Building an alignment model...

[perfrej]

Hi all!

With a mount that takes up to 25 alignment stars to make a really good pointing and tracking model, has refraction compensation and dual axis tracking, getting a good model is key. You all know how it goes:

• select star
  
• slew to it
  
• expose continously
  
• adjust with buttons
  
• sync
  

25 times... Takes a full evening to complete. Both Jonas Grinde and I looked for a way to automate the procedure and I have come up with the solution. Now, I now that T-Point can do it and I know that the ASA software can do it, but neither of them gets the information back to the mount, so all the processing is in the PC which then becomes a requirement for simple operation. Not good.

This is what I came up with as a solution:

create a number of Az/Alt points that cover your sky evenly

let the scope, for each of them

• slew to the location
  
• take a four second exposure
  
• plate solve it
  
• use the solution as target sync coordinates to the mount
  

Well, it works like a dream! I did a 21-point model the night before yesterday and noted that the last couple of slews missed the target by around - and even less than - 1 arc second. The handset reports, after the alignment, that:

• expected RMS error for slews and tracking is 3.4 arc seconds
  
• the polar alignment is 1 minute 1 second off the pole (and that I should turn the knobs 0.07 turns right and 0.02 turns up to fix it
  
• scope orthogonal error is 9 minutes 27 seconds
  

All this in about ten minutes.

This seems to be the way to go, clearly!

/per

Note: this image has the run log of my run two nights ago but the user interface is the newest version.

[NickK]

Good stuff.

Basically I'm aiming at a portable mount that I plonk down - it performs a set of slews and plate solves, feeds back the polar alignment at the end of it. Even better would be that it uses worm screws to automatically set the polar alignment.

[perfrej]

Good stuff.

Basically I'm aiming at a portable mount that I plonk down - it performs a set of slews and plate solves, feeds back the polar alignment at the end of it. Even better would be that it uses worm screws to automatically set the polar alignment.

That would be the GM1000HPS... Works with my ASCOM Driver and my model building software It does not, however, turn the screws, but I guess you can afford a two minute "screw-the-star-to-the-center-of-the-CCD" procedure to get your mount pole aligned...

/p

[skybadger]

Hi Perfrej,

Where would I get such a nice piece of modelling tool ?

Cheers

Mike

[perfrej]

Hi Perfrej,

Where would I get such a nice piece of modelling tool ?

Cheers

Mike

Mike,

I am still trying to figure out how I should make this available, open source, freeware, donor-ware, commercial product, so I do not have a definite answer. I'll put you on the list for now and get back to you. For sure, if it turns into a commercial product, the price tag will be something that each and every amateur astronomer can accept

/per

[Steve Ward]

Fantastic set-up Per ,

I wouldn't worry too much about the price of the software , it'll be a drop in the ocean compared with the cost of a mount like yours . . .

Just make sure that your "completely remote" approach is secure , or you'll have all us mere mortals hacking in and using your kit behind your back . . . .

Following this with great admiration , amazed at the accuracy you've got there . . . . keep it up . .

Steve.