Rotator can't seem to zero in on the correct position

Sequence Generator Plate Solving
1

Not sure if this fits under the Plate Solving thread but since the rotator is used in conjunction with the Plate solve I thought this might be the best place to post.

Last night, running SGP 2.5.0.12 I had the “Rotate camera to:” set for 270.0. SGP attempted to plate solve rotate the camera 10 times as follows:targeted Allowable error for the center is set to 75 pixs and rotator target is 270 degress +/-3
Attempt #1:
7:24:57 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 327.07 degrees…
7:24:57 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 327.07; Reported pos rotator position: 331.43
7:24:57 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:24:57 PM] [DEBUG] [Center Scope Thread] Retrying auto center. Total Error > Allowable error: 128.8 > 75.0
7:24:57 PM] [DEBUG] [Center Scope Thread] RA Error: 118.9
7:24:57 PM] [DEBUG] [Center Scope Thread] DEC Error: -49.4
7:24:57 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 270 ± 3

Attempt #2
7:25:25 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 24 degrees…
7:25:25 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 24.00; Reported pos rotator position: 274.36
25:25 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:25:26 PM] [DEBUG] [Center Scope Thread] Retrying auto center. Total Error > Allowable error: 89.0 > 75.0
7:25:26 PM] [DEBUG] [Center Scope Thread] RA Error: 86.9
7:25:26 PM] [DEBUG] [Center Scope Thread] DEC Error: -19.2
7:25:26 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 90 ± 3

Attempt #3
7::25:55 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 318.09 degrees…
7:25:55 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 318.09; Reported pos rotator position: 340.36
7:25:55 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:25:55 PM] [DEBUG] [Center Scope Thread] Retrying auto center. Total Error > Allowable error: 145.6 > 75.0
7:25:55 PM] [DEBUG] [Center Scope Thread] RA Error: 99.0
7:25:55 PM] [DEBUG] [Center Scope Thread] DEC Error: -106.7
7:25:55 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 270 ± 3

Attempt #4
7:26:22 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 6.14 degrees…
7:26:22 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 6.14; Reported pos rotator position: 292.30
7:26:22 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:26:22 PM] [DEBUG] [Center Scope Thread] Automatic Auto Center Success - Total Error <= Allowable error: 68.1 <= 75.0 (Passed Allowable Error after this 4th attempt)
7:26:22 PM] [DEBUG] [Center Scope Thread] RA Error: 59.6
7:26:22 PM] [DEBUG] [Center Scope Thread] DEC Error: -32.9
7:26:22 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 90 ± 3

Attempt #5 (Now it’s just trying to get the rotator to within 3 degrees)
7:26:53 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 294.72 degrees…
7:26:53 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 294.72; Reported pos rotator position: 3.82 (Almost made it)
7:26:53 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:26:53 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 270 ± 3

Attempt #6 (Something seem to have gone wrong here)
7:27:05 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 319.43 degrees…
7:27:05 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 319.43; Reported pos rotator position: 339.07
7:27:05 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:27:05 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 270 ±3

Attempt #7 (now reported rotator error is 8.84 degrees)
7:27:20 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 8.84 degrees…
7:27:20 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 8.84; Reported pos rotator position: 289.64
7:27:20 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:27:20 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 90 ± 3

Attempt #8 (now reported rotator error is 10.77 degrees)
7:27:39 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 287.65 degrees…
7:27:39 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 287.65; Reported pos rotator position: 10.77
7:27:39 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:27:39 PM] [DEBUG] [Center Scope Thread] Retrying rotator. Total Error > Allowable error: 270 ± 3

Attempt #9
7:27:51 PM] [DEBUG] [Telescope Thread] Syncing the rotator to 305.33 degrees…
7:27:51 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync complete. Camera angle is 305.33; Reported pos rotator position: 353.11
7:27:51 PM] [DEBUG] [Telescope Thread] Auto center complete…
7:27:51 PM] [DEBUG] [Center Scope Thread] Unable to achieve results below allowable error (75 px) in 10 attempts!

Now it failed after 9 attempts but states 10 attempts. and somereason it requested the rotator to move to 270
7:27:58 PM] [DEBUG] [Telescope Thread] Center telescope message received…
7:27:58 PM] [DEBUG] [Telescope Thread] Solving with Plate Solver PlateSolve2…
7:27:59 PM] [DEBUG] [Center Scope Thread] Error in auto center update thread, Thread was being aborted.
7:27:59 PM] [DEBUG] [Telescope Thread] Skipping step 2, have previous sync from last Validate frame
7:27:59 PM] [DEBUG] [Telescope Thread] Performing auto center step 3 (rotator)…
7:27:59 PM] [DEBUG] [Telescope Thread] Moving rotator to 270.0…
7:27:59 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Moving rotator to 270
7:27:59 PM] [DEBUG] [Telescope Thread] ASCOM Rotator: Sync offset is -47.78366

then it went into the recovery and SGP locked up. I had to Control-Alt-Delete it.

Here’s the log
sg_logfile_20160220192005.txt (505.5 KB)

After I restarted SGP I unchecked “Rotate camera to” before starting the sequence and everything ran fine for the remainder of the night.

