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Position Ephemeris - Printable Version

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Position Ephemeris - bigmasterdrago - 2020-03-28

I read that the "Rs" tab is the distance from the object to Earth. Is there a way to have it show Kilometers? Is it geocentric or topocentric (my location)?

RE: Position Ephemeris - theskyhound - 2020-03-28

It automatically selects the most appropriate units. It will switch to kn when near the earth.

RE: Position Ephemeris - bigmasterdrago - 2020-04-07

When trying to determine when closest approach happens, normally we assume when brightest. This is not necessarily so due to changes in phase angle etc. Since my column Re is only showing AU = 0.00, I cannot really figure out when that happens. in the ephemeris since it has not switched to kilometers. Looks to be ~Apr 8, 19:30UT based on Horizons and others. I used the just downloaded the MPC NEA Today els. The position tomorrow (Apr 8) at 15:00cdt shows 22h38m23.9s +32d54'01s in ST4. This should closely jive with that of Horizons (Apr 8, 22:00UT) 22 39 33.13 +32 29 47.7. Position difference is ~1/2 degree away. I've checked over the location lat and long, times, etc and cannot discover the dependency. Please help.

[Image: fcMhoZ6.jpg]

RE: Position Ephemeris - theskyhound - 2020-04-07

Ok, it is supposed to switch so something is wrong. I am preparing the next update and will have this fixed when it comes out.

RE: Position Ephemeris - bigmasterdrago - 2020-07-16

Thanks for the fix with the distance. It now can read hundredths of an A.U. I've also been experimenting with the MPC NEA and the MPC NEA Today asteroid downloads. I'm not sure what the difference is except that the Today looks to build a list with epochs now. I've also now found that as long as I stay within about a 12 hour window, the generated ephemerides are very close to those made at Horizons. This helps greatly with chart making. I still have been unable to copy and paste from a set of orbital elements created by Horizons so that I can plan several days ahead on a possible position fix of a close pass asteroid. i.e. 2016 DY30 on July 19 ~5UT. Maybe I'm still doing something wrong. I'm trying to copy and paste the text below.

2459049.708333333 = A.D. 2020-Jul-19 05:00:00.0000 TDB
EC= 5.110455240473311E-01 QR= 5.463558241559977E-01 IN= 7.681152919084764E-01
OM= 1.584502008168773E+02 W = 2.489835182502317E+02 Tp= 2459111.211830436718
N = 8.344366050810789E-01 MA= 3.086792306767361E+02 TA= 2.481067701965983E+02
A = 1.117396099282022E+00 AD= 1.688436374408047E+00 PR= 4.314288201259102E+02

RE: Position Ephemeris - theskyhound - 2020-07-16

I just pasted the text above and it worked fine. When reporting a problem please explain how it goes wrong. For instance, is there are error? What procedure did you use? It saves me guessing and a lot of time going back and forth.

1. Open the Minor Planets database.
2. Click on Enter New Minor Planet
3. Copy the text to the clipboard
4. Click on Paste
5. Enter the designation of the object (obviously HORIZONS does not include it)
6. Click Ok
7. Click Accept

RE: Position Ephemeris - bigmasterdrago - 2020-07-17

Okay. Seems to work. And the copy and paste works. Thanks for that fix. But... in the elements in post #5, would you say the epoch is 2020-Jul-19 05:00. If I take those elements with the epoch date of July 19 5:00 and then run the position ephemeris starting date July 19 I get an ephemeris that agrees with Horizons very closely. You get a pair of gold stars! Finally it works for me also. You have one more happy camper. Thanks again from one old man to another.