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Imaging Quality and Target Selection Tool
#1
I have a somewhat complex horizon and am trying to get the Target Selection Tool to list objects filtered by the number of hours that objects are above my local horizon.

At a first glance, it looks like the right way to do this is to use the Night Filters and the Image Quality and Duration parameters.

The problem that I am having is that if SkyTools decides that the best image quality is A, then it insists that the total duration is defined by the time that the object is available at that quality level.  This is true even if I set the Image Quality filter to something less.

As an example, I am looking at M103 for tonight (just an object picked somewhat at random with Image Quality of A).  The object is near 45 degrees altitude at dusk, and never gets any lower than that until it goes behind my tree line just after 2am.  The blue image quality line in the Target Selection Tool shows it around 60 or 65 at dusk.  From there, it stays well above that until it drops to zero just after 2am (going behind the trees).

The problem is that the Target Selection Tool shows a Start Time of 22:00 with Duration of 03:45.  I've tried using the Exposure Calculator to select other image qualities, and I've set up an Imaging Project with an exposure goal of C.  Neither of these actions affects the Start Time or Duration in the Target Selection Tool.

What I want is to be able to create a target list and then have the Target Selection Tool show me the objects on a given night, filtered by the amount of darkness time that they are above my horizon (my horizon is high enough in every direction, that I want to start imaging as soon as an object clears the tree line and continue until it drops below the tree line on the other side).  I also generally don't want to image an object unless it has 4 hours of availability.

As it stands now, M103 would not appear on a list filtered by 4 hours of Duration - not because it's unavailable, but because it doesn't have an image quality of A for at least 4 hours, even if I would be happy with image quality of B.  As far as I am concerned, the object is actually available from about 7:30pm to 2:00am, which is a duration of 6.5 hours.

Is there a way that I can get the Target Selection Tool to work for me?

Thanks,
-Wade
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#2
Hello,

There are two separate issues here:

1. You should define an obstructed horizon for your location. Once you do so, SkyTools will limit observations for your targets so that they will always be above the obstructed horizon. To do this, open your observing location and click on Create next to Obstructed Horizon on the bottom left.

2. How you expect things to work in planning is how they should work. E.g. if you set the minimum IQ to "C" it should start at the "C" block. But I think you may not be using the tools in the optimal way.

Here are some things to consider:

1. The Target selection tool is for selecting targets, so it operates on target objects rather than Imaging Projects. This is also true of the Exposure Calculator. So the settings for the Imaging Project do not affect it. Instead, look at the settings at the top of the dialog. But remember, the Target Selection tool is not meant for planning your observations. It is meant for selecting appropriate targets.

2. The Exposure Calculator is completely independent of any of the other tools. Changing its settings has no effect on the other tools, including the Target Selection and Scheduler.

3. Once you create a project, you should be using the Scheduler to plan your night of observation. It is the Scheduler that considers the minimum IQ that you set for your project. But even with the Scheduler it may sometimes appear to be inconsistent with the times that it uses to schedule. This is because for simplicity sake, the blue line on the Nightbar and (and related timings) is computed for the "representative filter." If you have more than one filter, one of the other filters may in fact start earlier or go later.
Clear skies,
Greg

SkyTools Developer
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#3
BTW I very much appreciate your asking this question. I am becoming very concerned because people are not asking enough of these kinds of questions, and that makes me uneasy. Maybe everyone is a genius, or my instructions are amazingly clear. But I worry that people are becoming confused, or frustrated, and simply giving up rather than asking for help.

I am standing by here to help!
Clear skies,
Greg

SkyTools Developer
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#4
Thanks for the response.

I've already set up the horizon data and that works fine. I can easily see when objects are below my obstructed horizon by the blue line in the Target Selection tool.

Based on your suggestion above, I took a look at the scheduler. It's not quite what I am looking for in my workflow. The biggest deal is that it seems to require that I create an imaging plan before any objects will show up there.

Here's what I am trying to do:

I live in an area with few clear nights a year. My imaging opportunities are pretty rare. I keep my imaging rig set up in the back yard all the time and uncover it when we get a clear night. Most of the time, I'll need to get things running after I get home from work (and half of the year, this is after it's already dark). I find that often times, I'll end up with a wasted opportunity because I don't know what I want to image.

What I'm looking for is a way to very quickly find out what's going to be visible in my available sky for 4 hours or more, along with when it's rises and sets relative to my tree line. The Target Selection tool would do exactly that, except that it tends to rule out the very best targets because they are the ones with an "A" quality score because they may be an A for only part of the night, even if they were B or better for the whole time they were visible.

