| 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) |
| 2026-07-29 00:00 |
09:49:17.05 |
-00:33:53.8 |
HIP 48118 |
17.96 |
| 2026-07-29 12:00 |
09:49:19.12 |
-00:34:02.0 |
HIP 48118 |
18.15 |
| 2026-07-30 00:00 |
09:49:21.21 |
-00:34:10.3 |
HIP 48118 |
18.36 |
| 2026-07-30 12:00 |
09:49:23.29 |
-00:34:18.7 |
HIP 48118 |
18.58 |
| 2026-07-31 00:00 |
09:49:25.39 |
-00:34:27.1 |
HIP 48118 |
18.81 |
| 2026-07-31 12:00 |
09:49:27.49 |
-00:34:35.7 |
HIP 48118 |
19.05 |
| 2026-08-01 00:00 |
09:49:29.59 |
-00:34:44.4 |
HIP 48118 |
19.31 |
| 2026-08-01 12:00 |
09:49:31.70 |
-00:34:53.2 |
HIP 48118 |
19.58 |
| 2026-08-02 00:00 |
09:49:33.81 |
-00:35:02.1 |
HIP 48118 |
19.86 |
| 2026-08-02 12:00 |
09:49:35.93 |
-00:35:11.0 |
HIP 48118 |
20.14 |
| 2026-08-03 00:00 |
09:49:38.06 |
-00:35:20.1 |
HIP 48118 |
20.45 |
| 2026-08-03 12:00 |
09:49:40.18 |
-00:35:29.2 |
HIP 48118 |
20.76 |
| 2026-08-04 00:00 |
09:49:42.32 |
-00:35:38.5 |
HIP 48118 |
21.08 |
| 2026-08-04 12:00 |
09:49:44.45 |
-00:35:47.8 |
HIP 48118 |
21.41 |
| 2026-08-05 00:00 |
09:49:46.59 |
-00:35:57.2 |
HIP 48118 |
21.74 |
| 2026-08-05 12:00 |
09:49:48.74 |
-00:36:06.8 |
HIP 48118 |
22.09 |
| 2026-08-06 00:00 |
09:49:50.89 |
-00:36:16.4 |
HIP 48118 |
22.45 |
| 2026-08-06 12:00 |
09:49:53.04 |
-00:36:26.1 |
HIP 48118 |
22.81 |
| 2026-08-07 00:00 |
09:49:55.20 |
-00:36:35.8 |
HIP 48118 |
23.19 |
| 2026-08-07 12:00 |
09:49:57.35 |
-00:36:45.7 |
HIP 48252 |
23.35 |
| 2026-08-08 00:00 |
09:49:59.52 |
-00:36:55.7 |
HIP 48252 |
23.44 |
| 2026-08-08 12:00 |
09:50:01.68 |
-00:37:05.7 |
HIP 48252 |
23.54 |
| 2026-08-09 00:00 |
09:50:03.85 |
-00:37:15.8 |
HIP 48252 |
23.65 |
| 2026-08-09 12:00 |
09:50:06.02 |
-00:37:26.1 |
HIP 48252 |
23.78 |
| 2026-08-10 00:00 |
09:50:08.20 |
-00:37:36.4 |
HIP 48252 |
23.92 |
| 2026-08-10 12:00 |
09:50:10.37 |
-00:37:46.8 |
HIP 48252 |
24.08 |
| 2026-08-11 00:00 |
09:50:12.55 |
-00:37:57.2 |
HIP 48252 |
24.25 |
| 2026-08-11 12:00 |
09:50:14.73 |
-00:38:07.8 |
HIP 48252 |
24.43 |
| 2026-08-12 00:00 |
09:50:16.92 |
-00:38:18.4 |
HIP 48252 |
24.63 |
| 2026-08-12 12:00 |
09:50:19.10 |
-00:38:29.1 |
HIP 48252 |
24.84 |
| 2026-08-13 00:00 |
09:50:21.29 |
-00:38:39.9 |
HIP 48252 |
25.06 |
| 2026-08-13 12:00 |
09:50:23.48 |
-00:38:50.8 |
HIP 48252 |
25.30 |
| 2026-08-14 00:00 |
09:50:25.66 |
-00:39:01.8 |
HIP 48252 |
25.54 |
| 2026-08-14 12:00 |
09:50:27.86 |
-00:39:12.8 |
HIP 48252 |
25.80 |
| 2026-08-15 00:00 |
09:50:30.05 |
-00:39:23.9 |
HIP 48252 |
26.07 |
| 2026-08-15 12:00 |
09:50:32.24 |
-00:39:35.1 |
HIP 48252 |
26.36 |
| 2026-08-16 00:00 |
09:50:34.43 |
-00:39:46.4 |
HIP 48252 |
26.65 |
| 2026-08-16 12:00 |
09:50:36.63 |
-00:39:57.7 |
HIP 48252 |
26.95 |
| 2026-08-17 00:00 |
09:50:38.82 |
-00:40:09.1 |
HIP 48252 |
27.27 |
| 2026-08-17 12:00 |
09:50:41.01 |
-00:40:20.6 |
HIP 48252 |
27.59 |
| 2026-08-18 00:00 |
09:50:43.21 |
-00:40:32.1 |
HIP 48252 |
27.92 |
| 2026-08-18 12:00 |
09:50:45.40 |
-00:40:43.8 |
HIP 48252 |
28.27 |
| 2026-08-19 00:00 |
09:50:47.60 |
-00:40:55.5 |
HIP 48252 |
28.62 |