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Understanding Optimum Observation time
#1
Hi,
I'm a new user with SkyTools 3 Standard Edition.
I'm trying to understand the logic/formula behind what is displayed as "Optimum" observation time for an object.
At first I thought it might be the time at which the object was highest in the sky - but after plotting a few sample objects in Stellarium for the displayed "Optimum" time - I'm not so sure that is what SkyTools is shooting for.

Thanks in advance.
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#2
Hello,

SkyTools is much more powerful than other software that you are used to. It can calculate the visual contrast for an extended object at any time of the night, under varying conditions, which includes atmospheric extinction (which depends on more than the simple altitude) and the brightness of the sky background at the eyepiece. For stellar objects it similarly calculates how detectable the objects is to the eye. It samples the night every few minutes and calculates these things for your object. The optimum time is when the visual contrast or detectability is maximized.

You can read more about this in the help system. I suggest "Visual Detection Difficulty Estimation" under Advanced topics. I also suggest the Visual Observing topic under Observing with SkyTools. You may also find the manual for the Starter Edition to be very helpful. It and other guides can be found here:

https://skyhound.com/skytools_guides.html

Video tutorials here:
https://skyhound.com/skytools_tutorials.html

Clear skies,
Greg
Clear skies,
Greg

SkyTools Developer
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#3
Thanks!
I have no knowledge of any options or user controls on how to adjust atmospheric extinction parameters.  I would assume the software determines those parameters based on time of night and perhaps some kind of general darkness statistics having to do with various times throughout the night.  Otherwise - I would want to know how to make those adjustments.

Also on another note - I've recently purchased an Orion Intellescope system and I've set it up with AZ/ALT setting circles so that I can practice using it in the house.  Having the AZ/ALT coordinates for stars I can perform its star alignment and then find objects.
I can then use Cartes du Ciel to confirm the object the intellescope found has the correct AZ/ALT coordinates.

Tonight after doing the alignment I wanted to test it by finding some of the alpha stars in some of the constellations above the horizon.

I thought it would be cool if SkyTools gave me a list of stars that would be visible. 
I was surprised to find when I selected "All Stars" from the "List of filters" drop-down - it returned zero objects.
However when I selected "All Classes" from that same drop-down - it returns about 20 items.
I also tried "Multiple", "variable" and "Binary" stars - with no results.

So I guess it can't list available stars?
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#4
Atmospheric extinction is estimated based on the temperature and relative humidity selections for the location.

It would seem to me to be a lot more straight forward if you would connect SkyTools to your telescope directly rather than control with another app.

You didn't tell me two really important things:

1.Which tool are you using? E.g., the Nightly Planner? Real Time? Something else?

2. What observing list are you using? Where did you get it? Forgive my asking such a basic question, but did it have any stars in it? In order to display only stars from your observing list, there must first be stars in the list. Same for multiple stars, etc.

Of course it can display available stars. Presumably you created an observing list of Alpha stars, perhaps via the Database Power Search? Then selected that list in the planner?
Clear skies,
Greg

SkyTools Developer
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#5
(2019-01-15, 12:20 AM)theskyhound Wrote: Atmospheric extinction is estimated based on the temperature and relative humidity selections for the location.

It would seem to me to be a lot more straight forward if you would connect SkyTools to your telescope directly rather than control with another app.

You didn't tell me two really important things:

1.Which tool are you using? E.g., the Nightly Planner? Real Time? Something else?

2. What observing list are you using? Where did you get it? Forgive my asking such a basic question, but did it have any stars in it? In order to display only stars from your observing list, there must first be stars in the list. Same for multiple stars, etc.  

Of course it can display available stars. Presumably you created an observing list of Alpha stars, perhaps via the Database Power Search? Then selected that list in the planner?


Hi Greg and thanks again.
I thought I was using the Nightly Planner - I believe the Real Time is for the version above mine - and I don't have it in mine.

I believe my understanding about how the list is generated was faulty.
I assumed when I made a change to the filter setting a new list would be generated - kind of like a query being initiated.
But I see now that is not the case.

I'm getting the impression that one must first generate a list - and that list is then either compiled into a file or compiled into RAM.  Then filtering which is displayed above the columns - is done off that generated list.  

I had falsely assumed the filtering was part of the initial query (list generation) process.

