| Parameter |
Value |
| Designation |
50P/Arend |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2007-11-02T19:43:29.481600Z |
| Orbit solution date (soln_date, UTC) |
2025-10-01T16:07:23Z |
| Obs used |
1874 |
| NEO |
- |
| M1 |
13.900 |
| K1 |
9.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-07-01.0000000 |
| e |
0.53063813 |
| q (au) |
1.918329 |
| a (au) |
4.087100 |
| i (deg) |
19.155639 |
| Ω (om, deg) |
355.310553 |
| ω (w, deg) |
49.039728 |
| M (ma, deg) |
159.384273 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.457 + 4.038\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.457 |
| n |
4.038 |
| gf |
1.000 |
| gb |
-1.000 |
| 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 |
| 2023-08-17 |
2024-05-13 |
+13.6006 |
-5.552 |
| 2024-05-13 |
2025-05-02 |
-14.3888 |
+6.578 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
11:54:12.75 |
-04:14:51.4 |
HIP 58042 |
7.34 |
| 2026-07-29 12:00 |
11:54:29.53 |
-04:16:56.2 |
HIP 58042 |
6.67 |
| 2026-07-30 00:00 |
11:54:46.38 |
-04:19:01.7 |
HIP 58042 |
8.89 |
| 2026-07-30 12:00 |
11:55:03.31 |
-04:21:07.6 |
HIP 58042 |
12.57 |
| 2026-07-31 00:00 |
11:55:20.32 |
-04:23:14.2 |
HIP 58042 |
16.79 |
| 2026-07-31 12:00 |
11:55:37.40 |
-04:25:21.3 |
HIP 58197 |
17.59 |
| 2026-08-01 00:00 |
11:55:54.56 |
-04:27:28.9 |
HIP 58197 |
18.27 |
| 2026-08-01 12:00 |
11:56:11.80 |
-04:29:37.1 |
HIP 58197 |
20.10 |
| 2026-08-02 00:00 |
11:56:29.11 |
-04:31:45.8 |
HIP 58268 |
17.08 |
| 2026-08-02 12:00 |
11:56:46.50 |
-04:33:55.1 |
HIP 58268 |
13.50 |
| 2026-08-03 00:00 |
11:57:03.96 |
-04:36:04.9 |
HIP 58268 |
10.92 |
| 2026-08-03 12:00 |
11:57:21.49 |
-04:38:15.2 |
HIP 58268 |
10.18 |
| 2026-08-04 00:00 |
11:57:39.10 |
-04:40:26.0 |
HIP 58268 |
11.65 |
| 2026-08-04 12:00 |
11:57:56.78 |
-04:42:37.4 |
HIP 58268 |
14.71 |
| 2026-08-05 00:00 |
11:58:14.53 |
-04:44:49.3 |
HIP 58443 |
12.21 |
| 2026-08-05 12:00 |
11:58:32.35 |
-04:47:01.7 |
HIP 58443 |
7.65 |
| 2026-08-06 00:00 |
11:58:50.23 |
-04:49:14.7 |
HIP 58443 |
4.12 |
| 2026-08-06 12:00 |
11:59:08.19 |
-04:51:28.1 |
HIP 58443 |
5.01 |
| 2026-08-07 00:00 |
11:59:26.22 |
-04:53:42.0 |
HIP 58443 |
9.14 |
| 2026-08-07 12:00 |
11:59:44.32 |
-04:55:56.5 |
HIP 58443 |
13.88 |
| 2026-08-08 00:00 |
12:00:02.48 |
-04:58:11.5 |
HIP 58569 |
12.69 |
| 2026-08-08 12:00 |
12:00:20.71 |
-05:00:26.9 |
HIP 58569 |
8.07 |
| 2026-08-09 00:00 |
12:00:39.00 |
-05:02:42.9 |
HIP 58569 |
4.53 |
| 2026-08-09 12:00 |
12:00:57.36 |
-05:04:59.3 |
HIP 58569 |
5.27 |
| 2026-08-10 00:00 |
12:01:15.79 |
-05:07:16.2 |
HIP 58569 |
9.35 |
| 2026-08-10 12:00 |
12:01:34.28 |
-05:09:33.6 |
HIP 58569 |
14.15 |
| 2026-08-11 00:00 |
12:01:52.83 |
-05:11:51.5 |
HIP 58569 |
19.14 |
| 2026-08-11 12:00 |
12:02:11.45 |
-05:14:09.9 |
HIP 58569 |
24.22 |
| 2026-08-12 00:00 |
12:02:30.13 |
-05:16:28.7 |
HIP 58797 |
20.40 |
| 2026-08-12 12:00 |
12:02:48.86 |
-05:18:48.0 |
HIP 58797 |
15.31 |
| 2026-08-13 00:00 |
12:03:07.66 |
-05:21:07.7 |
HIP 58797 |
10.32 |
| 2026-08-13 12:00 |
12:03:26.52 |
-05:23:27.9 |
HIP 58797 |
5.76 |
| 2026-08-14 00:00 |
12:03:45.44 |
-05:25:48.6 |
HIP 58797 |
3.86 |
| 2026-08-14 12:00 |
12:04:04.42 |
-05:28:09.7 |
HIP 58797 |
7.21 |
| 2026-08-15 00:00 |
12:04:23.45 |
-05:30:31.2 |
HIP 58797 |
12.05 |
| 2026-08-15 12:00 |
12:04:42.54 |
-05:32:53.2 |
HIP 58872 |
12.74 |
| 2026-08-16 00:00 |
12:05:01.68 |
-05:35:15.6 |
HIP 58872 |
13.10 |
| 2026-08-16 12:00 |
12:05:20.89 |
-05:37:38.4 |
HIP 58981 |
13.58 |
| 2026-08-17 00:00 |
12:05:40.14 |
-05:40:01.7 |
HIP 58981 |
10.80 |
| 2026-08-17 12:00 |
12:05:59.45 |
-05:42:25.4 |
HIP 58981 |
10.31 |
| 2026-08-18 00:00 |
12:06:18.81 |
-05:44:49.5 |
HIP 58981 |
12.39 |
| 2026-08-18 12:00 |
12:06:38.22 |
-05:47:14.0 |
HIP 59109 |
9.76 |
| 2026-08-19 00:00 |
12:06:57.69 |
-05:49:38.9 |
HIP 59109 |
7.14 |