darks

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXterminator
  • NormalizedScaleGradient

Comet Hunting Tailgate Party: C/2023 A3 Tsuchinshan ATLAS from Dell City, Texas

Posted on by
1

Our last visit to Dell City, Texas ended with a fun event: going comet hunting with new friends. 

I knew from comet hunting with my husband the previous evening that C/2023 A3 Tsuchinshan-ATLAS would be visible in the early evening sky.  But this time, I wanted to image it over the Cornudas Mountains to the west of town.  I also wanted to have a view over the flat fields to the mountains and the sky above – which I could find by driving just a few blocks north of the center of town.

I invited some new local friends to join us, and they came in a pickup truck loaded with lawn chairs.  It was a comet tailgate party!

We had a great time visiting while we watched the sky as Venus appeared, followed by some bright stars, followed by the comet.  We could see it naked eye!  We could even see the comet’s tail naked eye!  It was pretty impressive.

It’s taken me over a month to learn how to and successfully process these pictures.  Each picture used one set of images for the comet, stars, sky, and foreground/mountains, but each part was processed separately.  The earlier pink picture where the comet is higher in the sky was made from 120 4 second shots (8 minutes of data).  The later orange picture where the comet is lower in the sky was made from 75 10 second shots (12.5 minutes of data).

One of the things I tried to do while processing was to make sure that all the fuzz around the comet and the anti-tail were real and not processing artifacts.  You can use the sliders below to compare the final images with the comet-only portion to see that, if anything, the final images show less fuzz than what was in the data.  (The comet-only data was calibrated, blur exterminated, star exterminated, comet-aligned, stacked, dynamic background extracted, and stretched.)

Comet C/2023 A3 4 second Comet Only and Final images
Comet C/2023 A3 10 second Comet Only and Final images

This event is high on my list of “coolest astro things I’ve seen.”  And I’m glad I had such a great group of folks to share it with.

What cool things have you shared with friends recently?

Camera geek info:

  • Canon EOS 60D in manual mode, 4 second and 10 second exposures, ISO 800
  • Canon EF 85 mm f/1.8 lens at f/8, manual focus at infinity
  • Intervalometer
  • Tripod
  • Dell City, Texas Bortle 2-3 dark skies

Frames:

  • October 13, 2024 
    • 120 4 second lights for pink image with higher comet
    • 75 10 second lights for orange image with lower comet
    • 30 0.01 second flats
    • 30 0.01 second flat darks
    • 30 4 second darks
    • 30 10 second darks

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXterminator
  • NormalizedScaleGradient

Comet C/2023 A3 Tsuchinshan ATLAS with M5

Posted on by
3

Comet C/2023 A3 Tsuchinshan ATLAS put on quite a show after it rounded the sun and passed by the Earth on its way likely out of our solar system.  With an orbital eccentricity greater than 1, its orbit appears to be hyperbolic, meaning it’s not coming back unless something perturbs its orbit.

In this picture, you can see the comet’s bright nucleus and coma, its long dust tail, and its anti-tail, but not a separate ion tail.

When comets travel close to the sun, solar radiation heats up the comet nucleus, and it outgasses. Outgassing delivers both gas and dust to the region around the nucleus, forming a coma, a (temporary) atmosphere around the comet.  The solar radiation and solar wind act on this coma to push the gas and dust away from the sun to form a tail.  Three separate tails can be visible: the ion tail, the dust tail, and the anti-tail. The ion tail, also called the gas tail or type I tail, is the tail formed by the ionized gasses pushed away from the comet, and it points away from the sun.  The dust tail, also called the type II tail, is the tail formed by the dust pushed away from the comet, and it stays more in the comet’s orbit and appears to curve away from the gas tail.  The anti-tail consists of the larger dust particles that were not pushed as much and remained in the comet’s orbit.  The anti-tail appears to point towards the sun, and it is only visible when the Earth passes through the comet’s orbital plane near the time when the comet passed by the sun.  Because of these special conditions to see the anti-tail, it is not observed with most comets.