The huge difference for me between the Target Selection tool and the Scheduler is the need to have some kind of imaging plan ahead of time. I want to have the Target Selection tool looking at large observing lists that may contain entire catalogs. Then I want to sit down for a few hours and run the calendar control through the next few months to see what targets are available. This would be a huge value to me because I could then keep a list of targets prominently placed in my back yard for each week of the year. So when I get a clear night, I could just look at what's available for that week and pick one.

Honestly, the image planning functionality is a lesser priority to me. I've been imaging long enough that I don't need a lot of help in planning which filters and exposure times, etc. to use. Picking a target, when almost all of my imaging is done opportunistically and at the last minute, is the hard part.

So please consider it a feature request that the Target Selection tool (or equivalent functionality) could allow me to filter based on the time any given object spends at my specified quality level or better. Actually, I would be happy if I could avoid the image quality duration completely and just had a filterable column that shows the amount of dark time each object spends above my obstructed horizon on the selected night.

Thanks,
-Wade
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#5
Hi Wade,

You are thinking narrowly with only a rudimentary idea of how software might help you out. I am way out ahead of you on this. You have not yet recognized the value of my software, but I believe that I can help you change your view and help you do better imaging in the process.

Before I can do that, please take a moment to tell me something about your control system, the types of objects you observe, and what you are ultimately trying to accomplish with your images. In return I will outline how you can use SkyTools to accomplish what you want, and what the benefits are.
Clear skies,
Greg

SkyTools Developer
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#6
I have an imaging rig set up all the time.  I switch the configuration occasionally between wide field and long focal length.  During the summertime I transport the rig to a remote site at each new moon.

I have two different automation setups that I use.  Historically, I've used CCDAutoPilot & MaxIm/DL fully automated.  I create sessions in CCDAP and start the system before dusk.  I collect the data from the computer at the scope the next morning.

For the last year, I have been using Sequence Generator Pro with PHD2.  My usage pattern is similar to what I do with CCDAP.  I made the switch primarily to gain familiarity with SGP, since I spend a lot of time helping people with their imaging setups, particularly at the remote site star parties in the summer.

For both setups, I have a number of template sessions that I use as starting points, depending on the nature of the imaging.  For example, I have a template session for RGB imaging and a separate template session for narrow band imaging.  

My goal is to collect data whenever I have a clear night.  I am not working towards any particular goals with regard to targets.  I'm mainly interested in picking a target that will frame well with whatever configuration that I'm using and will be available for enough time on a given night to gather usable data.  I also tend to not publish my work.  I image simply because I enjoy doing it (although my wife has been pressing me to share more of my work, so I've been posting some of it to Astrobin).  I do tune the session parameters based on a review of the imaging field.  I consider both the stars and the target object itself.

I've been both an astrophotographer and visual astronomer for more than 20 years.  I know the sky pretty well and currently pick my imaging targets by looking at the sky and picking something that I am familiar with.

What I'm looking to do is to expand my target list beyond the ones that I know.  In particular, I'd like to find interesting targets that are not commonly imaged.  My current thinking is that I want to have a list of candidate objects for each week of the year.  That way, when I have a clear night, I can look at the list for that week and pick one, either that I've not done before, or one for which I would like to collect more or better data.

I've been working with SkyTools with some "what if" scenarios.  For example, I've been wanting to image Jones 1 in Pegasus.  My best opportunity to do that is at Oregon Star Party on a year when the new moon is in late August.  It's a dim object that benefits from the SQM 22 skies there, even though it's better placed seasonally a bit later.  My home skies are closer to SQM 20.5.  I tried to get SkyTools to offer it as a potential target, but it's duration in the Target Selection tool tends to filter it out.  Note that this is an unusual scenario in that I actually have a known target that I want to get.  I used it as a "what if" scenario so that I could see what parameters I would have to use to get SkyTools to suggest it.

I hope that makes sense.

Thanks,
-Wade

On Edit:  Oh, and I just wanted to clarify that I referenced Jones 1.  It's also known as PK 104-29.1 or PN G104.2-29.6.  That's fine.  I do see it on the Target Selection list.  It's just another one with a really low duration time, which is why it gets filtered out when I narrow the list by Duration.
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#7
Hi Wade,

Thank you for explaining in detail what you are doing. I think that you will find that SkyTools does exactly what you want it to do, but you need to be willing to use it as intended.

Everything in SkyTools Imaging revolves around the creation of an Imaging Project. What you are doing is a great start, but you need to add the step of creating an imaging project to your work flow. SkyTools cannot really be used without it, and if you try to avoid it, you are avoiding the most useful features of the software.

