| Parameter |
Value |
| Designation |
C/2002 F1 (Utsunomiya) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2002-04-22T21:33:43.323840Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:15Z |
| Obs used |
161 |
| NEO |
- |
| M1 |
10.600 |
| K1 |
18.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2002-04-05.0000000 |
| e |
0.99953997 |
| q (au) |
0.438299 |
| a (au) |
952.755523 |
| i (deg) |
80.876930 |
| Ω (om, deg) |
289.029545 |
| ω (w, deg) |
125.900029 |
| M (ma, deg) |
359.999400 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.274 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.274 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.973 |
| δ90 |
10.000 |
| Parameter |
Symbol |
Range |
Description |
| Absolute magnitude at 1 AU from Sun and Earth |
H0 |
-5 to 20 |
Intrinsic brightness of the comet |
| Photometric slope parameter |
n |
2 to 6 |
Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor |
gf |
0.8 to 1 |
Degree of forward scattering |
| Backward scattering asymmetry factor |
gb |
-1 to -0.5 |
Degree of backward scattering |
| Partitioning coefficient |
k |
0.8 to 1 |
Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio |
δ90 |
1 to 10 |
Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2002-03-20 |
2002-04-04 |
-4.1418 |
-0.069 |
| 2002-04-04 |
2002-04-14 |
+15.8305 |
+4.380 |
| 2002-04-14 |
2002-04-22 |
-15.9612 |
-5.633 |
| 2002-04-23 |
2002-06-02 |
-3.3496 |
-1.321 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
19:42:49.80 |
-86:54:02.9 |
HIP 94254 |
29.87 |
| 2026-03-26 12:00 |
19:43:05.28 |
-86:54:34.5 |
HIP 94254 |
29.71 |
| 2026-03-27 00:00 |
19:43:20.47 |
-86:55:06.2 |
HIP 94254 |
29.55 |
| 2026-03-27 12:00 |
19:43:35.36 |
-86:55:38.0 |
HIP 94254 |
29.39 |
| 2026-03-28 00:00 |
19:43:49.94 |
-86:56:10.0 |
HIP 94254 |
29.24 |
| 2026-03-28 12:00 |
19:44:04.22 |
-86:56:42.0 |
HIP 94254 |
29.10 |
| 2026-03-29 00:00 |
19:44:18.19 |
-86:57:14.1 |
HIP 94254 |
28.96 |
| 2026-03-29 12:00 |
19:44:31.84 |
-86:57:46.3 |
HIP 94254 |
28.82 |
| 2026-03-30 00:00 |
19:44:45.18 |
-86:58:18.7 |
HIP 94254 |
28.69 |
| 2026-03-30 12:00 |
19:44:58.20 |
-86:58:51.1 |
HIP 94254 |
28.57 |
| 2026-03-31 00:00 |
19:45:10.90 |
-86:59:23.6 |
HIP 94254 |
28.45 |
| 2026-03-31 12:00 |
19:45:23.27 |
-86:59:56.2 |
HIP 94254 |
28.34 |
| 2026-04-01 00:00 |
19:45:35.31 |
-87:00:28.9 |
HIP 94254 |
28.23 |
| 2026-04-01 12:00 |
19:45:47.02 |
-87:01:01.7 |
HIP 94254 |
28.13 |
| 2026-04-02 00:00 |
19:45:58.40 |
-87:01:34.6 |
HIP 94254 |
28.03 |
| 2026-04-02 12:00 |
19:46:09.44 |
-87:02:07.5 |
HIP 94254 |
27.94 |
| 2026-04-03 00:00 |
19:46:20.13 |
-87:02:40.6 |
HIP 94254 |
27.85 |
| 2026-04-03 12:00 |
19:46:30.48 |
-87:03:13.7 |
HIP 94254 |
27.77 |
| 2026-04-04 00:00 |
19:46:40.47 |
-87:03:46.9 |
HIP 94254 |
27.70 |
| 2026-04-04 12:00 |
19:46:50.12 |
-87:04:20.2 |
HIP 94254 |
27.63 |
| 2026-04-05 00:00 |
19:46:59.40 |
-87:04:53.5 |
HIP 94254 |
27.57 |
| 2026-04-05 12:00 |
19:47:08.33 |
-87:05:27.0 |
HIP 94254 |
27.52 |
| 2026-04-06 00:00 |
19:47:16.89 |
-87:06:00.5 |
HIP 94254 |
27.47 |
| 2026-04-06 12:00 |
19:47:25.08 |
-87:06:34.1 |
HIP 94254 |
27.42 |
| 2026-04-07 00:00 |
19:47:32.89 |
-87:07:07.7 |
HIP 94254 |
27.39 |
| 2026-04-07 12:00 |
19:47:40.33 |
-87:07:41.4 |
HIP 94254 |
27.36 |
| 2026-04-08 00:00 |
19:47:47.38 |
-87:08:15.2 |
HIP 94254 |
27.33 |
| 2026-04-08 12:00 |
19:47:54.05 |
-87:08:49.0 |
HIP 94254 |
27.32 |
| 2026-04-09 00:00 |
19:48:00.33 |
-87:09:23.0 |
HIP 94254 |
27.30 |
| 2026-04-09 12:00 |
19:48:06.22 |
-87:09:56.9 |
HIP 94254 |
27.30 |
| 2026-04-10 00:00 |
19:48:11.70 |
-87:10:30.9 |
HIP 94254 |
27.30 |
| 2026-04-10 12:00 |
19:48:16.79 |
-87:11:05.0 |
HIP 94254 |
27.31 |
| 2026-04-11 00:00 |
19:48:21.46 |
-87:11:39.2 |
HIP 94254 |
27.32 |
| 2026-04-11 12:00 |
19:48:25.72 |
-87:12:13.3 |
HIP 94254 |
27.34 |
| 2026-04-12 00:00 |
19:48:29.57 |
-87:12:47.6 |
HIP 94254 |
27.37 |
| 2026-04-12 12:00 |
19:48:32.99 |
-87:13:21.9 |
HIP 94254 |
27.41 |
| 2026-04-13 00:00 |
19:48:35.98 |
-87:13:56.2 |
HIP 94254 |
27.45 |
| 2026-04-13 12:00 |
19:48:38.55 |
-87:14:30.5 |
HIP 94254 |
27.49 |
| 2026-04-14 00:00 |
19:48:40.67 |
-87:15:04.9 |
HIP 94254 |
27.55 |
| 2026-04-14 12:00 |
19:48:42.36 |
-87:15:39.4 |
HIP 94254 |
27.61 |
| 2026-04-15 00:00 |
19:48:43.60 |
-87:16:13.8 |
HIP 94254 |
27.67 |
| 2026-04-15 12:00 |
19:48:44.39 |
-87:16:48.3 |
HIP 94254 |
27.75 |
| 2026-04-16 00:00 |
19:48:44.73 |
-87:17:22.9 |
HIP 94254 |
27.83 |