Hello Richard,

> O.K. Sam -  I hadn’t picked up the fact that the spread of observations during the 30-day arc was very poor. That
> explains it in that the MPC and JPL ephemerides are different because of the actual observations employed along with any
> weighting factors, etc. also differ.
>
> Given Maik’s linkage, when do you think we can expect the new orbit to be published so that we can then plan an
> observing campaign to recover the object?

Personally, I think the linkage is safe. It would be a very big coincidence to have 2007 HE4 moving on a perfectly
fitted arc of one month without systematic deviations which are usually a tell-tale sign of an incorrect link.

I have also checked several logbooks of observatories for possible observations, especially of the favourable apparition
of 1963/64, but was not successful. Elizabeth Roemer missed it by 2.3 degrees on 1964 Feb 4, when she was imaging
59P/Kearns-Kwee. Denning would have been then maybe of magnitude 14-15.

Unfortunately, 1964 not many surveys were operating, POSS I was already over. But it is not astonishing to miss such a
faint comet, there are many which have been missed that were even brighter.

I think the final decision will be the next perihelion. It is not perfect but also not awfully bad and it may reach 18
mag or brighter. Here's an orbit for this epoch.

Orbital elements:  D/1894 F1
    Perihelion 2025 Dec 4.06727 TT =  1:36:52 (JD 2461013.56727)
A1: -3.83e-9    A2: 3.58e-10  AU/day^2
Epoch 2025 Dec  1.0 TT = JDT 2461010.5   Earth MOID: 0.5820   Ju: 0.0606
M 359.67526526                      Ma: 0.0222                   Meyer
n   0.10587093     Peri.  109.41912
a   4.42538997     Node    20.62196
e   0.6471858      Incl.    4.02545                       (J2000 ecliptic)
P   9.31           H   15.0     G   0.15   q 1.56134008  Q 7.28943986
242 of 312 observations 1894 Mar. 27-2007 May 18; mean residual 3".28

I think it would be good to publish an orbit for folks to be aware and try to recover it early.

Regards

Maik
--
"One cannot discover comets lying in bed." * Lewis Swift
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