| Parameter |
Value |
| Designation |
C/1997 T1 (Utsunomiya) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1997-12-10T03:28:30.063360Z |
| Orbit solution date (soln_date, UTC) |
2022-02-03T20:42:52Z |
| Obs used |
681 |
| NEO |
- |
| M1 |
7.900 |
| K1 |
18.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1997-11-20.0000000 |
| e |
0.99851974 |
| q (au) |
1.359109 |
| a (au) |
918.157376 |
| i (deg) |
127.992638 |
| Ω (om, deg) |
53.702748 |
| ω (w, deg) |
95.965142 |
| M (ma, deg) |
359.999286 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.692 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.692 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
09:28:34.34 |
-38:26:54.1 |
HIP 46517 |
8.64 |
| 2026-07-29 12:00 |
09:28:36.92 |
-38:26:53.8 |
HIP 46517 |
8.16 |
| 2026-07-30 00:00 |
09:28:39.50 |
-38:26:53.6 |
HIP 46517 |
7.68 |
| 2026-07-30 12:00 |
09:28:42.09 |
-38:26:53.7 |
HIP 46517 |
7.21 |
| 2026-07-31 00:00 |
09:28:44.68 |
-38:26:54.1 |
HIP 46517 |
6.74 |
| 2026-07-31 12:00 |
09:28:47.28 |
-38:26:54.6 |
HIP 46517 |
6.28 |
| 2026-08-01 00:00 |
09:28:49.88 |
-38:26:55.4 |
HIP 46517 |
5.83 |
| 2026-08-01 12:00 |
09:28:52.48 |
-38:26:56.4 |
HIP 46517 |
5.40 |
| 2026-08-02 00:00 |
09:28:55.09 |
-38:26:57.7 |
HIP 46517 |
4.97 |
| 2026-08-02 12:00 |
09:28:57.70 |
-38:26:59.2 |
HIP 46517 |
4.57 |
| 2026-08-03 00:00 |
09:29:00.32 |
-38:27:00.9 |
HIP 46517 |
4.19 |
| 2026-08-03 12:00 |
09:29:02.94 |
-38:27:02.9 |
HIP 46517 |
3.85 |
| 2026-08-04 00:00 |
09:29:05.56 |
-38:27:05.0 |
HIP 46517 |
3.55 |
| 2026-08-04 12:00 |
09:29:08.19 |
-38:27:07.5 |
HIP 46517 |
3.31 |
| 2026-08-05 00:00 |
09:29:10.82 |
-38:27:10.1 |
HIP 46517 |
3.14 |
| 2026-08-05 12:00 |
09:29:13.45 |
-38:27:13.0 |
HIP 46517 |
3.05 |
| 2026-08-06 00:00 |
09:29:16.08 |
-38:27:16.1 |
HIP 46517 |
3.06 |
| 2026-08-06 12:00 |
09:29:18.72 |
-38:27:19.4 |
HIP 46517 |
3.15 |
| 2026-08-07 00:00 |
09:29:21.36 |
-38:27:23.0 |
HIP 46517 |
3.32 |
| 2026-08-07 12:00 |
09:29:24.00 |
-38:27:26.8 |
HIP 46517 |
3.57 |
| 2026-08-08 00:00 |
09:29:26.65 |
-38:27:30.8 |
HIP 46517 |
3.88 |
| 2026-08-08 12:00 |
09:29:29.29 |
-38:27:35.1 |
HIP 46517 |
4.23 |
| 2026-08-09 00:00 |
09:29:31.94 |
-38:27:39.6 |
HIP 46517 |
4.62 |
| 2026-08-09 12:00 |
09:29:34.59 |
-38:27:44.3 |
HIP 46517 |
5.03 |
| 2026-08-10 00:00 |
09:29:37.23 |
-38:27:49.3 |
HIP 46517 |
5.47 |
| 2026-08-10 12:00 |
09:29:39.88 |
-38:27:54.5 |
HIP 46517 |
5.92 |
| 2026-08-11 00:00 |
09:29:42.54 |
-38:27:59.9 |
HIP 46517 |
6.39 |
| 2026-08-11 12:00 |
09:29:45.19 |
-38:28:05.5 |
HIP 46517 |
6.87 |
| 2026-08-12 00:00 |
09:29:47.84 |
-38:28:11.4 |
HIP 46517 |
7.35 |
| 2026-08-12 12:00 |
09:29:50.49 |
-38:28:17.5 |
HIP 46517 |
7.85 |
| 2026-08-13 00:00 |
09:29:53.14 |
-38:28:23.9 |
HIP 46517 |
8.35 |
| 2026-08-13 12:00 |
09:29:55.80 |
-38:28:30.4 |
HIP 46517 |
8.85 |
| 2026-08-14 00:00 |
09:29:58.45 |
-38:28:37.2 |
HIP 46517 |
9.36 |
| 2026-08-14 12:00 |
09:30:01.10 |
-38:28:44.2 |
HIP 46658 |
9.71 |
| 2026-08-15 00:00 |
09:30:03.75 |
-38:28:51.5 |
HIP 46658 |
9.28 |
| 2026-08-15 12:00 |
09:30:06.40 |
-38:28:58.9 |
HIP 46658 |
8.87 |
| 2026-08-16 00:00 |
09:30:09.05 |
-38:29:06.6 |
HIP 46658 |
8.48 |
| 2026-08-16 12:00 |
09:30:11.69 |
-38:29:14.5 |
HIP 46658 |
8.10 |
| 2026-08-17 00:00 |
09:30:14.34 |
-38:29:22.7 |
HIP 46658 |
7.75 |
| 2026-08-17 12:00 |
09:30:16.98 |
-38:29:31.0 |
HIP 46658 |
7.42 |
| 2026-08-18 00:00 |
09:30:19.62 |
-38:29:39.6 |
HIP 46658 |
7.11 |
| 2026-08-18 12:00 |
09:30:22.26 |
-38:29:48.4 |
HIP 46658 |
6.84 |
| 2026-08-19 00:00 |
09:30:24.90 |
-38:29:57.4 |
HIP 46658 |
6.61 |