C/2025 31 (ATLAS) Interstellar Comet

 

Comet/ 2025 31 (ATLAS) Interstellar Comet.
Captured 16-02-2025 from the Jodrell Plank Observatory, Suffolk UK.
Using the Seestar S30 Smart Telescope with Infra Red filter. 60 sec exposures stacked.
Image Credit: Pip Stakkert and Kurt Thrust

Plate Solver animation showing the SDSS (Sloan Digital Sky Survey) view without the comet, overlaid on the same star field with the comet as captured with the Seestar S30. SDSS and Plate Solver Image Credit: Astrometry Net.

Star Map showing he approximate position of Comet C/2025 31 (ATLAS)
on the evening 16_02_2026. Base image Credit: Wikipedia

Enlargement of the Seestar S30 image local to the comet
- faint hint of cometary nucleus and tail?

" Interstellar origin: Comet C/2025 3I/ATLAS is the third confirmed object from outside our Solar System observed by astronomers, after 1I/ʻOumuamua (2017) and 2I/Borisov (2019).

It was first detected on 1 July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescopes in Chile.

Its orbit is hyperbolic, meaning it’s not gravitationally bound to the Sun and is just passing through.It has passed perihelion, its closest point to the Sun, and is heading back out of the Solar System, never to return.

Kurt and the JPO Team were very keen to capture a photograph of this 'interstellar traveller' using the Observatory's 5 inch aperture Meade Apo Refractor and also to try and obtain a spectral profile. Unfortunately, the exceptionally inclement weather here on the UK's East Coast made this impossible.

On the 16th of February, we were presented with a small 'weather window' during which, we we would have an opportunity to catch some cometary photons. As the Seestar S30 is quick to set up and as we had seen an image of the Comet captured by a local astronomer using the slightly larger Seestar S50, we decided to give it a go, more in hope than expectation to be honest.

When we looked at the one minute sub exposures that we captured and the stacked data, we could find no evidence of the comet.

Our processing technician Pip Stakkert decided to use SIRIL freeware and apply the processing python script, 'Veralux Alchemy', in order to 'stretch' any very faint  nebulosity, which might be associated with the comet's 'coma' (atmosphere). To everyone's surprise a patch of nebulosity the right size for the cometary coma and in the expected location against the night sky in the Constellation Gemini, suddenly became visible. 

We checked with the Sloan Sky Survey Database to identify any local non-cometary nebulosity, which might have been present and made visible with the Veralux script but came up with a blank. 

It is always possible to create artificial artifacts when processing very faint astronomical objects and the comet is very faint at approximately magnitude 15. We are however, relatively confident that we have actually captured an image of this rare interstellar comet before it leaves our solar system forever.

The SOHO Satellite image of C/2025 31 (ATLAS) shows water gushing from the comet. Credit: TECH STOCK and ESA

Post Perihelion the comet has shown out-gassing and dust creation. The above spectral profiles show very strong wavelengths associated with water, carbon dioxide and carbon monoxide.

Spectral Profile Credit:

Phys.org

SPHEREx imaging reveals increased sublimation activity on 3I/ATLAS

Jan 23, 2026

All very exciting stuff if 'real' ! Who would have thought that the diminutive Seestar S30 with its 30mm aperture, might capture such a tiny and dim object moving fast in the night sky? " - Joel Cairo CEO of the Jodrell Plank Observatory.

"What It Is 31/ATLAS

• 3I/ATLAS is a comet from outside our Solar System — only the third such interstellar object ever confirmed (after 1I/ʻOumuamua and 2I/Borisov). 

• Its “ATLAS” tag comes from the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey that discovered it on 1 July 2025 in Chile. 

• It has an unbound (hyperbolic) orbit, meaning it came from interstellar space and will not return after passing through our Solar System. 

☀️ Journey Through the Solar System

• Perihelion (closest approach to the Sun): reached around late October 2025 at ~1.4 AU (just inside Mars’s orbit). 

• Closest Earth approach: it passed Earth at a safe distance of about 1.8 AU (≈270 million km) in December 2025. 

• Its brightness peaked while near the inner system, but it has since faded and is now challenging to observe, requiring moderate to large telescopes if still visible. 

🔭 Scientific Interest

• As an interstellar comet, 3I/ATLAS offers a rare window into material from beyond our Solar System — potentially much older and compositionally different from typical Solar System comets. 

• Observations (e.g., spectroscopy) have been used to study its coma and tail and to better understand its physical and chemical properties" - Professor C.P T Chat visiting astro-physicist at the Jodrell Plank Observatory - the UK's most easterly Astronomical Observatory.. 

The Sun Today 17-03-2026

 

The Solar Photosphere. Seestar S30 with added Baader White light filter.
 Image Credit:Pip Stakkert.

