Primer on Comet 2023 A3 Tsuchinshan

[Sureshks]

Hi all,

A few months ago I alerted people to Comet 2023 A3 Tsuchinshan, which will make its perihelion pass on Sept. 27th. So far, the comet appears to be hanging in as it continues to move closer to the Sun. It's too close to the Sun presently for Earth-bound observers, but is being monitored by space-based telescopes, such as the STEREO solar telescope.

If it holds together after passing within 36 million miles of the Sun, the comet will loop around, and then in front of the Sun from our vantage point, before starting to depart again for the outer solar system whence it came. During this time in late-September/early-October, it could become very bright and possibly become the best comet for us in the northern hemisphere since Comet 2020 F3 NEOWISE in July 2020.

Predicting comet brightness is a fool's errand. But the predictions I've seen suggest that it could peak in the naked eye range (magnitude 0 - +2) in late September and early October, when it is located too close to the Sun to get a good look. During this time the comet could brighten even more than that due to a process called forward light scattering (sorta like how a car's headlights seem to get much brighter in a fog when it's pointed in your direction). Some predictions suggest that this could enhance the comet's brightness into the magnitude -1 or -2 range. If so, it might be possible to see the comet in the daytime during the Annular solar eclipse on October 2nd that passes thru Chile and Argentina.

Mid-October is when we in the northern hemisphere are expected to get our best views. By then it will have started fading in brightness, and could be closer to 3rd or 4th magnitude. However, our viewing angle improves each night as the comet moves further away from the Sun in the western sky after sunset. As it does, we may get a good broadside view of the gas & dust tails (and possible anti-tail). This will be when the comet is most photogenic as evening twilight ends around 7:30pm or so.

We should get a better estimation of the comet's appearance and brightness in late-September when southern hemisphere viewers get an early look in the predawn sky, right after the comet passes perihelion but before it passes in front of the Sun. It will also pass within the field of NASA's Solar and Heliospheric Observatory (SOHO) from October 7-10th, right as it is becoming easier for us to view after sunset.

So start prepping your cameras, binoculars and telescopes for a comet that (hopefully) lives up to it's hype!

See this cool animation of the comet's path in September & October from TheSkyLive.com:
- Hit the Play button on the bottom. You can also zoom in and change the orientation and viewing angle by holding down on the screen.

https://theskylive.com/3dsolarsystem?ob ... pwdE74faPg

For more info on this comet, see this article from UniverseToday.com:

https://www.universetoday.com/168058/co ... _VYZPxVqDw

Suresh

[Sureshks]

Hi all,

Here's an update on Comet 2023 A3 from Bob King that's available on the Sky & Telescope website.

https://skyandtelescope.org/astronomy-n ... edictions/

So far, so good! The comet is still intact and appears to be near its predicted brightness. It is just emerging from the Sun's glare this week for observers in the southern hemisphere as a 5th magnitude condensed glow with a short tail. It appears to be a very dusty comet, which bodes well in terms of it developing a detailed tail.

Here in MSP we should get our first shot at viewing this comet the week of September 23rd, before dawn. It will then sweep in front of the Sun during early October, and could brighten greatly due to forward light scattering.

One estimate places it's peak magnitude at -4.8 around October 9th. If so, the comet could be accessible in broad daylight. The club might want to plan some events at ELO that week.

In mid-to-late October it will be visible is our western sky after sunset as it begins its journey back to the outer solar system and starts to fade. At that time, it could be sporting a long, detailed tail and perhaps also an anti-tail.

Get ready!!

Suresh

[KSeverson]

Are there any comment chasers out there who would be willing to share vantage points with good horizons, relatively dark, etc for either Eastern or Western observing? I have been trying for a few days to catch this comet from the western shore of Bde Maka Ska which gives me a fairly decent eastern horizon, but isn't dark I am not sure it is a low enough horizon, either. So far the only pictures I've seen from our area are from Duluth which has ideal horizons over the lake.

I am considering the overlook behind the MVNWR interpretive center, the Mendota bridge bike path, Red Wing or Frontenac State Park for tomorrow morning. I haven't paid close enough attention to the topography around club properties to ascertain whether they al might be good options.

Anyone put there having any luck with this comet yet?

[clayton]

2 members reporting seeing it at CGO through binoculars. I tried from Belwin Conservancy observation area https://maps.app.goo.gl/SsocpXH1k57Fr46 ... eview.copy. I choose it after looking at some topography from https://www.dnr.state.mn.us/maps/mntopo/index.html.

I did not see it with binoculars but got a very unimpressive image with a 500mm prime lens by taking multiple photos near where I expected it to be found.

comet.jpeg

[dwindseth]

I live close to Medicine Lake in Plymouth. There is a park on the western side of the lake for eastern looking views.