How To: Add an object to the SkyChart - Interstellar comet C/2019 Q4 Example

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Posts: 128
Joined: Thu Aug 23, 2018 8:22 pm
Location: Missouri, USA

Tue Oct 15, 2019 10:03 am

I recently was messing around trying to figure out how to add my own object into the SkyChart if I know the orbital elements. This is usually done for you automatically when you update the Asteroid or Comet databases by using the SkyChart settings, and navigating and clicking on the internet download button. In this example, the newly discovered interstellar visitor, C/2019 Q4 Borisov had at the time, not yet been added to the Comet database that gets downloaded (they were still making observations to get the orbital elements confirmed), but they had published the results to that point and had some rough estimated elements published.

Where to get "orbital elements": I like the Minor Planet Center's online database, you can find it here: At the top of this page you should see a box to enter the name of the object, in this example I'm using "C/2019 Q4" Click show and you will get the following Table, I have made the text of the elements you need to enter into Prism BOLD:
C/2019 Q4 (Borisov)
First observed at MARGO, Nauchnij on 2019-08-30.

epoch 2019-04-27.0
epoch JD 2458600.5
perihelion date 2019-12-08.40006
perihelion JD 2458825.90006
argument of perihelion (°) 208.98541
ascending node (°) 308.20581
inclination (°) 43.99379
eccentricity 3.3835756

perihelion distance (AU) 2.0126273
radial non-grav. param.
transverse non-grav. param.
semimajor axis (AU)
mean anomaly (°)
mean daily motion (°/day)
aphelion distance (AU)
period (years)
P-vector [x] -0.81496106
P-vector [y] 0.56670903
P-vector [z] -0.12115833
Q-vector [x] -0.19479186
Q-vector [y] -0.46478201
Q-vector [z] -0.86373249
recip semimajor axis orig (AU) -1.182275
recip semimajor axis future (AU) -1.18249
recip semimajor axis error (AU) 0.0057168
reference E2019-S62
observations used 457
residual rms (arc-secs) 0.50
perturbers coarse indicator M-v
perturbers precise indicator 0038h
first observation date used 2019-08-30.0
last observation date used 2019-09-23.0
computer name Williams
orbit quality code

Now in Prism, open your SkyChart, click the Gears icon to go into SkyChart Setup, Navigate to the "Solar System / Comets" tab, Check the box "Load Comets", below that Click the Display Tab, click the "Orbit and Trajectory" button. This will display a widow "Orbits of the Solar System" with two tabs, the first is "User Comet"

Enter the elements in the corresponding boxes, a Name for the object, the Perihelion date in Julian Day format (check the bold list above), the Eccentricity of the orbit, the Inclination, Longitude of the Ascending Node, Perihelion and finally the distance to Perihelion.

Check the box that says "Put this object in the sky chart"
Optional - Click on the Trajectory tab, and check "Display object trajectory" enter the number of days you want to see and click OK, then OK again to get back to the skychart.

In the upper left hand side of your skychart you should see a box with your objects name in it, Double click on it and your skychart will center on your object. If you elected to display the trajectory you should see it as a yellow line.

I will add some screenshots here in the coming days for this. Please let me know if you found this How To helpful or not. Clear sky's!
Hamza Touhami
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Posts: 564
Joined: Sat May 20, 2017 6:05 pm
Location: Phoenix,AZ

Thu Oct 17, 2019 12:18 pm

Awesome Scott
Hamza Touhami | Site Administrator
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