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Pluto Observation

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#1 Allan Wade

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Posted 15 June 2021 - 11:03 AM

I remembered today the discussions over the last few years about observing Pluto in smaller scopes. With opposition coming up I decided tonight was my chance. 
 

First I tracked it down in the 32” using Sky Safari 6 with its extended star data base to magnitude 17. It makes locating Pluto pretty quick and easy.

 

Using that knowledge I put the TOA130 into action. It was easy to get orientated using the brighter asterisms in the field of view that I could see in the 32”. I started off with the 10 Ethos for 100x, and had some early indications of Pluto. I swapped it out for the 6 Delos for 166x and the magnitude 13 field stars I was using popped into strong direct vision. Pluto was quite obvious with averted vision, to the point I could almost hold it with direct vision.

 

This is my first attempt at Pluto with anything less than 12”, and I was surprised at how easy it was. I did have a very good sky tonight, well above average seeing and transparency for my site, so that certainly helped. 

I don’t know what is the smallest aperture used for a successful Pluto observation, but given what I saw tonight, I figure someone with great eyes could probably do it with a 4”.

 


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#2 RyanSem

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Posted 15 June 2021 - 11:09 AM

That's pretty neat. I saw Pluto for the first time a couple years ago in my friend's 9.25 Evo. Even then, it was fairly hard to make out, but we both confirmed its location against SkySafari. I turned to my 4" Mak and couldn't see it for the life of me. Same star field, just no Pluto.

 

About 2 weeks ago I found myself in very favorable skies, with the Milky Way visible above head, and beautiful transparency on top of a nearby mountain. I pointed my 8" Evo and found it within a couple seconds. Couldn't hold onto it with direct vision, but it was pretty steady using AV. Unfortunately, the others in my group couldn't see it, but then again, it was some of their first times looking through a scope. (And, after being blown away my Saturn, I don't think they appreciated the subtleties of finding near-impossible objects). 

 

Now I wish I brought my little scope to try - didn't realize it was nearing opposition!


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#3 Rutilus

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Posted 15 June 2021 - 11:15 AM

This is my first attempt at Pluto with anything less than 12”, and I was surprised at how easy it was. I did have a very good sky tonight, well above average seeing and transparency for my site, so that certainly helped. 

I don’t know what is the smallest aperture used for a successful Pluto observation, but given what I saw tonight, I figure someone with great eyes could probably do it with a 4”.

Well done in seeing Pluto.  I hope to be able to observe it this year with my C9.25 sct.


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#4 Dave Mitsky

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Posted 15 June 2021 - 02:38 PM

It's been a couple of years since I last observed Pluto.  I'm planning on doing it again soon.



#5 sanbai

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Posted 15 June 2021 - 09:51 PM

Out of reach in my area, I'm afraid. I think on Friday I crossed magnitude 13 with the C8 and good seeing, but Pluto would require a much better night, less pollution, and more patience.

Anyway, maybe I should not give up that soon. You gave my hope!

#6 Sarciness

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Posted 16 June 2021 - 12:15 AM

I'm pretty sure it's not possible in my region, but it does sound wonderful!



#7 Allan Wade

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Posted 16 June 2021 - 12:59 AM

Out of reach in my area, I'm afraid. I think on Friday I crossed magnitude 13 with the C8 and good seeing, but Pluto would require a much better night, less pollution, and more patience.

Anyway, maybe I should not give up that soon. You gave my hope!

 

 

I'm pretty sure it's not possible in my region, but it does sound wonderful!

I’ve seen Pluto in a 12” from Bortle 5 and that was not a particularly difficult observation. But obviously the closer you get to Bortle 1 the easier it is to see in smaller scopes.


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#8 Sarciness

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Posted 16 June 2021 - 01:46 AM

I’ve seen Pluto in a 12” from Bortle 5 and that was not a particularly difficult observation. But obviously the closer you get to Bortle 1 the easier it is to see in smaller scopes.

I've got Bortle 8 to 9 and a Newtonian 10''.



#9 Allan Wade

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Posted 16 June 2021 - 04:41 AM

I've got Bortle 8 to 9 and a Newtonian 10''.

There should be a law against Bortle 9.


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#10 Sarciness

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Posted 16 June 2021 - 07:07 PM

There should be a law against Bortle 9.

I wish they would shut off some or all of the lights for an hour or two each night... I wonder whether smart sensors will one day be used? I really hope so- 99% of light is just wasted. I could read a book on my roof from the skyglow alone.
 



#11 sanbai

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Posted 16 June 2021 - 07:27 PM

Back here.

