Plate solving didn't work after workflow change

Sequence Generator Plate Solving
1

Here’s my equipment and software:
Windows 7 Home Premium on a bootcamped macbook, SGP 2.2.9.2015, Licensed Pinpoint
Atik 314L+, Nautilus Filter Wheel, Stellarvue 80mm apo, CGEM mount

Here’s a link to my last log file: http://danshallenberger.com/sg_logfile_20140506211019.txt

Ok, this has always been my workflow when starting imagine:

  1. setup mount & telescope for visual and run 2+4 star alignment (CGEM), then polar alignment, then center on bright star for focusing camera
  2. install camera/filter wheel assembly and connect all cables
  3. start up stellarium scope, then stellarium
  4. start up SGP and connect camera, filter wheel and mount, then focus camera
  5. framing wizard to compose image, then Center Now in Target Settings

Plate solving has always just worked, and worked well. But not last night. My workflow above is what I always do, but since it was supposed to be clear several nights in a row, I thought I would bring in my OTA and gear, but leave the mount setup since it’s polar aligned. Then all I had to do last night was add the OTA and camera stuff and start.

So I added my OTA and camera gear, then connected everything to SGP, tried to plate solve and it kept failing over and over. I can’t remember the error message, but it said that it didn’t recognize the stars. It was the exact same setup I always use.

One thing that happened two nights ago… I did edit my equipment profiles last weekend, adding new ones and changing the names of the original because I got a new OTA, but I was using my original equipment profile for the last two nights. So when I opened SGP and the starting sequence came up, the fields that are normally pre-populated with my camera, filter wheel and mount were empty. I had to manually select them again. Then in the framing and mosaic the camera details were gone, like pixels and scale. Those were always pre-populated before I changed my profiles.

I closed and restarted SGP and then everything was in there, but now my plate solving won’t work.

Any ideas? I’m not sure what happened. I’ll try again tonight, but I’m not sure what to try.

2

I would double check your hint data (arcseconds/pixel and RA/Dec). Also if you have internet connectivity maybe do a blind solve which will pre-populate these values for you.

Thanks,
Jared

3

Thanks, Jared, for your quick reply. This is one of the top reasons I purchased SGP, plus it’s just plain awesome :smile:

Are you talking about blind solving after creating a sequence in Framing Wizard? I was going to, but the Solve and Blind Solve buttons in the Target Settings window are grayed out. The Location RA & DEC are populated with the location of the target I chose in the Framing Wizard, but everything is zeros in the Reference Data area.

If I remember correctly, the RA and DEC hints, as well as the Scale setting in the Target Settings window under Reference Data were populated once I chose a target with the framing wizard. Is this right? If so, now they are not. In the Target Settings window under Reference Data just says “Flickr, AstroBin or File” and the RA Hint, DEC hint and Scale all have zeros. I never had to do anything before except open SGP, select a target, create a sequence, go into Target Settings and click Center Now, and it worked.

Also, I wanted to test Pinpoint to make sure it was working and I clicked Browse within Target Settings to open a previous image from last week, clicked Solve and it worked.

It seems like everything changed when I edited my Equipment Profile and I’m not sure why. After that, different fields did not pre-populate. I’m considering uninstalling, downloading the latest version 2.3 and reinstalling to see if that works. I might even delete my equipment profiles and just start over again.

4

I think the reference data that you are getting from the target settings is just fine. What I’m recommending is a slight change to your workflow:

  1. setup mount & telescope for visual and run 2+4 star alignment (CGEM), then polar alignment, then center on bright star for focusing camera
  2. install camera/filter wheel assembly and connect all cables
  3. start up stellarium scope, then stellarium
  4. start up SGP and connect camera, filter wheel and mount, then focus camera
  5. framing wizard to compose image, then Center Now in Target Settings
    6) Blind solve and Sync scope to get correct pointing location OR sync to the star in step 1

If you’re a mobile observer this is even more important as you’re setting up and tearing down night after night. Essentially SGP needs your telescope to have a very accurate RA/Dec location or solves will fail. In addition to 6 above I would also recommend turning on the “Blind Solve Failover” option in the Plate Solve area of the Control Panel. When PinPoint fails this will invoke your blind solver (by default nova.astrometry.net, which DOES require an internet connection.)

I think your hint data was just off for your mount and your scope settings. I would start checking there. I would check these things:

  1. Verify that your mount has an accurate RA/Dec. Slew to a bright star and perform a sync on that star
  2. Verify that your arcseconds/pixel for your camera are correct in the Camera Control Panel
  3. Verify that your angle is correct in the Camera Control Panel (not really important for pinpoint)

Once you’ve done those things do a “Solve and Sync” and see if it’s successful. It hopefully should be. From there run Auto Center or whatnot and things should be good.

Thanks,
Jared

5

Again, thanks Jared for a quick and detailed response. It’s supposed to be clear (mostly) tonight so I’ll try what you suggest. Let me clarify a couple of things, though, to make sure I understand.

  1. Does it matter if the mount has an accurate pointing model? Last night, when I had the plate solving problems, I just turned on the mount and skipped through the CGEM alignment process, selecting Quick Align. That would mean that the mount itself would have no pointing model established, but I think that doesn’t matter when plate solving.

  2. I saw in a tutorial video a while back, I think Harry’s Shed, where he connected all his gear and then first did Solve and Sync in the Scope Centering module to establish where the telescope is pointing. Is that what you’re talking about in step 6 above? If the scope needs a pointing model before solving works, why would this work? I’ve never had to do that in the past, but every single time I’ve setup, I’ve always established a pointing model either by using AlignMaster to polar align or visual with celestron’s 2+4.

