| 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) |
| 2026-05-12 00:00 |
19:36:29.71 |
-87:46:39.2 |
HIP 97658 |
9.18 |
| 2026-05-12 12:00 |
19:35:58.59 |
-87:47:10.5 |
HIP 97658 |
9.22 |
| 2026-05-13 00:00 |
19:35:26.73 |
-87:47:41.7 |
HIP 97658 |
9.31 |
| 2026-05-13 12:00 |
19:34:54.13 |
-87:48:12.7 |
HIP 97658 |
9.43 |
| 2026-05-14 00:00 |
19:34:20.78 |
-87:48:43.5 |
HIP 97658 |
9.60 |
| 2026-05-14 12:00 |
19:33:46.68 |
-87:49:14.1 |
HIP 97658 |
9.81 |
| 2026-05-15 00:00 |
19:33:11.83 |
-87:49:44.6 |
HIP 97658 |
10.05 |
| 2026-05-15 12:00 |
19:32:36.22 |
-87:50:14.8 |
HIP 97658 |
10.33 |
| 2026-05-16 00:00 |
19:31:59.85 |
-87:50:44.9 |
HIP 97658 |
10.64 |
| 2026-05-16 12:00 |
19:31:22.72 |
-87:51:14.7 |
HIP 97658 |
10.98 |
| 2026-05-17 00:00 |
19:30:44.81 |
-87:51:44.4 |
HIP 97658 |
11.35 |
| 2026-05-17 12:00 |
19:30:06.14 |
-87:52:13.8 |
HIP 97658 |
11.74 |
| 2026-05-18 00:00 |
19:29:26.69 |
-87:52:43.0 |
HIP 97658 |
12.16 |
| 2026-05-18 12:00 |
19:28:46.47 |
-87:53:12.0 |
HIP 97658 |
12.59 |
| 2026-05-19 00:00 |
19:28:05.46 |
-87:53:40.7 |
HIP 97658 |
13.04 |
| 2026-05-19 12:00 |
19:27:23.68 |
-87:54:09.3 |
HIP 97658 |
13.51 |
| 2026-05-20 00:00 |
19:26:41.12 |
-87:54:37.5 |
HIP 97658 |
13.99 |
| 2026-05-20 12:00 |
19:25:57.77 |
-87:55:05.6 |
HIP 97658 |
14.48 |
| 2026-05-21 00:00 |
19:25:13.64 |
-87:55:33.3 |
HIP 97658 |
14.99 |
| 2026-05-21 12:00 |
19:24:28.73 |
-87:56:00.9 |
HIP 97658 |
15.51 |
| 2026-05-22 00:00 |
19:23:43.03 |
-87:56:28.1 |
HIP 97658 |
16.03 |
| 2026-05-22 12:00 |
19:22:56.54 |
-87:56:55.1 |
HIP 97658 |
16.57 |
| 2026-05-23 00:00 |
19:22:09.27 |
-87:57:21.9 |
HIP 97658 |
17.11 |
| 2026-05-23 12:00 |
19:21:21.21 |
-87:57:48.3 |
HIP 97658 |
17.66 |
| 2026-05-24 00:00 |
19:20:32.36 |
-87:58:14.5 |
HIP 97658 |
18.22 |
| 2026-05-24 12:00 |
19:19:42.73 |
-87:58:40.4 |
HIP 97658 |
18.78 |
| 2026-05-25 00:00 |
19:18:52.31 |
-87:59:06.0 |
HIP 97658 |
19.35 |
| 2026-05-25 12:00 |
19:18:01.11 |
-87:59:31.3 |
HIP 97658 |
19.93 |
| 2026-05-26 00:00 |
19:17:09.13 |
-87:59:56.2 |
HIP 97658 |
20.50 |
| 2026-05-26 12:00 |
19:16:16.37 |
-88:00:20.9 |
HIP 97658 |
21.09 |
| 2026-05-27 00:00 |
19:15:22.83 |
-88:00:45.3 |
HIP 97658 |
21.67 |
| 2026-05-27 12:00 |
19:14:28.51 |
-88:01:09.3 |
HIP 97658 |
22.26 |
| 2026-05-28 00:00 |
19:13:33.42 |
-88:01:33.1 |
HIP 97658 |
22.86 |
| 2026-05-28 12:00 |
19:12:37.56 |
-88:01:56.5 |
HIP 97658 |
23.45 |
| 2026-05-29 00:00 |
19:11:40.94 |
-88:02:19.5 |
HIP 97658 |
24.05 |
| 2026-05-29 12:00 |
19:10:43.55 |
-88:02:42.2 |
HIP 97658 |
24.65 |
| 2026-05-30 00:00 |
19:09:45.40 |
-88:03:04.6 |
HIP 97658 |
25.26 |
| 2026-05-30 12:00 |
19:08:46.49 |
-88:03:26.6 |
HIP 97658 |
25.86 |
| 2026-05-31 00:00 |
19:07:46.84 |
-88:03:48.3 |
HIP 97658 |
26.47 |
| 2026-05-31 12:00 |
19:06:46.44 |
-88:04:09.6 |
HIP 97658 |
27.08 |
| 2026-06-01 00:00 |
19:05:45.31 |
-88:04:30.5 |
HIP 97658 |
27.69 |
| 2026-06-01 12:00 |
19:04:43.44 |
-88:04:51.1 |
HIP 97658 |
28.31 |
| 2026-06-02 00:00 |
19:03:40.84 |
-88:05:11.3 |
HIP 97658 |
28.92 |