| Parameter |
Value |
| Designation |
170P/Christensen |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2023-04-20T08:14:01.852800Z |
| Orbit solution date (soln_date, UTC) |
2025-04-11T15:35:57Z |
| Obs used |
987 |
| NEO |
- |
| M1 |
9.400 |
| K1 |
13.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-05-22.0000000 |
| e |
0.30421190 |
| q (au) |
2.923152 |
| a (au) |
4.201211 |
| i (deg) |
10.124302 |
| Ω (om, deg) |
142.923756 |
| ω (w, deg) |
225.533342 |
| M (ma, deg) |
321.846548 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.260 + 5.247\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.260 |
| n |
5.247 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2021-06-30 |
2022-11-28 |
+5.3605 |
-1.798 |
| 2023-07-15 |
2024-03-18 |
-13.6949 |
+6.498 |
| 2024-03-18 |
2025-01-24 |
+9.8383 |
-5.868 |
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 |
11:21:30.31 |
+07:55:28.7 |
HIP 55337 |
31.20 |
| 2026-09-20 12:00 |
11:21:54.15 |
+07:53:18.5 |
HIP 55337 |
34.61 |
| 2026-09-21 00:00 |
11:22:17.98 |
+07:51:08.4 |
HIP 55337 |
38.74 |
| 2026-09-21 12:00 |
11:22:41.78 |
+07:48:58.6 |
HIP 55751 |
41.29 |
| 2026-09-22 00:00 |
11:23:05.57 |
+07:46:48.9 |
HIP 55751 |
36.10 |
| 2026-09-22 12:00 |
11:23:29.34 |
+07:44:39.3 |
HIP 55751 |
31.31 |
| 2026-09-23 00:00 |
11:23:53.09 |
+07:42:30.0 |
HIP 55751 |
27.13 |
| 2026-09-23 12:00 |
11:24:16.82 |
+07:40:20.8 |
HIP 55751 |
23.88 |
| 2026-09-24 00:00 |
11:24:40.53 |
+07:38:11.9 |
HIP 55751 |
21.98 |
| 2026-09-24 12:00 |
11:25:04.22 |
+07:36:03.1 |
HIP 55751 |
21.76 |
| 2026-09-25 00:00 |
11:25:27.89 |
+07:33:54.5 |
HIP 55751 |
23.29 |
| 2026-09-25 12:00 |
11:25:51.53 |
+07:31:46.1 |
HIP 55751 |
26.24 |
| 2026-09-26 00:00 |
11:26:15.16 |
+07:29:37.9 |
HIP 55751 |
30.21 |
| 2026-09-26 12:00 |
11:26:38.76 |
+07:27:29.9 |
HIP 55988 |
27.31 |
| 2026-09-27 00:00 |
11:27:02.34 |
+07:25:22.2 |
HIP 55988 |
22.00 |
| 2026-09-27 12:00 |
11:27:25.89 |
+07:23:14.6 |
HIP 55988 |
17.32 |
| 2026-09-28 00:00 |
11:27:49.42 |
+07:21:07.3 |
HIP 55988 |
13.89 |
| 2026-09-28 12:00 |
11:28:12.93 |
+07:19:00.2 |
HIP 55988 |
12.76 |
| 2026-09-29 00:00 |
11:28:36.41 |
+07:16:53.3 |
HIP 55988 |
14.48 |
| 2026-09-29 12:00 |
11:28:59.87 |
+07:14:46.6 |
HIP 55988 |
18.25 |
| 2026-09-30 00:00 |
11:29:23.30 |
+07:12:40.2 |
HIP 55988 |
23.08 |
| 2026-09-30 12:00 |
11:29:46.70 |
+07:10:34.0 |
HIP 56143 |
22.32 |
| 2026-10-01 00:00 |
11:30:10.08 |
+07:08:28.1 |
HIP 56143 |
18.33 |
| 2026-10-01 12:00 |
11:30:33.43 |
+07:06:22.4 |
HIP 56143 |
15.82 |
| 2026-10-02 00:00 |
11:30:56.75 |
+07:04:17.0 |
HIP 56143 |
15.50 |
| 2026-10-02 12:00 |
11:31:20.04 |
+07:02:11.8 |
HIP 56143 |
17.49 |
| 2026-10-03 00:00 |
11:31:43.30 |
+07:00:07.0 |
HIP 56143 |
21.15 |
| 2026-10-03 12:00 |
11:32:06.53 |
+06:58:02.3 |
HIP 56143 |
25.76 |
| 2026-10-04 00:00 |
11:32:29.74 |
+06:55:58.0 |
HIP 56355 |
30.18 |
| 2026-10-04 12:00 |
11:32:52.91 |
+06:53:53.9 |
HIP 56355 |
30.97 |
| 2026-10-05 00:00 |
11:33:16.05 |
+06:51:50.1 |
HIP 56355 |
32.89 |
| 2026-10-05 12:00 |
11:33:39.16 |
+06:49:46.7 |
HIP 56537 |
34.00 |
| 2026-10-06 00:00 |
11:34:02.23 |
+06:47:43.5 |
HIP 56537 |
28.11 |
| 2026-10-06 12:00 |
11:34:25.27 |
+06:45:40.6 |
HIP 56537 |
22.33 |
| 2026-10-07 00:00 |
11:34:48.28 |
+06:43:38.0 |
HIP 56537 |
16.78 |
| 2026-10-07 12:00 |
11:35:11.25 |
+06:41:35.8 |
HIP 56537 |
11.76 |
| 2026-10-08 00:00 |
11:35:34.19 |
+06:39:33.9 |
HIP 56537 |
8.26 |
| 2026-10-08 12:00 |
11:35:57.09 |
+06:37:32.3 |
HIP 56537 |
8.45 |
| 2026-10-09 00:00 |
11:36:19.95 |
+06:35:31.0 |
HIP 56574 |
12.09 |
| 2026-10-09 12:00 |
11:36:42.78 |
+06:33:30.1 |
HIP 56574 |
17.07 |
| 2026-10-10 00:00 |
11:37:05.57 |
+06:31:29.5 |
HIP 56679 |
15.59 |
| 2026-10-10 12:00 |
11:37:28.31 |
+06:29:29.3 |
HIP 56679 |
13.54 |
| 2026-10-11 00:00 |
11:37:51.02 |
+06:27:29.4 |
HIP 56787 |
10.68 |