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What is Plate Solving?

Plate Solving is a method of measuring the exact position and field of view of an imaging CCD camera or DSLR, and in turn can be used to sync to a go-to mount to enhance the pointing accuracy. The PS software will take an exposure, identify the stars and use this against various star catalogues to perform the calculation.

What is Pinpoint LE?

Pinpoint LE is a Plate Solving program included in MaximDL. Various depths of star catalogues can be downloaded separately.

What is CCD Commander?

CCDC is an imaging automation program that can communicate and automate a range of other programs. In this case it is doing the hard work of automating MaximDL / Pinpoint and EQMOD. It is the main interface for Plate Solving where the tasks are set up and the results can be seen. It can also use a planetarium program for choosing targets, I use The Sky by Software Bisque.

What is EQMOD?

EQMOD is a alternative PC interface for various go-to mounts. It allows much more flexibility over standard PC/Mount interfaces. In this case I am using EQDIR to go directly into a Skywatcher EQ6.

How does it work?

All the user input is done within CCDC and The Sky. CCDC has an action list where you can drop in and configure different processes. I can go into The Sky and select an imaging target or alignment position. CCDC can then see this position and use it as a go-to action. After each go-to action I add and configure the “Plate Solve” action.

Then just hit play and away it goes. CCDC gives a comprehensive log of the action results, and from here you can see the calculation including position, arc seconds per pixel, and even the focal length of the imaging scope. After the Plate Solving is complete you can then add in a imaging action, and it will also automate all of your exposures. Now this is too easy.

Advantage number 1: forget about manual star alignment

If you are using your set-up just for imaging, do you have to use your eyes to look through a finder scope or have to replace your CCD camera to use an eyepiece then go through a star alignment procedure? The problem with this is that it is time consuming, frustrating and possibly inaccurate unless you have a very good understanding of your alignment stars.

With CCDC, pick 3 points in the sky where you want to do you alignment and it will take exposures at these 3 positions and perform the alignments with EQMOD automatically. Why are you cold, go and have a cup of tea.

Advantage number 2: forget about pointing and pointing accuracy

Although there is an advantage for pointing in terms of star alignment, if you have a permanent polar-aligned setup, what I have found is that you don’t need star alignment at all. When the Plate Solving is down to 1 or 2 mins to calculate a position, you can Plate Solve at every step of the imaging process.

I can switch on my mount, and just point it north in it’s standard starting position. From then I go to my first imaging target and then Plate Solve, and from there just Plate Solve on every target. The accuracy is incredible and it means I can be imaging in 10 minutes even with focusing included.

Advantage number 3: easy returning to targets

One of the things I have found hard when imaging is the framing of objects and especially returning to objects. Returning to objects with Plate Solving is really easy. When on a target you can Plate Solve in CCDC to record the position of the CCD, then just recall this position when you wish to return to it. It works really well and is very fast to use.

Combine this with an ASCOM instrument rotator and it would be a powerful weapon. This would add the CCD angle into the equation and allow the exact framing within CCDC and The Sky, making composing images and especially mosaics a breeze.

Sounds too good to be true, what’s the catch?

With my QHY8 and Equinox 80, it works great and is starting to make a huge difference to how I do things. I’ve only tried it a few times with my 8″ Newt, but it’s much much harder to get a result. I’ve yet to really have a good go at it, but I suspect it’s because of the smaller FOV and therefore bigger room for error. This might be something that is very hard to full off at longer focal lengths.


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