Another item visible in the image is M5, a globular cluster in our galaxy.  It is the large bright “star” to the right of the comet nucleus.  Because this image was taken with an 85 mm lens, and M5 was sorted to the “stars” image in my processing, it just appears to be a large bright star.  I suspect with some additional processing, I could have made it look fuzzier, though there aren’t a lot of pixels at this scale.  The Messier objects are “fuzzy” objects that comet-hunter Charles Messier made a list of because they weren’t comets – so it’s fun to see one next to a comet.  M5 is 24,500 light years away from Earth and has an angular size of 23 arc-minutes, making it about 165 light years across.  It’s thought to be one of our galaxy’s older globular clusters, at 13 billion years old.

Processing this image was tricky for several reasons: 1) it was made from images taken with a camera on a tripod, so the sky was moving in each frame, 2) the comet was moving relative to the sky, and 3) the images were taken at dusk, when the sky gradient is also changing in every image.  I benefited greatly from following the methods and advice in Adam Block’s Comet Academy.  One additional trick I used was to run BlurXterminator in correction only mode on all the registered images as my first step since the 4 second tripod images had visible star trails. 

Getting to this image has taken almost a month of watching videos, learning new tools, and trying various tool combinations and settings.  Some of these steps had to be run on each individual image – all 233 of them – meaning some processing steps took many hours.  After all that work, I am happy with the results.

I started with this image because I thought it would be the easiest of my set of C2023A3 comet images to process … the other images are from darker skies in terms of light pollution but closer to dusk and include a foreground.  But the comet was brighter!  I’m really looking forward to processing them and sharing the result!  Hopefully they won’t take a month each to process!

Camera geek info:

  • Canon EOS 60D in manual mode, 4 second exposures, ISO 1600
  • Canon EF 85 mm f/1.8 lens, manual focus at infinity
  • Intervalometer
  • Tripod
  • Pearland, Texas Bortle 7-8 dark skies

Frames:

  • October 15, 2024
    • 233 4 second lights
    • 30 0.0025 second flats
    • 30 0.0025 second darks

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXterminator
  • StarNet2
  • NormalizedScaleGradient

Comet C/2023 A3 Tsuchinshan Atlas from Friendswood, Texas with a Telescope

Posted on by
3

I have a bunch of wide field comet images from Dell City, Texas and Pearland, Texas that are proving … challenging … to process, given that they were taken near dusk with a DSLR on a tripod.  Everything is changing – the Earth is rotating (so the stars are moving relative to the camera on a non-tracking tripod), the comet is moving relative to the stars, and the sky brightness is changing.  

But now Comet C/2023 A3 Tsuchinshan Atlas is getting higher in the night sky, so it is no longer visible only at dusk.  So I could set up my tracking mount and telescope to image it.  The tail is still really long – much longer than I can capture in the field of view of my telescope!

Even with a tracking mount and dark sky, processing a comet moving relative to the stars is still really challenging, and I really benefited from following the “Standard Comet” example in Adam Block’s Comet Academy.

Camera geek info:

  • Williams Optics Zenith Star 73 III APO telescope
  • Williams Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • ZWO ASiair Plus
  • iOptron CEM40
  • Friendswood, Texas Bortle 7-8 dark skies

Frames:

  • October 24, 2024
    • Interleaved LRGB lights
      • 11 60 second Gain 150 R lights
      • 10 60 second Gain 150 G lights
      • 10 60 second Gain 150 B lights
    • 30 0.05 second R flats
    • 30 0.02 second B and G flats
    • 30 0.05 second darks
    • 30 0.02 second darks
    • 30 60 second darks

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • ImageBlend

Capturing Comet PANSTARRS C/2021 S3 with two Ancient Globular Clusters M9 and NGC6356

Posted on by
Reply

I was looking through my comet posts after my post yesterday, and I discovered I hadn’t posted this image of Comet PANSTARRS C/2021 S3 with two globular clusters that I made last spring.  Enjoy!

I hadn’t planned on imaging comets when we were in Dell City last spring, but when I saw this combination of two globular clusters and comet PANSTARRS C/2021 S3, I knew I had to try it.