So once you find a target that you want to image, right-click on it and create an Imaging Project. This tells the Scheduler which filters you are using and what your exposure goals are for the project. You should have exposure goals, and you should let SkyTools help you set them.

Most projects that I create take less than a minute. Many take less. Most of the settings are special purpose and can usually be ignored (until you need one, and then I think you will find it to be very useful). You just need to take some time to familiarize yourself with the project settings.

Once you have created projects for your targets, then the Scheduler is used to plan your observations for the night in a way very similar to what you want the Target Selection tool to do. Use it to Schedule your projects before dusk. Then use what it recommends to program SGP or CCDAutoPilot. If weather interferes, just skip ahead to the time when things clear. I think you will discover that it is worth your while.

If you want to get the most benefit from SkyTools, then I recommend adding the step of taking a few minutes to log your images with your imaging projects. This will allow the Scheduler to tell you what images you need to get next time in order to complete your project, and ultimately will provide an archive of the images you have taken.
Clear skies,
Greg

SkyTools Developer
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#8
Hi Greg,

That sounds great, and I am open to learning how the workflow is intended.

That said, here is what I'm looking for the software to help me with:

(2018-11-05, 04:48 PM)theskyhound Wrote: So once you find a target that you want to image...

In the workflow that you describe, that is the very first step, before I can even create an imaging project.

What I am asking for is a way to do that efficiently.  SkyTools 4, as it exists right now, get's me really, really close to that.  If I could have a way to filter to Target Selection tool based on the amount of time that it is both dark, and the object is above my obstructed horizon, then I could do the rest of the things that you suggest.

It is tantalizingly close right now.  If I look at the blue quality line, the data is right there.  I just can't filter on it.

Perhaps a picture is worth a thousand words.  I've taken a screen shot of a target list that contains just the PN that I mentioned above.  I have the date set for next year's Oregon Star Party and have turned off all of the filters to make sure that it shows up.  I don't have a site set up yet for OSP, so it's my home site.  That's why there's a hard stop at the left of the blue line, due to my obstructed horizon.  But if you look at the blue quality line, you can see that this object spends many hours in the sky.  It clears my tree line just after 11pm and continues to improve until about 4am.  To me, that object is available from 11pm for about 5 hours.  Yet the Target Selection tool shows it only from 1:50am and only for 85 minutes.

What this means to me in terms of target selection, is that I must turn off the duration and quality filters in order to get it to show up at all.  And when I do that with a large list, I'll see lots of objects (perhaps hundreds if I use a catalog like NGC) that actually aren't available and would need to go through them one at a time to find actual candidates.

I hope that this makes sense,
-Wade


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#9
(2018-11-05, 05:33 PM)wadeh Wrote: Perhaps a picture is worth a thousand words.  I've taken a screen shot of a target list that contains just the PN that I mentioned above.  I have the date set for next year's Oregon Star Party and have turned off all of the filters to make sure that it shows up.  I don't have a site set up yet for OSP, so it's my home site.  That's why there's a hard stop at the left of the blue line, due to my obstructed horizon.  But if you look at the blue quality line, you can see that this object spends many hours in the sky.  It clears my tree line just after 11pm and continues to improve until about 4am.  To me, that object is available from 11pm for about 5 hours.  Yet the Target Selection tool shows it only from 1:50am and only for 85 minutes.

What this means to me in terms of target selection, is that I must turn off the duration and quality filters in order to get it to show up at all.  And when I do that with a large list, I'll see lots of objects (perhaps hundreds if I use a catalog like NGC) that actually aren't available and would need to go through them one at a time to find actual candidates.

I hope that this makes sense,
-Wade

Hi Wade,

Ok, so try this. Set the Night Filters to:
IQ > Any, Duration > 1 hour, and check the Night Filters box

What that says is that it must be observable for at least an hour, and it should be displayed in the list.

But I suggest this instead:
IQ > B, Duration > 1 hour (oe less if you want).

This will show you targets that are at B or above for at least an hour. 

Is that working?
Clear skies,
Greg

SkyTools Developer
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#10
One thing about my suggestions, is that I believe that it really matters if the quality is B or C. I would not personally image a target below an IQ of B. In fact, usually I only go for A. This will make for the most consistently good images, especially if you are stacking over more than one night. At an IQ of C the SNR will be 70% of what you would get at A, or to look at it another way, it would take much longer to reach a given SNR at C than at A. So this is why A or B are recommended.

That said, if you want to include objects that are available at IQ = C, then set it to C. No, you won't get a different start and duration time, but remember, we are only trying to select target objects. As you said, all the information is right there.
Clear skies,
Greg

SkyTools Developer
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