66 replies to this topic

[jeanc]

Hello Comet Atlas C/2019 Y4 will approach M97 in the next few days, the comet is currently 13mag bright and has an outer gas coma. Image from February 21st 22 UT 4x6min 8 "/ 2 RASA and CCD filter green. Regards Michael Jäger

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[jeanc]

a large rgb you find here https://spaceweather..._1582392791.jpg

[Dave Mitsky]

That's a great image.  Thanks!

[jeanc]

Hello GIF from feb 24 UT 22 showed the comet near M97 and M108 Regards Michael Jäger 

 

https://spaceweather..._1582612405.gif

[Dave Mitsky]

Thanks again!

[Jure Atanackov]

Very impressive animation, Michael! What a view! In addition to being superb, these images IMHO point out another interesting thing about the comet. The latest visual magnitude estimates on COBS put the comet at about magnitude 13.5-14.0, but they were made with medium sized to large telescopes in which only about 1-1.5' of coma was visible. Your images show a much, much larger outer coma. Taking the apparent size of M97 (3.4') and comparing it to the comet, it appears the comet's apparent diameter is about 5-6'. So visual observers using large telescopes are missing a lot of the outer coma. Your estimate of magnitude 13 already indicates this. There will likely be an apparent jump in brightness when the comet comes into visual range of large binoculars under dark skies and observed coma diameters increase.

 

Taking this into account it becomes very interesting to think about whether the comet is above the Bortle survival limit at q=0.253 a.u. (the limit would be at H0=~8.5). Taking current estimates of magnitude 13.5-14, the comet is well below the Bortle limit for any reasonable value of n (H0 from about 9.8 to 11.0). However, if the comet is actually brighter, the absolute magnitude could be closer to the Bortle survival limit - opening the possibility for a decently bright comet, although buried deep in twilight. Getting similar vibes to comet C/2002 V1 (NEAT).

[jeanc]

Thank you Jure. on deep green image we found a coma

almost 15'. let's hope the best

[Jure Atanackov]

Thank *you* for providing us with your images and updates!

 

15'!   Maybe someone with large binoculars and pristine skies can try to observe this comet?

[Jure Atanackov]

Just had a look at estimates posted in 'comets-ml' (great to be back in the group, I thought it was gone ...). There are two interesting reports, both CCD photometry, not visual. One is by Michael Matiazzo, who got CCD V m1=12.5 as far back as Feb 18. The other is by Thomas Lehmann, who got m1=12.2 at coma diameter of 8.6' even earlier (Feb 17.28UT)! At the time visual observations indicated a brightness of m1~14. Latest visual estimates on COBS put the comet at m1=11.9, with a 4.5' coma, much brighter and still nowhere near 10-15' coma reported here. The estimate was still made with a large telescope, not binoculars.

 

One has to wonder just how bright the comet really is right now.

[Phillip Creed]

I'm going to give it a go to see if I can locate this comet visually once the moon gets out of the evening sky in about a week or so.  Might take some quick images, too.  Sky conditions are not the best from my backyard (~5.5 ZNLM, tails off greatly near the horizons), but it might be a good test of its visibility with a small telescope (115mm f/7 triplet).

If I can see it with the AT115EDT, next weapon of choice would be an old pair of 11x70 Oberwerks, but that might be optimistic.

I remember coming across a formula for determining the telescopic limiting magnitude that goes something like this:

LM = NLM + 3 * log (aperture / 7mm) + 2 * log (magnification),

but I can't for the life of me remember the source or origin for this formula.  It does seem pretty close, particularly the ability to see fainter stars in globular clusters and/or small, distinct DSOs like 1' - 3' galaxies.  For extended DSOs and comets, one would have to more conservative, of course.

For a set of 25x100s, it would come down to roughly a 6-mag boost in stellar LM and maybe 4-5 or so for a comet or extended/diffuse DSO.  Someone under a ~6 NLM sky might be able to get the comet with 25x100s if it's 11th magnitude or brighter.

