Plate solve before slewing to first target

Sequence Generator Plate Solving
1

There must be an easy way to do this, but I cannot figure it out and found no threads on the topic.

I want to plate solve before slewing to the first target.

Desired workflow:
0. Start SGP

  1. Run sequence
  2. Sequence opens dome, cools camera, etc.
  3. Sequence initiates a “Plate solve & sync”. >> From one day to the next, sometimes my mount controller SiTech II loses the scope’s position. It may not have been parked correctly, or the controller was turned off, or … Before starting SGP, the scope is always positioned so as to be looking at the (closed) dome’s slit, but its precise position may be unknown.<<
  4. Only then does the sequence slew to the first target.

I know I can plate solve manually before starting the sequence.
Is there any way to have this plate solve as the first step of the sequence. This would allow one to launch the sequence with a delayed start and not have to worry about the scope’s initial position not being sync’ed properly?

Kris

2

I think what you are after is called a “blind solve and sync”. Most use this as the plate solver backup and, in cases where the mount loses its exact position the sequence automation resembles:

  • Start
  • Slew
  • Focus
  • Center on first target
    • Plate solve fails
    • Backup “blind solver” invoked
    • Success and sync mount position
    • Continue
  • Sequence stuff…

We do not currently provide an option that prevents the first solve from failing and just always running the blind solver (though it’s a reasonable idea). I have added it to the backlog

3

[The idea of invoking the blind solver off the bat is a good one, but that is not my main concern.
I can live with a failed plate solve followed by a backup blind solve.]

What I want to avoid is the first SLEW before the plate solve, as I am not always sure that SiTech has the correct RA/DEC before it slews.

I need SGP to open the dome, (focus – though not important), start tracking, plate solve (if necessary with backup blind solve), and only then SLEW to first target.

4

Currently, SGPro does not offer a “sync mount before start” option, but I can add this to the feature backlog too.

Do you mean, in terms of safety… like the mount’s notion of its current location is WAY off?

5

That is correct. It is a safety concern.

Occasionally the mount controller (SiTech II) does not know where the scope is pointed.
It appears to lose the parking position information. This can happen when there is an abnormal SGP termination. Or it occurs due to an operator error (me). I want the plate-solve before-SGP-slews-to-first-target to re-initialize the scope’s starting position.

Without this, the slew may snag cables or point toward the floor, or …

6

To be clear: During a sequence, SiTech does not lose position information.
In fact the sequences execute flawlessly once I run the initial plate solve (manually). And yes, I usually run it “blind”.

7

We would need to think about this… it will require a little thought adding an option into the sequence, that without (possible) manual intervention before starting the sequence, might cause failure. Using this option requires that the mount be pointed at the sky manually before running the sequence. The slew before solving is typically required in order to move the scope from the park position to a position where it has a view of the sky (not necessarily the target).

8

Thanks for your replies.

I will also ask the SiTech forum if there is an easy way to set the mount’s park position manually to some (approximate) Alt/Az coordinates.

9

I think I can close this discussion.

In summary, for future reference:

  • At this point in time, there is no option in SGP to do an automatic (blind or otherwise) plate-solve before slewing to first target. Ken is putting this feature on the backlog list of future enhancements.
  • One can, of course, start SGP, connect equipment, open observatory, (blind) plate solve manually and only then start the sequence. This is the safest option.
  • There is no easy way in SiTech II either, e.g., to set Alt/Az of mount manually. If the mount has lost the park position: One can return the mount to a marked point on the inside of the observatory, which roughly represents the park position (i.e., by jogging in SiTech software or via hand controller), before starting the imaging session. There is a small risk in my case that the mount has slipped (mine is a friction drive) and that SiTech therefore has the wrong Alt/Az information, and/or side of pier; or that the park position is otherwise messed up. If the mount has not slipped and SiTech was not turned off, I can start sequence without an initial (parking position) plate solve in SGP. Advice to self: When in doubt about the state of the mount’s park position, plate solve manually in SGP before starting the sequence.