Filtering Effect of Transparency & Seeing Settings on Nightly Planner

[Random]

Hello,
I was using the Nightly Planner to create an observing plan for a Messier Marathon and I noticed that as I changed the Transparency and Seeing settings, the number of objects scheduled for observation would change. It is my understanding that Transparency & Seeing affect the Observation Difficulty rating but I was curious how Nightly Planner uses the Transparency & Seeing settings to filter the number of objects scheduled for observation? My filters were set to Log filter: Any, Any quality, Ignore Difficulty, and Ignore Splitability.

The other thing is that if there is a filtering effect going on, I assumed the combination of Prime Transparency and Excellent Seeing to result in the largest number of objects scheduled for observation. In ST4 with the settings I used, that number was "105 out of 112 scheduled for observation". But when I changed the settings to Prime Transparency and Poor Seeing, that number increased to "110 out of 112 scheduled for observation." Another example that I would not intuit would be 

1. Excellent Seeing/Typical Transparency: 83 objects of 112 scheduled for observation
2. Good Seeing/Good Transparency: 88 objects of 112 scheduled for observation
3. Good Seeing/Typical Transparency: 91 objects of 112 scheduled for observation

I would've expected the first two combinations above to result in a higher number of objects scheduled for observation compared to the 3rd.

Settings:
Date: Evening of 3/29/2025
Observatory: Utah Desert Remote Observatory
Telescope: Antares 12 inch Dobsonian
Observer: New Observer 
Observing List: Messier

I included a screenshot of the settings I was using and a table of the number of objects out of 112 scheduled for observation as the transparency and seeing settings were changed, also attached to this post:

https://docs.google.com/spreadsheets/d/1...sp=sharing

[PMSchu]

Hi Random,

I see that you have the 'Plan' box checked at the upper center of your screen shot with 1 minute slew and observing times. This may be interacting with the filter options. Try unchecking the 'Plan' box and see what happens. I'm running ST4.1.11.14 Visual Pro and with the 'Plan' box unchecked, I have an Observing List (OL) that displays minor planets (MPs) down to 27.8 magnitude. When I check the 'Plan' box, only MPs brighter than 16 magnitude are listed for my 13" dobsonian scope.

I'm using 'Good' transparency and 'Good' seeing.

Hope this helps,

Phil S.

[theskyhound]

Hello,

Phil has put his finger on it. The Plan feature is a very complex algorithm that has to consider timings as objects are viewed and the sky moves. For example, changing one object can affect everything that happens after that. I think this explains what you are seeing.

I think the test you are looking for is to uncheck the Plan, then experiment with different transparency and seeing settings, with the quality and difficulty filters set to something meaningful (I recommend High Quality only and Visible at any difficulty).