12 replies to this topic

[mwr]

A spectacular image of this comet showing the tail partially eroded by the solar wind (09-02-2023 / 11"RASA / QHY600):

 

http://fg-kometen.vd..._3_02092023.htm

 

https://forum.astron...0/#post-1829173

 

 

Are spectra available yet?

Edited by mwr, 03 September 2023 - 04:57 AM.

[robin_astro]

 

 

 

Are spectra available yet?

Too low for me but one of the coma from a week ago on a French spectroscopy forum. Very little dust by the looks

 

http://www.astrosurf...3-p1-nishimura/

 

Robin

[Octans]

Not a spectrum, but equivalent production rates for OH/CN/C2 and dust brightness from narrowband imaging were also posted a few days ago here: https://www.astronom...org/?read=16223

 

Dust to gas (OH/CN/C2) ratio is below average for comets overall, but not atypical for comets with that perihelion distance.

 

Worth keeping an eye out for sodium though. Could potentially be pretty bright after perihelion.

Edited by Octans, 03 September 2023 - 03:53 PM.

[mwr]

Too low for me 

Very low for me (8° altitude). I got up early this morning before work (4 am local time) to take an image and a spectrum with my grab and go setup https://www.cloudyni...51-sky-tracker/ (the Fuji X-A1 was replaced by a Canon 450 Da):

 

 

 

 

I estimate a brightness of 6.3 mag by using differential photometry (tricolor green channel).

 

May be a weak sodium line is just detectable (the spectrum is very noisy and I'm operating at the limit of my low budget setup; the Na D line could be an artifact). To be confirmed by ProAm spectra.

[robin_astro]

A nice result at such high air mass.  Difficult to say about the sodium but if the spectrum image is at the same scale as the main image I would say probably a hot pixel It is very narrow compared with the size of the coma and there is a hot pixel streak in the stacked spectrum around that position (There is a similar one in the blue/green at ~ 5100A which might be giving the sharp spike on the top of the Swan band there)

 

Cheers

Robin

[robin_astro]

A spectrum by Christian Buil

https://groups.io/g/...topic/101209364

confirms only weak dust reflectance and no obvious Sodium emission, though the twilight sky background subtraction (including some sodium emission) is difficult.

My 2020/F3 (NEOWISE) spectra for comparison

https://britastro.or...e77e0992eb70386

 

Cheers

Robin

[mwr]

 Difficult to say about the sodium but if the spectrum image is at the same scale as the main image I would say probably a hot pixel It is very narrow compared with the size of the coma and there is a hot pixel streak in the stacked spectrum around that position (There is a similar one in the blue/green at ~ 5100A which might be giving the sharp spike on the top of the Swan band there)

 

Your are absolutely right! A spectrum from this morning (the conditions were even worse) showed no interfering hot pixels and no sodium line:

 

[mwr]

A spectrum by Christian Buil

https://groups.io/g/...topic/101209364

confirms only weak dust reflectance and no obvious Sodium emission, though the twilight sky background subtraction (including some sodium emission) is difficult.

 

In the meantime Christian has reduced his spectrum:

 

http://www.astrosurf...comment-2325308

 

(the "Spectroscopy and Photometry" forum on "Astrosurf" is obviously one of the more vivid fora)

Edited by mwr, 11 September 2023 - 04:33 AM.

[Octans]

FYI, if anyone wants to see sodium, now's already a good time. The sodium tail itself won't appear until the 17th (basically just looks like a dot right now in all filters), but a very quick look at some narrowband filtered images this evening suggests the sodium is comparable to or even brighter than the green C2 emission (although the dust continuum now seems a lot brighter than both).

Edited by Octans, 16 September 2023 - 01:45 AM.

[mwr]

 but a very quick look at some narrowband filtered images this evening suggests the sodium is comparable to or even brighter than the green C2 emission (although the dust continuum now seems a lot brighter than both).

Octans, could you give us a link to the images or post the images here? 

[Octans]

The images don't look like much of anything, just a dot. Here's a 1-s exposure through a 10 nm Na filter on Friday. However, comparing against an r' image (where it looks basically identical), it's ~2x brighter in the Na image than expected from the r' brightness if it were continuum (i.e., solar colored), so there's some fairly strong sodium emission there. Should be even stronger now with the comet past perihelion, but has been cloudy since then, so haven't had another look.

Attached Thumbnails

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Edited by Octans, 17 September 2023 - 07:53 PM.

[astro rocketeer]

Very low for me (8° altitude). I got up early this morning before work (4 am local time) to take an image and a spectrum with my grab and go setup https://www.cloudyni...51-sky-tracker/ (the Fuji X-A1 was replaced by a Canon 450 Da):

 

 

Folie1.JPG

 

Folie2.JPG

 

I estimate a brightness of 6.3 mag by using differential photometry (tricolor green channel).

 

May be a weak sodium line is just detectable (the spectrum is very noisy and I'm operating at the limit of my low budget setup; the Na D line could be an artifact). To be confirmed by ProAm spectra.

Thanks for sharing this. I was curious about the spectrum of this comet. Excellent capture and graph. What program are you using to produce that graph? is that from Rspec? Thanks.

[mwr]

 is that from Rspec? Thanks.

Yes, it's from RSpec.

 

Even better targets for the SA-100/RSpec combination were the comets C/2020 F3 (NEOWISE) and C/2022 E3 (ZTF):

 

https://www.cloudyni...-comet-neowise/

https://www.cloudyni...t-c2022-e3-ztf/

 

The same setup allowed to detect the C2 molecule in a butane torch and Comet 46P Wirtanen:

 

https://www.cloudyni...comet-wirtanen/