Mark

2

Mark,

Thanks for the detailed logs… unfortunately it is not possible for me to understand what is going on… there is too much of the story missing. In order to troubleshoot effectively, we will need:

  • SGPro logs
  • ASCOM rotator logs
  • Before / After images (an image of before rotation and then one after the camera rotation completes)

The problem is either:

  • A bug in SGPro (lots of other folks use real rotators in SGPro so this is less likely, but not impossible)
  • A weird bug in the angle calculation of image angle in PS2
  • A bug in the ASCOM rotator driver
  • A physical / mechanical issue like clutch slip or the camera not being tightly coupled to the rotator

Without those three things, we can’t really tell.

3

Hi Ken,

Thanks for the feedback. This is only the 3rd time using the rotator, so it could possibly be something I’m doing wrong. However I did check all of the mechanical things making sure everything was tight and no chance of cables getting caught up, so I don’t think that was it. I’ll see if I can try and find the information you requested.

You did mention about wanting the SGPro log files. I attached what I thought was the SGPro log files in my first report. was that not the correct log file? as for the other files I’m going to need help locating them. I looked for them on my system but no luck.

If anyone can help, I’m going to need a little help locating the files Ken is asking me for:

  1. ASCOM rotator logs - The rotator is the Optec Pyxis. I looked on my system but I can not find the log files. Any idea on where they might be stored? Do I need to turn on logging first and if so how do I do that?
  2. Before/after images - image before rotation and after rotation, where are those stored?

I’m guessing I’ll need to change some settings, maybe turning logging on, and do another imaging session to get the information needed?

Thanks,
Mark

4

Yep, that one was just fine. I will often summarize stuff for the benefit of others reading posts later.

They probably do not exists. Take a look through your rotator ASCOM driver’s settings dialog. There will probably be an option to turn the “trace” logs on. If you still can’t find them send the driver’s author a quick question about it… hopefully they can direct you to the log location.

They are not stored. Before you invoke an operation with rotation, right click the image and save it off (before). After the rotation option is complete (step 4), abort the centering and rotation process and then do the same for the new image on the screen (after). This will allow us to test more thoroughly with the plate solver you are dependent upon for accurate rotation.

Yes, but hopefully all you need to do is turn rotation back on for the target, right click the target and select “Center and Rotate”.

5

Thanks Ken for the help. I’ll get things ready so when the next clear night arrives I’ll be able to gather up the information and send it.

Mark

6

I have the same issue with my Pyxis Rotator. Here’s a video of the behavior. Rotator cycling - YouTube You can see from Platesolve2 the rotation error is changing but never getting close enough to solve.

7

Is there some sort of calibration process you can do with that rotator? Seems like the angle is quite a ways off.

Thanks,
Jared

8

Ok, this may be a bit of a necrobump because the original post was from 2016, but I had this problem too. If you are using a refractor the image may be reversed on the chip, causing the rotator to rotate in the exact opposite direction of where it needs to go, causing it to flip flop back and forth.

I clicked “reverse rotation direction” in the ascom driver to fix this, but I don’t know if this will solve your problem.

image

The other thing I did was plate solve in SGP to identify the actual rotation angle of the camera. Once I got that, I disconnected the rotator from SGP, launched my rotator’s software (Nitecrawler in my case) and changed the angle the rotator itself thought it had to the actual rotation of the camera. The advantage of doing this is that SGP and your rotator will be in sinc, preventing an erroneous initial rotation after you first connect the rotator for a night’s imaging.

Now every time SGP rotates my camera it is within 0.1 on the first try, and no longer flops back and forth.

9

There is a way to set the Sky Position Angle in the Pyxis Commander app. I had done this per the manual for the rotator by doing a Frame & Focus, then doing a plate solve to see what the Position Angle is. Then, you set the PA in the app.

I hadn’t considered the rotation direction to be reversed. I’ll give that a shot. Thanks for the suggestion.

Dave
Thunder Creek Observatory

10

You may have to dork around with the software to figure out how to manually set the rotation angle and have it be “sticky”. It is easy in the nightcrawler software, but it still took me a while to figure out how to do it properly. This step is ancillary, however- The key thing is getting the rotation direction correct.

I had a long evening of frustration watching my rotator go back and forth until I got that sorted.

Part of this hobby that I absolutely love is that every time you solve a problem you get to do your victory dance, then figure out where the next problem is.

1 Like
11

I actually just fixed this about 10 minutes ago…so there’s that :slight_smile: however rather than resulting in an invalid rotation it will result in a failed rotation in auto center which will require an additional iteration of the auto center to fix rotation…but if you have a NiteCrawler, this will likely save you a substantial amount of time.

Thanks,
Jared

12

Also a good way to check rotation direction. If you increase the angle, SGP expects that the camera should be moving clockwise. If it’s moving counter-clockwise then you should reverse it.

Jared

13

Which way is clockwise? Not to be cute but which way do you mean relative to the camera? Looking at the back of the camera looking toward the sky or looking at the front of the camera with the sky at your back?

14

From my experience, clockwise is looking at the back of camera looking towards the sky.

15

Sorry, yes, that was ambiguous. Looking at the back of the camera (towards the sky), it should rotate clockwise.

Thanks,
Jared

16

Reversing rotation direction in the Pyxis commander app’s settings solved it. Confirmed that it was backwards from the folks at Optec too. Thanks all! No more need for Manual Rotator.

Dave
Thunder Creek Observatory