| 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) |
| 2026-05-12 00:00 |
09:57:31.08 |
+15:20:07.9 |
HIP 48881 |
11.96 |
| 2026-05-12 12:00 |
09:57:37.69 |
+15:19:41.0 |
HIP 48881 |
10.41 |
| 2026-05-13 00:00 |
09:57:44.46 |
+15:19:13.1 |
HIP 48881 |
8.86 |
| 2026-05-13 12:00 |
09:57:51.40 |
+15:18:44.2 |
HIP 48881 |
7.33 |
| 2026-05-14 00:00 |
09:57:58.51 |
+15:18:14.4 |
HIP 48881 |
5.89 |
| 2026-05-14 12:00 |
09:58:05.79 |
+15:17:43.7 |
HIP 48881 |
4.67 |
| 2026-05-15 00:00 |
09:58:13.23 |
+15:17:12.0 |
HIP 48881 |
3.94 |
| 2026-05-15 12:00 |
09:58:20.84 |
+15:16:39.4 |
HIP 48881 |
4.03 |
| 2026-05-16 00:00 |
09:58:28.62 |
+15:16:05.9 |
HIP 48881 |
4.95 |
| 2026-05-16 12:00 |
09:58:36.55 |
+15:15:31.5 |
HIP 48881 |
6.39 |
| 2026-05-17 00:00 |
09:58:44.66 |
+15:14:56.1 |
HIP 48881 |
8.11 |
| 2026-05-17 12:00 |
09:58:52.92 |
+15:14:19.8 |
HIP 48881 |
9.99 |
| 2026-05-18 00:00 |
09:59:01.35 |
+15:13:42.7 |
HIP 48881 |
11.98 |
| 2026-05-18 12:00 |
09:59:09.93 |
+15:13:04.6 |
HIP 48881 |
14.04 |
| 2026-05-19 00:00 |
09:59:18.68 |
+15:12:25.6 |
HIP 48881 |
16.17 |
| 2026-05-19 12:00 |
09:59:27.58 |
+15:11:45.7 |
HIP 48881 |
18.36 |
| 2026-05-20 00:00 |
09:59:36.65 |
+15:11:05.0 |
HIP 49010 |
18.90 |
| 2026-05-20 12:00 |
09:59:45.87 |
+15:10:23.4 |
HIP 49010 |
17.84 |
| 2026-05-21 00:00 |
09:59:55.24 |
+15:09:40.8 |
HIP 49010 |
17.03 |
| 2026-05-21 12:00 |
10:00:04.77 |
+15:08:57.5 |
HIP 49010 |
16.51 |
| 2026-05-22 00:00 |
10:00:14.46 |
+15:08:13.2 |
HIP 49010 |
16.33 |
| 2026-05-22 12:00 |
10:00:24.30 |
+15:07:28.1 |
HIP 49010 |
16.52 |
| 2026-05-23 00:00 |
10:00:34.28 |
+15:06:42.1 |
HIP 49010 |
17.09 |
| 2026-05-23 12:00 |
10:00:44.42 |
+15:05:55.3 |
HIP 49010 |
18.01 |
| 2026-05-24 00:00 |
10:00:54.71 |
+15:05:07.7 |
HIP 49010 |
19.25 |
| 2026-05-24 12:00 |
10:01:05.15 |
+15:04:19.2 |
HIP 49010 |
20.77 |
| 2026-05-25 00:00 |
10:01:15.74 |
+15:03:29.8 |
HIP 49168 |
21.44 |
| 2026-05-25 12:00 |
10:01:26.47 |
+15:02:39.7 |
HIP 49168 |
20.94 |
| 2026-05-26 00:00 |
10:01:37.35 |
+15:01:48.7 |
HIP 49214 |
20.65 |
| 2026-05-26 12:00 |
10:01:48.37 |
+15:00:56.9 |
HIP 49214 |
18.07 |
| 2026-05-27 00:00 |
10:01:59.53 |
+15:00:04.3 |
HIP 49214 |
15.54 |
| 2026-05-27 12:00 |
10:02:10.84 |
+14:59:10.9 |
HIP 49214 |
13.09 |
| 2026-05-28 00:00 |
10:02:22.29 |
+14:58:16.7 |
HIP 49214 |
10.83 |
| 2026-05-28 12:00 |
10:02:33.88 |
+14:57:21.7 |
HIP 49214 |
8.94 |
| 2026-05-29 00:00 |
10:02:45.62 |
+14:56:25.9 |
HIP 49214 |
7.71 |
| 2026-05-29 12:00 |
10:02:57.48 |
+14:55:29.3 |
HIP 49214 |
7.55 |
| 2026-05-30 00:00 |
10:03:09.49 |
+14:54:31.9 |
HIP 49214 |
8.54 |
| 2026-05-30 12:00 |
10:03:21.64 |
+14:53:33.7 |
HIP 49214 |
10.40 |
| 2026-05-31 00:00 |
10:03:33.92 |
+14:52:34.8 |
HIP 49214 |
12.77 |
| 2026-05-31 12:00 |
10:03:46.33 |
+14:51:35.1 |
HIP 49214 |
15.45 |
| 2026-06-01 00:00 |
10:03:58.88 |
+14:50:34.6 |
HIP 49214 |
18.31 |
| 2026-06-01 12:00 |
10:04:11.57 |
+14:49:33.4 |
HIP 49214 |
21.30 |
| 2026-06-02 00:00 |
10:04:24.38 |
+14:48:31.4 |
HIP 49395 |
21.71 |