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Version 4.0c Update Changes

I have released an update to SkyTools 4 imaging. You can read about the fixes and changes here:

I wanted to describe one of the changes in more detail because it may be a little confusing at first. This change was made to the Target Selection tool. It involves the way that the minimum IQ filter works for the Nightly Filters.

There are three target list columns that are related: Start, Duration, and IQ. Prior to the update, they displayed an auto-selected period of time during which it was best to image on this night. This was usually the "A" period, during which the IQ was rated as "A", or if "A" was not reached during the night, or didn't last long enough, it would display the "B" rated period, and so on.

When you filtered the list to only show the targets with an IQ = "B" period, these columns remained the same. By selecting a minimum IQ of "B" you were in effect saying that you were interesting in imaging at "B" or better. So the problem was, if the exposure time period represented the "A" period, there was no way to know how long the "B" period lasted.

But worse than that, the Duration filter wasn't actually doing what it was intended to do. It was supposed to be including only those targets that were at or above the minimum IQ for at least the Duration specified. But it was in fact testing the auto-selected Duration at the IQ that was auto-selected. So if it was displaying the duration of the "A" period of the night, selecting a minimum IQ of B would have no effect.

That sounds about as clear a s mud.

Anyhow, I made the following change:

When the Night Filters are enabled, the time period displayed in the Start and Duration columns corresponds to the minimum IQ that you select. If you set the IQ to "A" these columns will display the "A" time period, and only those targets that achieve an "A" time period will be displayed.

When you set the minimum IQ to "B" the Start and Duration columns correspond to the "B" time period during the night and only those targets that achieve "B" during the night will be displayed. Naturally, to avoid confusion the "IQ" column will describe the time period, so if you set IQ to "B" the IQ column will now read "B" for all of the displayed targets, regardless of whether or not it achieves "A" at some point during the night. That's the potentially confusing part.

Now, when you filter on the Duration, the filter will apply to the Duration displayed, which is the duration at the minimum IQ selected. Therefore, if you set the minimum IQ to "C" and the minimum Duration to 30 minutes, the targets that achieve an IQ of "C" for at least 30 minutes will be displayed, which is the way the Duration filter was meant to work. The Start and Duration columns will reflect this as well, and all of the IQs will be displayed a "C".

Note that if you disable the Night Filters, the Start, Duration and IQ columns will return to displaying the auto-selected "best" time period during the night, as before.

I will leave you all with a tip: unless you are observing a target that is timely, such as a supernova or a comet, you should always strive to do your imaging during the "A" period of the night. If your target does not make "A", find another targetĀ and come back for it another time.

One last thing: I am considering adding the shaded IQ periods below the NightBar on the Target Selection tool, as displayed on the Scheduler and other tools. I think this will make the time periods available for each target much more clear.
Clear skies,

SkyTools Developer

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