Date   

Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

 

That will work for model building, but you need the current temperature as you are imaging, so you really need a way where the temperature is updated on a consistent basis.

the modeling adjusts based on temp at time of modeling and current temp when imaging

On Tue, Aug 18, 2020 at 8:56 PM Joseph Beyer <jcbeyer2001@...> wrote:
I don't own an environmental sensor that interfaces directly with my computer but I manually enter current temperature and barometric pressure from my backyard weather station into the APCC-Pro Pointing Model tab when I run a model.  The data is pulled through to APPM and I assume used in the calculation of the pointing and tracking model.  Is this assumption correct?

On Tue, Aug 18, 2020 at 7:16 PM Bill Long <bill@...> wrote:
Per my chat with Ray, having accurate temperature data is THE most important thing. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Tuesday, August 18, 2020 6:47 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC
 
HI Marcelo

Temperature does have some impact on the modeling (talking with Ray on this) so you might consider having an environmental sensor in there like an MGBox V2

On Tue, Aug 18, 2020 at 6:17 PM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
OK, thank you very much. Good to know. :)
 
My telescope is an Esprit 100, so I guess I don't need an atmospheric pressure detector at the moment.



--
Brian 



Brian Valente



--
Brian 



Brian Valente


Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

Bill Long
 

Correct. That method should work fine. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Joseph Beyer <jcbeyer2001@...>
Sent: Tuesday, August 18, 2020 8:55 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC
 
I don't own an environmental sensor that interfaces directly with my computer but I manually enter current temperature and barometric pressure from my backyard weather station into the APCC-Pro Pointing Model tab when I run a model.  The data is pulled through to APPM and I assume used in the calculation of the pointing and tracking model.  Is this assumption correct?

On Tue, Aug 18, 2020 at 7:16 PM Bill Long <bill@...> wrote:
Per my chat with Ray, having accurate temperature data is THE most important thing. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Tuesday, August 18, 2020 6:47 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC
 
HI Marcelo

Temperature does have some impact on the modeling (talking with Ray on this) so you might consider having an environmental sensor in there like an MGBox V2

On Tue, Aug 18, 2020 at 6:17 PM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
OK, thank you very much. Good to know. :)
 
My telescope is an Esprit 100, so I guess I don't need an atmospheric pressure detector at the moment.



--
Brian 



Brian Valente


Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

Joseph Beyer
 

I don't own an environmental sensor that interfaces directly with my computer but I manually enter current temperature and barometric pressure from my backyard weather station into the APCC-Pro Pointing Model tab when I run a model.  The data is pulled through to APPM and I assume used in the calculation of the pointing and tracking model.  Is this assumption correct?

On Tue, Aug 18, 2020 at 7:16 PM Bill Long <bill@...> wrote:
Per my chat with Ray, having accurate temperature data is THE most important thing. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Tuesday, August 18, 2020 6:47 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC
 
HI Marcelo

Temperature does have some impact on the modeling (talking with Ray on this) so you might consider having an environmental sensor in there like an MGBox V2

On Tue, Aug 18, 2020 at 6:17 PM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
OK, thank you very much. Good to know. :)
 
My telescope is an Esprit 100, so I guess I don't need an atmospheric pressure detector at the moment.



--
Brian 



Brian Valente


Re: APPM and color cameras #APCC

Worsel
 

Dean

I am unclear on what you mean "no one has tried it yet"...do you mean no one has tried an IMX571 or no one has tried an APS-C sensor.  The latter is yes, it has been tried and works as far as APPM modelling.

Bryan


Re: APCC Pro Modeling and side by side setup.

Keith Olsen
 

Great,  thanks Bryan!


Re: APPM and color cameras #APCC

Dean Jacobsen
 

Thanks Bryan, that is encouraging information. 

Yes, perhaps no one here has tried it yet.  
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: APPM and color cameras #APCC

Roland Christen
 

Maybe nobody knows?

Rolando



-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 8:51 pm
Subject: Re: [ap-gto] APPM and color cameras #APCC

No responses so I guess it must have been a dumb question.  :-)
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

Bill Long
 

Per my chat with Ray, having accurate temperature data is THE most important thing. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Tuesday, August 18, 2020 6:47 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC
 
HI Marcelo

Temperature does have some impact on the modeling (talking with Ray on this) so you might consider having an environmental sensor in there like an MGBox V2

On Tue, Aug 18, 2020 at 6:17 PM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
OK, thank you very much. Good to know. :)
 
My telescope is an Esprit 100, so I guess I don't need an atmospheric pressure detector at the moment.



--
Brian 



Brian Valente


Re: APPM and color cameras #APCC

Worsel
 

Dean

Give us a little more time than 7 hours...

I use a Canon DSLR to build models...no problem at all.

Bryan


Re: APCC Pro Modeling and side by side setup.

