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Automatic Meridian Flip with NB Filters

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#1 kisstek

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Posted 24 June 2019 - 11:04 PM

I just started do automatic meridian flips using APT. They've all worked out so far but they also have all been LRGB images. I've had the plate solver using 5 second exposures and that's been working so far.

 

Last night, I tried doing the Eagle Nebula using my HSO filters. Since my HSO exposures need more time than my LRGB subs, I upped the plate solver exposure time to 10 seconds. Everything worked reasonably well right up to when it did the flip and then tried to recenter the Eagle Nebula using the plate solver with 10 second exposures. Unfortunately, it just happened to be on the S2 filter. A 10 second exposure thru the S2 filter is basically blank. ASPS wasn't able to solve the position, APT cancelled the plan. frown.gif I was able to switch to the L filter and do the plate solving, recalculate the number of remaining images, and restart things.

 

But that was at 1am and manually intervening in the flip kind of defeats the whole idea of an "automatic" meridian flip.

 

I could up the plate solving exposure time to 90-180 seconds. That probably would work no matter which filter happened to get selected. But that also wastes a bunch of time, especially if the L filter gets selected!

 

So is there a more elegant way to handle this kind of situation? I kind of wish APT allowed you to specify which filter to use when doing the plate solving exposures and then switch back to whatever is the next one in the plan. But I don't see anything like that.



#2 View2

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Posted 24 June 2019 - 11:21 PM

Plate solve with no filter if have wheel?

#3 kisstek

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Posted 24 June 2019 - 11:41 PM

Plate solve with no filter if have wheel?

APT uses whatever filter that happens to be the one to be used for the next exposure in the imaging plan. It's pretty much random chance as to which one happens to be up when the time for the flip arrives. And L would work every time if I could choose. But I don't get to choose. I may get a fast filter or I may get a really slow one. But the length of the exposure is fixed long before that random selection occurs.



#4 cfosterstars

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Posted 25 June 2019 - 03:03 AM

SGP allows you to set which filter to use for plateslove. I dont know about APT. I would look for that sort of option. 


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#5 kathyastro

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Posted 25 June 2019 - 05:16 AM

You might need to use SGP.  I tell it do do plate solving with the L filter, and all is good.


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#6 schmeah

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Posted 25 June 2019 - 05:54 AM

I would check with Ivo on the APT forum. I have a no flip mount so can’t help with this one, but I suspect if a script isn’t yet written for this, it probably can be fairly simply.

 

Derek



#7 kisstek

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Posted 25 June 2019 - 10:00 AM

OK, thanks. I'll check out SGP and NINA. I was putting that off, hoping I wouldn't have to learn a new piece of SW for a little while longer. But if I have, I have to.

 

But first I'll check in on the APT forum to see if I really have to.



#8 cfosterstars

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Posted 25 June 2019 - 03:58 PM

I have been using SGP for about three years now. There are lots of things I just dont even think about. Meridian flips and retargeting after one are two of them. I have never had a failure except for when there have been clouds. Platesolve, framing and mosaics wizard, auto centering and rotation, they just work with no hassle. A bunch of posters have complained about autofocus but I love it. Again, it just works. I never worry about focus. Even with multiple targets and even multiple OTA over a night. My biggest issue has been weather and the moon. Thats the way you want it to be.

 

APT was designed to be like BYEOS but with more features and better support. I tried it out, but it is just not as powerful as SGP. NINA and Voyager and the new kids on the block and have gotten a lot of press on CN. I have seen no compelling reason to switch. I tried a bunch of packages over the years and will probably stick with SGP unless there is some problem with support at some point.


Edited by cfosterstars, 25 June 2019 - 04:01 PM.

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#9 kisstek

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Posted 25 June 2019 - 06:26 PM

I have been using SGP for about three years now. There are lots of things I just dont even think about. Meridian flips and retargeting after one are two of them. I have never had a failure except for when there have been clouds. Platesolve, framing and mosaics wizard, auto centering and rotation, they just work with no hassle. A bunch of posters have complained about autofocus but I love it. Again, it just works. I never worry about focus. Even with multiple targets and even multiple OTA over a night. My biggest issue has been weather and the moon. Thats the way you want it to be.

 

APT was designed to be like BYEOS but with more features and better support. I tried it out, but it is just not as powerful as SGP. NINA and Voyager and the new kids on the block and have gotten a lot of press on CN. I have seen no compelling reason to switch. I tried a bunch of packages over the years and will probably stick with SGP unless there is some problem with support at some point.

I was going to try SGP once my new CEM60 arrives. Well, IF it arrives. But I'd like autofocus (APT's seems to be limited to refractors) and I wish my flips were more robust. But I'm going to have to bite the bullet as they say and try it sooner than originally planned.

 

Setting my plate solver exposure to 60 seconds last night did work. Still had to stay up to make sure though. Grumble, grumble.

 

But all of my O3 subs after the flip have donuts! Argh!! Ha and S2 are fine. So: in focus (Ha), out of focus (O3), in focus (S2), in focus (Ha), out of focus (O3), in focus (S2), ... Another "fun" puzzle to solve.



#10 schmeah

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Posted 25 June 2019 - 08:14 PM

Seems to me that you can script APT to plate solve using the luminance filter after plan finishes and you script a goto++ to another target. I’m going to try it tonight. You should be able to do the same thing after a flip.

 

Derek



#11 kisstek

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Posted 25 June 2019 - 08:50 PM

Seems to me that you can script APT to plate solve using the luminance filter after plan finishes and you script a goto++ to another target. I’m going to try it tonight. You should be able to do the same thing after a flip.

 

Derek

There's a "SolveGoto" command to invoke the plate solver. But for the script you're proposing, the first script needs to be sized so that it finishes right before the flip time, then run the flip and plate solver plane, and then finish the second half of the collection. If I'm understanding what you're proposing.

 

I'd find the sizing of the first half to be difficult. APT's estimate of completion times have proven very inaccurate for me. Running to long on the first half such that it either triggered an automatic flip or running into the hard stops on the mount would mess up the whole scheme.



#12 CharlesW

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Posted 25 June 2019 - 09:36 PM

If you bin 2x2 or 3x3 and use 10 second exposures you’ll see a lot more success if you have to do this with NB. But why not plate solve with L for all purposes and then switch back to NB? I assume your filters are reasonably parfocal but plate solving images can be quite out of focus and still work. 



#13 kisstek

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Posted 25 June 2019 - 10:12 PM

If you bin 2x2 or 3x3 and use 10 second exposures you’ll see a lot more success if you have to do this with NB. But why not plate solve with L for all purposes and then switch back to NB? I assume your filters are reasonably parfocal but plate solving images can be quite out of focus and still work. 

I do use L for the initial framing. But once the imaging plan begins, what filter is used during the plate solving for recentering after the meridian flip is out of my control.



#14 CharlesW

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Posted 25 June 2019 - 11:01 PM

You should get on APT’s support forum and ask for filter selection and binning as a feature request for plate solving. He must not be thinking along those lines yet. 


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#15 kisstek

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Posted 25 June 2019 - 11:54 PM

You should get on APT’s support forum and ask for filter selection and binning as a feature request for plate solving. He must not be thinking along those lines yet. 

Yup. And I just downloaded SGP so I can check it out too.




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