| 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 |
0.999 |
| gb |
-0.588 |
| 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) |
| 2026-03-26 00:00 |
10:00:52.91 |
+14:43:23.3 |
HIP 49010 |
17.00 |
| 2026-03-26 12:00 |
10:00:42.19 |
+14:44:38.9 |
HIP 49010 |
14.14 |
| 2026-03-27 00:00 |
10:00:31.63 |
+14:45:53.4 |
HIP 49010 |
11.34 |
| 2026-03-27 12:00 |
10:00:21.24 |
+14:47:06.8 |
HIP 49010 |
8.61 |
| 2026-03-28 00:00 |
10:00:11.02 |
+14:48:19.0 |
HIP 49010 |
5.98 |
| 2026-03-28 12:00 |
10:00:00.97 |
+14:49:30.2 |
HIP 49010 |
3.58 |
| 2026-03-29 00:00 |
09:59:51.09 |
+14:50:40.2 |
HIP 49010 |
2.10 |
| 2026-03-29 12:00 |
09:59:41.39 |
+14:51:49.2 |
HIP 49010 |
3.15 |
| 2026-03-30 00:00 |
09:59:31.85 |
+14:52:57.0 |
HIP 49010 |
5.35 |
| 2026-03-30 12:00 |
09:59:22.49 |
+14:54:03.6 |
HIP 49010 |
7.73 |
| 2026-03-31 00:00 |
09:59:13.31 |
+14:55:09.2 |
HIP 49010 |
10.14 |
| 2026-03-31 12:00 |
09:59:04.30 |
+14:56:13.6 |
HIP 49010 |
12.52 |
| 2026-04-01 00:00 |
09:58:55.47 |
+14:57:16.9 |
HIP 49010 |
14.87 |
| 2026-04-01 12:00 |
09:58:46.81 |
+14:58:19.1 |
HIP 48842 |
15.67 |
| 2026-04-02 00:00 |
09:58:38.34 |
+14:59:20.1 |
HIP 48842 |
13.41 |
| 2026-04-02 12:00 |
09:58:30.04 |
+15:00:20.0 |
HIP 48842 |
11.21 |
| 2026-04-03 00:00 |
09:58:21.92 |
+15:01:18.8 |
HIP 48842 |
9.08 |
| 2026-04-03 12:00 |
09:58:13.99 |
+15:02:16.4 |
HIP 48842 |
7.03 |
| 2026-04-04 00:00 |
09:58:06.24 |
+15:03:12.9 |
HIP 48842 |
5.10 |
| 2026-04-04 12:00 |
09:57:58.67 |
+15:04:08.2 |
HIP 48842 |
3.41 |
| 2026-04-05 00:00 |
09:57:51.28 |
+15:05:02.4 |
HIP 48842 |
2.39 |
| 2026-04-05 12:00 |
09:57:44.08 |
+15:05:55.5 |
HIP 48842 |
2.76 |
| 2026-04-06 00:00 |
09:57:37.06 |
+15:06:47.4 |
HIP 48842 |
4.11 |
| 2026-04-06 12:00 |
09:57:30.23 |
+15:07:38.2 |
HIP 48842 |
5.73 |
| 2026-04-07 00:00 |
09:57:23.59 |
+15:08:27.8 |
HIP 48842 |
7.42 |
| 2026-04-07 12:00 |
09:57:17.13 |
+15:09:16.3 |
HIP 48842 |
9.10 |
| 2026-04-08 00:00 |
09:57:10.86 |
+15:10:03.6 |
HIP 48842 |
10.76 |
| 2026-04-08 12:00 |
09:57:04.77 |
+15:10:49.8 |
HIP 48842 |
12.39 |
| 2026-04-09 00:00 |
09:56:58.88 |
+15:11:34.8 |
HIP 48842 |
13.97 |
| 2026-04-09 12:00 |
09:56:53.18 |
+15:12:18.7 |
HIP 48842 |
15.51 |
| 2026-04-10 00:00 |
09:56:47.66 |
+15:13:01.5 |
HIP 48842 |
17.01 |
| 2026-04-10 12:00 |
09:56:42.34 |
+15:13:43.0 |
HIP 48842 |
18.46 |
| 2026-04-11 00:00 |
09:56:37.20 |
+15:14:23.5 |
HIP 48842 |
19.86 |
| 2026-04-11 12:00 |
09:56:32.26 |
+15:15:02.8 |
HIP 48842 |
21.22 |
| 2026-04-12 00:00 |
09:56:27.51 |
+15:15:40.9 |
HIP 48842 |
22.52 |
| 2026-04-12 12:00 |
09:56:22.95 |
+15:16:17.9 |
HIP 48842 |
23.78 |
| 2026-04-13 00:00 |
09:56:18.58 |
+15:16:53.7 |
HIP 48842 |
24.99 |
| 2026-04-13 12:00 |
09:56:14.40 |
+15:17:28.4 |
HIP 48842 |
26.15 |
| 2026-04-14 00:00 |
09:56:10.42 |
+15:18:02.0 |
HIP 48842 |
27.26 |
| 2026-04-14 12:00 |
09:56:06.63 |
+15:18:34.4 |
HIP 48842 |
28.32 |
| 2026-04-15 00:00 |
09:56:03.04 |
+15:19:05.6 |
HIP 48842 |
29.33 |
| 2026-04-15 12:00 |
09:55:59.64 |
+15:19:35.7 |
HIP 48842 |
30.29 |
| 2026-04-16 00:00 |
09:55:56.43 |
+15:20:04.7 |
HIP 48842 |
31.20 |