Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Which is the best mount for research work?

  • Please log in to reply
23 replies to this topic

#1 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 13 June 2021 - 09:51 PM

I was just wondering...which is the best mount #1 out there, which even beats the 10 microns... and is very responsive to guide input...Is the ASA DDM500?

Thanks for replying...

clear skies(Its finally beginning to get clear here toosmile.gif)

Ayaan



#2 TxStars

TxStars

    Mercury-Atlas

  • *****
  • Posts: 2,670
  • Joined: 01 Oct 2005
  • Loc: Lost In Space

Posted 13 June 2021 - 11:13 PM

It would depend on how much the grant is for and what the study is trying to show/learn/prove ??


  • MCinAZ likes this

#3 Phil Sherman

Phil Sherman

    Gemini

  • *****
  • Posts: 3,496
  • Joined: 07 Dec 2010
  • Loc: Cleveland, Ohio

Posted 13 June 2021 - 11:23 PM

While I'm sure that there are better mounts available than a 10 Micron, even that mount should be overkill. The lower limit for imaging with any mount is the seeing. Seeing defines the lower limit of guiding which is reachable by many mounts, even those costing a lot less than the 10 Micron. If seeing gives you stars that are 3 arcsec in diameter and you can guide to better than 0.5 arcsec with a mid range price mount, you won't see much difference with a premium mount that guides to 0.1 arcsec.



#4 skybsd

skybsd

    Fly Me to the Moon

  • *****
  • Posts: 5,136
  • Joined: 01 Feb 2008

Posted 14 June 2021 - 12:14 AM

I was just wondering...which is the best mount #1 out there, which even beats the 10 microns... and is very responsive to guide input...Is the ASA DDM500?

Thanks for replying...

clear skies(Its finally beginning to get clear here toosmile.gif)

Ayaan

  • Researching what, exactly? 
  • What does the grant package (funding, constraints, restrictions, etc) look like? 

 

skybsd 


  • happylimpet likes this

#5 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 14 June 2021 - 12:40 AM

I was just curious to know-

About the seeing-I asked about which mount is most responsive to guide input



#6 TxStars

TxStars

    Mercury-Atlas

  • *****
  • Posts: 2,670
  • Joined: 01 Oct 2005
  • Loc: Lost In Space

Posted 15 June 2021 - 09:35 PM

For instant response a converted Mill surplus SAM launcher would have the quickest movement and response, but would nock most optics out of alignment on start up, and be way more than you really need..

As far as off the shelf normal mounts, a good direct drive mount would be a good choice..


Edited by TxStars, 15 June 2021 - 10:05 PM.


#7 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 15 June 2021 - 09:39 PM

Yes...a slew speed of more than 30 degrees/sec is not my liking anyway...So the direct drive novas come into mind. Which tracks best and is most responsive to guide input? And which mount can battle the seeing the best?



#8 WadeH237

WadeH237

    Cosmos

  • *****
  • Posts: 7,606
  • Joined: 24 Feb 2007
  • Loc: Ellensburg, WA

Posted 16 June 2021 - 07:46 AM

Do you have specific and quantifiable requirements?  You mention responsiveness to guide input, but can you quantify it?  How much payload?  What aperture and length scope (to understand the moment of inertia)?  What data are you trying to collect?

 

Any of the usual premium suspects (Astro-Physics, Software Bisque and 10Micron) should be able to far exceed the accuracy required to exceed both seeing and the resolution of your instrument.  I'm sure that ASA can, as well, but is probably far more expensive than the others.  Without knowing more about what you are actually trying to do, we have no way of knowing what you actually need (and just saying "I want the best" isn't helpful, since "best" is relative to the mission).


  • psandelle and Miguelo like this

#9 StarmanDan

StarmanDan

    Aurora

  • *****
  • Posts: 4,868
  • Joined: 27 Aug 2007
  • Loc: Where the stars at night are big and bright...

Posted 16 June 2021 - 12:46 PM

Most mounts now are reasonably adequate for just about any research you want to do. I have an Orion Atlas mount and it is more than capable with my 8 inch SCT of capturing light curves of variable stars, asteroids, supernovae, and exoplanets. I also do asteroid occultations with it. For long runs requiring all night acquisition on a single target, you might consider a fork mount instead of an EQ. It eliminates the meridian flip requirement of most EQ mounts and makes reducing the data a little easier.

Edited by StarmanDan, 16 June 2021 - 12:47 PM.


#10 SimonIRE

SimonIRE

    Surveyor 1

  • -----
  • Posts: 1,558
  • Joined: 16 Dec 2018
  • Loc: South East England

Posted 16 June 2021 - 12:57 PM

You’re listed as being 13 years old (lucky you).

So forgive me for being inquisitive - what exactly is your use case? Without that it’s impossible to answer your question fully. Exoplanet surveying arguably needs a high precision system but my 10 Microns are easily capable. You mention an DDM500. This has a half tonne capacity but it’s listed precision is no better than the DDM100. And anyone buying an ASA mount is unlikely to be thinking about guiding. If I was to buy another mount and I couldn’t buy a 10 micron, I’d look at the Planewave DD offerings.

