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Scratch one off the bucket list - Ceres disc resolved in 20"

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#1 Bart Declercq

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Posted 29 January 2018 - 06:46 PM

I haven't been doing a lot with my new-ish 20" F/4 equatorially mounted Newtonian in the past few months, mostly thanks to the horrible weather we've been having (December 2017 & January 2018 have been the cloudiest months in recorded weather history in Belgium and november wasn't too brilliant either) but tonight, between cloudy spells I managed to get some pictures I'd been meaning to get now that Ceres is in opposition and an enormous 0.79" in diameter.

 

The attached image is a combination of two shots, one of Castor, the lovely double star in Gemini and one of Ceres (with a faint background star nearby) - I processed them in the same way (Lucy Richardson deconvolution, same settings) so the results would be somewhat comparable - I was going to look for a star closer in brightness to Ceres, but the clouds decided otherwise. Still, Ceres's visible disc was obvious even when recording - it looked very similar to the way you can see Jupiter's moons while recording with a smaller scope - the difference with a star is quite obvious.

 

The imaging scale was 0.11"/pixel but in the stacking I did a 3x resample which was downsampled 50% in post-processing  - resulting in an image scale of 0.075"/pixel

 

Ceres_20180130.jpg


Edited by Bart Declercq, 29 January 2018 - 06:47 PM.

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#2 Sunspot

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Posted 29 January 2018 - 06:50 PM

Extremely impressive!!


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#3 John Boudreau

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Posted 29 January 2018 - 07:08 PM

Very nicely done Bart! bow.gif waytogo.gif

 

You must have one hell of a bucket list! mrevil.gif


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#4 JMP

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Posted 29 January 2018 - 07:18 PM

Nice!


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#5 boott

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Posted 29 January 2018 - 07:30 PM

Awesome!


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#6 sfugardi

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Posted 29 January 2018 - 07:51 PM

Bart, congratulations! What filter were you using to capture Ceres? Very impressive disk and scope. Thanks for posting

 

Regards,

Steve


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#7 moonwatching ferret

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Posted 29 January 2018 - 08:39 PM

nice image. i would be happy just to be able to take out my 16 f7 scope also on a gem but like you i'v had nothing but horible weather. can you post a pic of the scope. I thought 16 f7 on a gem was crazy but a 20 that must be huge


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#8 RedLionNJ

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Posted 29 January 2018 - 09:18 PM

Awesome result, Bart!

 

What's next - showing Charon as a bump on Pluto next summer? :)


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#9 Sunspot

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Posted 29 January 2018 - 10:53 PM

Awesome result, Bart!

 

What's next - showing Charon as a bump on Pluto next summer? smile.gif

Don't laugh...grin.gif grin.gif


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#10 troyt

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Posted 30 January 2018 - 04:30 AM

well done smile.gif


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#11 Bart Declercq

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Posted 30 January 2018 - 05:37 AM

Very nicely done Bart! bow.gif waytogo.gif

 

You must have one hell of a bucket list! mrevil.gif

Thanks, and yes - the bucket list is extensive and this was one of the first - another will be imaging Vesta's rotation (I've actually managed to detect the non-roundness of Vesta using a 12" scope, but I'll have to wait for a Vesta opposition where it's high enough in the sky in Belgium) - Gravitational light-bending (the Einstein cross) is another one on my list :)


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#12 Bart Declercq

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Posted 30 January 2018 - 05:39 AM

Bart, congratulations! What filter were you using to capture Ceres? Very impressive disk and scope. Thanks for posting

 

Regards,

Steve

I was using an Astronomik ProPlanet 642 BP filter, so this was mostly infrared light - if I get the chance, I might try in Red & Green to get better resolution, but the seeing need to be really good for green te work.


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#13 Bart Declercq

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Posted 30 January 2018 - 05:41 AM

nice image. i would be happy just to be able to take out my 16 f7 scope also on a gem but like you i'v had nothing but horible weather. can you post a pic of the scope. I thought 16 f7 on a gem was crazy but a 20 that must be huge

I've got a Flickr-album showing the construction of my observatory with the scope installed in the last few pics : https://www.flickr.c...157677194231264

 

I'm not sure if a 20" F/4 is crazier than a 16" F/7 - yours is almost 50% longer than mine (if it's a Newton anyway)... I can't even look through the eyepiece when working near the zenith now...



#14 Bart Declercq

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Posted 30 January 2018 - 05:43 AM

Awesome result, Bart!

 

What's next - showing Charon as a bump on Pluto next summer? smile.gif

I wish - and actually I think it wouldn't be impossible, except that I'd need to wait a few decades until Pluto gets to a decent height in the sky for me - Belgium is at 50°N, so Pluto is really low in the sky for me.