We'll find out in about a week or so, one way or the other.

Clear Skies,
Phil

[Jure Atanackov]

Fwiw, Terry Lovejoy got the comet at magnitude 10.7 last night in bright moonlight. That's 2-3 magnitudes brighter than about 2 weeks ago. This might get very interesting soon.

Edited by Jure Atanackov, 05 March 2020 - 03:23 PM.

[Phillip Creed]

Should be visible in the next few days.  I saw an observation from Bob King of Minnesota who had it at 11.5 a few days ago using a 15"-reflector @ 64X just after moonset.

There always seems to be a bump in brightness estimates once the bulk of observers transition from telescopes to binoculars.  I don't remember exactly why that is, but it's typically a palpable one.

In either case, I expect that a set of 70-100mm binoculars under dark skies is all that will be needed in a few days.

Clear Skies,

Phil

[Jure Atanackov]

Latest visual estimates put the comet at brighter than magnitude 10, maybe closer to magnitude 9, apparently already visible in 50 mm binoculars. This is becoming really interesting, the absolute magnitude may be around +7, well above the Bortle survival limit for this comet.

Edited by Jure Atanackov, 11 March 2020 - 04:20 PM.

[kdenny2]

http://astro.vanbuit...nl/comet/2019Y4

 

Am I reading this correctly? Mag -7.3 at closest approach to Earth on May 23rd? At 17.5 degrees from the Sun it would be visible just after sunset no problem.

Edited by kdenny2, 11 March 2020 - 06:26 PM.

[Aquarellia]

Hi

Yesterday I observed this now easy to see comet. If the weather cooperates, next week I'll try with my bino Vixen 5' from a very dark zone in the French Alps, that will be during a winter astro event.

I saw a little dissymmetry of the pseudo nucleus and a huge coma (5')

 

Here my observation:

 

Clear sky to you all

Michel

[Rich (RLTYS)]

Took this image of C/2019 Y4 ATLAS with the Slooh Canary Island 2 wide field scope last evening (3-11-20). Image shows a faint, roundish outer coma with a "drop" shaped pseudo nucleus (PN). From this PN a short, faint tail is noted, PA of this tail is ~175 degrees. Used a reversed image as this shows the tail better.

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[CrazyPanda]

Latest visual estimates put the comet at brighter than magnitude 10, maybe closer to magnitude 9, apparently already visible in 50 mm binoculars. This is becoming really interesting, the absolute magnitude may be around +7, well above the Bortle survival limit for this comet.

Saw it last night fairly easily in my 60mm finder scope at 10x mag from a class 4 sky with the Moon about an hour away from rising.

[kdenny2]

https://theskylive.com/c2019y4-info

 

Down to at least +9.6. Looking forward to observing it myself, whenever it clears up in Illinois.

 

http://astro.vanbuit...nl/comet/2019Y4

 

If the brightening trend were to continue (which it probably won't) the comet would reach an apparent magnitude of -7.7 at its closest approach to earth with an elongation of 17.5 degrees from the Sun. Given how unsteady and unreliable comets can be there's obviously a huge degree of uncertainty with these predictions. An absolute magnitude of +7 would be more than McNaught but less than Halley, so I think there's reason to be cautiously optimistic that this could become a spectacular comet in May.

Edited by kdenny2, 14 March 2020 - 12:52 PM.

[project nightflight]

Visual observation of C/2019 Y4 on 2020-03-15 at 19:00 UT from observing site in Lower Austria (green LP zone). The comet is already visible even with a small 2.6“ Apo. It appeared as a very diffuse roundish glow, no central condensation or nucleus was visible. Using a Hyperion zoom eyepiece, the best impression of the comet was with magnifications from 20x to 25x (exit pupil around 3mm). A Lumicon Swan Band filter enhanced the visibility of the coma.

