| 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) |
| 2026-07-29 00:00 |
10:39:38.93 |
+11:45:10.0 |
HIP 52257 |
24.22 |
| 2026-07-29 12:00 |
10:40:01.46 |
+11:43:08.1 |
HIP 52257 |
23.30 |
| 2026-07-30 00:00 |
10:40:24.02 |
+11:41:05.8 |
HIP 52257 |
23.85 |
| 2026-07-30 12:00 |
10:40:46.62 |
+11:39:03.3 |
HIP 52257 |
25.77 |
| 2026-07-31 00:00 |
10:41:09.27 |
+11:37:00.5 |
HIP 52241 |
28.05 |
| 2026-07-31 12:00 |
10:41:31.95 |
+11:34:57.4 |
HIP 52241 |
29.12 |
| 2026-08-01 00:00 |
10:41:54.68 |
+11:32:54.0 |
HIP 52241 |
31.29 |
| 2026-08-01 12:00 |
10:42:17.44 |
+11:30:50.3 |
HIP 52525 |
32.25 |
| 2026-08-02 00:00 |
10:42:40.24 |
+11:28:46.4 |
HIP 52525 |
26.30 |
| 2026-08-02 12:00 |
10:43:03.09 |
+11:26:42.2 |
HIP 52525 |
20.33 |
| 2026-08-03 00:00 |
10:43:25.96 |
+11:24:37.8 |
HIP 52525 |
14.36 |
| 2026-08-03 12:00 |
10:43:48.88 |
+11:22:33.1 |
HIP 52525 |
8.37 |
| 2026-08-04 00:00 |
10:44:11.83 |
+11:20:28.1 |
HIP 52525 |
2.42 |
| 2026-08-04 12:00 |
10:44:34.82 |
+11:18:22.9 |
HIP 52525 |
3.69 |
| 2026-08-05 00:00 |
10:44:57.84 |
+11:16:17.4 |
HIP 52525 |
9.68 |
| 2026-08-05 12:00 |
10:45:20.90 |
+11:14:11.7 |
HIP 52525 |
15.71 |
| 2026-08-06 00:00 |
10:45:43.99 |
+11:12:05.7 |
HIP 52707 |
12.96 |
| 2026-08-06 12:00 |
10:46:07.11 |
+11:09:59.5 |
HIP 52707 |
7.33 |
| 2026-08-07 00:00 |
10:46:30.27 |
+11:07:53.1 |
HIP 52707 |
3.55 |
| 2026-08-07 12:00 |
10:46:53.46 |
+11:05:46.4 |
HIP 52707 |
6.71 |
| 2026-08-08 00:00 |
10:47:16.69 |
+11:03:39.6 |
HIP 52707 |
12.30 |
| 2026-08-08 12:00 |
10:47:39.94 |
+11:01:32.4 |
HIP 52707 |
18.21 |
| 2026-08-09 00:00 |
10:48:03.23 |
+10:59:25.1 |
HIP 52707 |
24.22 |
| 2026-08-09 12:00 |
10:48:26.55 |
+10:57:17.5 |
HIP 52911 |
27.35 |
| 2026-08-10 00:00 |
10:48:49.89 |
+10:55:09.8 |
HIP 52911 |
23.31 |
| 2026-08-10 12:00 |
10:49:13.27 |
+10:53:01.8 |
HIP 52911 |
20.32 |
| 2026-08-11 00:00 |
10:49:36.67 |
+10:50:53.6 |
HIP 52911 |
18.91 |
| 2026-08-11 12:00 |
10:50:00.11 |
+10:48:45.3 |
HIP 52911 |
19.43 |
| 2026-08-12 00:00 |
10:50:23.57 |
+10:46:36.7 |
HIP 52911 |
21.76 |
| 2026-08-12 12:00 |
10:50:47.05 |
+10:44:28.0 |
HIP 52999 |
24.97 |
| 2026-08-13 00:00 |
10:51:10.56 |
+10:42:19.0 |
HIP 52999 |
24.54 |
| 2026-08-13 12:00 |
10:51:34.10 |
+10:40:09.9 |
HIP 52999 |
25.62 |
| 2026-08-14 00:00 |
10:51:57.66 |
+10:38:00.6 |
HIP 52999 |
28.06 |
| 2026-08-14 12:00 |
10:52:21.25 |
+10:35:51.2 |
HIP 53170 |
26.96 |
| 2026-08-15 00:00 |
10:52:44.86 |
+10:33:41.6 |
HIP 53170 |
24.53 |
| 2026-08-15 12:00 |
10:53:08.49 |
+10:31:31.8 |
HIP 53170 |
23.51 |
| 2026-08-16 00:00 |
10:53:32.14 |
+10:29:21.8 |
HIP 53170 |
24.11 |
| 2026-08-16 12:00 |
10:53:55.82 |
+10:27:11.8 |
HIP 53170 |
26.20 |
| 2026-08-17 00:00 |
10:54:19.52 |
+10:25:01.5 |
HIP 53431 |
28.38 |
| 2026-08-17 12:00 |
10:54:43.23 |
+10:22:51.2 |
HIP 53431 |
22.55 |
| 2026-08-18 00:00 |
10:55:06.97 |
+10:20:40.7 |
HIP 53431 |
17.00 |
| 2026-08-18 12:00 |
10:55:30.72 |
+10:18:30.0 |
HIP 53431 |
12.13 |
| 2026-08-19 00:00 |
10:55:54.49 |
+10:16:19.3 |
HIP 53431 |
9.11 |