Globular cluster M9, the brighter one to the left, is 25,800 light years away from us.  It’s 90 light years across, giving it an apparent size of 12 arcminutes.  Globular cluster NGC6356, the smaller one to the right, is 49,200 light years away from us.  Its apparent diameter is 8 arcminutes, giving it a diameter of 115 light years across.  Globular clusters are mind-bogglingly old parts of our galaxy and can be used to infer the age of the universe.  There are some interesting open questions about them, including their exact ages and whether they formed as part of our galaxy or were accreted later (probably a mix of both).  In the paper I found giving the ages for these two globular clusters, it shows that M9 is 14.60 ± 0.22 billion years old with one model, 14.12 ± 0.26 billion years old with a second model, and 12 billion years old in the literature.  It shows that NGC6356 is 11.35 ± 0.41 billion years old with one model, 13.14 ± 0.64 billion years old with a second model, and 10 billion years old in the literature.  No matter which age ends up being correct, ~10 billion years old is amazingly OLD!

Comet PANSTARRS C/2021 S3 was discovered by the Panoramic Survey Telescope and Rapid Response System located at Haleakala Observatory, Hawaii on images taken on September 24, 2021.  It reached perihelion (its closest point to the sun) on February 14, 2024 (the day after this image was taken) at 1.32 AU distance.  Its orbital eccentricity is higher than 1, meaning it’s on a parabolic trajectory and isn’t coming back.

I feel very fortunate that my trip out to the dark skies was timed so I could image this comet with two ancient globular clusters.  I also feel fortunate that I imaged it in a time when so many processing tools are being developed to make processing the image so much easier!  The tools I have this year are so much more powerful than the ones I had last year.

Camera geek info:

  • Williams Optics Zenith Star 73 III APO telescope
  • Williams Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila LRGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • ZWO ASiair Plus
  • iOptron CEM40
  • Dell City, Texas Bortle 2-3 dark skies

Frames:

  • February 13, 2024
    • Interleaved LRGB lights
      • 5 60 second Gain 150 L lights (only used for the comet)
      • 5 60 second Gain 150 R lights
      • 5 60 second Gain 150 G lights
      • 4 60 second Gain 150 B lights
    • 30 0.05 second LRGB flats
    • 30 0.05 second darks
    • 30 60 second darks

Processing geek info:

  • PixInsight
  • BlurXterminator
  • NoiseXterminator
  • StarXTerminator
  • ImageBlend

Comet vs Clouds: A Glimpse of Comet Tsuchinshan-ATLAS C/2023 A3

Posted on by
1

On Sunday morning, we got up at 4:00 AM to drive to a spot with a long view to the East to go comet hunting.  I successfully got the telescope set up prior to the time when Comet Tsuchinshan-ATLAS C/2023 A3 was supposed to rise.  However, when the comet did rise, the ASIAIR could find stars, but couldn’t plate solve to figure out if it was pointing exactly right.  So I ended up starting imaging without having successfully scanned to the predicted comet location.  Since I could see a tiny comet in the first shot, I let the system take an automated sequence of shots.  60 second shots were too bright, so I started with 10 second shots, and when they became too bright, I switched to 1 second shots.

I also tried taking pictures with an 85 mm lens on my Canon EOS 60D, but that didn’t pick up the comet at all.  What it did pick up was the reason I didn’t get very many good comet images … clouds!  Of course, clouds are terrible for astrophotography, but they do lead to nice sunrise pictures.

We stayed for the sunrise, went out to breakfast, and then headed home.

Astrophotography is really two hobbies: capturing the images and processing them.

When we got home, I worked on processing the images I’d gotten.  I could see the comet in the 10 second images and in the 1 second images, but the 1 second image ones were generally partially through the clouds.  So I ended up using only the 10 second images.  Because there weren’t any stars captured in these short images, I only needed to process for the comet and use Comet Alignment to align the frames.

I’m hoping that I’ll get some better images later this fall.  Are you making plans to try to see this one?

Camera geek info:

  • Williams Optics Zenith Star 73 III APO telescope
  • Williams Optics Flat 73A
  • ZWO 2” Electronic Filter Wheel
  • Antila RGB filters
  • ZWO ASI183MM-Pro-Mono camera
  • ZWO ASiair Plus
  • iOptron CEM40
  • Bacliff, Texas Bortle 6 suburban skies

Frames:

  • 4 10 second red lights
  • 7 10 second green lights
  • 5 10 second blue lights
  • 30 0.02 second flats for green and blue
  • 30 0.05 second flats for red
  • 30 0.02 second flat darks for green and blue
  • 30 0.05 second flats darks for red
  • 1 second dark from library 

Processing geek info:

  • PixInsight
  • Generalized Hyperbolic Stretch
  • NoiseXterminator

Comet Nishimura September 2

Posted on by
1

Comet Nishimura on September 2, 2023

Having learned how to process comets thanks to the excellent videos by Adam Block, I went back and finished processing my first image of Comet Nishimura from September 2, 2023.  That morning we got up at 3:30 AM and drove over to Bacliff, Texas to get a good view to the East, and got set up.  I found the comet, started taking pictures, and enjoyed watching the sunrise.  As the sun rose over the flat water, we saw dolphins arcing out of the water – one of my favorite sights on the Texas Gulf Coast.  

