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equatorial daytime GOTO

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#1 Nicole Sharp

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Posted 25 August 2019 - 02:18 PM

Does anyone know if SynScan (Sky-Watcher or Orion) equatorial mounts (e.g. Sirius/HEQ5 or Sirius Pro/AZ-EQ5) support equatorial GOTO functionality in the daytime?  I think that Celestron and iOptron do, just less sure about SynScan.  A list of equatorial mounts that support this feature would be helpful.

 

Specifically, I want to equatorially align the mount to Sol, and then GOTO Mercury (or any other object bright enough to be seen in the telescope in the daytime).  Or even better, do a two-object daytime equatorial alignment (e.g. to Sol and Luna, or Sol and another bright star) for better GOTO accuracy.

 

The major difficulty I figure would be the polar alignment.  It would have to be estimated from the latitude and direction of true north.  That might be fine for say Solar tracking, but for accurate GOTO of other objects in the daytime could be a problem without a way to reduce the cone error in the daytime.

 

An inaccurately aligned mount could be disastrous for (e.g.) GOTO Mercury when Mercury is close to Sol.  Would have to only slew to targets with the Solar filter on, and check that no Solar light is coming through after a GOTO before removing the filter.


Edited by Nicole Sharp, 25 August 2019 - 02:24 PM.


#2 sg6

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Posted 25 August 2019 - 03:30 PM

The Synscan app on Android sort of supports it. You do the polar alignment and the app offers a couple of stars. Pick 2 and it will slew to each in turn and you just accept wherever they go as perfect.

 

Mount is then happy and you can goto.

Accuracy is questionable as it is totally reliant on the "polar alignment" and no way would I tell it to go to Mercury, unless I had a solar filter already in position, or similar.

 

Half an idea there is an option to just "polar align" and go from there without any more action. Search through the manual, there do have a use. Again all depends on the polar alignment.



#3 Don W

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Posted 25 August 2019 - 03:50 PM

I know the Celestron Nexstar scopes up to and including the CGX has a Solar System Align system. I use it with an SLT, GT, SE, AVX mounts for solar observing. It has to be toggled on in the setup. The default is off. Used them for the eclipse in Nebraska and it followed the sun very well for several hours.


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#4 Nicole Sharp

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Posted 25 August 2019 - 03:52 PM

The Synscan app on Android sort of supports it. You do the polar alignment and the app offers a couple of stars. Pick 2 and it will slew to each in turn and you just accept wherever they go as perfect.

 

Mount is then happy and you can goto.

Accuracy is questionable as it is totally reliant on the "polar alignment" and no way would I tell it to go to Mercury, unless I had a solar filter already in position, or similar.

 

Half an idea there is an option to just "polar align" and go from there without any more action. Search through the manual, there do have a use. Again all depends on the polar alignment.

 

That seems to be what I've been reading so far.  A lot of people seem to just do the faux alignment (align to stars without actually looking at them), but that's not going to give very accurate GOTOs and makes an accurate polar alignment very critical, which is difficult to do in the daytime.

 

I've been thinking though, and I don't think there are any types of daytime astrophotography or astrovideography where an equatorial GOTO would be absolutely necessary, but it would be a nice feature to have to be able to go from object to object to object accurately in the daytime.  E.g. tracing the path of Mercury during the Mercury transit with an equatorial alignment can be done with ordinary Solar tracking, without needing full GOTO functionality.  Likewise, Solar and Lunar video astronomy can just use ordinary tracking without needing GOTO.  Short-exposure daytime imaging of Mercury or Venus can be done with an altazimuth alignment instead on a mount like the Sirius Pro (AZ-EQ5), which could be more accurately Solar-aligned in altazimuth without needing to deal with polar error.  Likewise, something like a daytime occultation could be done in altazimuth short exposures without needing an equatorial alignment.  And any objects requiring equatorial long exposures could be done with better results at night instead.  Long-exposure imaging of Venus would require an equatorial alignment, but Venus is usually bright enough in the daytime to do a one-object alignment to and then track without needing full GOTO.  The telescope would just then have to be realigned if switching to another object, such as for Solar imaging.


Edited by Nicole Sharp, 25 August 2019 - 04:10 PM.


#5 Nicole Sharp

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Posted 25 August 2019 - 04:00 PM

I know the Celestron Nexstar scopes up to and including the CGX has a Solar System Align system. I use it with an SLT, GT, SE, AVX mounts for solar observing. It has to be toggled on in the setup. The default is off. Used them for the eclipse in Nebraska and it followed the sun very well for several hours.