 

It'd be an interesting test for Damian Peach's remote 1m telescope :)


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#15 RedLionNJ

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Posted 30 January 2018 - 09:55 AM

 

Awesome result, Bart!

 

What's next - showing Charon as a bump on Pluto next summer? smile.gif

I wish - and actually I think it wouldn't be impossible, except that I'd need to wait a few decades until Pluto gets to a decent height in the sky for me - Belgium is at 50°N, so Pluto is really low in the sky for me.

 

It'd be an interesting test for Damian Peach's remote 1m telescope smile.gif

 

I had the same thoughts regarding height in the sky. Bit of a bummer, really.

 

I'm not convinced the ChileScope is ever going to live up to its potential for hi-res imaging - seeing seems to be totally average, despite the mountaintop location. The Pic appears far better.



#16 Planethunter80

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Posted 30 January 2018 - 05:34 PM

Outstanding image. Thank You for sharing it with us. waytogo.gif 


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#17 m1618

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Posted 30 January 2018 - 11:16 PM

My wife takes a glance at the screen, "oh big whoop... dots."
On a Ceres note, great stuff! What kind of mount for that 20?!


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#18 Bart Declercq

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Posted 31 January 2018 - 03:45 AM

My wife takes a glance at the screen, "oh big whoop... dots."
On a Ceres note, great stuff! What kind of mount for that 20?!

The mount is an original "Mesu" mount - not a lot of pictures online because only a relatively small number were built - https://www.yumpu.co...stro-imagingcom

 

It's a bit of a "reverse fork" mount, with a single central pillar with the telescope on one side and (in my current situation) counterweights on the other side - when I had a smaller scope, there were telescopes mounted on both sides but right now it's only the one big scope.

 

Carrying capacity of the mount is 2x63kg - my current OTA weighs about 50kg, so with camera's and stuff I'm pretty close to the limit - it works well but balance is an issue (attach a heavier camera and you need to add counterweights at the back and adjust the big counterweight on the other side) - it's a friction mount so if it's out of balance GOTO's start to fail and if it's far out of balance it can't track anymore.

 

Advantage:  0 backlash, 0 Periodic Error.

 

Mesu still makes mounts (MESU 200 & MESU 300) but they're more classical GEM type mounts, still friction drive.


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#19 stanislas-jean

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Posted 31 January 2018 - 12:58 PM

Excellent.

Stanislas-Jean


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#20 Konstantin 1980

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Posted 26 February 2018 - 07:46 AM

I watched Ceres 2 weeks ago. The telescope is 254 mm. The asteroid disk is very easy to see, there were no problems with its observation. Confidently visible yellowish color. The asteroid disk is much larger than the diffraction disk of stars, it is simply impossible to confuse it, that the disk is real easy and immediately catches your eye. I did not even consider it necessary to talk about this observation. A telescope with a diameter of 20 inches can catch asteroid disk size 0.3 ", they will be different from diffraction, I saw the shape of the asteroid Vesta visually, in 254 mm . For a 20 inch telescope, the asteroid disk of Ceres, is a very easy target. If everything is properly configured 


Edited by Konstantin 1980, 26 February 2018 - 07:52 AM.


#21 Bart Declercq

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Posted 27 February 2018 - 07:04 AM

I watched Ceres 2 weeks ago. The telescope is 254 mm. The asteroid disk is very easy to see, there were no problems with its observation. Confidently visible yellowish color. The asteroid disk is much larger than the diffraction disk of stars, it is simply impossible to confuse it, that the disk is real easy and immediately catches your eye. I did not even consider it necessary to talk about this observation. A telescope with a diameter of 20 inches can catch asteroid disk size 0.3 ", they will be different from diffraction, I saw the shape of the asteroid Vesta visually, in 254 mm . For a 20 inch telescope, the asteroid disk of Ceres, is a very easy target. If everything is properly configured 

Sure, it's certainly possible to detect the disk in much smaller telescopes, I never claimed otherwise - but you don't see many people trying - "resolving the disk" to me implies more than just detecting it though, here I can measure the size of the disk and get a pretty good size estimate, that's not possible IMHO with a much smaller telescope. It's like the difference between detecting the Encke gap in Saturn's rings versus resolving it - you can "detect" it with a small scope as a slight darkening of the ring, but you wouldn't be able to distinguish between a "gap" that's just a darker ring vs a narrower but even darker gap, they would both look the same.

 

And regarding Vesta - I did it in 2010 - https://www.cloudyni...d-in-12-newton/

 

Regarding "catching" asteroid disks at 0.3" with a 20" telescope... I doubt it's really feasible, but it may depend on your definition of "catching" - it might be possible to detect the difference in diffraction pattern, but it would be quite subtle, I would certainly not call it "resolving".




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