Thank you for the info, and that sounds reasonable.

I am going to try download the comet database. and see if I can use Skyview.

I am bit worry that I am using old data, but maybe it is still valid.

this is from this pdf I found in the web:

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SiTechExe Help
SkyView Orbits
as of Version 0.91V

Here's a screen shot:
http://siderealtechnology.com/CometAsteroidsScreenGrab.jpg
Comets:
If you want to select and/or goto/track Comets, here's a step by step procedure:
1. Download the file named Soft00Cmt.txt from the minor planet center.
You can do that by clicking on the menu item labeled Orbits/Load Comets From Internet: Soft00Cmt.txt
This file is only 150K, currently, there's about 900 comets in it.
Normally, this file can be downloaded here:
http://www.minorplanetcenter.net/iau/Ephemerides/Comets/Soft00Cmt.txt
If you want to get this file somewhere else, you can change the path in the SiTechExe/Config tab/ChangeConfig/Misc.
However, it has to have the exact same format as Soft00Cmt.txt.
If you want, you can download this file manually, then place it here:
C:\ProgramData\SiTech\SiTechExe\Database\Soft00Cmt.txt
Your path may vary depending on your windows computer and location settings.
This should be downloaded occasionally, to get the latest orbital elements.
2. Once you've downloaded the file, you can select the menu item:
Orbits/Load Comets From Existing Soft00Cmt.txt
This will calculate the Comet orbits, and put the data into memory.
3. Set up the limiting magnitude you want for the comets under the Magnitudes menu.
4. Under the Objects menu, turn on Comets
Now there should be comets on SkyView.
You can search for a particular comet by selecting the Orbits/Search For Comet
You can put in an integer here, it will return the indexed comet. For instance, "1" would return "Hale Bopp", "10" would return "P/2000 S1 (Skiff)"
Otherwise, it will look for the string you specify. It's not case sensitive, you can use lower or upper. It returns the first occurance of your string.
Thus, "C/2013 E" would return "C/2013 E1 (McNaught)", even though there is an "E2".
I think the coolest feature is the menu item Orbits/Comet Selection and Sorting.
It loads all the comets from the Soft00Cmt.txt file into a listBox and you can sort by Altitude, Magnitude, Motion, Distance from Earth or File order.
For instance, to look for the brightest comet that's above the horizon, you can sort by Magnitude, and then look through the Altitudes column to find the highest one you're interested in.
Double click on an entry (or click the OK button) , and you have the option to GoTo/Sync or Center Skyview on the Comet.
If you want to GoTo the comet, you can make sure the "Track Planetoid" is checked. This is the default.

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On 4/4/2020 2:42 PM, Don W wrote: