| Parameter |
Value |
| Designation |
C/1977 H1 (Helin) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1977-06-30T23:22:37.151040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:27Z |
| Obs used |
35 |
| NEO |
- |
| M1 |
14.600 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1977-04-22.0000000 |
| e |
0.99999249 |
| q (au) |
1.117547 |
| a (au) |
148777.258886 |
| i (deg) |
43.194938 |
| Ω (om, deg) |
20.138583 |
| ω (w, deg) |
249.358219 |
| M (ma, deg) |
359.999999 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.630 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.630 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
03:40:04.05 |
+54:22:46.7 |
HIP 17200 |
24.29 |
| 2026-05-12 12:00 |
03:40:06.69 |
+54:22:49.8 |
HIP 17200 |
24.20 |
| 2026-05-13 00:00 |
03:40:09.33 |
+54:22:53.0 |
HIP 17200 |
24.12 |
| 2026-05-13 12:00 |
03:40:11.97 |
+54:22:56.4 |
HIP 17200 |
24.05 |
| 2026-05-14 00:00 |
03:40:14.62 |
+54:22:59.8 |
HIP 17200 |
23.99 |
| 2026-05-14 12:00 |
03:40:17.27 |
+54:23:03.4 |
HIP 17200 |
23.94 |
| 2026-05-15 00:00 |
03:40:19.92 |
+54:23:07.1 |
HIP 17200 |
23.89 |
| 2026-05-15 12:00 |
03:40:22.57 |
+54:23:10.9 |
HIP 17200 |
23.85 |
| 2026-05-16 00:00 |
03:40:25.22 |
+54:23:14.8 |
HIP 17200 |
23.82 |
| 2026-05-16 12:00 |
03:40:27.87 |
+54:23:18.9 |
HIP 17200 |
23.80 |
| 2026-05-17 00:00 |
03:40:30.53 |
+54:23:23.0 |
HIP 17200 |
23.79 |
| 2026-05-17 12:00 |
03:40:33.18 |
+54:23:27.3 |
HIP 17200 |
23.79 |
| 2026-05-18 00:00 |
03:40:35.84 |
+54:23:31.6 |
HIP 17200 |
23.79 |
| 2026-05-18 12:00 |
03:40:38.49 |
+54:23:36.1 |
HIP 17200 |
23.80 |
| 2026-05-19 00:00 |
03:40:41.15 |
+54:23:40.7 |
HIP 17200 |
23.82 |
| 2026-05-19 12:00 |
03:40:43.80 |
+54:23:45.4 |
HIP 17200 |
23.85 |
| 2026-05-20 00:00 |
03:40:46.46 |
+54:23:50.2 |
HIP 17200 |
23.89 |
| 2026-05-20 12:00 |
03:40:49.11 |
+54:23:55.1 |
HIP 17200 |
23.94 |
| 2026-05-21 00:00 |
03:40:51.77 |
+54:24:00.1 |
HIP 17200 |
23.99 |
| 2026-05-21 12:00 |
03:40:54.42 |
+54:24:05.2 |
HIP 17200 |
24.05 |
| 2026-05-22 00:00 |
03:40:57.07 |
+54:24:10.5 |
HIP 17200 |
24.12 |
| 2026-05-22 12:00 |
03:40:59.72 |
+54:24:15.8 |
HIP 17200 |
24.20 |
| 2026-05-23 00:00 |
03:41:02.37 |
+54:24:21.3 |
HIP 17200 |
24.29 |
| 2026-05-23 12:00 |
03:41:05.02 |
+54:24:26.8 |
HIP 17200 |
24.38 |
| 2026-05-24 00:00 |
03:41:07.66 |
+54:24:32.5 |
HIP 17200 |
24.48 |
| 2026-05-24 12:00 |
03:41:10.30 |
+54:24:38.3 |
HIP 17200 |
24.59 |
| 2026-05-25 00:00 |
03:41:12.95 |
+54:24:44.2 |
HIP 17200 |
24.71 |
| 2026-05-25 12:00 |
03:41:15.58 |
+54:24:50.1 |
HIP 17200 |
24.84 |
| 2026-05-26 00:00 |
03:41:18.22 |
+54:24:56.2 |
HIP 17200 |
24.97 |
| 2026-05-26 12:00 |
03:41:20.85 |
+54:25:02.4 |
HIP 17200 |
25.11 |
| 2026-05-27 00:00 |
03:41:23.49 |
+54:25:08.7 |
HIP 17200 |
25.26 |
| 2026-05-27 12:00 |
03:41:26.11 |
+54:25:15.1 |
HIP 17200 |
25.41 |
| 2026-05-28 00:00 |
03:41:28.74 |
+54:25:21.6 |
HIP 17200 |
25.57 |
| 2026-05-28 12:00 |
03:41:31.36 |
+54:25:28.2 |
HIP 17200 |
25.74 |
| 2026-05-29 00:00 |
03:41:33.98 |
+54:25:34.9 |
HIP 17200 |
25.92 |
| 2026-05-29 12:00 |
03:41:36.59 |
+54:25:41.7 |
HIP 17200 |
26.10 |
| 2026-05-30 00:00 |
03:41:39.20 |
+54:25:48.6 |
HIP 17200 |
26.28 |
| 2026-05-30 12:00 |
03:41:41.81 |
+54:25:55.6 |
HIP 17200 |
26.48 |
| 2026-05-31 00:00 |
03:41:44.41 |
+54:26:02.7 |
HIP 17200 |
26.68 |
| 2026-05-31 12:00 |
03:41:47.01 |
+54:26:09.9 |
HIP 17200 |
26.88 |
| 2026-06-01 00:00 |
03:41:49.61 |
+54:26:17.2 |
HIP 17200 |
27.09 |
| 2026-06-01 12:00 |
03:41:52.20 |
+54:26:24.6 |
HIP 17200 |
27.31 |
| 2026-06-02 00:00 |
03:41:54.78 |
+54:26:32.1 |
HIP 17200 |
27.53 |