Topics

Comet C/2019 Y4 (ATLAS)

Khalid Baheyeldin
 

(Taking this out from a now crowded thread).

I first saw Comet! C/2019 Y4 ATLAS by chance. I was imaging M82, and it showed up in KStars. The above image is a crop from 120 seconds @ ISO 400. Nothing spectacular, but it does show a tiny tail.

Some sources say that it may be a fragment of the Great Comet of 1844/1845 CE, since the orbits match.

According to Cartes de Ciels, it is supposed to brighten up considerably in late May as its reaches perihelion inside of Mercury's orbit, and may reach magnitude -11 (so as bright as the moon). It will be a dawn comet though.

I then took a time lapse video of the C/2019 Y4 (ATLAS) comet.

Here is a video made using CdC on when it will brighten up, and where in the sky.

The attached .csv file has the expected positions and magnitude pre-sunrise until perihelion.
You can open it in Excel or OpenOffice.

Aisling Lightworks
 

Nice capture! I'm hoping to see this comet soon. 

Roman Hujer
 

C/2019 Y4 (ATLAS) 2020-03-14 22:30 UT, Bulovka Czech Repubiic, Newton 150/750mm, MPCC M III, Canon EOS 1300D, 30x120sec ISO1600. Dark, Flat, Bias, EQ5 OnStep, ASIAIR + SkySafari Pro, PixInsight .

This photo is first lihgt from my new EQ5 OnStep :-)

Khalid Baheyeldin
 

Very nice Roman.
I don't see a distinct tail though. Perhaps it is a vantage point or distance thing, and it was not showing on the 14th, but showed it on the 18th?

Roman Hujer
 

There's an ionic tail, but the green diffuse fog is on final picture more pronounced.

R.

 

For your long exposures, are you tracking the comet by guiding off of the comet itself? Or is there a way of putting in ephemeris data into OnStep to perform open loop tracking?  I seem to recall someone mentioning how to do that.

Dave Schwartz
 

Congrats to Khalid on having his YouTube time lapse linked by the Sky & Tel weekly news article. 
https://skyandtelescope.org/astronomy-news/comet-atlas-will-it-become-a-naked-eye-object/

hitosi sato
 
Edited

Hi Khalid and all
I found the tutorial for guiding by using PHD2 and  CDC.
http://www.astrofriend.eu/astronomy/tutorials/tutorial-comet-autoguiding/04-tutorial-comet-autoguiding.html
In the latest CDC(4.3-4119), there was a fix for the high-latitude comet guiding.
The latest version of the CDC says it's now possible to guide this comet(C/2019 Y4) using PHD2 and the CDC.

Hitosi

 

On Sat, Mar 28, 2020 at 08:10 PM, hitosi sato wrote:
I found the tutorial for guiding by using PHD2 and  CDC.
http://www.astrofriend.eu/astronomy/tutorials/tutorial-comet-autoguiding/04-tutorial-comet-autoguiding.html
I tried it out on my desktop setup (OnStep simulated) and it looks pretty straitforward.  I'll have to try it out for real before the moon gets too bright.  Thanks

 

On Sun, Mar 29, 2020 at 07:10 AM, Richard Shagam wrote:
I tried it out on my desktop setup (OnStep simulated) and it looks pretty straitforward.  I'll have to try it out for real before the moon gets too bright.  Thanks
I found the comet last night, but was unable to offset track on it using the Comet Tracker in PHD2.Has anyone been able to do this? I was able to hand stack an image of it from 29 x 120 sec subs in GIMP (way too much work for the result!) 

hitosi sato
 

Hi Richard

Thank you for experimenting with the tutorial method I introduced.
I think the image processing using GIMP was very hard work.
I don't have the skills to understand why it didn't work and I don't have the same experience, but there are some detailed explanations on the PHD2 HELP page.
https://openphdguiding.org/man-dev/Tools.htm
According to the PHD2 tools HELP, It need to make PHD2 comet rate learning by controlling the lock position once.
Did the PHD2 comet rate learning function work well?

And you can also post to the PHD2 Forum if you still have the guide log and debug log for PHD2.
Patrick, the author of CDC, and other members will give detailed lectures at the forum.
I am very interested in how PHD2 controls the mount when guiding the comet.
Whether OnStep operates by changing the guide rate or adding an offset to the guide pulse.etc!

Thank you
Hitosi

Aisling Lightworks
 

Hello. I used the comet tracking offset in PHD2 to successfully follow Atlas y4 for an hour and a half before the clouds moved in. It worked well. I used RA -91.66 DEC -27.708 and it followed it very precisely. I had to tweak these figures by hand after comparing its movement between exposures.

Khalid Baheyeldin
 

On Fri, Apr 3, 2020 at 01:32 AM, Aisling Lightworks wrote:
Hello. I used the comet tracking offset in PHD2 to successfully follow Atlas y4 for an hour and a half before the clouds moved in. It worked well. I used RA -91.66 DEC -27.708 and it followed it very precisely. I had to tweak these figures by hand after comparing its movement between exposures.
Very nice result.

Did you get the RA/DEC from a planetarium first, and plug them in the comet tracker?

By tweaking the figures, can you provide more info on how this was done?

Aisling Lightworks
 

Yes, first I got the comets apparent motion from sky Safari. Plugged them into PHD2s comet tracking feature. Hit "Enable" and it automatically started moving the mount by that rate. I noticed the comet was still moving a bit in my images so I just adjusted the values in real time until it no longer moved between images. Knowing the pixel scale of your image makes this pretty easy.

Khalid Baheyeldin
 

On Fri, Apr 3, 2020 at 03:56 PM, Aisling Lightworks wrote:
I noticed the comet was still moving a bit in my images so I just adjusted the values in real time until it no longer moved between images.
So trial and error then? Or some calculation?

Aisling Lightworks
 

A bit of both. PHD2 takes the numbers in arc seconds per hour. Knowing the scale of your image gives you a ballpark to shoot for.

Khalid Baheyeldin
 

I tried the feature using INDI's simulators.
It looks to me that the feature wants you to center the comet in the imaging camera, then guide on a star, and it will get the RA and DEC automatically from there.

Maybe it is refraction compensation (for Goto) that is causing that offset (it is on by default in OnStep).

Aisling Lightworks
 

There is a training mode too. You can either train it up by centering it or just put the RA/DEC offset in manually. I did it manually.

Aisling Lightworks
 

I followed it for 8 hours last night and got some decent data on it. I can't turn them into a decent still image because my skills are lacking. I'll take another crack at it later but here's the video of its motion.

https://www.instagram.com/p/B-lO-hRnPCl/?igshid=75nugmisgdi2

Khalid Baheyeldin
 

That video is great in itself ...

Well done ...