Worsel
 

Keith

On the Pointing Model tab of APPC Pro, click Model (far left).

The model that is presently loaded will by shown in the title bar of the window.  To load a new model, click File->Load Model.  All the models you have generated in the past will be listed.

Models have an extension of PNT and include the year, month, day, and START time of APPM generation run.  If it was a Verify model, the name will include Verify.

All you need to do is keep track of the filename given to each each model when generated and you can switch between them.

Bryan


Re: Exposure comparisons with CCD cameras

Benoit Schillings
 

Median combined can be an issue for very slight background variation.
How confident are you of the software auto-scaling... I would do a
simple mean for the comparaison, even if you end up with a few hot
pixels

-- benoit

On Tue, Aug 18, 2020 at 6:07 PM W Hilmo <y.groups@hilmo.net> wrote:

“I'm not shooting RGB, I'm shooting NB where the 10 min object signal is at 700 or so out of 65,000.”



I realize that you weren’t shooting RGB, and I know that you can’t do a single 60 minute broad band exposure without saturating the sensor. I am saying that if you were shooting RGB (and if the sensor had sufficient well depth to deal with that), I would expect the two results to be closer to each other. The reason for that is that that the dominant noise would be shot noise from a much higher signal in the background sky. Since you are shooting narrow band, both the signal and shot noise are very small. That makes the read noise relatively more significant.



In terms of S/N, the difference between 1x3600 seconds and 6x600 seconds is the read noise of the camera. You may also be giving up something by using median combine instead of a combination of statistical rejection and mean combine – but the specifics of that are less clear to me.



From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@aol.com> via groups.io
Sent: Tuesday, August 18, 2020 2:53 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras





If you were shooting RGB, or if you were using a camera with very low read noise, I’m guessing that the final comparison between the two results would be much closer.

I'm not shooting RGB, I'm shooting NB where the 10 min object signal is at 700 or so out of 65,000. And the faintest detail in the thin wisps next to the brightest part are on the order of 160 in that exposure time. In the 1 hour exposure they are 6 times higher, which is still low compared to the max level before saturation. I could go 10 hours before reaching saturation of the brightest part of the nebula.



I was not trying to compare RGB, only Narrowband for extremely faint objects. I cannot do RGB here due to massive light pollution, so it's a moot point. I'm simply saying that for very faint stuff, long exposure NB has an advantage. It's not only me, but others have shown similar results. The noise in the CCD is the same for both exposures - that is, the noise produced by the camera is high for both images. The download noise may be the limiting factor, so therefore it behooves to increase the exposure time and thus minimize the number of downloads if you want to capture the faintest possible detail.



By the way, I have changed the image posted on AstroBin with some more info.

https://www.astrobin.com/916uf7/C/



Rolando





-----Original Message-----
From: W Hilmo <y.groups@hilmo.net>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 4:06 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

I think that to understand what’s going on, you need to separate read noise from shot noise.



In the single 60 minute image, there is 60 minutes worth of signal, 60 minutes worth of shot noise and 1 instance of read noise. In the 6 x 10 image, there is 60 minutes worth of signal, 60 minutes worth of shot noise and 6 instances of read noise. In theory, I believe that the math suggests that with a zero read noise camera, there would be no difference in S/N between the two final images. If I remember correctly, you are using a camera with a KAF-8300 CCD, which has pretty high read noise. Also, you are imaging a narrow band object, so the signal level in the faint areas is very low.



If you were shooting RGB, or if you were using a camera with very low read noise, I’m guessing that the final comparison between the two results would be much closer.



From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@aol.com> via groups.io
Sent: Tuesday, August 18, 2020 1:56 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras



Aha, thank you for the explanation.



Rolando







-----Original Message-----
From: sbasprez via groups.io <beneckerus=aol.com@groups.io>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 3:52 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

The lower background noise floor in the 60 minute image is easily explained mathematically. Noise in a sum of stacked of images is increased by the square root of the number of subs stacked. So summing the stack of 10 subs results in 3.16 time the noise of a single sub. The signal on the other hand adds linearly. So the signal in the summed stack is equal to the 60 minute exposure, but the noise floor in the stack is higher than the 60 minute single frame.


Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

Bill Long
 

I would add that modeling is not some strange voodoo. You can model while you are getting ready for a night of imaging well before its even astro dark. The idea that gear needs to be permanently mounted to get good benefits from modeling is wrong. People should install APCC Pro, even if its with the trial, and give a run and see how it works for you.

It will do the following things:
  1. Give you a greater appreciation for Ray. He's kind of the unsung A-P hero behind the scenes. 
  2. Give you much improved guiding over what you had without the model.
  3. Allow you to appreciate further the sounds of an A-P mount slewing around. 
  4. Allow you to try your hand at some unguided imaging with confidence that you aren't naked in the woods with nothing at all correcting the mount.
  5. Bestow upon you a newfound OCD over Polar Alignment quality.
  6. Give you some time to tuck the little ones in bed, read a story, all while the mount just does it all for you.
These are not in any order of importance, just random thoughts. Try it though -- I dare you! I bet you will wonder how you lived (and more importantly imaged) without it.