So if the mount needs to have at least a rudimentary pointing model established, pointing to a bright star and doing a quick sync will do that?

Thank you so much for your personal attention to helping me with this.

6

It’s extremely critical that the mount has an accurate pointing model when you’re attempting to plate solve “sky images”. So if you’re taking images with your camera and plate solving those (like Center Here or Auto Center) it’s very important that your mount knows where it’s at. Pinpoint and Elbrus can both only solve images within a few degrees of your RA/Dec hints. For camera images we get these hints from your mount. So if your mount is off then the hints for these images are off. These are NOT blind solvers, thus they need hints. So you need a pointing model that can get you within a degree of your target.

2) I saw in a tutorial video a while back, I think Harry's Shed, where he connected all his gear and then first did Solve and Sync in the Scope Centering module to establish where the telescope is pointing. Is that what you're talking about in step 6 above?

That’s correct.

If the scope needs a pointing model before solving works, why would this work?

Harry has a permanent setup. He likely has a very accurate pointing model that gets saved night after night. So when he starts up he’s ready to go. He already has a pointing model. But for those that don’t you can sync to a star and then plate solving camera frames should be good.

For solves you don’t have to have an accurate model really…you just need an accurate sync. However for slews and meridian flips you’ll want a decent model as a single star sync will only get you so far when you start slewing across the sky.

It will work for small slews. For larger slews, multi target imaging or multi night imaging you’re better off putting in the time to setup a 2+4 alignment. Or setup the blind solve failover and disregard most of this…provided you have internet connectivity or want to put in the time to setup and understand ANSVR.

Thanks,
Jared

7

I completely understand now. I didn’t know that the mount had to have a pointing model established for SGP to plate solve. It all makes sense though. And before this, I didn’t know the different between a camera solve and blind solve… now I get it. I went back and watched Harry’s video and it’s very clear.

So every time I power up my mount, I need to either create a pointing model (2+4 or a quick sync) or use blind solve to establish where it’s pointing. I assume when I do a blind solve in SGP, the results are sent to the mount. Otherwise SGP would know the mounts position, but the mount wouldn’t.

I don’t understand why it worked when I used AlignMaster to polar align. I never did a 2+4 then and plate solving worked. I assume that AlignMaster created at least a simple pointing model and sent it to my mount. In the future, if I leave my mount setup in my lawn for more than one day, I’ll leave power going to it to save the pointing model. Or just do it again. It doesn’t take long.

This wasn’t really even an SGP issue, but you helped me understand anyhow. So I think you very much for the detailed info and time you put into helping me. Much appreciated.

8

Yes to both. That’s why it’s Solve and SYNC. Any camera plate solve will also sync your mount.

I don’t understand why it worked when I used AlignMaster to polar align

With alignmaster you actually don’t want a model at all…and if you have one you’ll want to clear it. Alignmaster uses an iterative method to get you polar aligned. It assumes that your mount has a perfect model and thus any error is completely polar alignment. So if you have a model that is correcting your pointing then that will tend to fight alignmaster.

Glad to have helped get you on the right track!
Jared

9

Ok, I setup tonight and was able to get about one and a half hours of testing in before the clouds ruined the evening.

First, I did a full 2+4 alignment visually, then connected all my camera gear and opened SGP and plate solving worked immediately! Nice.

Second, I disconnected everything and cycled my CGEM, telling it to use Quick Align to make sure any pointing model was gone. I reconnected back to my computer and opened SGP and did a Blind Sync, and it worked perfectly. It updated the pointing model in my CGEM, updated Stellarium and regular plate solving worked perfectly.

The only issue I had was with centering, and this could be totally unrelated to SGP because it worked perfectly before tonight. When I clicked the Center Target button, before tonight it would do its thing and within 2 iterations, my target was within 5-6 pixels of centered. Tonight, it just would not get any closer than 30+/- pixels, even after three attempts. Once, the first run was 27 pixels, second 31 pixels and the third was 34 pixels. It got worse! I have no clue what’s going on. But 30 pixels I can live with until I resolve this.

Thanks yet again for all your help. Not only is it working now, but I understand the process a lot more clearly than before.

Have a good night.

10

Most likely backlash in the mount. I believe when you build a model this gets taken into account to some degree. So if this was after you cleared the model this is somewhat understandable.

Also, depending on what your pixel scale is, 30 pixels could be a little or a lot.

Glad you got it working!
Jared

11

One thing that can cause SGP not to centre an object is specifying it’s position using a different coordinate system to what the plate solver uses.

The plate solver uses J2000 so if the position is JNow this will be different. The current Celestron mounts use JNow positions but the sync should take care of this.

I found that I had to set a J2000 position for the target to get the image to centre correctly.

Chris

12

SGP doesn’t do any translation between coordinates. So for best results everything should communicate with the same coordinates. Be that JNow or J2000 or something entirely different. As long as everything (Plate solver, mount, planetarium if used) are set to the same then everything should be good.

And as Chris mentioned the plate solvers use J2000 by default.

Thanks,
Jared

13

I just wanted to add that after some experimentation, I figured out my issue with my mount being unable to slew to within 30 or so pixels during a Center action. I’m adding this in case someone else finds this thread and has the same problems, they will know what solved my issue.

I was trying to think of anything that had changed from now until back when my mount would easily solve to just a few pixels of being centered, and one thing that changed is that I upgraded my mount motor firmware to 6.50. So I downgraded back to 6.17 and the problem is now gone. When I perform a Center, it will end up within a few pixels of being perfectly centered. I have no clue why MC firmware 6.50 would create that problem, but it’s gone now.

Everything is working perfectly now and I’ve learned a LOT since starting this thread.