185P/Petriew
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2023-04-24 |
2023-07-10 |
+6.1286 |
-1.317 |
| 2023-07-10 |
2024-02-06 |
-6.5810 |
+1.508 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
14:46:36.51 |
-16:16:35.3 |
HIP 72292 |
13.34 |
| 2026-02-03 12:00 |
14:46:42.24 |
-16:16:41.4 |
HIP 72292 |
12.66 |
| 2026-02-04 00:00 |
14:46:47.79 |
-16:16:46.5 |
HIP 72292 |
12.14 |
| 2026-02-04 12:00 |
14:46:53.16 |
-16:16:50.7 |
HIP 72292 |
11.76 |
| 2026-02-05 00:00 |
14:46:58.34 |
-16:16:54.1 |
HIP 72292 |
11.54 |
| 2026-02-05 12:00 |
14:47:03.34 |
-16:16:56.5 |
HIP 72292 |
11.46 |
| 2026-02-06 00:00 |
14:47:08.16 |
-16:16:58.1 |
HIP 72292 |
11.52 |
| 2026-02-06 12:00 |
14:47:12.78 |
-16:16:58.7 |
HIP 72292 |
11.69 |
| 2026-02-07 00:00 |
14:47:17.23 |
-16:16:58.4 |
HIP 72292 |
11.97 |
| 2026-02-07 12:00 |
14:47:21.48 |
-16:16:57.3 |
HIP 72292 |
12.33 |
| 2026-02-08 00:00 |
14:47:25.54 |
-16:16:55.2 |
HIP 72292 |
12.76 |
| 2026-02-08 12:00 |
14:47:29.42 |
-16:16:52.2 |
HIP 72292 |
13.23 |
| 2026-02-09 00:00 |
14:47:33.10 |
-16:16:48.3 |
HIP 72292 |
13.74 |
| 2026-02-09 12:00 |
14:47:36.59 |
-16:16:43.4 |
HIP 72292 |
14.28 |
| 2026-02-10 00:00 |
14:47:39.90 |
-16:16:37.6 |
HIP 72292 |
14.82 |
| 2026-02-10 12:00 |
14:47:43.00 |
-16:16:30.9 |
HIP 72292 |
15.37 |
| 2026-02-11 00:00 |
14:47:45.92 |
-16:16:23.3 |
HIP 72292 |
15.92 |
| 2026-02-11 12:00 |
14:47:48.64 |
-16:16:14.7 |
HIP 72292 |
16.46 |
| 2026-02-12 00:00 |
14:47:51.16 |
-16:16:05.2 |
HIP 72292 |
16.99 |
| 2026-02-12 12:00 |
14:47:53.49 |
-16:15:54.7 |
HIP 72292 |
17.51 |
| 2026-02-13 00:00 |
14:47:55.62 |
-16:15:43.3 |
HIP 72292 |
18.00 |
| 2026-02-13 12:00 |
14:47:57.55 |
-16:15:30.9 |
HIP 72292 |
18.48 |
| 2026-02-14 00:00 |
14:47:59.29 |
-16:15:17.6 |
HIP 72292 |
18.93 |
| 2026-02-14 12:00 |
14:48:00.82 |
-16:15:03.3 |
HIP 72292 |
19.36 |
| 2026-02-15 00:00 |
14:48:02.16 |
-16:14:48.1 |
HIP 72292 |
19.77 |
| 2026-02-15 12:00 |
14:48:03.30 |
-16:14:31.9 |
HIP 72292 |
20.15 |
| 2026-02-16 00:00 |
14:48:04.23 |
-16:14:14.7 |
HIP 72292 |
20.51 |
| 2026-02-16 12:00 |
14:48:04.97 |
-16:13:56.6 |
HIP 72292 |
20.85 |
| 2026-02-17 00:00 |
14:48:05.50 |
-16:13:37.4 |
HIP 72292 |
21.16 |
| 2026-02-17 12:00 |
14:48:05.83 |
-16:13:17.4 |
HIP 72292 |
21.45 |
| 2026-02-18 00:00 |
14:48:05.96 |
-16:12:56.3 |
HIP 72292 |
21.72 |
| 2026-02-18 12:00 |
14:48:05.88 |
-16:12:34.3 |
HIP 72292 |
21.97 |
| 2026-02-19 00:00 |
14:48:05.60 |
-16:12:11.3 |
HIP 72292 |
22.21 |
| 2026-02-19 12:00 |
14:48:05.12 |
-16:11:47.3 |
HIP 72292 |
22.42 |
| 2026-02-20 00:00 |
14:48:04.43 |
-16:11:22.3 |
HIP 72292 |
22.62 |
| 2026-02-20 12:00 |
14:48:03.54 |
-16:10:56.4 |
HIP 72292 |
22.81 |
| 2026-02-21 00:00 |
14:48:02.44 |
-16:10:29.5 |
HIP 72292 |
22.99 |
| 2026-02-21 12:00 |
14:48:01.13 |
-16:10:01.5 |
HIP 72292 |
23.16 |
| 2026-02-22 00:00 |
14:47:59.63 |
-16:09:32.6 |
HIP 72292 |
23.33 |
| 2026-02-22 12:00 |
14:47:57.91 |
-16:09:02.8 |
HIP 72292 |
23.50 |
| 2026-02-23 00:00 |
14:47:55.99 |
-16:08:31.9 |
HIP 72292 |
23.67 |
| 2026-02-23 12:00 |
14:47:53.86 |
-16:08:00.0 |
HIP 72292 |
23.85 |
| 2026-02-24 00:00 |
14:47:51.53 |
-16:07:27.1 |
HIP 72292 |
24.04 |