| Parameter |
Value |
| Designation |
111P/Helin-Roman-Crockett |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2013-01-30T15:06:06.327360Z |
| Orbit solution date (soln_date, UTC) |
2013-01-28T09:17:54Z |
| Obs used |
137 |
| NEO |
- |
| M1 |
8.400 |
| K1 |
17.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-01-28.0000000 |
| e |
0.10962077 |
| q (au) |
3.704303 |
| a (au) |
4.160366 |
| i (deg) |
4.228807 |
| Ω (om, deg) |
89.793998 |
| ω (w, deg) |
3.377942 |
| M (ma, deg) |
359.694623 |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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 |
20:13:58.70 |
-21:15:03.5 |
HIP 99632 |
15.33 |
| 2026-03-26 12:00 |
20:14:21.34 |
-21:14:10.6 |
HIP 99632 |
19.79 |
| 2026-03-27 00:00 |
20:14:43.85 |
-21:13:17.9 |
HIP 99632 |
24.58 |
| 2026-03-27 12:00 |
20:15:06.22 |
-21:12:25.6 |
HIP 99952 |
28.77 |
| 2026-03-28 00:00 |
20:15:28.45 |
-21:11:33.6 |
HIP 99990 |
24.05 |
| 2026-03-28 12:00 |
20:15:50.55 |
-21:10:41.9 |
HIP 99990 |
19.58 |
| 2026-03-29 00:00 |
20:16:12.52 |
-21:09:50.6 |
HIP 99990 |
15.61 |
| 2026-03-29 12:00 |
20:16:34.34 |
-21:08:59.6 |
HIP 99990 |
12.56 |
| 2026-03-30 00:00 |
20:16:56.03 |
-21:08:08.9 |
HIP 99990 |
11.19 |
| 2026-03-30 12:00 |
20:17:17.58 |
-21:07:18.6 |
HIP 99990 |
12.04 |
| 2026-03-31 00:00 |
20:17:38.99 |
-21:06:28.6 |
HIP 99990 |
14.69 |
| 2026-03-31 12:00 |
20:18:00.27 |
-21:05:39.0 |
HIP 99990 |
18.36 |
| 2026-04-01 00:00 |
20:18:21.40 |
-21:04:49.7 |
HIP 100201 |
16.92 |
| 2026-04-01 12:00 |
20:18:42.38 |
-21:04:00.8 |
HIP 100201 |
12.30 |
| 2026-04-02 00:00 |
20:19:03.23 |
-21:03:12.3 |
HIP 100201 |
8.10 |
| 2026-04-02 12:00 |
20:19:23.93 |
-21:02:24.2 |
HIP 100201 |
5.38 |
| 2026-04-03 00:00 |
20:19:44.49 |
-21:01:36.5 |
HIP 100201 |
6.31 |
| 2026-04-03 12:00 |
20:20:04.90 |
-21:00:49.2 |
HIP 100201 |
9.88 |
| 2026-04-04 00:00 |
20:20:25.17 |
-21:00:02.2 |
HIP 100201 |
14.18 |
| 2026-04-04 12:00 |
20:20:45.29 |
-20:59:15.7 |
HIP 100201 |
18.69 |
| 2026-04-05 00:00 |
20:21:05.26 |
-20:58:29.6 |
HIP 100201 |
23.27 |
| 2026-04-05 12:00 |
20:21:25.08 |
-20:57:43.9 |
HIP 100394 |
27.45 |
| 2026-04-06 00:00 |
20:21:44.76 |
-20:56:58.7 |
HIP 100394 |
28.28 |
| 2026-04-06 12:00 |
20:22:04.28 |
-20:56:13.9 |
HIP 100378 |
29.65 |
| 2026-04-07 00:00 |
20:22:23.65 |
-20:55:29.5 |
HIP 100608 |
28.03 |
| 2026-04-07 12:00 |
20:22:42.87 |
-20:54:45.6 |
HIP 100608 |
24.79 |
| 2026-04-08 00:00 |
20:23:01.93 |
-20:54:02.1 |
HIP 100608 |
22.03 |
| 2026-04-08 12:00 |
20:23:20.85 |
-20:53:19.1 |
HIP 100608 |
19.94 |
| 2026-04-09 00:00 |
20:23:39.60 |
-20:52:36.6 |
HIP 100608 |
18.70 |
| 2026-04-09 12:00 |
20:23:58.20 |
-20:51:54.5 |
HIP 100608 |
18.47 |
| 2026-04-10 00:00 |
20:24:16.64 |
-20:51:12.9 |
HIP 100608 |
19.25 |
| 2026-04-10 12:00 |
20:24:34.93 |
-20:50:31.8 |
HIP 100608 |
20.91 |
| 2026-04-11 00:00 |
20:24:53.05 |
-20:49:51.2 |
HIP 100740 |
21.19 |
| 2026-04-11 12:00 |
20:25:11.01 |
-20:49:11.1 |
HIP 100740 |
20.63 |
| 2026-04-12 00:00 |
20:25:28.82 |
-20:48:31.6 |
HIP 100740 |
20.91 |
| 2026-04-12 12:00 |
20:25:46.46 |
-20:47:52.5 |
HIP 100740 |
22.00 |
| 2026-04-13 00:00 |
20:26:03.93 |
-20:47:14.0 |
HIP 100740 |
23.76 |
| 2026-04-13 12:00 |
20:26:21.25 |
-20:46:36.0 |
HIP 100740 |
26.03 |
| 2026-04-14 00:00 |
20:26:38.39 |
-20:45:58.5 |
HIP 100740 |
28.68 |
| 2026-04-14 12:00 |
20:26:55.37 |
-20:45:21.6 |
HIP 101039 |
30.48 |
| 2026-04-15 00:00 |
20:27:12.19 |
-20:44:45.2 |
HIP 101039 |
26.94 |
| 2026-04-15 12:00 |
20:27:28.83 |
-20:44:09.4 |
HIP 101039 |
23.58 |
| 2026-04-16 00:00 |
20:27:45.31 |
-20:43:34.2 |
HIP 101039 |
20.45 |