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Issue with Imaging Project Composition and Tiles
#1
I am trying to build an Imaging Project for C/2017 T2 (PANSTARRS).  When I go to the Composition and Tiles tab, most everything is greyed out.  I am unable to frame the object or rotate the camera.  These functions seem to work fine on other objects.  Is there something special about comets that does not allow this?  This is a problem when you are trying to frame the comet with other objects in the FOV.

Rod
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#2
Hi Rod,

Comets are complicated. The way SkyTools 4 generally works is that the imaging project has no date or time associated with it. These things are not assigned until the observation is scheduled. So normally, there can be no meaningful composition at the imaging project stage for a moving object. But there are tools in place to help with this. For smaller comets that you want to capture in a specific field, just go ahead and ignore the composition at this stage. Concentrate instead on the exposure goals. I don't know how you use SkyTools to make your observations, and the possibilities are nearly endless, so it is difficult for me to be specific at this point. The general idea is to use the tools at hand, such as the Target Selection tool and the Interactive atlas, to find a time when you want to make your observation. The on the Scheduler you can force your observation at that specific time. This can be done via the "From and to" time constraints. Usually all you need to do is set the From time and then manually schedule the comet. If everything is set up properly and the comet is observable, it wall be scheduled at the time you select. Beware that your Min. Q setting is not too high. One of my Youtube videos covered manually scheduling targets. There are similar features to force ACP Export to make observations at a specific time.

For comets with long tails that you want to fit into the field of view you will need to do a real composition. On the lower right of the composition tab is a Moving Object Offset feature. This is primarily used for comets. It allows you to compose the camera FOV relative to the comet such that the tail will be visible.
Clear skies,
Greg

SkyTools Developer
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#3
Thanks for the explanation!  Now that I have selected the Moving Object Offset, when the telescope slews will it use this fixed window or will it slew to the fixed offset from the comet's current calculated position?  In other words, will the frame move with the comet or will the frame remain fixed and the comet will move in each exposure?

As a follow-up question, within the Imaging Project, I have defined the Minimum Imaging Quality (IQ) as B and with all of the variables ST4 calculates the Exposure Time as 101 minutes to reach the target SNR.  Then selecting this object, Schedule Project.  The schedule created only schedules during the IQ A time (20 minutes - 11x1min).  If I select Schedule Project again on this object, it then does (according to the Schedule) a Meridian Flip (even though this object crossed the Meridian several hours before) and the schedules the remaining imaging during the IQ B time (94 minutes - 52x1min).  Why does the original schedule which is set for IQ B not schedule during both A and B times?

Rod
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#4
Its relative to the position of the comet at the time it is scheduled.

Its always going to try to schedule during the A time if available. Its a "minimum" IQ setting. If you want to force it to the B period, set the time sliders such that it can't get to any part of the A period.

Remember, it is trying its best to help you get the best images. That's what it does.
Clear skies,
Greg

SkyTools Developer
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#5
So even though I select that it can Image down to IQ B, it will only schedule for IQ A if available?  Is there no way to schedule for both IQ A and B together?

Also, if I select to schedule twice, why does the schedule indicate a Meridian flip between the two schedules since the object is already on the west side of the meridian?

   

Rod
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#6
No, I did not say that. It will always schedule for A if A is available. It will not limit it just to the A period under most circumstances, but it is a very complex algorithm, and it is very difficult to second guess or explain what it is doing without being able to see all of the details. Most of the time when I catch it doing something wrong, after further investigation it turns out to be doing what it is designed to do after all.

As for the meridian flip, it certainly looks like something has gone wrong. I haven't seen it do that before. I will look into it.
Clear skies,
Greg

SkyTools Developer
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