Here is a step by step example for writing 103P/Hartley 2 data directly to the Comets.txt files stored in the Sky Data folder. You can add single or multiple comets using this method.
1. Go to http://www.minorplanetcenter.net/iau/MPEph/MPEph.html
2. Enter 103P/Hartley 2 into the search box.
Make sure under "Format for elements output:" you select "Starry Night (Sienna Software)":
3. Click on
4. An elements.txt will be downloaded to your computer.
5. Open the elements.txt file and you will see the following:
6. Open the Starry Night comets.txt file, add the new line of data, and save.
Note, I have changed its name from Hartley to 103P/Hartley 2.
The comets.txt file is located in the following locations:
Windows: (C:) ---> ProgramFiles ---> Starry Night folder ---> SkyData ---> Comets.txt
Mac OSX: Macintosh HD ---> Applications ---> Starry Night folder ---> right click the Starry Night program icon ---> Choose "Show package contents" ---> Contents ---> Resources ---> Sky Data ---> Comets.txt
7. Start Starry Night. Open the FIND tab. Search for "103P" (begins with) and the comet will show up:
Minor Planet Center's orbital elements for 103P/Hartley 2 are attached (April 2012) if you wish to use them.