Bill

PS. Ray is pretty cool. 🙂 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of uncarollo2 <chris1011@...> via groups.io <chris1011@...>
Sent: Tuesday, August 18, 2020 1:52 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC
 

1) How often do I need to redo the modeling,
Unless you change something on the setup, the model should work any time in any weather. Depends somewhat also on the pixel scale. If you are working at long focal lengths you would need to add an atmospheric pressure detector to add to the model terms.

Rolando


-----Original Message-----
From: Marcelo Figueroa via groups.io <marfig1970@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 3:20 pm
Subject: [ap-gto] A couple of doubts about modeling and about not using guiding. #Mach2GTO #APCC

Hi,
 
While waiting for the weather to finally allow me to test my Mach2 (it's winter here in the southern hemisphere), I have a couple of doubts about modeling:
 
(my installation is semi-permanent in my backyard)
 
1) How often do I need to redo the modeling, for example, do I need one for the winter and one for the summer?
 
2) If I change the camera, do I also need to redo the modeling?
 
 
One more thing. A small advantage of guiding is that it acts in fact as a weather monitor, if it gets cloudy the guide star is lost and the session is aborted. In the case of going unguided, how do I monitor the weather. Do I need any additional equipment?
 
Thank you,


Re: APPM and color cameras #APCC

Dean Jacobsen
 

No responses so I guess it must have been a dumb question.  :-)
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

 

HI Marcelo

Temperature does have some impact on the modeling (talking with Ray on this) so you might consider having an environmental sensor in there like an MGBox V2

On Tue, Aug 18, 2020 at 6:17 PM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
OK, thank you very much. Good to know. :)
 
My telescope is an Esprit 100, so I guess I don't need an atmospheric pressure detector at the moment.



--
Brian 



Brian Valente


Re: A couple of doubts about modeling and about not using guiding. #APCC #Mach2GTO

Marcelo Figueroa
 

OK, thank you very much. Good to know. :)
 
My telescope is an Esprit 100, so I guess I don't need an atmospheric pressure detector at the moment.


Re: Exposure comparisons with CCD cameras

W Hilmo
 

I'm not shooting RGB, I'm shooting NB where the 10 min object signal is at 700 or so out of 65,000.”

 

I realize that you weren’t shooting RGB, and I know that you can’t do a single 60 minute broad band exposure without saturating the sensor.  I am saying that if you were shooting RGB (and if the sensor had sufficient well depth to deal with that), I would expect the two results to be closer to each other.  The reason for that is that that the dominant noise would be shot noise from a much higher signal in the background sky.  Since you are shooting narrow band, both the signal and shot noise are very small.  That makes the read noise relatively more significant.

 

In terms of S/N, the difference between 1x3600 seconds and 6x600 seconds is the read noise of the camera.  You may also be giving up something by using median combine instead of a combination of statistical rejection and mean combine – but the specifics of that are less clear to me.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 2:53 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

 

 

If you were shooting RGB, or if you were using a camera with very low read noise, I’m guessing that the final comparison between the two results would be much closer.

I'm not shooting RGB, I'm shooting NB where the 10 min object signal is at 700 or so out of 65,000. And the faintest detail in the thin wisps next to the brightest part are on the order of 160 in that exposure time. In the 1 hour exposure they are 6 times higher, which is still low compared to the max level before saturation. I could go 10 hours before reaching saturation of the brightest part of the nebula.

 

I was not trying to compare RGB, only Narrowband for extremely faint objects. I cannot do RGB here due to massive light pollution, so it's a moot point. I'm simply saying that for very faint stuff, long exposure NB has an advantage. It's not only me, but others have shown similar results. The noise in the CCD is the same for both exposures - that is, the noise produced by the camera is high for both images. The download noise may be the limiting factor, so therefore it behooves to increase the exposure time and thus minimize the number of downloads if you want to capture the faintest possible detail.

 

By the way, I have changed the image posted on AstroBin with some more info.

 

Rolando

 

 

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 4:06 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

I think that to understand what’s going on, you need to separate read noise from shot noise.

 

In the single 60 minute image, there is 60 minutes worth of signal, 60 minutes worth of shot noise and 1 instance of read noise.  In the 6 x 10 image, there is 60 minutes worth of signal, 60 minutes worth of shot noise and 6 instances of read noise.  In theory, I believe that the math suggests that with a zero read noise camera, there would be no difference in S/N between the two final images.  If I remember correctly, you are using a camera with a KAF-8300 CCD, which has pretty high read noise.  Also, you are imaging a narrow band object, so the signal level in the faint areas is very low.