[Jure Atanackov]

Just had a look at C/2019 Y4 from under Bortle class 3 skies with my 11x70 binoculars. The comet is impressively bright! I though I would need a bit of time and effort to find it, but it was just there, obvious as soon as I had the right field. Large and diffuse coma with a distinct central condensation visible with averted vision. I need to calculate my magnitude estimate, but I don't think it is much fainter than 8. magnitude.

 

Cautiously optimistic about future prospects for this comet (still remember the C/2002 T7 fiasco after similarly impressive brightening in Dec 2003 / early Jan 2004). Also feeling good about having caught the comet, I am getting a sinking feeling we will be going into lockdown due to the coronavirus very soon.
Clear skies!
Jure

[Dave Mitsky]

I brought my 15x70s with me to the orange-zone Naylor Observatory tonight hoping to see Comet C/2019 Y4 (ATLAS) but the sky was just not dark enough.  I was able to locate the comet with the observatory's 17" f/15 classical Cassegrain at 170x but it wasn't more than a faint fuzzball.  I also viewed the comet at 116x and 216x, with the latter providing the best view.  I was unable to detect it with the 5" f/5 finder scope.

 

https://www.heavens-...lt=170.0&tz=EST

[Phillip Creed]

Just had a look at C/2019 Y4 from under Bortle class 3 skies with my 11x70 binoculars. The comet is impressively bright! I though I would need a bit of time and effort to find it, but it was just there, obvious as soon as I had the right field. Large and diffuse coma with a distinct central condensation visible with averted vision. I need to calculate my magnitude estimate, but I don't think it is much fainter than 8. magnitude.

 

Cautiously optimistic about future prospects for this comet (still remember the C/2002 T7 fiasco after similarly impressive brightening in Dec 2003 / early Jan 2004). Also feeling good about having caught the comet, I am getting a sinking feeling we will be going into lockdown due to the coronavirus very soon.
Clear skies!
Jure

What's a good light curve fit for this comet look like?

I'm guessing it can't brighten at this clip for TOO much longer.  But I have to figure even it's a more pedestrian n=4 curve, it's going to be visible to the naked-eye.

One thing that might prevent the best observations in the next few months, though, is the prospect of COVID-19 lockdowns.  Simply driving to a dark sky might be against regulations.

Of course, if it were to somehow maintain its current rate of brightening...it wouldn't really matter.

Clear Skies,
Phil

[kdenny2]

What's a good light curve fit for this comet look like?

I'm guessing it can't brighten at this clip for TOO much longer.  But I have to figure even it's a more pedestrian n=4 curve, it's going to be visible to the naked-eye.

One thing that might prevent the best observations in the next few months, though, is the prospect of COVID-19 lockdowns.  Simply driving to a dark sky might be against regulations.

Of course, if it were to somehow maintain its current rate of brightening...it wouldn't really matter.

Clear Skies,
Phil

How bright does it get with an n=4 curve?

[Mike Lynch]

Take a look at today's https://www.spaceweather.com/ photo and text about this comet.

 

Too optimistic? Maybe so, and maybe it will fail expectations miserably....

 

But, if you ask me, it would be a bright spot in the midst of this pandemic...even if I can't go further than my backyard.... But maybe I can convince bored neighbors to turn out their lights and go out to see it, too!!  (By calls, texts, and flyers on their doors, of course!)

 

Mike

[Jure Atanackov]

Take a look at today's https://www.spaceweather.com/ photo and text about this comet.

 

Too optimistic? Maybe so, and maybe it will fail expectations miserably....

 

But, if you ask me, it would be a bright spot in the midst of this pandemic...even if I can't go further than my backyard.... But maybe I can convince bored neighbors to turn out their lights and go out to see it, too!!  (By calls, texts, and flyers on their doors, of course!)

 

Mike

Want more optimism? There could be significant forward scattering brightness enhancement around perihelion, if the comet is dusty. Maybe around 1.0-1.5 magnitudes.