| Parameter |
Value |
| Designation |
239P/LINEAR |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2019-01-09T23:17:42.864000Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:28:01Z |
| Obs used |
365 |
| NEO |
- |
| M1 |
15.300 |
| K1 |
13.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-10-04.0000000 |
| e |
0.63143654 |
| q (au) |
1.647599 |
| a (au) |
4.470327 |
| i (deg) |
11.305620 |
| Ω (om, deg) |
255.944518 |
| ω (w, deg) |
220.383718 |
| M (ma, deg) |
273.660407 |
Magnitude
Scatter + Global Linear
$$
M_a = (18.785 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
18.785 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.656 |
| k |
0.800 |
| 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 |
| 2018-10-08 |
2019-01-09 |
+4.7782 |
-0.935 |
| 2019-01-11 |
2019-04-18 |
-10.8877 |
+2.304 |
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 |
22:32:54.90 |
+02:06:23.6 |
HIP 111374 |
19.79 |
| 2026-05-12 12:00 |
22:33:06.19 |
+02:08:28.6 |
HIP 111374 |
19.79 |
| 2026-05-13 00:00 |
22:33:17.36 |
+02:10:33.2 |
HIP 111374 |
20.40 |
| 2026-05-13 12:00 |
22:33:28.41 |
+02:12:37.4 |
HIP 111374 |
21.56 |
| 2026-05-14 00:00 |
22:33:39.35 |
+02:14:41.2 |
HIP 111374 |
23.18 |
| 2026-05-14 12:00 |
22:33:50.16 |
+02:16:44.7 |
HIP 111374 |
25.16 |
| 2026-05-15 00:00 |
22:34:00.86 |
+02:18:47.7 |
HIP 111508 |
26.76 |
| 2026-05-15 12:00 |
22:34:11.43 |
+02:20:50.4 |
HIP 111508 |
23.43 |
| 2026-05-16 00:00 |
22:34:21.89 |
+02:22:52.6 |
HIP 111508 |
20.13 |
| 2026-05-16 12:00 |
22:34:32.22 |
+02:24:54.4 |
HIP 111508 |
16.86 |
| 2026-05-17 00:00 |
22:34:42.43 |
+02:26:55.8 |
HIP 111508 |
13.64 |
| 2026-05-17 12:00 |
22:34:52.51 |
+02:28:56.7 |
HIP 111508 |
10.46 |
| 2026-05-18 00:00 |
22:35:02.47 |
+02:30:57.2 |
HIP 111508 |
7.36 |
| 2026-05-18 12:00 |
22:35:12.30 |
+02:32:57.3 |
HIP 111508 |
4.44 |
| 2026-05-19 00:00 |
22:35:22.01 |
+02:34:56.9 |
HIP 111508 |
2.31 |
| 2026-05-19 12:00 |
22:35:31.59 |
+02:36:56.1 |
HIP 111508 |
3.26 |
| 2026-05-20 00:00 |
22:35:41.04 |
+02:38:54.7 |
HIP 111508 |
5.91 |
| 2026-05-20 12:00 |
22:35:50.37 |
+02:40:52.9 |
HIP 111508 |
8.82 |
| 2026-05-21 00:00 |
22:35:59.56 |
+02:42:50.7 |
HIP 111508 |
11.78 |
| 2026-05-21 12:00 |
22:36:08.63 |
+02:44:47.9 |
HIP 111508 |
14.73 |
| 2026-05-22 00:00 |
22:36:17.56 |
+02:46:44.6 |
HIP 111481 |
17.51 |
| 2026-05-22 12:00 |
22:36:26.36 |
+02:48:40.9 |
HIP 111481 |
20.28 |
| 2026-05-23 00:00 |
22:36:35.04 |
+02:50:36.6 |
HIP 111481 |
23.06 |
| 2026-05-23 12:00 |
22:36:43.58 |
+02:52:31.9 |
HIP 111481 |
25.84 |
| 2026-05-24 00:00 |
22:36:51.98 |
+02:54:26.6 |
HIP 111481 |
28.60 |
| 2026-05-24 12:00 |
22:37:00.25 |
+02:56:20.8 |
HIP 111481 |
31.34 |
| 2026-05-25 00:00 |
22:37:08.39 |
+02:58:14.4 |
HIP 111779 |
30.16 |
| 2026-05-25 12:00 |
22:37:16.40 |
+03:00:07.5 |
HIP 111779 |
27.42 |
| 2026-05-26 00:00 |
22:37:24.27 |
+03:02:00.1 |
HIP 111779 |
24.71 |
| 2026-05-26 12:00 |
22:37:32.00 |
+03:03:52.2 |
HIP 111779 |
22.04 |
| 2026-05-27 00:00 |
22:37:39.59 |
+03:05:43.6 |
HIP 111779 |
19.39 |
| 2026-05-27 12:00 |
22:37:47.05 |
+03:07:34.6 |
HIP 111779 |
16.78 |
| 2026-05-28 00:00 |
22:37:54.37 |
+03:09:24.9 |
HIP 111779 |
14.20 |
| 2026-05-28 12:00 |
22:38:01.55 |
+03:11:14.7 |
HIP 111779 |
11.66 |
| 2026-05-29 00:00 |
22:38:08.59 |
+03:13:03.9 |
HIP 111779 |
9.15 |
| 2026-05-29 12:00 |
22:38:15.50 |
+03:14:52.5 |
HIP 111779 |
6.69 |
| 2026-05-30 00:00 |
22:38:22.26 |
+03:16:40.6 |
HIP 111779 |
4.29 |
| 2026-05-30 12:00 |
22:38:28.87 |
+03:18:28.0 |
HIP 111779 |
2.09 |
| 2026-05-31 00:00 |
22:38:35.35 |
+03:20:14.8 |
HIP 111779 |
1.44 |
| 2026-05-31 12:00 |
22:38:41.68 |
+03:22:01.0 |
HIP 111779 |
3.33 |
| 2026-06-01 00:00 |
22:38:47.87 |
+03:23:46.6 |
HIP 111779 |
5.56 |
| 2026-06-01 12:00 |
22:38:53.92 |
+03:25:31.6 |
HIP 111779 |
7.83 |
| 2026-06-02 00:00 |
22:38:59.82 |
+03:27:15.9 |
HIP 111779 |
10.08 |