Starship Asterisk*

Most of Comet Tsuchinshan-ATLAS

Explanation: On October 14 it was hard to capture a full view of Comet C/2023 A3 Tsuchinshan-ATLAS. Taken after the comet's closest approach to our fair planet, this evening skyview almost does though. With two telephoto frames combined, the image stretches about 26 degrees across the sky from top to bottom, looking west from Gates Pass, Tucson, Arizona. Comet watchers that night could even identify globular star cluster M5 and the faint apparition of periodic comet 13P Olbers near the long the path of Tsuchinshan-ATLAS's whitish dust tail above the bright comet's coma. Due to perspective as the Earth is crossing the comet's orbital plane, Tsuchinshan-ATLAS also has a pronounced antitail. The antitail is composed of dust previously released and fanning out away from the Sun along the comet's orbit, visible as a needle-like extension below the bright coma toward the rugged western horizon.

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Charles Messier would have gone crazy with this picture: 3 objects, 1 of which could be mistaken as a comet (M5), and 2 which really are comets !

A remarkable image! I'd never have seen comet 13P Olbers had it not been pointed out.

johnnydeep wrote: ↑Fri Oct 18, 2024 6:53 pm A remarkable image! I'd never have seen comet 13P Olbers had it not been pointed out.

Pointed out by whom? Where is it?

Is this it?


Ann

Ann wrote: ↑Fri Oct 18, 2024 7:01 pm

johnnydeep wrote: ↑Fri Oct 18, 2024 6:53 pm A remarkable image! I'd never have seen comet 13P Olbers had it not been pointed out.

Pointed out by whom? Where is it?

Is this it?


APOD 18 October 2024 annotated.png


Ann

That's it - I'm impressed! - you found it. The annotated image is at the "identify" link in the text.

In the APOD, it sure looks like M5 has a tail. It fooled me into thinking that it was 13P Olbers, until johnnydeep pointed it out.

johnnydeep wrote: ↑Fri Oct 18, 2024 8:33 pm

Ann wrote: ↑Fri Oct 18, 2024 7:01 pm

johnnydeep wrote: ↑Fri Oct 18, 2024 6:53 pm A remarkable image! I'd never have seen comet 13P Olbers had it not been pointed out.

Pointed out by whom? Where is it?

Is this it?


APOD 18 October 2024 annotated.png


Ann

That's it - I'm impressed! - you found it. The annotated image is at the "identify" link in the text.

Thanks, I missed the link in the caption.

However, we may note that Comet 13P Olbers is faintly cyan-green in color, just like we expect from a comet. Not so Comet Tsuchinshan-ATLAS. I have been scratching my head at the completely non-green, white to yellow-white color of everybody's favorite comet of October. A few pictures of Tsuchinshan-ATLAS show a faint blue ion tail, but in most images the ion tail is invisible. And not a single portrait of this comet has shown its coma to be even the slightest hint of green.

Why is Comet Tsuchinshan-ATLAS so persistently white to yellow-white in color? Is it just so dusty that the dust-reflected yellow-white light from the Sun completely drowns out any green light from the coma?

Ann

Ann wrote: ↑Sat Oct 19, 2024 4:18 am

johnnydeep wrote: ↑Fri Oct 18, 2024 8:33 pm

Ann wrote: ↑Fri Oct 18, 2024 7:01 pm

Pointed out by whom? Where is it?

Is this it?


APOD 18 October 2024 annotated.png


Ann

That's it - I'm impressed! - you found it. The annotated image is at the "identify" link in the text.

Thanks, I missed the link in the caption.

However, we may note that Comet 13P Olbers is faintly cyan-green in color, just like we expect from a comet. Not so Comet Tsuchinshan-ATLAS. I have been scratching my head at the completely non-green, white to yellow-white color of everybody's favorite comet of October. A few pictures of Tsuchinshan-ATLAS show a faint blue ion tail, but in most images the ion tail is invisible. And not a single portrait of this comet has shown its coma to be even the slightest hint of green.

Why is Comet Tsuchinshan-ATLAS so persistently white to yellow-white in color? Is it just so dusty that the dust-reflected yellow-white light from the Sun completely drowns out any green light from the coma?

Ann

I've imaged it carefully, and don't have a hint of color other than scattered yellow sunlight. Don't know if the other colors are absent, or washed out. This is from last night (17 Oct). Tail is 25 degrees long, and there are three Messier objects in the field! Lots of funky structure in the coma, too.
_

Guess what famous comet resembled comet Tsuchinshan-ATLAS?


Just like comet Tsuchinshan-ATLAS, Hale-Bopp had a bright white (but rapidly dimming) dust tail and a non-green coma.

Ann

Ann wrote: ↑Sat Oct 19, 2024 4:18 am Why is Comet Tsuchinshan-ATLAS so persistently white to yellow-white in color? Is it just so dusty that the dust-reflected yellow-white light from the Sun completely drowns out any green light from the coma?

So, revisting my data from 17 October this morning (it's snowing lightly... no new images last night!) I combined 9 minutes each RGB and carefully calibrated the color. Then, pushing the saturation up a bit, we can just see a bit of blue or cyan around the coma. I'm pretty sure it's real, but there's sure not a lot there. I think your suggestion of it being washed out is most likely. This coma is very bright... I had to limit the subs to 10 seconds to avoid saturation.
_

Will you take a look at this portrait of Tsuchinshan-ATLAS by Gerald Rhemann from October 19th? The coma is green, and a blue ion tail is nestled in the bright white dust tail!


There's some info on the technical details of the picture here.

Ann

Ann wrote: ↑Wed Oct 23, 2024 6:13 pm Will you take a look at this portrait of Tsuchinshan-ATLAS by Gerald Rhemann from October 19th? The coma is green, and a blue ion tail is nestled in the bright white dust tail!

Comet Tsuchinshan-ATLAS on October 19th. Credit: Gerald Rhemann.

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There's some info on the technical details of the picture here.

Ann

Nice pic. And I even see a faint anti-tail!

Ann wrote: ↑Wed Oct 23, 2024 6:13 pm Will you take a look at this portrait of Tsuchinshan-ATLAS by Gerald Rhemann from October 19th? The coma is green, and a blue ion tail is nestled in the bright white dust tail!

Comet Tsuchinshan-ATLAS on October 19th. Credit: Gerald Rhemann.

---

There's some info on the technical details of the picture here.

Ann

Hmm. I like the ion tail, but something is off with the cyanogen coma- overprocessed in some way. I got this a couple of nights ago, and I think it's a much better representation of color in the coma.
_

Chris Peterson wrote: ↑Wed Oct 23, 2024 10:05 pm

Ann wrote: ↑Wed Oct 23, 2024 6:13 pm Will you take a look at this portrait of Tsuchinshan-ATLAS by Gerald Rhemann from October 19th? The coma is green, and a blue ion tail is nestled in the bright white dust tail!

Comet Tsuchinshan-ATLAS on October 19th. Credit: Gerald Rhemann.

---

There's some info on the technical details of the picture here.

Ann

Hmm. I like the ion tail, but something is off with the cyanogen coma- overprocessed in some way. I got this a couple of nights ago, and I think it's a much better representation of color in the coma.
_

Click to view full size image

I agree with you, Chris. The green coma of Gerald Rhemann's comet picture seems "too suddenly green" and even "green in a strange place", like a child stealing her Mom's lipstick and applying the lipstick where it shouldn't be.


I don't mean that Gerald Rehmann's comet is "wearing its green coma the way the child is wearing lipstick", but it does look a bit strange. I do like yours better!

Ann