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APCC/A-P Mount Imagers - Read This

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#1 rockstarbill

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Posted 20 January 2019 - 02:45 AM

Hello Astro Friends,

 

Even if you are not a user of APCC, you should probably read this. Especially if you are interested in unguided imaging using Astro-Physics mounts. As an owner of both an A-P mount and a SB Paramount, one thing that is clear between the two brands, is that SkyX T-Point/ProTrack does a wonderful job of tracking correction that can allow for pretty good unguided imaging, and in the past APCC and its model mapper APPM were okay at it, but for anything in the 5 minute range, you would likely not appreciate the result. That feedback has been given to the dev for APCC/APPM by many folks, and that dev recently spent some time reworking the APPM logic entirely. Recently a new Beta of APCC was released that had a completely reworked APPM. When I was informed of this, I was quite excited to give it a spin. After all, getting rid of guiding for modest exposure times is something I am keenly interested in. 

 

So, I installed the new software. For users of automation that allows for scripting (like Voyager, for example) he also nicely added the -auto switch to the APPM executable. This allows you to call APPM from your scripts and have it automatically run your pointing model for you, load it into APCC, and enable it. grin.gif  Super cool!

 

Anyhow, here are the notes I took while imaging (that were also provided to the dev, verbatim):

 

  • The new -auto feature works perfectly. The model ran automatically and loaded it into APCC to digest, and the model was automatically enabled. Awesome.
  • The -auto feature did leave APPM running. While not a problem for me, perhaps putting in a switch to close it after APCC consumes the model would be useful? Small tiny detail though. smile.gif
  • The model worked very well. I was able to do 5 minute HA unguided exposures with a fresh PEMPro curve I recorded the previous night. I was imaging at at 1.42"/px using the AP130 GTX, GTX Field Flattener and FLI ML16200 camera. In the past I was not able to unguided image with APPM for 5 minutes. My seeing that night was horrid as well at about 5" (yuck!) and I was shooting in the direction of the moon. In better conditions I should be able to get longer images with nice round stars. I tried 10 mins, and things slightly started getting a bit oval on me.
  • I never used the Open Weather Map Free API before, so I decided to set this up in APCC so I could have something a bit more accurate than me just plugging in a temp, this worked perfectly all night long.
  • I did have one motor stall condition occur, but I do not think it was related to a problem with either APCC or the V2 driver. I immediately went outside and there was nothing happening in terms of cable snags or any blockage of the mount. It was running on 14.1V AC power at the time. It only happened one time, and the rest of the night ran without issue.

Here is a sample frame from the night (Monkey Head Nebula):

 

https://1drv.ms/f/s!...keUsC6for3IcNRA

 

And here are some metrics from the tools I use to evaluate data frames:

 

CCDI_APPM.png

 

FWHME_APPM.png

 

As I mentioned in the feedback, my seeing was not good, I was imaging pointing in the direction of the moon, and the results were still much better than past attempts with APPM vs ProTrack and T-Point. If you are an A-P mount user and want to try your hand at some unguided imaging, I strongly suggest giving the new APCC Pro (Pro is required to use the APPM software and to load that into APCC) a try. It worked exceptionally well, even in bad conditions. I plan to test this again once it clears up around these parts, but I am very optimistic that unguided imaging with APCC Pro and A-P mounts is something quite possible now, and will hopefully continue to improve in the future.


Edited by rockstarbill, 20 January 2019 - 02:48 AM.

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#2 rockstarbill

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Posted 20 January 2019 - 04:37 AM

For those interested in my mention of a PEC Curve here is the before and after.

 

The data acquisition for the curve itself was 10 worm cycles long:

 

1_PEC_New_Before.JPG

 

The validation run was 5 worm cycles long:

 

1_PEC_New_After.JPG

 

PEMPro played a huge part in this, but PEC does play a role in T-Point/ProTrack as well. 