First of all, thanks for bringing the topic of the extended star data base in Skysafari. My smartphone is running short of memory space, so it was out of consideration. I forgot about it when I got my new Samsung tablet (very good for observing with the OLED screen). This error has been amended today: I bought the extension for jusf $3! (I'll pass with the galaxy extension, and not becauseof price or memory space...)

Last friday I was missing stars in Skysafari compared to what I was seeing around NGC 4631 - 4627 (a highlight of the night). I was wondering why...

Now I think I have to retract what I said in my previous post. I may well achieve Pluto-like magnitudes with my C8 from my just-decent observing site (and mosquito paradise). I'll certainly will try to find the limit with (the one "with little effort").

#12 Allan Wade

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Posted 16 June 2021 - 07:59 PM

While I think Sky Safari 5 is a better app than Sky Safari 6, the stars are a lot more accurate in SS6 with the extended star data base into the magnitude 17’s. So I use SS6 at the eyepiece to chase down a lot of faint and obscure stuff and it makes the process so easy. The only downside is if the objects are in the magnitude 17’s or 18’s, it does take a while to get proper night vision back after I put the iPad away.



#13 sanbai

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Posted 17 June 2021 - 10:07 AM

Well, it seems there are still some gaps in the star catalog. Yesterday I was checking from my (light polluted) backyard and I was missing stars in SS6pro+extension that I saw with the telescope and in the DSS Image. Curious enough, SS is showing fainter stars in that area that were out of my reach.

This seemed already the case in few areas I observed, but at the end I centered my observation on HD107793 (in Mel111), between 12 Com and HD107935.

I have this issue also in Stellarium (superimposed DSS helps a lot), but it seems CdC shows the two missing stars (~mag 14). I'm pretty bad with this two applications (with no time to overcome the learning curve :( ) so don't take me seriously.

#14 sanbai

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Posted 17 June 2021 - 01:01 PM

Attached a DSS picture with the stars I saw but are missing in Skysafari (red circle).

 

If it's true those stars are in order of magnitude 14, then there's a chance I can observe Pluto, even in the backyard. Weather, duties and the time at which will be well positioned will sure prevent that. Anyway, now and the coming days there's a good opportunity to see ~and identify~ Pluto: The planetoid is next to a good group of stars that are shown in SS and fit within the field of a C8+Ethos6. I have checked a DSS image and there should be no confusion.

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Edited by sanbai, 17 June 2021 - 01:02 PM.


#15 dhkaiser

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Posted 17 June 2021 - 01:57 PM

My Guide 9.1 software has both your circled stars as 12.5 mag... 

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#16 sanbai

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Posted 17 June 2021 - 03:11 PM

My Guide 9.1 software has both your circled stars as 12.5 mag... 

Thanks for checking!

This makes more sense based on my experience in my backyard. Maybe I can squeeze 0.5 mag more with favorable conditions and effort. DSO observing there is quite disappointing (unless you haven't been in a better place).

Pluto will have to wait for the next visit to the mosquito observing site.

 

Edit: indeed, CdC says mag ~12.5, I was looking to the wrong window.


Edited by sanbai, 18 June 2021 - 11:07 AM.


#17 Redbetter

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Posted 21 June 2021 - 11:35 PM

 

I don’t know what is the smallest aperture used for a successful Pluto observation, but given what I saw tonight, I figure someone with great eyes could probably do it with a 4”.

 

Good job.  I am not surprised that it was near direct vision with the TOA 130, especially from extremely dark skies in the southern hemisphere.  It has consistently been in reach of the 110ED in recent years in ~21.5 MPSAS skies, even though it only reaches about 30 degrees here.  My estimation is that for me it should be well within reach of a 4" in these same conditions, but I have not masked down the 110 to try it.  I suspect it might be in reach of a 90mm, but I would need very good seeing and transparency to have a shot.

 

I have tried for a few times with the 80ED at least twice in recent years, sometimes in 21.8+ MPSAS conditions, but never with sufficiently good seeing to bring in stars past 14.0 this low in the sky.  I have done 14.3 mag on stars higher in the sky with this scope, but Pluto keeps getting dimmer each year as it moves into the far outer reaches, so I don't see it happening with the 80 going forward.

 

Back when Pluto was near perihelion Brian Skiff was able to detect it with a Pronto on one of his attempts on Anderson Mesa.  That jibes with what I can detect with similar aperture, and I have generally found his telescopic limiting magnitudes a match for my own.  



#18 Tyson M

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Posted 22 June 2021 - 04:10 AM

I want a crack at pluto this year. Been an awful year for observing for me. Super busy and days off have not been conducive for much observing. 



#19 Dave Mitsky

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Posted 27 June 2021 - 12:07 AM

By the way, there's a finder chart with stars displayed down to 14th magnitude on pages 48 and 49 of the July issue of Sky & Telescope.


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