| Parameter |
Value |
| Designation |
185P/Petriew |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2012-08-13T01:18:02.707200Z |
| Orbit solution date (soln_date, UTC) |
2024-02-22T12:37:21Z |
| Obs used |
715 |
| NEO |
Yes |
| M1 |
13.600 |
| K1 |
10.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-04-17.0000000 |
| e |
0.69879499 |
| q (au) |
0.933837 |
| a (au) |
3.100337 |
| i (deg) |
13.997316 |
| Ω (om, deg) |
214.100822 |
| ω (w, deg) |
181.937558 |
| M (ma, deg) |
176.384777 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.159 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.159 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.827 |
| k |
0.988 |
| 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) |
| 2026-03-26 00:00 |
14:39:21.87 |
-15:04:18.1 |
HIP 71715 |
16.54 |
| 2026-03-26 12:00 |
14:39:07.62 |
-15:02:45.7 |
HIP 71567 |
14.55 |
| 2026-03-27 00:00 |
14:38:53.21 |
-15:01:12.5 |
HIP 71567 |
10.74 |
| 2026-03-27 12:00 |
14:38:38.63 |
-14:59:38.4 |
HIP 71567 |
6.89 |
| 2026-03-28 00:00 |
14:38:23.89 |
-14:58:03.5 |
HIP 71567 |
3.02 |
| 2026-03-28 12:00 |
14:38:09.00 |
-14:56:27.7 |
HIP 71567 |
1.07 |
| 2026-03-29 00:00 |
14:37:53.95 |
-14:54:51.1 |
HIP 71567 |
4.95 |
| 2026-03-29 12:00 |
14:37:38.75 |
-14:53:13.6 |
HIP 71567 |
8.96 |
| 2026-03-30 00:00 |
14:37:23.40 |
-14:51:35.3 |
HIP 71567 |
13.01 |
| 2026-03-30 12:00 |
14:37:07.90 |
-14:49:56.2 |
HIP 71567 |
17.10 |
| 2026-03-31 00:00 |
14:36:52.24 |
-14:48:16.4 |
HIP 71567 |
21.23 |
| 2026-03-31 12:00 |
14:36:36.45 |
-14:46:35.7 |
HIP 71299 |
25.06 |
| 2026-04-01 00:00 |
14:36:20.51 |
-14:44:54.2 |
HIP 71299 |
21.42 |
| 2026-04-01 12:00 |
14:36:04.43 |
-14:43:11.9 |
HIP 71299 |
17.99 |
| 2026-04-02 00:00 |
14:35:48.20 |
-14:41:28.9 |
HIP 71299 |
14.95 |
| 2026-04-02 12:00 |
14:35:31.84 |
-14:39:45.1 |
HIP 71299 |
12.64 |
| 2026-04-03 00:00 |
14:35:15.35 |
-14:38:00.6 |
HIP 71299 |
11.55 |
| 2026-04-03 12:00 |
14:34:58.72 |
-14:36:15.3 |
HIP 71299 |
12.04 |
| 2026-04-04 00:00 |
14:34:41.96 |
-14:34:29.2 |
HIP 71299 |
13.98 |
| 2026-04-04 12:00 |
14:34:25.07 |
-14:32:42.5 |
HIP 71299 |
16.91 |
| 2026-04-05 00:00 |
14:34:08.05 |
-14:30:55.0 |
HIP 71299 |
20.43 |
| 2026-04-05 12:00 |
14:33:50.91 |
-14:29:06.8 |
HIP 71299 |
24.29 |
| 2026-04-06 00:00 |
14:33:33.64 |
-14:27:17.9 |
HIP 71189 |
22.71 |
| 2026-04-06 12:00 |
14:33:16.25 |
-14:25:28.4 |
HIP 71189 |
21.33 |
| 2026-04-07 00:00 |
14:32:58.75 |
-14:23:38.1 |
HIP 71189 |
20.89 |
| 2026-04-07 12:00 |
14:32:41.13 |
-14:21:47.2 |
HIP 71189 |
21.47 |
| 2026-04-08 00:00 |
14:32:23.40 |
-14:19:55.6 |
HIP 71189 |
23.01 |
| 2026-04-08 12:00 |
14:32:05.55 |
-14:18:03.4 |
HIP 71189 |
25.35 |
| 2026-04-09 00:00 |
14:31:47.60 |
-14:16:10.6 |
HIP 70934 |
28.11 |
| 2026-04-09 12:00 |
14:31:29.54 |
-14:14:17.1 |
HIP 70934 |
26.79 |
| 2026-04-10 00:00 |
14:31:11.38 |
-14:12:23.0 |
HIP 70934 |
26.27 |
| 2026-04-10 12:00 |
14:30:53.12 |
-14:10:28.4 |
HIP 70934 |
26.62 |
| 2026-04-11 00:00 |
14:30:34.76 |
-14:08:33.1 |
HIP 70934 |
27.82 |
| 2026-04-11 12:00 |
14:30:16.30 |
-14:06:37.3 |
HIP 70815 |
28.38 |
| 2026-04-12 00:00 |
14:29:57.75 |
-14:04:40.9 |
HIP 70815 |
23.96 |
| 2026-04-12 12:00 |
14:29:39.11 |
-14:02:43.9 |
HIP 70815 |
19.76 |
| 2026-04-13 00:00 |
14:29:20.38 |
-14:00:46.5 |
HIP 70815 |
15.95 |
| 2026-04-13 12:00 |
14:29:01.57 |
-13:58:48.5 |
HIP 70815 |
12.93 |
| 2026-04-14 00:00 |
14:28:42.67 |
-13:56:50.0 |
HIP 70815 |
11.37 |
| 2026-04-14 12:00 |
14:28:23.70 |
-13:54:51.0 |
HIP 70815 |
11.90 |
| 2026-04-15 00:00 |
14:28:04.64 |
-13:52:51.6 |
HIP 70815 |
14.30 |
| 2026-04-15 12:00 |
14:27:45.52 |
-13:50:51.7 |
HIP 70815 |
17.85 |
| 2026-04-16 00:00 |
14:27:26.32 |
-13:48:51.3 |
HIP 70815 |
22.01 |