Because the September 2 images involved a compact comet with not much tail and a short range of locations and a rapidly brightening background, I modified the excellent instructions from Adam Block as follows:

Register and process images as normal (noting the reference image), then removing the comet using a circular mask that covered the first and last locations and PixelMath.  I could get away with this because the comet didn’t have a large tail and hadn’t moved very far and there were no visible stars in the masked-out region.  In this case, I integrated unweighted; if I were doing it again, I would use the weighting I determined below.

Run SubframeSelector to determine what parameter to weight the images with – PSF SNR seemed to best reflect the lower quality due to the sky brightening in the last images.

Run CometAlignment on the debayerd data to get comet-aligned images.  Use PixelMath to make a mask to mask the comet core.  Run StarXterminator to generate comet-only images.  Integrate the images using PSF SNR weighting.  Then post-process as normal.  I could barely see the comet tail in these images and I tried a variety of stretches to try to pull it out.  I ended up using STF and Histogram Transfer plus Curves.  

Finally, put the stars image and the comet image back together using PixelMath.

Whew!  Comet processing is a lot more complicated than galaxies and nebulae.  Fun to see something new in the sky, though.

Camera geek info:

  • Canon EOS 60D in manual mode, 60 second exposures, ISO 800 
  • Williams Optics Zenith Star 73 III APO telescope
  • Williams Optics Flat 73A
  • SkyTech 2” LPRO-MAX CCD Filter
  • iOptron CEM40
  • Bacliff, Texas Bortle 6 suburban skies

Frames:

  • 24 60 second lights
  • 30 0.03 second flats
  • 30 0.03 second flat darks
  • 30 60 second darks

Processing geek info:

  • PixInsight
  • NoiseXterminator
  • StarXTerminator

Comet Nishimura with Photobomber

Posted on by
3

Comet C/2023 P1 Nishimura on September 8, 2023

Comet C/2023 P1 Nishimura with Airplane Photobomber on September 8, 2023

For the past two weekends, we’ve gotten up at 3:30 AM to drive to a spot with a long view to the East to go comet hunting.  I had setup issues with my tracking mount both times – the GoTo tracking did not want to three star align.  On both days, I managed to overcome that obstacle in time to capture some images of the comet.  On September 8, the time frame between when the comet cleared the haze on the horizon and the time that the sky got bright pre-dawn was surprisingly short (about 20 minutes).  Also on September 8, I had a funny picture where an airplane had photobombed my comet image and flew right in front of the comet.  

Astrophotography is really two hobbies: capturing the images and processing them.

And I still haven’t mastered processing comets.  

But thanks to the excellent videos from Adam Block and a software update on Russ Croman’s extremely useful StarXterminator program (where my Comet Nishimura data from September 2 appears in the release notes), I have finally managed to produce some decent comet pictures.  I registered all the images with the one with the airplane photobomb so I could combine the final comet image with the airplane lights to make a photobomb picture.

It’s fun to find surprises in the night sky!

Camera geek info:

  • Canon EOS 60D in manual mode, 30 second exposures, ISO 800 for 4 frames, ISO 400 for the remainder
  • Williams Optics Zenith Star 73 III APO telescope
  • Williams Optics Flat 73A
  • SkyTech 2” LPRO-MAX CCD Filter
  • iOptron CEM40
  • Bacliff, Texas Bortle 6 suburban skies

Frames:

  • 38 30 second lights, 24 used for stars
  • 31 0.02 second flats
  • 30 0.02 second flat darks
  • 34 30 second darks

Processing geek info:

  • PixInsight
  • NoiseXterminator
  • StarXTerminator
  • Generalized Hyperbolic Stretch