| Parameter |
Value |
| Designation |
C/2000 W1 (Utsunomiya-Jones) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2000-12-26T13:25:20.971200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:08Z |
| Obs used |
440 |
| NEO |
- |
| M1 |
12.600 |
| K1 |
10.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-12-11.0000000 |
| e |
1.00000177 |
| q (au) |
0.321181 |
| a (au) |
-181492.894591 |
| i (deg) |
160.165435 |
| Ω (om, deg) |
10.765960 |
| ω (w, deg) |
51.508868 |
| M (ma, deg) |
-0.000000 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.558 + 3.641\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.558 |
| n |
3.641 |
| gf |
0.800 |
| gb |
-1.000 |
| k |
0.978 |
| δ90 |
1.000 |
| 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 |
| 2000-11-18 |
2000-11-30 |
-31.0615 |
-1.440 |
| 2000-11-30 |
2000-12-24 |
+5.5320 |
+1.050 |
| 2000-12-28 |
2001-04-26 |
-1.8686 |
+0.093 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
09:53:00.89 |
-00:55:12.8 |
HIP 48582 |
30.72 |
| 2026-09-20 12:00 |
09:53:02.75 |
-00:55:27.2 |
HIP 48582 |
30.22 |
| 2026-09-21 00:00 |
09:53:04.61 |
-00:55:41.7 |
HIP 48582 |
29.72 |
| 2026-09-21 12:00 |
09:53:06.45 |
-00:55:56.2 |
HIP 48582 |
29.22 |
| 2026-09-22 00:00 |
09:53:08.29 |
-00:56:10.7 |
HIP 48582 |
28.72 |
| 2026-09-22 12:00 |
09:53:10.12 |
-00:56:25.1 |
HIP 48582 |
28.22 |
| 2026-09-23 00:00 |
09:53:11.93 |
-00:56:39.6 |
HIP 48582 |
27.73 |
| 2026-09-23 12:00 |
09:53:13.74 |
-00:56:54.1 |
HIP 48582 |
27.24 |
| 2026-09-24 00:00 |
09:53:15.53 |
-00:57:08.6 |
HIP 48582 |
26.75 |
| 2026-09-24 12:00 |
09:53:17.31 |
-00:57:23.2 |
HIP 48582 |
26.27 |
| 2026-09-25 00:00 |
09:53:19.08 |
-00:57:37.7 |
HIP 48582 |
25.79 |
| 2026-09-25 12:00 |
09:53:20.85 |
-00:57:52.2 |
HIP 48582 |
25.31 |
| 2026-09-26 00:00 |
09:53:22.60 |
-00:58:06.7 |
HIP 48582 |
24.83 |
| 2026-09-26 12:00 |
09:53:24.34 |
-00:58:21.2 |
HIP 48582 |
24.36 |
| 2026-09-27 00:00 |
09:53:26.06 |
-00:58:35.7 |
HIP 48582 |
23.89 |
| 2026-09-27 12:00 |
09:53:27.78 |
-00:58:50.2 |
HIP 48582 |
23.42 |
| 2026-09-28 00:00 |
09:53:29.48 |
-00:59:04.8 |
HIP 48582 |
22.96 |
| 2026-09-28 12:00 |
09:53:31.18 |
-00:59:19.3 |
HIP 48582 |
22.50 |
| 2026-09-29 00:00 |
09:53:32.86 |
-00:59:33.8 |
HIP 48582 |
22.04 |
| 2026-09-29 12:00 |
09:53:34.53 |
-00:59:48.3 |
HIP 48582 |
21.58 |
| 2026-09-30 00:00 |
09:53:36.18 |
-01:00:02.8 |
HIP 48582 |
21.13 |
| 2026-09-30 12:00 |
09:53:37.83 |
-01:00:17.3 |
HIP 48582 |
20.68 |
| 2026-10-01 00:00 |
09:53:39.46 |
-01:00:31.7 |
HIP 48582 |
20.24 |
| 2026-10-01 12:00 |
09:53:41.08 |
-01:00:46.2 |
HIP 48582 |
19.80 |
| 2026-10-02 00:00 |
09:53:42.69 |
-01:01:00.7 |
HIP 48582 |
19.36 |
| 2026-10-02 12:00 |
09:53:44.28 |
-01:01:15.1 |
HIP 48582 |
18.92 |
| 2026-10-03 00:00 |
09:53:45.86 |
-01:01:29.6 |
HIP 48582 |
18.49 |
| 2026-10-03 12:00 |
09:53:47.43 |
-01:01:44.0 |
HIP 48582 |
18.07 |
| 2026-10-04 00:00 |
09:53:48.99 |
-01:01:58.4 |
HIP 48582 |
17.64 |
| 2026-10-04 12:00 |
09:53:50.53 |
-01:02:12.8 |
HIP 48582 |
17.22 |
| 2026-10-05 00:00 |
09:53:52.06 |
-01:02:27.2 |
HIP 48582 |
16.81 |
| 2026-10-05 12:00 |
09:53:53.58 |
-01:02:41.5 |
HIP 48582 |
16.39 |
| 2026-10-06 00:00 |
09:53:55.08 |
-01:02:55.9 |
HIP 48582 |
15.99 |
| 2026-10-06 12:00 |
09:53:56.57 |
-01:03:10.2 |
HIP 48582 |
15.58 |
| 2026-10-07 00:00 |
09:53:58.04 |
-01:03:24.5 |
HIP 48582 |
15.18 |
| 2026-10-07 12:00 |
09:53:59.50 |
-01:03:38.8 |
HIP 48582 |
14.79 |
| 2026-10-08 00:00 |
09:54:00.95 |
-01:03:53.0 |
HIP 48582 |
14.40 |
| 2026-10-08 12:00 |
09:54:02.38 |
-01:04:07.3 |
HIP 48582 |
14.01 |
| 2026-10-09 00:00 |
09:54:03.80 |
-01:04:21.5 |
HIP 48582 |
13.63 |
| 2026-10-09 12:00 |
09:54:05.20 |
-01:04:35.7 |
HIP 48582 |
13.25 |
| 2026-10-10 00:00 |
09:54:06.59 |
-01:04:49.8 |
HIP 48582 |
12.88 |
| 2026-10-10 12:00 |
09:54:07.96 |
-01:05:03.9 |
HIP 48582 |
12.52 |
| 2026-10-11 00:00 |
09:54:09.32 |
-01:05:18.0 |
HIP 48582 |
12.16 |