Astro-Physics mount Meridian Delay and Robostar

Voyager
1

Hi Leo,

I believe I have setup Voyager settings correctly to get ready to image very soon. I have tested indoors in my house and things appear to work pretty well.

I know you have an A-P Mach1 and I was wondering if you ever use Meridian Delay feature either with ASCOM driver or Keypad? Anyway, my first target to image is NGC 7479 which is also known as (AKA) Superman Galaxy. The nearest star for Robofocus is Markab which is very close to NGC 7479. Initially I set the Meridian Delay to default of “0” in A-P V2 ASCOM driver. I started Voyager and connected all necessary devices successfully. Then from “On-the-Fly” window, I initiated a GoTo to NGC 7479 and the mount slewed successfully to the target. Then from the “Setup” window and from “AutoFocus” tab of this window, I clicked on “Point Closest Focus Star with RoboStar” button and it very quickly slewed to Markab star so it appears to be working very well.

Then I repeated this test by setting Meridian Delay of A-P V2 ASCOM driver to “6” so that the first slew to target object (NGC 7479 in this case), the scope would slew under the mount and I was able to do that successfully. Next was to select “Point Closest Focus Star with RoboStar” from “Setup” window, it took a really long time for Voyager to properly find the nearest RoboStar and when it finally finished calculating, it slewed to an unknown star at other side of the Meridian which was pretty far from target object.

My goal is to image NGC 7479 using Meridian Delay of “6” meaning the scope starts under the mount so that when the imaging session is finished, the scope will be above the mount and I am trying to avoid Meridian Flipping during imaging session and use RoboStar for auto focusing during the sequence. It seems that Voyager may be a little confused about Astro-Physics Meridian Delay feature when the scope is currently under the mount.

Have you every tried what I am trying and would it work? If you are not sure what I am trying to do, please feel free to ask.

Thank you,
Peter

2

Hello Peter,

i developed the AP delay 10 year ago … so the driver was not so much stable … i used a couple of time but i prefer to manage meridian because is easy and fast and more safe (my second AP mount not have Keypad).

Anyway delay is for meridian … calculating star for RoboStar (developed years after) probably is not a best solution. You can solve using LocalField that doesn’t need star pointing calculation.

The first time i have a clear sky i’ll investigate on interactions of AP delay and RoboStar, probably RoboStar see real coords and manage pier side (you can force mount like equatorial this remove pier side calculation in RoboStar but also meridian management, sure if you put 6 hours delay this is not a problem).

Also you can solve not using RoboStar but putting one Focus Star in Sequence choosed near the object this generate a simple goto without investigating on distance and pier side.

All the best
LO

3

Hi Leo,

Thanks for the prompt response. I kind of expected what you were going to say. I will try “one star Focus Star” and that sounds like it should work.

Do I have to run VCurve First Light Wizard for LocalField?

Thank you,
Peter

4

For LocalField is better to do first light wizard or you must calculate yourself the value of “Focuser step for sample” field. this value is usually equivalent at steps necessary to increase HFD of 2 point in linear zone of focus curve(so out of focus). Isn’t easy but can you do some trial/error cycle if you dont want to use first light wizard.

But due to the fact you asked initial for RoboStar focus i think you’ve already done this task. First light wizard needed only one time and work for Robostar and LocalField focus.

All the best
LO

5

Sounds good to me.

Thanks,
Peter