I really like the Orion Sirius Pro (Sky-Watcher AZ-EQ5) since it provides the "best of both worlds."  But if the Celestron Advanced VX has better daytime functions, that might be a cheaper and easier option perhaps.

 

But from what I've read on Celestron (and iOptron), the Solar-System alignment still only allows you to use one alignment object, yes?  So you cannot use (e.g.) both Sol and Luna as alignment points, only one or the other.  A one-object alignment is definitely better than a zero-object (faux) alignment, but still puts a lot of the equatorial GOTO accuracy on how accurate the initial polar alignment is.  The altazimuth Solar-System alignment (on iOptron, Orion, Sky-Watcher, and Celestron) also only allows one alignment object, but the mount's zero position can usually be set more accurately in altazimuth coordinates than in equatorial coordinates.


Edited by Nicole Sharp, 25 August 2019 - 04:32 PM.


#6 SkipW

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Posted 25 August 2019 - 05:01 PM

But from what I've read on Celestron (and iOptron), the Solar-System alignment still only allows you to use one alignment object, yes?  So you cannot use (e.g.) both Sol and Luna as alignment points, only one or the other.  A one-object alignment is definitely better than a zero-object (faux) alignment, but still puts a lot of the equatorial GOTO accuracy on how accurate the initial polar alignment is.  The altazimuth Solar-System alignment (on iOptron, Orion, Sky-Watcher, and Celestron) also only allows one alignment object, but the mount's zero position can usually be set more accurately in altazimuth coordinates than in equatorial coordinates.

To answer your question, for the Celestron mounts, yes... SS align only allows one object. I think this is a shortcoming, but I don't have to write the firmware, either!

 

Other ideas:

 

If you can leave the mount out, align it at night and then hibernate it and wake it up the next day. That works very well. If you can't do that, you might be able to use Hibernate (with the mount at its index positions so you can set it up to the same position again) or Last Alignment if you have to take the mount down and set it up again, and then 'sync' on the sun using the adjustment knobs. Maybe.



#7 Don W

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Posted 25 August 2019 - 05:38 PM

I really hate to repeat myself, but the solar system align on the Nexstar mounts works very well. I have been using it for over a dozen years.


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#8 Nicole Sharp

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Posted 25 August 2019 - 05:47 PM

I really hate to repeat myself, but the solar system align on the Nexstar mounts works very well. I have been using it for over a dozen years.

 

Just finished re-reading the AVX manual, and yes I agree with you.  However, I would still really like an AZ-EQ mount if possible.  Plus the Sirius Pro (AZ-EQ5) uses a belt drive which provides better performance than the gear drives found in the Sirius (HEQ5) and AVX.  Also, the Sirius Pro (AZ-EQ5) can be used as a manual AZ mount or manual GEM without a power supply, which I don't think is supported on the Sirius (HEQ5) or AVX.  I don't own a power supply, and would have to run the mount from an idling car engine, so being able to use the mount manually as well as for motorized tracking would be a significant advantage for me.  The Sirius Pro (AZ-EQ5) will also preserve the alignment if it suddenly loses power, which I am not sure is supported on the Sirius (HEQ5) or AVX.

 

I sent emails to Orion and Sky-Watcher to confirm whether or not they have the same daytime GOTO functionality as Celestron NexStar, but could take a few days to get answers.  Usually crowdsourcing answers from Cloudy Nights is faster ;-) .

 

Any reports on the functionality of daytime GOTO on SynScan mounts?


Edited by Nicole Sharp, 25 August 2019 - 05:48 PM.


#9 freestar8n

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Posted 25 August 2019 - 07:22 PM

With many mounts if you set them up in daytime they will be able to point at the sun or other visible object directly. So go ahead and do a goto to the object and center it roughly by physically rotating the mount and not using the hand control. As long as the mount is level and latitude is set right you should be able to get close to the object just by rotating the mount in azimuth.

That will get you close to the object and you will also be nearly polar aligned. Then you can center the object with the hand control and synch on it. You should then have decent pointing and tracking. Adding another object should help with goto.

As always be careful with the sun. And don’t forget to cover the finder!

Frank

#10 Nicole Sharp

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Posted 26 August 2019 - 03:58 PM

My initial feedback from Sky-Watcher said that equatorial SynScan mounts do not support Solar-System alignments for GOTO.  Apparently this is only available on either altazimuth SynScan mounts or when performing the alignment wirelessly from the SynScan mobile app (something I would not wish to do).  Ordinary tracking is still supported though I think just not full GOTO.

 

If anyone has a SynScan equatorial mount (e.g. Orion Sirius), I'd like to hear if you can do a GOTO after aligning to a Solar-System object.


Edited by Nicole Sharp, 26 August 2019 - 04:01 PM.



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