We need more info.

Edited by SimonIRE, 16 June 2021 - 12:59 PM.

  • psandelle likes this

#11 TxStars

TxStars

    Mercury-Atlas

  • *****
  • Posts: 2,670
  • Joined: 01 Oct 2005
  • Loc: Lost In Space

Posted 16 June 2021 - 06:29 PM

Yes knowing what you are trying to do and what the budget for this is $$.. Will make things easier..

Or is this just a  "If I were to win the lotto" What should I buy? thing?



#12 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 18 June 2021 - 04:56 AM

I just wanted to know-which mount can image at 0.05 arcsec/pixel?



#13 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 18 June 2021 - 04:56 AM

Basically the highest precision system made which can battle the seeing successfully without adaptive optics



#14 WadeH237

WadeH237

    Cosmos

  • *****
  • Posts: 7,606
  • Joined: 24 Feb 2007
  • Loc: Ellensburg, WA

Posted 18 June 2021 - 08:16 AM

I just wanted to know-which mount can image at 0.05 arcsec/pixel?

None.

 

The atmosphere won't allow it.  The very best conditions, at exotic locations such as the Atacama desert in the Andes mountains of South America can get down to 0.5 arc seconds seeing on the very best nights, but that is 10x what you are looking for.

 

There are lots of mounts that can beat the seeing.  My AP1600 with encoders has a theoretical accuracy of 0.019 arc seconds, which easily beats your 0.05 target.  On the best nights at my location, I can get guiding to about 0.2 arc seconds RMS.  More typically, I am around 0.4 or 0.5 arc seconds RMS due to seeing.  Keep in mind that the guiding RMS error is not the same thing as seeing.  My 0.2 arc second RMS guide error results in around 2 arc second FWHM stars.

 

Basically the highest precision system made which can battle the seeing successfully without adaptive optics

I think that you have a misunderstanding about what seeing does to an image.

 

As I mentioned above, no mount can "battle seeing".  The nature of seeing is that it blurs the image as the apparent position of the stars shifts around.  The amount of blur is related to the exposure time and atmospheric conditions, not mount accuracy.  By the time you've taken even a 2 or 3 second exposure, the seeing will have blurred the stars significantly.

 

There are systems that do something called "lucky imaging".  This basically means that they are taking very short exposures and keeping only the sharpest ones.  There are some people doing a (weak) form of lucky imaging by taking hundreds or thousands of exposures around 5 seconds.  Also, as I mentioned above, a 5 second exposure can be significantly blurred by seeing.  To really do lucky imaging right, you need to take exposures that are milliseconds long.  You can't do that with an amateur level camera because the read noise is too high.

 

There are exotic cameras called "electron multiplying CCD's" that have nearly zero read noise.  They can do true lucky imaging, but are very expensive.  Here is a web page that describes a project that investigate astrophotography with such a system.  I don't remember the full details, but I seem to recall that he was able to get real images down to about 0.5 arc seconds resolution with this system.  I also don't remember the price, but I think that it was in the tens of thousands of dollars for a used camera.  Even then, I suspect that he had to write his own processing software to stack the images (not a problem for him because he wrote CCDStack, which is one of the premier stacking programs).

 

Finally, there are no amateur adaptive optics systems that can beat seeing.  The professional research instruments that use adaptive optics for this purpose have a high power laser that they point into the upper atmosphere so that the spot appears as an artificial star in the frame.  They then have large, segmented mirrors where individual areas of the mirror can quickly tip/tilt to react to seeing as detected by analyzing the artificial star in real time.


Edited by WadeH237, 18 June 2021 - 08:19 AM.

  • Oscar Szentirmai, psandelle, R Botero and 1 other like this

#15 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 18 June 2021 - 11:07 PM

Oh, I see. I have known lucky imaging for more than 4 months now...Aren't 10 microns better at guiding than astrophysics mounts? Like, I have seen some images on astrobin imaged with a (I think paramount ME II)at a pixel scale of less than 0.1 arcseconds...I don't exactly remember where.



#16 WadeH237

WadeH237

    Cosmos

  • *****
  • Posts: 7,606
  • Joined: 24 Feb 2007
  • Loc: Ellensburg, WA

Posted 18 June 2021 - 11:25 PM

Aren't 10 microns better at guiding than astrophysics mounts?

Nope. They are both excellent.
 

Like, I have seen some images on astrobin imaged with a (I think paramount ME II)at a pixel scale of less than 0.1 arcseconds...I don't exactly remember where.

Pixel scale is like the magnification numbers on the box of a department store telescope. Anyone can stack some Barlows to get whatever pixel scale (actually called "image scale") that they want.  That doesn't necessarily mean that the image will support that resolution - and in the case of 0.1 arc seconds, there is virtually no real world scenario where you'd be able to actually make use of it.  It's the imaging equivalent of "empty magnification", like running 500x power on a 60mm achromatic refractor.

