From: hastro-l Mailing List
Date: November 2023
Subject: Comet Halley in Aphel
Contributed by Rob H. Van Gent

According to JPL's online ephemeris app
  https://ssd.jpl.nasa.gov/horizons/app.html#/
aphelion distance will be 35.1434652 au on 9 December 2023 at 1h 00.0m UT.
The greatest geocentric distance, 36.1162710 au, occurred about four 
months ago on 29 July 2023 at 14h 14.6m UT.
The next greatest geocentric distance will be 36.1122136 au on 28 July 2024 
at 05h 52.4m UT.

Repeating the same exercise with IMCCE's online ephemeris calculator 
("Ephemerides de position")
  https://ssp.imcce.fr/forms/ephemeris
the aphelion distance is predicted as 35.1412239 au on 7 December 2023 
at 18h 17.0m UTC.
Similarly, the greatest geocentric distance, 36.1140698 au, is computed 
to have occurred on 29 July 2023 at 14h 11.5m UTC.
Aldo Vitagliano's SOLEX software
  http://www.solexorb.it/
predicts an aphelion distance of 35.140945 au on 7 December 2023 at 
09h 36m 02s TT.
The greatest geocentric distance, 36.113802 au, is computed to have occurred 
on 29 July 2023 at 14h 11m 43s TT.