Skyhound Forums
Another Visual Sky Simulation issue? - Printable Version

+- Skyhound Forums (https://skyhound.com/forums)
+-- Forum: SkyTools Support (https://skyhound.com/forums/forumdisplay.php?fid=20)
+--- Forum: SkyTools 3 General Support (https://skyhound.com/forums/forumdisplay.php?fid=12)
+--- Thread: Another Visual Sky Simulation issue? (/showthread.php?tid=475)



Another Visual Sky Simulation issue? - chrisp9au - 2019-03-11

Running Windows 10, SkyTools 3 Standard.
In the Visual Sky Simulation, why are globular clusters devoid of stars in the display?
For example, the attached Visual Sky Simulation display of 47 Tucana, Zero stars?
It's the same for any globular that I select.
Thank you.


RE: Another Visual Sky Simulation issue? - theskyhound - 2019-03-11

Hello,

That's not a limitation of SkyTools itself, but because all of the available deep star catalogs intentionally mask out the centers of globular clusters. There are too many stars and they overlap too much to get good positions for them. I will be rebuilding the star database from the Gaia catalog in the future, but I have not yet checked to see if they did the same.


RE: Another Visual Sky Simulation issue? - PMSchu - 2019-03-11

Hi Chris,

If you download one of the Palomar Sky Survey (PSS) images for a bright globular cluster, you'll see that the center of the cluster is 'burned out' with no resolvable stars. Images like this are the starting point for many of the star catalogs & if the core of the cluster is 'burned out', the stars can't be identified individually.

As Greg said, the newer catalogs may not have this limitation.

I hope this helps,

Phil S.


RE: Another Visual Sky Simulation issue? - chrisp9au - 2019-03-11

(2019-03-11, 12:41 PM)theskyhound Wrote: Hello,

That's not a limitation of SkyTools itself, but because all of the available deep star catalogs intentionally mask out the centers of globular clusters. There are too many stars and they overlap too much to get good positions for them. I will be rebuilding the star database from the Gaia catalog in the future, but I have not yet checked to see if they did the same.

Thanks Greg

(2019-03-11, 06:37 PM)PMSchu Wrote: Hi Chris,

If you download one of the Palomar Sky Survey (PSS) images for a bright globular cluster, you'll see that the center of the cluster is 'burned out' with no resolvable stars. Images like this are the starting point for many of the star catalogs & if the core of the cluster is 'burned out', the stars can't be identified individually.

As Greg said, the newer catalogs may not have this limitation.

I hope this helps,

Phil S.
Thanks Phil


RE: Another Visual Sky Simulation issue? - theskyhound - 2019-03-11

By the way, one way around this in SkyTools is to download a DSS image for the globular cluster you are interested in and display it in the chart background. The masks were often much wider than necessary, and the image fills in the chart nicely. I suggest a DSS 2 image.


RE: Another Visual Sky Simulation issue? - chrisp9au - 2019-03-11

(2019-03-11, 07:58 PM)theskyhound Wrote: By the way, one way around this in SkyTools is to download a DSS image for the globular cluster you are interested in and display it in the chart background. The masks were often much wider than necessary, and the image fills in the chart nicely. I suggest a DSS 2 image.

Thanks Greg.

I note that the representation of objects such as the Magellanic clouds is a large disk showing their extent. 
Could not globular clusters also be represented in this way? It would provide a better guide than a blank space? 
Anyway, I know you are very busy with other projects, especially ST 4 Visual which I;m looking forward to.
Thanks again, Chris


RE: Another Visual Sky Simulation issue? - theskyhound - 2019-03-11

Hello,

All objects are indicated by some sort of outline or symbol, including Globular Clusters. Things to try:

1. Open the View Controls and ensure that the display of Globular Clusters is turned on

2. Open the Chart Preferences and for Globular Clusters ensure that the outline color is visible against the background and at least one pixel wide. If you want the area to be filled with color, enable Fill and ensure that the color is visible against the background.