 

Just wanted to be full on open kimono on the variables here. The results were fantastic.

 

Thanks Ray!



#3 lucam

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Posted 20 January 2019 - 09:53 PM

Bill, thanks for the report on the new APCC beta. I have installed it but I have still not played with model building and unguided imaging with my Mach1. Cloudless nights are at such a premium that I find it hard to give up imaging time to improving the set up, shortsighted as it may be. 

 

I was wondering if you have any tips to share to achieve such a perfect PEC curve. I have run PEM Pro (the latest beta) a few nights ago under average seeing conditions (probably around 3 arc-sec FWHM) and the curve was pretty close to the factory one but certainly not better than +/-1 arc-sec. I followed Roland's suggestions in how to run the PEC analysis in PEM Pro. 

 

Also, in the pointing model, how many images did you acquire? 

 

Thanks,

 

--Luca


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#4 rockstarbill

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Posted 20 January 2019 - 10:27 PM

Bill, thanks for the report on the new APCC beta. I have installed it but I have still not played with model building and unguided imaging with my Mach1. Cloudless nights are at such a premium that I find it hard to give up imaging time to improving the set up, shortsighted as it may be. 

 

I was wondering if you have any tips to share to achieve such a perfect PEC curve. I have run PEM Pro (the latest beta) a few nights ago under average seeing conditions (probably around 3 arc-sec FWHM) and the curve was pretty close to the factory one but certainly not better than +/-1 arc-sec. I followed Roland's suggestions in how to run the PEC analysis in PEM Pro. 

 

Also, in the pointing model, how many images did you acquire? 

 

Thanks,

 

--Luca

The Mach1 in my experience doesnt correct as well as the 1100 does. Why that is, I dont know. Whether that is actually true or not, I also do not know. In the Mach 1 data sets I have looked at for PEMPro, the 1100 seems to correct better. I use Roland's guidance for working with PEMPro, so you and I are doing the same thing. I do work to get my PA as close as possible before I run my PEMPro, and due to trees I have to adjust the DEC to +20 degrees, rather than recording at 0 DEC. Ray has confirmed that this change is perfectly fine. The data  I posted shows that as well.

 

For my pointing model, again due to trees, I have a very limited portion of the sky to operate within, but I use 80 points for the model, 3-4 of which I will lose due to a tree on the West run. 

 

Quick edit: 

 

When you are acquiring data with PEMPro, turn off the drift correction and look at the lines. If they are not within +/-1-2" of each other (and are more like 5" in difference or something egregious like that) you should stop gathering data and work to better your alignment. This run I showed here was aligned using PEMPro (and not SharpCap or Polemaster, which IMO are way inferior methods to use for this purpose, and moreso worse for any use case at all) and the Alt was 8 arc-seconds, and Az was 10 arc-seconds. 


Edited by rockstarbill, 20 January 2019 - 10:55 PM.

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#5 rockstarbill

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Posted 23 January 2019 - 04:25 AM

I pointed Roland to this thread, and he had some pretty cool insight. While I am not likely to run off and buy encoders (not because they arent good, I just have to budget accordingly) he did give some pretty cool insight as to why they can add something to the mix here that is useful, EVEN if you have a well-corrected mount in terms of PE:

 

In the case of a non-encoder mount, you are relying on the accuracy of the worm wheel to produce a very precise sidereal drive rate. Even though the periodic errors of the worm gear can be eliminated below 1 arc sec with PEMPro, there are still non-zero errors on the worm wheel teeth so that the exact drive rate can vary just a tiny amount from one tooth to the next. During a 20 minute exposure the worm gear rotates approximately 3 times and thus contacts 3 worm wheel teeth during that time period. ......

It is worth saying that he thinks my stated goal of hitting the 10 min unguided mark is likely doable with what I have on hand, I still found this to be a pretty cool explanation of what those encoders actually get you from a lower level perspective. More gold from this guy, which he seems to pump out daily at this point. Really helps me understand things better, and I hope it helps some other people as well.


