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Automatic pausing of imaging when cloudy

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#1 BoldlyGoing

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Posted 24 March 2019 - 07:21 AM

You would think that as images are being collected, they could be analyzed to see if clouds are rolling in. A sudden drop in the brightness of the stars could signal whatever image acquisition software you're using to stop taking images until they come back, and maybe fire off some sort of alert to your cell phone or something.

 

Is there a software package that does this? I know several (CCD Autopilot, ACP) can integrate with very expensive cloud sensors made for permanent observatories, but why do we need an expensive cloud sensor when you already have an image of the sky above you?

 

I image unguided, so a passing cloud won't ruin things for me - it's a situation that could be recovered from.

 

If this existed, we could sleep instead of babysitting our imaging all night... especially on those nights that are clear apart from some high cirrus clouds that roll in sporadically.


Edited by BoldlyGoing, 24 March 2019 - 07:35 AM.


#2 gunny01

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Posted 24 March 2019 - 07:38 AM

SGP.



#3 RaulTheRat

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Posted 24 March 2019 - 08:12 AM

Well SGP can recover from failed imaging (as in the guide star gets lost and the next exposure can't start). What it can't do is analyse the last image, and if it contains for example thin cloud causing a loss of contrast, detect that, throw away that image, and try again repeatedly. That would be pretty cool, but it's a more complex task than just detecting that the guider has lost the star and waiting a few minutes before trying to restart everything.
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#4 t_image

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Posted 24 March 2019 - 09:02 AM

You would think that as images are being collected, they could be analyzed to see if clouds are rolling in. A sudden drop in the brightness of the stars could signal whatever image acquisition software you're using to stop taking images until they come back, and maybe fire off some sort of alert to your cell phone or something.

 

Is there a software package that does this? I know several (CCD Autopilot, ACP) can integrate with very expensive cloud sensors made for permanent observatories, but why do we need an expensive cloud sensor when you already have an image of the sky above you?

 

I image unguided, so a passing cloud won't ruin things for me - it's a situation that could be recovered from.

 

If this existed, we could sleep instead of babysitting our imaging all night... especially on those nights that are clear apart from some high cirrus clouds that roll in sporadically.

The way I work in AP I enjoy monitoring every exposure I take with my large monitor (usually capturing things in motion),

so I can't fully appreciate the method of leaving it to work while I sleep [no motivation to solve problem],

but I do understand the concept.

 

Without relying on some fancy hand-holding software and if you have an aversion to things that are "expensive," there are tools that exist that aren't any more complicated than using a smart phone.

 

All you need is:

determine your objective way of flagging a cloud-affected image (maybe take a baseline sub in the beginning, use it as a control), then compare it with the current taken image......

[number of apps out there that can do this-consider the motion-detection security types that have sensitivity settings].....

 

using a macro-recorder and a simple customized script with your overall os functionality, you can fully automate utilizing different software on the same machine to perform various task (such as moving a recent image to a watch folder, having the analysis software compare it with the baseline, then via macro either flag it for moving to trash or move it to the keep folder),

in addition you could set up a set of conditions where repeated attempts over a course of time that fail the "keep" would then trigger the system to shut down all various gear (park scope and mount), shut off camera, power down pc......

 

 

This is all really simple stuff if you are familiar with it. But like a new smartphone user you just need to dive in..........

 

The basic thing is if you can get your computer to do it with clicks and movements of a mouse and keypresses, then a macro recorder can automate it and the robust ones can even utilize logic conditionals to make automate decisions....

I've been doing such since the Microsoft macrorecorder tool in Windows 3.1...........

Even Task Scheduler is a powerful tool that no one uses.......



#5 maxmir

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Posted 24 March 2019 - 11:02 AM

Voyager does this function very well. I think SGP just added this recently.

It has been a while since I used ACP but you had to buy the scheduler which is quite expensive.

When I lived in Wisconsin I tried to get the author of CCD Autopilot to do this.
He did not want to risk peoples equipment at the time.

He lives in Arizona where full cloudless nights are normal.

Wisconsin you get 2 hours the clouds roll in for 1 hour then clear for 2 more etc.


Max

#6 CharlesW

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Posted 24 March 2019 - 11:36 AM

You don’t mention what capture program you are currently using, but why can’t you sleep through the night as it is? If you are unguided it just slews to a point in space and starts banging off exposures. If it’s cloudy and can’t focus, it’ll return to the last known focus point and keep banging away. Can’t plate solve for position, it’ll just rely on the pointing accuracy of the mount. If you are a Pixinsight user you can easily Blink your images in the morning and discard the ones with anomalies. 

 

How exactly is the capture program going to know when to resume if the main camera isn’t taking images to be analyzed? I’m not an SGP user so I don’t know, given the right equipment, if it can resume, but the only automation program I’m familiar with that can do it is ACP, and folks pay $$$$ for that. Also keep in mind that cloud detection isn’t for convenience, its for protection. Clouds=chance of rain. 