" With a short break in the cloud, Pip was able to use the observatory's little Seestar S30 to capture  'moderate solar activity ' on the Solar Photosphere.

The large sunspot visible '4374' is prominent towards the solar limb at approximately 3 o' clock.

Granulation related to convection movement is visible across the disc with hints of faculae visible. Neither are clearly apparent when using the solar filter that ships with the Seestar as standard kit.

Jolene McSquint Fleming, our instrumentation engineer, created the new solar filter in the JPO's clean room some time ago and we have been awaiting the opportunity to try it.

Jolene has been out of the picture for sometime, after having a minor accident in the Observatory's outreach vehicle. 

Just before the accident, I can clearly remember Kurt saying to her " Jolene, Jolene, Jolene, Jolene, please don't take the van just because you can". - Joel Cairo CEO of the Jodrell Plank Observatory.

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New book in the JPO library and Jupiter Io radio wave interactions.

 

Our imaging and post processing JPO team have been using GraXpert and Siril software for sometime but Joel thought this little booklet was worth an investment of £12 as a reference. On cursory inspection, this appears to be a 'solid' purchase.

Tonight, I reprogrammed the usb dongle feeding the signal from the LVST yagi aerial into the soundcard of the laptop running Spectrum Lab. 

For the next 24 hours, Spectrum Lab will be analysing radio signals centred on 20,100 khz. This will hopefully enable us to capture radio waves generated by interactions between the planet Jupiter and its innermost Galilean Moon Io.

Jupiter is currently riding high in the Northern Hemisphere and in the constellation Gemini." - Kurt Thrust current Director of the Jodrell Plank Observatory.

Narrow band imaging.

"Jolene Mc Squint-Fleming, our talented engineer at the JPO, was ecstatic this morning, when Royal Mail delivered three narrowband filters - Hydrogen alpha, Sulphur-ll and Oxygen-lll.

She is now 'beavering away in the clean room', with the  JPO 3d printer working overtime, to create filter holders to work with the range of telescopes and cameras we operate.

This recent acquisition will add another dimension to to the astrophotography to be undertaken in 2026 at the Jodrell Plank Observatory".  - Kurt Thrust current Director at the JPO - 'The UK's most easterly Astronomical Observatory.

Cygnus August 2025 - Sh 2-108 (Sharpless 2-108)

 

Sadr Gamma Cygni and associated HII regions and dark dust clouds. Ha luminosity and modified RGB SHO narrowband rendering. Seestar S30 August 2025. Image Credit all versions: Kurt Thrust. Image captured from the JPO, Lowestoft, Suffolk.

"Sadr (Gamma Cygni) is a bright, yellow-white supergiant star at the center of the Cygnus constellation's "Northern Cross" asterism, marking the swan's chest, and is surrounded by the extensive Sadr Region (IC 1318) of glowing nebulae and dust, though the star and nebula are at different distances, with the nebula much farther away. It's a prominent summer night sky target, easily visible to the naked eye, and part of a rich star-forming area in the Milky Way. 

Key Characteristics:

Location: Center of the Northern Cross in Cygnus.

Appearance: A bright, yellow-white supergiant, second only to Deneb in Cygnus's brightness.

Name Meaning: "Sadr" means "chest" in Arabic, referring to its position in the swan.

Distance: About 1,800 light-years from Earth.

Surrounding Nebula: The Gamma Cygni Nebula (IC 1318) appears to surround it but is much further away (around 4,900 light-years). The images from the Hubble Space Telescope are rendered using a modified RGB-SHO palette where Sulphur II emissions are allocated to the red channel, Hydrogen alpha to the green and Oxygen III to blue". - Joel Cairo CEO of the Jodrell Plank Observatory.

 

"Seasons Greetings to all stargazers and friends of this blog around the world! May the team at the JPO, the Uk's most easterly observatory, wish you and your families a very merry Christmas and an extremely happy New Year.

The above image, created by Lulu Thrust, features a very rare photograph of our current Director Kurt. It should be said that this photo was captured many years ago using a 'very soft filter'.

All the team at the JPO are looking forward to capturing and sharing with you, in 2026, more wonders of the cosmos." - Joel Cairo CEO of the Jodrell Plank Observatory.

Star in the East

 

Aldebaran, the Hyades and Pleiades. Image Credit: Kurt Thrust.
Canon 600d DSLR with Canon EOS F1.4 f=50mm lens
all on Star Adventurer EQ mount.

" Kurt was very unlucky not to capture any Geminid meteors as he was running two cameras on the night of the shower maximum. He did however capture this interesting region of the constellation Taurus. The whole team at the JPO, the UK's most easterly observatory, is now powering down for a 'chilled' Christmas break." - Joel Cairo CEO of the Jodrell Plank Observatory.