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Add TPoint Or Other Star Pointing Model (Answer: Show Your Interest)

Robert Capon

May 09, 2019 16:45

Answered

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Hi:

I'm using SkySafari 6 Pro to control a Meade LX65 goto telescope. I'm currently doing a 2-star alignment, and am able to do GOTO all over the sky and hit an object somewhere in a 0.8 degree field of view. It would be fantastic if SS6 or SS7 enabled a 10-star alignment to do a pointing model for greater precision.

Previously, I owned an observatory, and performed 300 plate TPoint models, achieving arcsecond pointing accuracy. I've since moved to a city and sold my observatory, and am just enjoying visual astronomy and casual observing at star parties. That's where SS6 comes in. I don't think SS6 needs to do 300 point models, because that's the domain of SkyX and TPoint and ACP for permanent fixed observatories. But for star parties, it would be great if SS6 could point a Meade or Celestron or other goto mount with pointing accuracy of a few arcminutes. A 10-point model would be a fantastic enhancement to SS6 (or SS7) for telescope control.

Fundamentally, I think people use SS6 as a personal planetarium program and to control telescopes for pretty casual observing. If you can achieve pointing accuracy of 3-5 arcminutes, a) objects will be near the center of eyepiece fields of view, and b) people can use their goto mount to slew in dense areas of the sky, stop on a fuzzy object and use SkySafari to tell you what you're looking at.

That would be really awesome!

Thanks,

Rob

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14 comments

• 0
  
  Donald Stimson May 17, 2019 01:45

  Rob, I don't know what protocol is used for SS control of your Meade goto telescope, but for my Celestron you can continue to add alignment stars up to 10 in total.  From the SS6 online manual:  "Note: for encoder-based "Push-To" systems, like the Tangent Instruments BBox, Celestron Astro-Master, JMI NGC-MAX, and Orion Intelliscope, SkySafari lets you perform a multi-star alignment (up to 10 stars)."  Now, I don't know how to tell if you have "an encoder-based 'Push-To' system!" (but my Celestron Evolution 8 apparently is as the scope's user's manual says you can add up to 10 stars to the alignment.

   

  Hope this helps,

  Don

   

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  Robert Capon May 17, 2019 01:59

  Hi Don:
  
  Thanks so much for writing. I'm using a Meade LX65 as my visual astronomy mount. The LX65 only has a provision for a two-star alignment. However, you can use a "High Precision Mode". The precision mode selects a nearby star and allows you to sync on it, improving GOTO accuracy in that area of the sky.

  I know the Celestron Evolution has some neat features. I chose the LX65 because it's very lightweight. The LX65 enables you to separate the OTA from the mount, and the mount only weighs 18 lbs, and has a nice built-in carry handle. That was very important for me. The LX65 also has a second saddle to mount an additional OTA. So I have a side-by-side 80mm apochromatic and the 8-inch SCT. It's a really fun combination, but unfortunately Meade doesn't offer a multi-star pointing model.

  I think a pointing model would be an amazing new feature in SkySafari, improving GOTO pointing accuracy for SkySafari users.

  Thank you again for the suggestion,

  Rob

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  Donald Stimson May 17, 2019 04:29

  Hi Rob,

   

  Any Celestron scope with WiFi (either included in the mount like the Evolution or added on later via a SkyPortal WiFi module) can use Sky Safari for alignment instead of the Celestron hand controller and take advantage of Sky Safari's 10-star alignment capability.  (In your original post you had said it would be great if Meade or Celestron could take advantage of a 10-star pointing model.)  So, this capability already exists for any Celestron with WiFi.

  I wonder if another approach you could take would be to request Meade to support an equivalent to Celestron's use of Sky Safari for alignment (since you don't appear to have gotten any response from the Sky Safari developers)?

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  Robert Capon May 17, 2019 11:02

  Thanks, Donald. That’s very helpful.

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  Robert Capon May 17, 2019 15:54

  Hi Donald:
  
  I've just learned that TheSkyHD TPoint supports Meade mounts, as well as ANY mount that TheSkyHD is able to control. It makes sense that it should be mount-independent because the iOS program is sending a pointing offset to the mount. The logic is pretty simple. Whenever you send a GOTO command to an object, the iOS program starts with the RA/DEC for the object, then applies a delta RA and delta DEC to arrive at new coordinates, which are sent to the telescope. The telescope doesn't need to know that the iOS program is slewing to M31. The mount only needs to GOTO a set of coordinates.

  So I'll just switch over to TheSkyHD until SkySafari can catch up with an integrated pointing model.

  Again, I really love the bells and whistles that SkySafari offers. The features are aesthetically very nice. But I really need the best pointing accuracy that I can get.

  Thank you again for your reply to my posting.

  Rob

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  Robert Capon May 17, 2019 18:54

  OK, scratch that. Software Bisque misspoke on their support response to me. TheSkyHD TPoint only works with the Paramount for now. So as of now, there doesn't appear to be an iOS program with a multi-star pointing model for Meade. RC

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  Donald Stimson May 17, 2019 19:19

  Ohh, that's too bad.  I was hoping you had a solution (though it looked to be a pricey one).  Have you tried reaching out to Meade?

  Don

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  Robert Capon May 17, 2019 20:31

  Hi Don:

  The wheels turn pretty slowly at Meade. I think the more likely bet will be TheSkyHD or SkySafari Pro XXX.

