An Asteroid...Apparently

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John Walsh avatar

Hey All,

I was imaging LDN 1584 last month when I noticed some aberrant small streaks in the stacked results over 2 nights. The position of the streak had changed from one night to the next so I blinked through the individual subs and saw what looked like a moving ‘star’ in the location of said streak.

I made a video of it's movement, plate-solved the coordinates, and cross-checked it against the MPC database of near-earth objects. This is an extreme close-up of around 60 2min subs, blinked in Pixinsight after registration.

Turns out to be an Asteroid named "44318 1998 RK24 ". At least it precisely follows the trajectory and location of this object on the date in question.

The only thing that bothers me is how bright it is. It apparently has a magnitude of 19.28 but I checked the stars around this area in Stellarium and they should be much brighter than 19.28, but the moving object is just as bright as them in my capture.

Is this just a product of pixels being saturated and therefore I can’t trust the brightness of the stars around it? I hope I’m making sense.

Anyway it is fairly cool for me if it is indeed the named asteroid. First time I’ve come across one.

asteroid.mov📷 asteroid-ezgif.com-video-to-gif-converter (1).gifasteroid-ezgif.com-video-to-gif-converter (1).gif

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Peter Hannah avatar

Are your images stretched? If so, check the raw calibrated frames.

Stretching may have saturated both the stars and the asteroid.

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John Walsh avatar

I think PI applied an STF to the subs before I blinked them

nico1038 avatar

Hi John,

Did your session take place on the late evening of December 25th or the early morning of the 26th?

I think a better candidate is (80) Sappho (magnitude 10) :

📷 Image21_Annotated5.jpgImage21_Annotated5.jpg

John Walsh avatar

Yes Nico! The 26th. How did I miss this candidate? Thank you very much!

What software or database did you use to discover that?

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Peter Hannah avatar

It’s definitely worth running PI’s Annotation script on some of your raw calibrated images (which is where I assumed your identification of the asteroid had come from).

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nico1038 avatar

John Walsh · Jan 22, 2026, 09:27 AM

Yes Nico! The 26th. How did I miss this candidate? Thank you very much!

What software or database did you use to discover that?

Just Pix and its databases. For this one you don't even need the xeph files: Sappho is included in the asteroid layer of the AnnotateImage script.

The indicator shows a slight inconsistency in its positioning. Would you mind giving your approximate location? I'm wondering if parallax could explain this.

John Walsh avatar

nico1038 · Jan 22, 2026 at 09:40 AM

John Walsh · Jan 22, 2026, 09:27 AM

Yes Nico! The 26th. How did I miss this candidate? Thank you very much!

What software or database did you use to discover that?

Just Pix and its databases. For this one you don't even need the xeph files: Sappho is included in the asteroid layer of the AnnotateImage script.

The indicator shows a slight inconsistency in its positioning. Would you mind giving your approximate location? I'm wondering if parallax could explain this.

Thank Nico. Ireland, Dublin as an approximation

Jan Erik Vallestad avatar

This is a good source for identifying any asteroids/small planets at any given time:
https://www.minorplanetcenter.net/cgi-bin/checkmp.cgi

Much better than having to rely on loading the right dataset in certain software. I recently used it on a project myself as I came upon a small planet orbiting through my image. Afterwards I loaded the specific object in Stellarium to confirm.

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nico1038 avatar

John Walsh · Jan 22, 2026, 09:42 AM

nico1038 · Jan 22, 2026 at 09:40 AM

John Walsh · Jan 22, 2026, 09:27 AM

Yes Nico! The 26th. How did I miss this candidate? Thank you very much!

What software or database did you use to discover that?

Just Pix and its databases. For this one you don't even need the xeph files: Sappho is included in the asteroid layer of the AnnotateImage script.

The indicator shows a slight inconsistency in its positioning. Would you mind giving your approximate location? I'm wondering if parallax could explain this.

Thank Nico. Ireland, Dublin as an approximation

The position on earth does make a difference! Using Dublin's coordinates, the position is perfect:

📷 Image21_Annotated7.jpgImage21_Annotated7.jpg

John Walsh avatar

Wow that’s so cool Nico!

John Walsh avatar

Jan Erik Vallestad · Jan 22, 2026 at 10:20 AM

This is a good source for identifying any asteroids/small planets at any given time:
https://www.minorplanetcenter.net/cgi-bin/checkmp.cgi

Much better than having to rely on loading the right dataset in certain software. I recently used it on a project myself as I came upon a small planet orbiting through my image. Afterwards I loaded the specific object in Stellarium to confirm.

Thanks Jan! Every day a learning experience with this hobby

Brian Puhl avatar

For things like this Stellarium has a plug in for asteroids as well, it’s usually my go-to.

📷 image.pngimage.png

Willem Jan Drijfhout avatar
Congrats John, these discoveries tend to give a lot of satisfaction.
The tool I use is Tycho tracker. It is designed to identify satellites, but also detects asteroids. You can feed it raw fits files and it analyses any moving object. Then it provides you with the results, including confidence factor. But for asteroids like this the confidence factor will be far above 90%. In a recent image where I detected an asteroid the way you did, it actually identified a second one, one that was discovered only as recently as 2001. 
If you are interested, you may want to check out a ‘mini instruction’ I wrote some time ago. It was mainly written so that I could repeat the steps later, as the software can be overwhelming at first.
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Jeff Bennett avatar

This is awesome John.

JohnAdastra avatar

You will probably find asteroids are present in a high number of your subframes if you take the time to look. They may appear as streaks or a row of dots. When you do pixel rejection in PixInsight or other apps they tend to get removed as those bright pixels are not in the same place and are then discarded in the final master light.

John

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