Edited by nmoushon, 24 January 2019 - 04:31 PM.

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#6 dhaval

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Posted 23 January 2019 - 11:15 AM

This is nice and thanks for doing this! I will look to install the new APCC beta when I am out at the remote observatory next time. This surely sounds exciting though - especially if you have a CMOS or very low read noise camera - if you can go 10 minutes unguided at around 1"/px image scale, that would be awesome. 

 

CS! 



#7 rockstarbill

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Posted 24 January 2019 - 01:50 AM

This is nice and thanks for doing this! I will look to install the new APCC beta when I am out at the remote observatory next time. This surely sounds exciting though - especially if you have a CMOS or very low read noise camera - if you can go 10 minutes unguided at around 1"/px image scale, that would be awesome. 

 

CS! 

While I dont know why this would be especially interesting for CMOS people, I am pleased to see that others are giving it a try.

 

The sample image file I posted was from a CCD camera with ~6.6e- noise and was a 5 minute exposure in HA.


Edited by rockstarbill, 24 January 2019 - 01:51 AM.


#8 dhaval

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Posted 24 January 2019 - 11:29 AM

While I dont know why this would be especially interesting for CMOS people, I am pleased to see that others are giving it a try.

 

The sample image file I posted was from a CCD camera with ~6.6e- noise and was a 5 minute exposure in HA.

What I meant was, any camera that has exceptionally low read noise - that way you can clear the noise floor and swamp it with signal really fast making unguided imaging a pleasure! 

 

To be clear, I am not a big fan of CMOS cameras, but they do have low read noise, but so do the 814 chip cameras (and those are CCDs, which is what I would go with anyday over a CMOS camera, at least the 1600MM-C one or its equivalent QHY version). 

 

CS!



#9 FiremanDan

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Posted 24 January 2019 - 01:22 PM

Good info. If we ever have a 24-hour span without rain, I'll have to download the new APCC. I'll also need to find the $400 or so to pay for it. 
I just looked outside, I just saw drug dealer doing the backstroke across the street. So it won't be today. 

But seriously I can't wait for this rain to stop (haven't set up since late Sep) so I can take up on that offer to help me dial in pempro! 


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#10 rockstarbill

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Posted 24 January 2019 - 04:48 PM

What I meant was, any camera that has exceptionally low read noise - that way you can clear the noise floor and swamp it with signal really fast making unguided imaging a pleasure!

To be clear, I am not a big fan of CMOS cameras, but they do have low read noise, but so do the 814 chip cameras (and those are CCDs, which is what I would go with anyday over a CMOS camera, at least the 1600MM-C one or its equivalent QHY version).

CS!


Okay that makes sense. Yes unguided imaging with a CMOS camera should be very doable with this change to APPM. The 814 and 834 sensors are great. The 834 has crazy low noise in addition to the exceptional QE the Sony sensors have. Unguided imaging with those sensors should be easy.

#11 rockstarbill

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Posted 26 January 2019 - 09:23 AM

QSI6120 and a 10" F4 Newt. 5 minutes unguided Lum frame with APPM.

https://1drv.ms/f/s!...mgQrDJVONjrBtMg

Pixel scale is 0.56"/px. Sky conditions were soupy and horrid. 70% moon opposite to the position of the telescope.

Still pretty darn good.

#12 rockstarbill

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Posted 31 January 2019 - 11:05 PM

Another update. Ray fixed some bugs in the APPM Beta and was kind enough to pass along the freshest build of the software. 

 

https://www.astrobin.../full/388591/0/

 

Here is a few hours of L data with the 10" Newt and 6120 unguided. These were short exposures of only 60 seconds, although I do have some 2 min frames that look good as well. At any rate, APPM seems to be working very well. I had to fix some issues with my Newt today, and plan to do some more testing with more aggressive exposure times once I get more clear skies.




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