  In the meantime, I added a Nagler 31mm 2-inch eyepiece to my setup. That increases the FOV from .8 degrees with a 24mm Panoptic to about 1.3 degrees with the Nagler. On my first outing with the Meade LX65 using the Panoptic, I located approximately 50 objects during the night. Almost all objects were somewhere in the FOV, although only a few objects were well-centered. The 31mm Nagler should keep almost all objects somewhere in the FOV.

  So I'm able to find most/all objects.

  It's trickier when you're slewing around in a dense area and you want to use SkySafari to identify what you're looking at. For example, if you're in Markarian's Chain, it would be great to have pointing accuracy to 3-5 arcminutes, so objects are near the center and you can identify them.

  Back in my observatory days, using TPoint and a 309 plate model, I could routinely achieve 5-10 arcseconds GOTO accuracy. I would do an automated TPoint run that would generate 309 random points in the sky, take a 2-second image of each, bin the images 3x3 for fast download, and do a plate solve and map the offset. The observatory and the mount moved together and could run 4 points a minute! If TheSkyX missed an object by more than 60 seconds, ACP would fix it. ACP was set up to do a pointing image after a GOTO, and would re-center the object if it was out of the 60 second tolerance that I set up. IT WAS FABULOUS!

  For visual astronomy, a few arcminutes would be fantastic if I could achieve it. One (so-so) solution is to use Meade's High Precision slew by syncing on an object and getting better pointing accuracy in a neighborhood of the sky. The problem is that you lose the precision as soon as you leave the neighborhood.

  Thanks again for your advice.

  Rob

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  Gervais Parent May 20, 2019 22:33

  A very interesting conversation.

  I woull be ready to pay for that. May be they can add a Pro Plus (Pro Point) version?

  I really think they already have the code to do that (or very close). Like TPoint (or MaxPoint), they can correct the pointing information send to the scope based on the model. It would be very very intersting!

  Gervais

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  Bill Tschumy May 21, 2019 17:55

  We have had some internal discussions about implementing something like TPoint for scope types like Celestron and Meade.  Nothing definite was decided but I am glad to know there is interest.

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  Robert Capon May 21, 2019 19:47

  Hi Bill:

  Thanks for your note. I'd like to second the comment that this is a feature I'd be willing to pay for as an add-on. Most people have thousands of dollars invested in their visual astronomy setup, and it would be worth an extra $25 to me for a multi-point add-on program.

  I checked with TheSkyHD, and TPoint only works with the Paramount. Furthermore, I read the TPoint user's guide, and it only works with equatorial mounts, which would be very limiting since many visual observers use Alt-Az mounts (including mine).

  Further, I don't think SkySafari needs 300+ plate-solve, multi term linear regression. People use TheSkyX on a work-horse PC to run their observatories, and that's where you want arcsecond pointing accuracy. SkySafari is used for control of telescopes in the field, such as at Star Parties. If SkySafari could do a multi-point alignment, it would be a dramatic improvement for telescope control.

  Presently, 2-star alignment is OK to get objects SOMEWHERE in a 30-60 arcminute field of view. In my case, I'm using an 8" SCT with a 24mm Panoptic so have 0.8 degrees FOV. With a 2-star alignment, the objects are usually somewhere in the field, but often barely in the field.

  If SkySafari can offer a 10-point model that improves pointing accuracy to 5-10 arcminutes, that would provide GOTO accuracy NEAR the center of most people's FOV.

  If it would be helpful, I would be very happy to Field Test this feature whenever you get to it. I'm a very experienced amateur astronomer, and until recently had a robotic observatory until I moved to the city.

  Thanks so much,

  Rob

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  Bentley Ousley May 25, 2019 18:29

  Yes, I would love to see some sort of scope-compensating model-algorithm added to Sky Safari. Nexus DSC has Mpoint, but I would like to see something a little more intuitive to use (and something supported natively in Sky Safari instead of being reliant on support from a third party ).

  I could imagine the alignment process being something akin to this:

   

  1) Align on Polaris

  2) Knowing your scope's location and time, Sky Safari suggests the 8 (or whatever) best candidate alignment stars (based on what bright stars would be well situated at that particular date and time _and_ what is needed in order to build the most accurate model) and then highlights them on the chart.

  3) Point the scope and align with each of the candidate stars and touch the (newly programmed) "Add to Model" button for each.  If one of the model points is obscured, choose another nearby star for alignment (or any star for that matter, the candidate stars are suggestions for the best model, not required). As each new model point is added, Sky Safari further refines the model. Any number of points may be added, so long as the points are at least 10 degrees apart.

  4) Enjoy your perfectly aligned evening of astronomy!

   

  If during the evening another alignment point is desired: highlighting, aligning and touching "Add to Model" creates and adds another point to the model. If that model-point is within 10 degrees of a current model point, the existing model point is replaced with the new model point.

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

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  TasmanSkies August 24, 2019 03:14

  Robert Capon, I'm interested in how you are driving your LX65 by SkySafari as I have the LX65 and SkySafari and an trying to figure out how to connect the two (SkyFi 3 doesn't list LX65 as supported and this thread is the only thing I found hitting on LX65) - this is off-topic but perhaps we can take it offline and you can tell me more? jeremy@jnt.nz

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  TasmanSkies August 24, 2019 03:38

  I am not sure how to register my support for this feature enhancement suggestion, other than upvoting the query, so I'm adding a comment to register my support - this would be a brilliant feature to add. The Meade handset firmware does not offer the ability to continue to add alignment stars like the Celestron does as Donald Stimson mentions, and the two-star alignment is barely adequate. Using SkySafari to build a pointing model that improves accuracy across the whole sky would be brilliant. I would certainly be willing to pay for the additional feature, perhaps as an in-app purchase optional extra, instead of a separate app version?