Ancestors

Written by Mark McCaughrean on 2025-01-19 at 09:45

Earlier this week, Comet C/2024 G3 (ATLAS) made its closest approach to the Sun.

While doing so, it made a dramatic appearance sweeping through the wide-field LASCO C3 coronagraph of the ESA/NASA SOHO mission over a few days.

Here’s my take, a triplet of Deep Red, Orange, & Blue filter images taken over an hour around 09:00UTC on 14 January, as an RGB composite.

[#]C2024G3 💫

[#]CometATLAS ☄️

[#]Perihelion 🌞

[#]Photography 📷

[#]SpaceScience 🛰️

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Written by Mark McCaughrean on 2025-01-19 at 09:52

I make no claim that this is a scientifically accurate representation of the comet.

It was changing shape as it moved rapidly around the Sun during its perihelion passage & the three filter images were taken separated by roughly 30 mins each.

Thus after downloading the images as FITS files from the SOHO archive & processing them to maximise the dynamic range, I simply shifted & rotated them to align. No image scale or distortion terms were used.

So it’s close, but certainly not perfect 🤷‍♂️

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Written by Mark McCaughrean on 2025-01-19 at 09:57

The short horizontal spikes either side of the head of the comet are artefacts due to saturation of the detector. The comet was very bright & even in these short 4 second filtered exposures, slightly over-exposed.

The 17 sec clear / white light images also taken show the tail better but are heavily wiped out in the head region.

The green diagonal spike from the head is real though & must indicate a specific ionised gas emitting brightly in the LASCO Orange filter (shown as green in the RGB).

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Toot

Written by Demallien on 2025-01-19 at 15:55

@markmccaughrean out of curiosity, what are the streaks to the right of the comet ? Normally when I get things like that in images it’s because of satellites, obviously not a concern here

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Descendants

Written by Mark McCaughrean on 2025-01-19 at 17:11

@demallien Very likely cosmic rays, either primaries directly from space or secondaries caused by primaries hitting the spacecraft. SOHO is at L1, constantly looking at the Sun, & is far from Earth’s protective magnetosphere. So it gets pretty battered by galactic CRs & of course stuff in the solar wind.

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