Comet 3I/ATLAS reached perihelion on 2025 October 29 and I've been doing video astrometry and photometry of it since Nov 21. I downloaded all astrometry from the MPC website and processed them with Bill Gray's online Find_Orb to fit an orbit to determine the residuals in RA and Dec for each observation.

The attached plots show the residuals (in arcsec) . My datapoints (MPC Z92) are plotted as black discs; stations reporting a telescope aperture of at least 0.5-m are plotted in red; all other observations are marked in grey. There's some discordant measurements but the trend shows that 3I is closely following its hyperbolic trajectory through the solar system. 

Orbital elements:  3I = C/2025 N1 (ATLAS)

   Perihelion 2025 Oct 29.48058 +/- 0.000532 TT = 11:32:01 (JD 2460977.98058)

Epoch 2025 Jul 10.0 TT = JDT 2460866.5   Earth MOID: 0.3648   Ju: 0.2465

q   1.35641460 +/- 3.29e-5          Ma: 0.0180   Sa: 0.4073      Auto-Find

H    9.48 G 0.15                    Peri.  128.00218 +/- 0.0010

z  -3.7890288379 +/- 0.000105       Node   322.15199 +/- 0.00029

e   6.1394940 +/- 0.000267          Incl.  175.11302 +/- 0.000047

1962 of 2199 observations 2025 Oct. 31-2026 Jan. 7; mean residual 0".35

There's no evidence of it veering off course to hurtle towards Harvard University...

Hopefully we can follow 3I as it moves into Gemini - then leaves us forever.