 

If you can post a link to a specific Astrobin image, I can look at it and tell you what they did.


  • psandelle likes this

#17 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 20 June 2021 - 02:16 AM

Yes, you are usually limited by seeing, an the resolution of your scope, and also other factors.



#18 555aaa

555aaa

    Vendor (Xerxes Scientific)

  • *****
  • Vendors
  • Posts: 2,160
  • Joined: 09 Aug 2016
  • Loc: Ellensburg, WA, USA

Posted 20 June 2021 - 09:34 AM

The thing that the mount has to battle is the wind, not the seeing. Once you have encoders, the accuracy problem is solved but then you are providing stiffness relative to upsetting forces. Geared mounts provide stiffness mechanically. Direct drive and friction roller direct drive mounts provide electronic stiffness. Geared mounts have a delay in upset response due to backlash and direct drive does not. The highest accuracy encoder installations use two or three read heads which is prohibitive on small mounts.

#19 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 20 June 2021 - 11:47 PM

Oh wow. I never knew all these things before. Thanks for all the information!waytogo.gif


Edited by Ayaan Hashim, 20 June 2021 - 11:48 PM.


#20 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 20 June 2021 - 11:49 PM

Yes mounts have to battle the wind too(but they are better off in an observatory)



#21 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • Posts: 1,299
  • Joined: 10 Dec 2015
  • Loc: Melbourne

Posted 22 June 2021 - 05:18 AM

I just wanted to know-which mount can image at 0.05 arcsec/pixel?


Hubble 😂
  • Woody218 likes this

#22 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 22 June 2021 - 05:52 AM

I think Hubble has gyroscopes inside but some of them failed.



#23 Oscar Szentirmai

Oscar Szentirmai

    Viking 1

  • -----
  • Posts: 576
  • Joined: 28 Dec 2006
  • Loc: London - UK

Posted 22 June 2021 - 07:48 AM

None.

 

The atmosphere won't allow it.  The very best conditions, at exotic locations such as the Atacama desert in the Andes mountains of South America can get down to 0.5 arc seconds seeing on the very best nights, but that is 10x what you are looking for.

 

There are lots of mounts that can beat the seeing.  My AP1600 with encoders has a theoretical accuracy of 0.019 arc seconds, which easily beats your 0.05 target.  On the best nights at my location, I can get guiding to about 0.2 arc seconds RMS.  More typically, I am around 0.4 or 0.5 arc seconds RMS due to seeing.  Keep in mind that the guiding RMS error is not the same thing as seeing.  My 0.2 arc second RMS guide error results in around 2 arc second FWHM stars.

 

I think that you have a misunderstanding about what seeing does to an image.

 

As I mentioned above, no mount can "battle seeing".  The nature of seeing is that it blurs the image as the apparent position of the stars shifts around.  The amount of blur is related to the exposure time and atmospheric conditions, not mount accuracy.  By the time you've taken even a 2 or 3 second exposure, the seeing will have blurred the stars significantly.

 

There are systems that do something called "lucky imaging".  This basically means that they are taking very short exposures and keeping only the sharpest ones.  There are some people doing a (weak) form of lucky imaging by taking hundreds or thousands of exposures around 5 seconds.  Also, as I mentioned above, a 5 second exposure can be significantly blurred by seeing.  To really do lucky imaging right, you need to take exposures that are milliseconds long.  You can't do that with an amateur level camera because the read noise is too high.

 

There are exotic cameras called "electron multiplying CCD's" that have nearly zero read noise.  They can do true lucky imaging, but are very expensive.  Here is a web page that describes a project that investigate astrophotography with such a system.  I don't remember the full details, but I seem to recall that he was able to get real images down to about 0.5 arc seconds resolution with this system.  I also don't remember the price, but I think that it was in the tens of thousands of dollars for a used camera.  Even then, I suspect that he had to write his own processing software to stack the images (not a problem for him because he wrote CCDStack, which is one of the premier stacking programs).

 

Finally, there are no amateur adaptive optics systems that can beat seeing.  The professional research instruments that use adaptive optics for this purpose have a high power laser that they point into the upper atmosphere so that the spot appears as an artificial star in the frame.  They then have large, segmented mirrors where individual areas of the mirror can quickly tip/tilt to react to seeing as detected by analyzing the artificial star in real time.

Excellent piece there...very informative!

Thnx, I enjoyed reading that.



#24 Ayaan Hashim

Ayaan Hashim

    Vostok 1

  • -----
  • topic starter
  • Posts: 144
  • Joined: 06 Jun 2021
  • Loc: Possibly Bortle 8-9, Mumbai, Maharashtra, India

Posted 23 June 2021 - 02:14 AM

The thing is...I want my setup(If I ever get one) to be completely customized by myself...Then I realized if I had to customize the way I wanted it to be I had to make the telescope and mount myself from scratch....




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics