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~30cm SSA - NEO confirmation scope with mount

Celestron RASA 11" Equipment Refractors
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~30cm SSA / NEO confirmation scope
Multiple choice poll 8 votes
13% (1 vote)
13% (1 vote)
38% (3 votes)
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Luka Poropat avatar
Luka Poropat avatar
Opinions on optics primarily used for SSA and NEO confirmation
  1. RASA 11/14 (4300€/20.000€)        (22kg/34kg)

   2. Officina stellare RiFast 300 (16.600€)   (20kg)
  1. Planewave DeltaRho 350 (24.400€)  ( (21kg)

I am fully aware of prices and performances with stigmas of these designs, however due keep in mind these are not for AP.

This is something in the lines for the future of our work, and given we are getting a new mount right now it would be also beneficial to know what could be done or which one would be ideal for it. Current mount in the idea is CEM70/CEM120 for the already fully remote rigged Esprit 100 (yes very much an overkill ). 

Drop your opinions, comments and similar down below. 
Prices are that due to EU and cannot realistically be dropped.
Wei-Hao Wang avatar
Wei-Hao Wang avatar
Is your NEO "near-earth object" as small asteroids, or artificial satellites at "near-earth orbit?"  Anyway, both can move very fast.

If you want to use filters, the Officina and PlaneWave will make much more sense.  If I am to choose between the two, I would based my decision on which one is easier to maintain and to collimate.  

On the other hand, it is possible to conduct many SSA studies without a filter.  That puts the RASA onto the map. 

One thing I found during our SSA studies is that telescope flexure can induce significant focus shift when we track the target from low to high elevation. This is usually not a problem for standard astronomical observations, since the telescope would move very slowly and it can take an hour or longer for the focus shift to actually impact the image quality (and a simple refocusing can solve that quickly).  For SSA, especially for objects on low-earth orbits. the telescope moves very quickly and you don't have time to conduct a standard focusing sequence in the middle.  So it is important to require:
  1. the scope is very stable and its focus does not change much with pointing direction, or
  2. you have a way to compensate the focus shift on-the-fly when you track the target.

Our CDK20 does not meet the requirement #1, so we hired a private company to develop something to do #2.  Unfortunately, I don't know if there exist any studies regarding #1 for the scopes you mentioned.  You pretty much have to test it by yourself.

As for mount, I strongly suggest a fork mount or the PlaneWave L mount.  Most German mounts like the two CEM you mentioned require meridian flip.  You definitely don't want that when you are in the middle of tracking a satellite or a fast moving NEO.  A fork mount can allow you to track the object from horizon to horizon.
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andrea tasselli avatar
andrea tasselli avatar
Wei-Hao Wang:
A fork mount can allow you to track the object from horizon to horizon.


Except at zenith (or close enough), which is a pole for Alt-Az mounts (and I know the hard way...).
andrea tasselli avatar
andrea tasselli avatar
I expect you would love this to have: https://www.astrosysteme.com/products/uwf300-f1-3/
Wei-Hao Wang avatar
Wei-Hao Wang avatar
andrea tasselli:
Wei-Hao Wang:
A fork mount can allow you to track the object from horizon to horizon.


Except at zenith (or close enough), which is a pole for Alt-Az mounts (and I know the hard way...).

That's correct.  Personally I am not a fan of Alt-Az mounts and that's one of the reasons.  Our PlaneWave L mount is on an equatorial plate form, so it doesn't have the zenith problem.  

But you know, every mount has such a singularity point.  For an EQ mount, it's the celestial poles.  If a fast moving object passes close enough to the celestial pole, many EQ mounts (German, fork, whatever form) will have troubles.
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andrea tasselli avatar
andrea tasselli avatar
Wei-Hao Wang:
But you know, every mount has such a singularity point. For an EQ mount, it's the celestial poles. If a fast moving object passes close enough to the celestial pole, many EQ mounts (German, fork, whatever form) will have troubles.


That is very much true but, technically, you don't need to track at the celestial poles. But you would need a field rotator or short expsoures.
Luka Poropat avatar
Luka Poropat avatar
Wei-Hao Wang:
Is your NEO "near-earth object" as small asteroids, or artificial satellites at "near-earth orbit?"  Anyway, both can move very fast.


Yes, Near Earth Objects, asteroids & comets. And that would probably be like 90% of the work. 
Currently all of our NEO confirmation stuff is without filters so mono is fine and thats why I included the RASAs as a (more affordable option).
Wei-Hao Wang:
A fork mount can allow you to track the object from horizon to horizon.

Yes I completely agree, would not be that of a big an issue for NEOs but its def a big plus. 
Currently our mount is a single arm equatorial fork so it does help indeed. 
andrea tasselli:
I expect you would love this to have: https://www.astrosysteme.com/products/uwf300-f1-3/

Wouldn't we all  
Wei-Hao Wang avatar
Wei-Hao Wang avatar
andrea tasselli:
Wei-Hao Wang:
But you know, every mount has such a singularity point. For an EQ mount, it's the celestial poles. If a fast moving object passes close enough to the celestial pole, many EQ mounts (German, fork, whatever form) will have troubles.


That is very much true but, technically, you don't need to track at the celestial poles. But you would need a field rotator or short expsoures.

Remember that the topic is fast moving targets on the sky, not traditional, steady, astronomical targets.  They can pass near the pole rapidly, and the probability of that is not lower than passing near the zenith.  So yes, we do need to track targets near the pole, no matter which pole you are talking about.