So now if I understand - there are two ways to generate a list (what I would consider to be a query into the DB)
1) Use the "Nightly Observing List Generator" - select one of the filtering options under "Type of list to create"
2) Use the "DB Power Search Tool"

Using the "Nightly Observing List Generator"
Show Pieces: returned 11 objects of various types.
Shallow Sky: returned about 10 objects
Interesting Deep Sky: returned zero objects (which I'm surprised because even the pleiades is viewable with naked eye)
NGC/IC: zero objects
Off the beaten path: zero objects
Interesting stars: 18 objects
Double stars: 187 objects

I'm worried that its filtering out objects which I may in fact be able to see.
And I wonder if there is a way to see the full list without any visibility filtering?

I think the DB Power Search Tool is going to provide much more viable lists.
I was able to get it to return 28xxx galaxies with one query.
Getting that large a number of items diminished my worries significantly
I was able to print that full list to a PDF file.

It would be nice if I could save the results of a generated list with all of columns of data such as RA, DEC, Magnitude etc.
Is there a way to do that?

I initially worked through the audio tutorials - and am now watching the video tutorials.
Thanks again

(2019-01-15, 10:26 PM)dw_Skyhound Wrote:
(2019-01-15, 12:20 AM)theskyhound Wrote: Oh yes - you asked about connecting it to telescope - I currently don't have any automated scopes.
My primary concern at this point is making sure the program is returning viable lists.

You mentioned generating a list of Alpha stars - I'll see if I can't figure out how to do that.
Thanks again.
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#6
Hello,

It is important to understand that when using the Nightly Observing List Generator that it works off from the settings on the Nightly Planner. It uses the night, telescope, location, and your time sliders. Sometimes people try it on a night of full moon, and wonder why more objects aren't listed. So take a careful look at the night and other planner selections before using it.

Please do not make assumptions about how useful a tool is until you understand it thoroughly. Note that all of these things do have extensive help pages.

If you feel it is not showing you objects that are detectable in your telescope, then look for errors in your telescope (ensure you have the proper units for the aperture and focal length) and location (ensure you have the proper longitude, latitude and sky brightness settings).

Your observing list can be printed or copied to the Windows clipboard for pasting into any document.
Clear skies,
Greg

SkyTools Developer
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#7
(2019-01-15, 10:35 PM)theskyhound Wrote: Thanks Greg!
I'll keep plugging along.
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#8
Hi dw_Skyhound,

I don't know if the ST3 Standard version includes the Data Manager like the Pro version or not, but if it does, you can download Observing Lists from the Skyhound website. I found a list there called 'Autostar Alignment Stars' that may be what you're looking for. The list contains many of the brightest stars in the sky.

The Skyhound site also has lists for the objects in Burnham's Celestial Handbook (BCH) that you might find interesting. BCH lists many interesting stars and DSO's by constellation. Skyhound also has observing lists compiled by many different sources.

Finally the Database Power Search can provide a list of stars that meet your criteria, such as brighter than 2 magnitude, etc. as well as many other objects.

I hope that I understood your question & that this is helpful,

Phil S.
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#9
(2019-01-16, 05:55 PM)PMSchu Wrote: Thank you kindly Phil!
Very kind of you to post those comments.

Yes the Standard vs does include the Data manager - and per your suggestion (as a test) I downloaded the "100 Brightest Galaxies"

Obtaining a list from another source is interesting because that list is not affected by your particular visibility limitations which you've set up in the software.  Date/Time, Location brightness, Observer pupil dilation, and Instrument parameters - all function to limit items that will be generated on a list.  

So the "100 Brightest Galaxies" list (if generated in SkyTools) would have had to be setup to ensure none of those 100 Galaxies were excluded from its list.  I wonder how the person who generated that list was able to ensure what Galaxies were included in the list?

Also, I was able to use the power search tool to pull a list of stars based on magnitude filtering.
Thanks for pointing that out.

When I get a chance I'll check out the lists for the objects in Burnham's Celestial Handbook.
Thanks very much for mentioning that!
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#10
Hi dw_Skyhound,

I'm glad my prior post was helpful. Regarding the effects of observer, age, telescope, etc., have you tried setting the visibility parameter at the right side of the observing list to 'Ignore Difficulty'? That should make most objects appear in the list unless they're below the horizon.

If you set the Database Power Search to 'Ignore Difficulty' the effects of observer, location, scope will be ignored there too.

Phil S.
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