#7 WadeH237

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Posted 24 March 2019 - 11:38 AM

Well SGP can recover from failed imaging (as in the guide star gets lost and the next exposure can't start). What it can't do is analyse the last image, and if it contains for example thin cloud causing a loss of contrast, detect that, throw away that image, and try again repeatedly. That would be pretty cool, but it's a more complex task than just detecting that the guider has lost the star and waiting a few minutes before trying to restart everything.

I'm not sure that I see the advantage to this.  In your scenario, SGP is still taking every exposure as planned - but you are giving *it* the responsibility of determining the quality of the image and tossing bad ones.

 

I would much rather go through the data myself, perhaps with the helps of a flexible analysis tool like PixInsight's SubframeSelector, to determine the quality of the subs.  Also, when I integrate the data, I might very well keep some less than optimal subs and use weighting to reduce their contribution to the integration (rather than eliminate them completely).


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#8 BoldlyGoing

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Posted 24 March 2019 - 11:59 AM

The reason I want this is so I can set up a goal of say, capturing 30 "good" subs from each filter, then park the mount. For that, the software needs to know what a good / cloud-free image looks like.

Currently I'm using TheSkyX Pro with a MyT mount, unguided.

#9 CharlesW

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Posted 24 March 2019 - 01:22 PM

Right now you’ve got a fairly narrow view of automation. You are only thinking about acquisition, but how are you going to choose what to image? That is really the most important part of all of this. Yep, you could scour Abin, see what folks are doing here in CN, but are you really going to do that night after night, year after year? There are a number of apps that will click off exposures but I think that CCD Navigator is still the best, easiest, selection app. CCD Navigator will take care of target selection, CCDAP will capture the image, and if you want, CCD Inspector will analyze the image and keep or discard it. You’re probably still better off keeping all the images and blinking them in Pixinsight. You’ve got a great mount, Navigator and CCDAP will make full use of it. 



#10 WadeH237

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Posted 24 March 2019 - 07:23 PM

The reason I want this is so I can set up a goal of say, capturing 30 "good" subs from each filter, then park the mount. For that, the software needs to know what a good / cloud-free image looks like.

Currently I'm using TheSkyX Pro with a MyT mount, unguided.

I guess that I just don't understand that strategy.

 

If I am going to image unattended (which is most of the time that I image), I want to go from dusk to dawn.  If the sky is clear, I want to be getting something.  It's rare that I have a single object that I'm going after that will be above my tree line all night long, so I usually have two objects.  I set the automation to image the first object from dusk until it reaches the tree line, and then it starts on the second object and goes until dawn.  My planning software tells me pretty accurately when an object is visible, as I have measured and set my horizon details.

 

With automation, the idea of parking the telescope when the sky is clear, just means that I'm throwing away the opportunity for more data.  And if clouds move in unexpectedly, I can just throw those subs away.



#11 BoldlyGoing

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Posted 25 March 2019 - 05:20 AM

I guess that I just don't understand that strategy.

 

If I am going to image unattended (which is most of the time that I image), I want to go from dusk to dawn.  If the sky is clear, I want to be getting something.  It's rare that I have a single object that I'm going after that will be above my tree line all night long, so I usually have two objects.  I set the automation to image the first object from dusk until it reaches the tree line, and then it starts on the second object and goes until dawn.  My planning software tells me pretty accurately when an object is visible, as I have measured and set my horizon details.

 

With automation, the idea of parking the telescope when the sky is clear, just means that I'm throwing away the opportunity for more data.  And if clouds move in unexpectedly, I can just throw those subs away.

How do you ensure you get enough good subs from each filter in that case? Do you rotate filters between each sub-exposure to ensure an even distribution? That would work, but I've always been wary of the wear that would put on my filter wheel. Perhaps I just need to get over that!



#12 Vassar1976

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Posted 25 March 2019 - 05:58 AM

BoldlyGoing,

 

I also have the MyT mount and use Voyager together with an AAG Cloudwatcher which was only $345 - perhaps you have been looking at the much more expensive cloud monitors?

 

You can set Voyager to suspend your imaging session at any combination of cloudy and/or overcast as signaled by the AAG, and resume when conditions improve.

 

Regarding getting enough images from each filter, Voyager also has a sequence option to repeat a sequence "N" times, so you could set your sequence up for something like 5 or 10 frames with each filter, and then to repeat the sequence any number of times.  Set a start and end time on the sequence and you have something that will get as many frames as possible with as even a distribution across your filters as possible.

 

On the idea of using a different filter on every frame, I wouldn't be too worried about wear and tear on your filter wheel, but I would be concerned about losing time to autofocus if you refocus every filter change.  If you don't do that, and use filter offsets, you may have suboptimal focus as filter offsets may not work as well as an autofocus action.

