| 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) |
| 2026-09-25 00:00 |
09:33:21.36 |
-38:50:17.7 |
HIP 46888 |
12.06 |
| 2026-09-25 12:00 |
09:33:23.33 |
-38:50:40.6 |
HIP 46888 |
12.48 |
| 2026-09-26 00:00 |
09:33:25.28 |
-38:51:03.7 |
HIP 46888 |
12.90 |
| 2026-09-26 12:00 |
09:33:27.22 |
-38:51:26.9 |
HIP 46888 |
13.34 |
| 2026-09-27 00:00 |
09:33:29.14 |
-38:51:50.2 |
HIP 46888 |
13.78 |
| 2026-09-27 12:00 |
09:33:31.04 |
-38:52:13.7 |
HIP 46888 |
14.23 |
| 2026-09-28 00:00 |
09:33:32.93 |
-38:52:37.3 |
HIP 46888 |
14.69 |
| 2026-09-28 12:00 |
09:33:34.81 |
-38:53:01.1 |
HIP 46888 |
15.16 |
| 2026-09-29 00:00 |
09:33:36.67 |
-38:53:24.9 |
HIP 46874 |
15.40 |
| 2026-09-29 12:00 |
09:33:38.51 |
-38:53:48.9 |
HIP 46874 |
15.16 |
| 2026-09-30 00:00 |
09:33:40.33 |
-38:54:13.0 |
HIP 46874 |
14.94 |
| 2026-09-30 12:00 |
09:33:42.14 |
-38:54:37.3 |
HIP 46874 |
14.73 |
| 2026-10-01 00:00 |
09:33:43.93 |
-38:55:01.6 |
HIP 46874 |
14.54 |
| 2026-10-01 12:00 |
09:33:45.71 |
-38:55:26.1 |
HIP 46874 |
14.36 |
| 2026-10-02 00:00 |
09:33:47.47 |
-38:55:50.7 |
HIP 46874 |
14.19 |
| 2026-10-02 12:00 |
09:33:49.21 |
-38:56:15.4 |
HIP 46874 |
14.04 |
| 2026-10-03 00:00 |
09:33:50.93 |
-38:56:40.3 |
HIP 46874 |
13.90 |
| 2026-10-03 12:00 |
09:33:52.64 |
-38:57:05.2 |
HIP 46874 |
13.78 |
| 2026-10-04 00:00 |
09:33:54.33 |
-38:57:30.3 |
HIP 46874 |
13.67 |
| 2026-10-04 12:00 |
09:33:56.00 |
-38:57:55.5 |
HIP 46874 |
13.58 |
| 2026-10-05 00:00 |
09:33:57.66 |
-38:58:20.8 |
HIP 46874 |
13.51 |
| 2026-10-05 12:00 |
09:33:59.29 |
-38:58:46.2 |
HIP 46874 |
13.45 |
| 2026-10-06 00:00 |
09:34:00.91 |
-38:59:11.7 |
HIP 46874 |
13.41 |
| 2026-10-06 12:00 |
09:34:02.51 |
-38:59:37.3 |
HIP 46874 |
13.39 |
| 2026-10-07 00:00 |
09:34:04.09 |
-39:00:03.0 |
HIP 46874 |
13.38 |
| 2026-10-07 12:00 |
09:34:05.65 |
-39:00:28.8 |
HIP 46874 |
13.39 |
| 2026-10-08 00:00 |
09:34:07.20 |
-39:00:54.8 |
HIP 46874 |
13.42 |
| 2026-10-08 12:00 |
09:34:08.72 |
-39:01:20.8 |
HIP 46874 |
13.46 |
| 2026-10-09 00:00 |
09:34:10.23 |
-39:01:46.9 |
HIP 46874 |
13.52 |
| 2026-10-09 12:00 |
09:34:11.71 |
-39:02:13.1 |
HIP 46874 |
13.60 |
| 2026-10-10 00:00 |
09:34:13.18 |
-39:02:39.4 |
HIP 46874 |
13.69 |
| 2026-10-10 12:00 |
09:34:14.63 |
-39:03:05.8 |
HIP 46874 |
13.79 |
| 2026-10-11 00:00 |
09:34:16.06 |
-39:03:32.3 |
HIP 46874 |
13.91 |
| 2026-10-11 12:00 |
09:34:17.47 |
-39:03:58.9 |
HIP 46874 |
14.05 |
| 2026-10-12 00:00 |
09:34:18.85 |
-39:04:25.5 |
HIP 46874 |
14.20 |
| 2026-10-12 12:00 |
09:34:20.22 |
-39:04:52.2 |
HIP 46874 |
14.36 |
| 2026-10-13 00:00 |
09:34:21.57 |
-39:05:19.1 |
HIP 46874 |
14.53 |
| 2026-10-13 12:00 |
09:34:22.90 |
-39:05:45.9 |
HIP 46874 |
14.72 |
| 2026-10-14 00:00 |
09:34:24.21 |
-39:06:12.9 |
HIP 46874 |
14.92 |
| 2026-10-14 12:00 |
09:34:25.50 |
-39:06:40.0 |
HIP 46874 |
15.13 |
| 2026-10-15 00:00 |
09:34:26.76 |
-39:07:07.1 |
HIP 46874 |
15.34 |
| 2026-10-15 12:00 |
09:34:28.01 |
-39:07:34.3 |
HIP 46874 |
15.57 |
| 2026-10-16 00:00 |
09:34:29.23 |
-39:08:01.5 |
HIP 46874 |
15.81 |