 

If you were shooting RGB, or if you were using a camera with very low read noise, I’m guessing that the final comparison between the two results would be much closer.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 1:56 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

 

Aha, thank you for the explanation.

 

Rolando

 

 

 

-----Original Message-----
From: sbasprez via groups.io <beneckerus@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 3:52 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

The lower background noise floor in the 60 minute image is easily explained mathematically.  Noise in a sum of stacked of images is increased by the square root of the number of subs stacked.  So summing the stack of 10 subs results in 3.16 time the noise of a single sub.  The signal on the other hand adds linearly.  So the signal in the summed stack is equal to the 60 minute exposure, but the noise floor in the stack is higher than the 60 minute single frame.


Re: Exposure comparisons with CCD cameras

sbasprez
 

I do have to confess to a minor error in my analysis.  I mixed up in my head 10 frames and the number of minutes.  I was using 10 and should have been 6.  So the difference in S/N ratio is 2.45 instead of 3.16 and 1/2.45 (0.41) instead of 1/3.16 (0.316).  Otherwise the concept is solid.

Is there a way to edit a reply so the it can be corrected? 


Re: Exposure comparisons with CCD cameras

Roland Christen
 


I use 5 sec guiding exposures.  I believe MaxIm applies the corrections immediately after each guider exposure.
I don't think that can be changed. I add a delay for the start of the next exposure. In the case of the image that I posted, I added a 10 second delay after which Maxim takes an exposure and applies the correction. You don't want to wait after the exposure, but you can wait before taking another one.

Rolando


-----Original Message-----
From: CurtisC via groups.io <calypte@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 4:02 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Rolando, one of your comments in your post at the head of this thread caught my eye.  I use MaxIm and a Superstar for guiding (with the Baader guide scope).  My main scope is a TEC140ED.  Mount is a 2010 vintage Mach1.  I use 5 sec guiding exposures.  I believe MaxIm applies the corrections immediately after each guider exposure.  Can this be changed?  Is there a way in MaxIm to separate the guide exposure from the guide move?  I don't even know if I want to try it, but I'm interested in anything that improves control of my equipment.


Re: AP1100 GTO will not slew to target

hallj1531@...
 

Just for future reference the cp2 would only work if I spliced in a different 12 v plug in . They are different.


Re: Exposure comparisons with CCD cameras

Roland Christen
 


If you were shooting RGB, or if you were using a camera with very low read noise, I’m guessing that the final comparison between the two results would be much closer.
I'm not shooting RGB, I'm shooting NB where the 10 min object signal is at 700 or so out of 65,000. And the faintest detail in the thin wisps next to the brightest part are on the order of 160 in that exposure time. In the 1 hour exposure they are 6 times higher, which is still low compared to the max level before saturation. I could go 10 hours before reaching saturation of the brightest part of the nebula.

I was not trying to compare RGB, only Narrowband for extremely faint objects. I cannot do RGB here due to massive light pollution, so it's a moot point. I'm simply saying that for very faint stuff, long exposure NB has an advantage. It's not only me, but others have shown similar results. The noise in the CCD is the same for both exposures - that is, the noise produced by the camera is high for both images. The download noise may be the limiting factor, so therefore it behooves to increase the exposure time and thus minimize the number of downloads if you want to capture the faintest possible detail.

By the way, I have changed the image posted on AstroBin with some more info.
https://www.astrobin.com/916uf7/C/

Rolando


-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 4:06 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

I think that to understand what’s going on, you need to separate read noise from shot noise.
 
In the single 60 minute image, there is 60 minutes worth of signal, 60 minutes worth of shot noise and 1 instance of read noise.  In the 6 x 10 image, there is 60 minutes worth of signal, 60 minutes worth of shot noise and 6 instances of read noise.  In theory, I believe that the math suggests that with a zero read noise camera, there would be no difference in S/N between the two final images.  If I remember correctly, you are using a camera with a KAF-8300 CCD, which has pretty high read noise.  Also, you are imaging a narrow band object, so the signal level in the faint areas is very low.
 
If you were shooting RGB, or if you were using a camera with very low read noise, I’m guessing that the final comparison between the two results would be much closer.
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 1:56 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
 
Aha, thank you for the explanation.
 
Rolando
 
 
 
-----Original Message-----
From: sbasprez via groups.io <beneckerus@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 3:52 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
The lower background noise floor in the 60 minute image is easily explained mathematically.  Noise in a sum of stacked of images is increased by the square root of the number of subs stacked.  So summing the stack of 10 subs results in 3.16 time the noise of a single sub.  The signal on the other hand adds linearly.  So the signal in the summed stack is equal to the 60 minute exposure, but the noise floor in the stack is higher than the 60 minute single frame.

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