 

If you don't want to buy a Cloudwatcher, you could have your system watch for something like a lost guide star.  Voyager lets you end a sequence with an error signal if the guide star is lost more than a specified number of times.  You could then wait for some time interval like 10 minutes and retry the sequence.   This loop can continue until the end time you specify in your sequence, and then you could move on to your second object for the night.

 

Cheers,

Rowland


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#13 BoldlyGoing

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Posted 25 March 2019 - 07:21 AM

Thanks, that all makes sense now. I'll check out Voyager and the Cloudwatcher for sure.



#14 WadeH237

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Posted 25 March 2019 - 08:02 AM

How do you ensure you get enough good subs from each filter in that case? Do you rotate filters between each sub-exposure to ensure an even distribution? That would work, but I've always been wary of the wear that would put on my filter wheel. Perhaps I just need to get over that!

With my ASI1600, I take pretty short exposures and rotate the filter every 3 to 5 subs.  With my ST10-XME, I rotate the filter with each exposure.

 

I've never considered wear on the filter wheel.  My ST10-XME with CFW-8 is about 13 years old and the filter wheel works as well now as when it was new.



#15 dhaval

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Posted 25 March 2019 - 03:30 PM

The best way to do this is through an automation program (like SGP and I am sure many others have it as well) and a cloud sensor. SkyAlert is an exceptional tool to have. Admittedly, you would want to use it in an observatory setting, but you can use it without an observatory as well. Just feed the SkyAlert data (it produces what is called a weather file) to the image acquisition program and the image acquisition program will allow you to automate the acquisition aspect. Meaning, if there are clouds rolling in, you can set the parameters in the image acquisition program (based on the weather file) to stop imaging. There are certain tools that will re-start imaging if the weather clears up after a while, but you are now looking at some really expensive tools. 

 

CS! 


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#16 Vassar1976

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Posted 25 March 2019 - 03:45 PM

There are certain tools that will re-start imaging if the weather clears up after a while, but you are now looking at some really expensive tools. 

 

CS! 

Actually, Voyager can do this and it costs 69 Euros.  Add an AAG Cloudwatcher for $345 and you're in business with suspend on clouds / restart on clear imaging.

 

Cheers,

Rowland



#17 dhaval

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Posted 25 March 2019 - 04:58 PM

Actually, Voyager can do this and it costs 69 Euros.  Add an AAG Cloudwatcher for $345 and you're in business with suspend on clouds / restart on clear imaging.

 

Cheers,

Rowland

There are many software that will do that. The problem lies in the fact that you don't know how long the clouds have been around and what is the position of the target in the sky after that interference and hence, if you can continue imaging that target. For example: the target may have set by the time the clouds clear up - in that case, and assuming you've set limits on the mount, your mount will now just hit the limits and most likely park (it may just stay there if that is how you have it configured), you still end up losing imaging time unless you manually intervene. I haven't seen any software really "pick it up" after clouds interfere with the exception of ACP Expert and ACP Expert costs $1500 (plus other softwares that cost another $500). What I was referring to was the complete functionality of restarting imaging after clouds interfere.

 

Unless Voyager also does what ACP Expert does, then I believe we are talking apples and oranges.

 

CS! 


Edited by dhaval, 25 March 2019 - 05:09 PM.

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#18 Vassar1976

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Posted 25 March 2019 - 05:21 PM

There are many software that will do that. The problem lies in the fact that you don't know how long the clouds have been around and what is the position of the target in the sky after that interference and hence, if you can continue imaging that target. For example: the target may have set by the time the clouds clear up - in that case, and assuming you've set limits on the mount, your mount will now just hit the limits and most likely park (it may just stay there if that is how you have it configured), you still end up losing imaging time unless you manually intervene. I haven't seen any software really "pick it up" after clouds interfere with the exception of ACP Expert and ACP Expert costs $1500 (plus other softwares that cost another $500). What I was referring to was the complete functionality of restarting imaging after clouds interfere.

 

Unless Voyager also does what ACP Expert does, then I believe we are talking apples and oranges.

 

CS! 

I used ACP Expert before switching to Voyager so I know exactly what you are talking about. 

 

Yes, Voyager can do this.  

 

I set up my targets as sequences with start and stop times.  If the cloud sensor says to suspend imaging, Voyager handles the event and goes to a Suspend block where you can define what you want it to do (stop tracking / park / close the roof / whatever you like).  Once the resume event occurs, Voyager returns control to the sequence that was running.  If the end time has been reached, that sequence simply passes control to the next action, which could be another sequence (target) or the end of the night routine.

 

ACP Expert also maintains as big a database of targets as you like, and dynamically chooses what to run based on what's available and meets your criteria at that time, so in the context of this functionality, that's the main thing you get for $1900 more than Voyager.    For Voyager, you have to plan your night in terms of targets, frames, start times, and end times.

 

I am not saying this is the only difference between ACP Expert and Voyager - just that it is the difference in the context of suspending and restarting imaging on weather events.

 

Cheers,

Rowland


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