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I tried to download orbital positions for the DSCOVR spacecraft in its Lissajous orbit around Sun-Earth L1 from JPL's Horizons web page but I was surprised to see the following!

No ephemeris for target "DSCOVR (spacecraft)" after A.D. 2017-JAN-03 12:06:08.1840 TDB

Question: Where can I download historical positions for DSCOVR between 2017 and the present? I think there is positional information available in the stream along with the EPIC Earth photos but I don't know where those are found.

SPACECRAFT TRAJECTORY: 
  Concatenated trajectories (DSN)
  Based on tracking data through 2015-Aug-4, prediction thereafter.

Trajectory name                            Start (TDB)          Stop (TDB)




DSCO-2015-02-11-Nominal_withMCC.V0.1    2015-Feb-11 23:46   2015-Mar-09
  23month_20150309_01.V0.1                2015-Mar-09         2015-Jul-13
  21day_20150803_01.V0.1                  2015-Jul-13         2015-Aug-03
  21day_20150803_01.V0.1                  2015-Aug-03         2015-Aug-04
  18month_20150804_01.V0.1                2015-Aug-04         2017-Jan-03 12:06
uhoh
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  • companion question: Why hasn't DSCOVR's trajectory determination been updated in JPL's Horizons after 2015-Aug-4? – uhoh Jun 27 '20 at 04:51
  • So far I've found https://epic.gsfc.nasa.gov/about/api and you can get a JSON for any given day like this https://epic.gsfc.nasa.gov/api/enhanced/date/2017-08-21 but the coordinates are probably geocentric and I haven't figured out how exactly to interpret them, do they use the J2000.0 ecliptic as a reference frame or the Earth's equator, or is it more complicated? Now I've found this: https://russss.github.io/epic-image-processing/index.html Eventually I'll get it but someone please feel free to post an answer first! – uhoh Jun 27 '20 at 07:10
  • Is the part about images in the title an oversight? It's not addressed in the question body. I could write a partial answer, but it seems that you already found that based on a comment. The coordinates part is much more interesting! – Organic Marble Jun 27 '20 at 13:15
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    @OrganicMarble I knew that wherever the "official site" with images could be found and downloaded there was also a json with some coordinates for each photo, so I included it in the title (i.e. find the official image download page and you've found the coordinates as well.) If you've found a place for images only and the coordinates are not there, then I guess it would still be an interesting/helpful answer to some readers and worth posting as a "supplementary answer". – uhoh Jun 27 '20 at 13:20

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