I am having the same problem.
I get the same error message "Apparent Alt/Elevation not found in ephemeris data".
The data IS there:
*****************************************************************************************************************************************************************************************************************************************************************
Date__(UT)__HR:MN R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt Azi____(a-app)___Elev L_Ap_Sid_Time APmag S-brt delta deldot S-O-T /r S-T-O Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR
*****************************************************************************************************************************************************************************************************************************************************************
$$SOE
2021-Nov-18 00:00 Cm 02 37 26.16 +12 30 48.6 02 38 37.76 +12 36 30.4 1720.045 820.0817 77.457834 5.983739 20 15 15.9215 -12.254 3.718 0.00269079633233 -0.2631059 165.1214 /T 14.8384 31.759023 64.509161 -14.28441 n.a. n.a.
2021-Nov-18 00:04 Cm 02 37 33.96 +12 31 43.5 02 38 45.57 +12 37 25.0 1711.117 820.3118 78.179302 6.602058 2
I noticed that the current header says "Azi____(a-app)___Elev"
but an old ephemerides (from 2020-11-10) uses the header "Azi_(a-appr)_Elev"
Maybe that throws HORIZONS off?
Any idea of when a new version of Horizons will be out (or ready for testing)?
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EDIT - I made it work
- I downloaded the data from JPL.
- As Ray mentioned, could not CTRL-A,CTRL-C. I had do manually select and copy the ephemerides data to the clipboard.
- I pasted the data from the clipboard into Notepad++. (Notepad also works)
- Then on line 69 of the file I replaced "Azi____(a-app)___Elev" with "Azi_(a-appr)_Elev" (ignore the quotes).
- Then I saved the .txt file.
- Horizons could read the .txt file with no errors.
- I saved the file in Horizons, to give it the default .eph extension.
- Success!
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