| 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) |
| 2026-03-26 00:00 |
03:36:30.07 |
+54:26:32.9 |
HIP 16888 |
9.50 |
| 2026-03-26 12:00 |
03:36:31.76 |
+54:26:25.2 |
HIP 16888 |
9.40 |
| 2026-03-27 00:00 |
03:36:33.46 |
+54:26:17.6 |
HIP 16888 |
9.31 |
| 2026-03-27 12:00 |
03:36:35.18 |
+54:26:10.2 |
HIP 16888 |
9.22 |
| 2026-03-28 00:00 |
03:36:36.91 |
+54:26:02.8 |
HIP 16888 |
9.14 |
| 2026-03-28 12:00 |
03:36:38.66 |
+54:25:55.5 |
HIP 16888 |
9.06 |
| 2026-03-29 00:00 |
03:36:40.43 |
+54:25:48.4 |
HIP 16888 |
8.99 |
| 2026-03-29 12:00 |
03:36:42.22 |
+54:25:41.3 |
HIP 16888 |
8.92 |
| 2026-03-30 00:00 |
03:36:44.02 |
+54:25:34.4 |
HIP 16888 |
8.86 |
| 2026-03-30 12:00 |
03:36:45.84 |
+54:25:27.5 |
HIP 16888 |
8.80 |
| 2026-03-31 00:00 |
03:36:47.68 |
+54:25:20.8 |
HIP 16888 |
8.75 |
| 2026-03-31 12:00 |
03:36:49.53 |
+54:25:14.2 |
HIP 16888 |
8.71 |
| 2026-04-01 00:00 |
03:36:51.39 |
+54:25:07.7 |
HIP 16888 |
8.67 |
| 2026-04-01 12:00 |
03:36:53.27 |
+54:25:01.3 |
HIP 16888 |
8.64 |
| 2026-04-02 00:00 |
03:36:55.17 |
+54:24:55.0 |
HIP 16888 |
8.62 |
| 2026-04-02 12:00 |
03:36:57.09 |
+54:24:48.8 |
HIP 16888 |
8.60 |
| 2026-04-03 00:00 |
03:36:59.01 |
+54:24:42.7 |
HIP 16888 |
8.60 |
| 2026-04-03 12:00 |
03:37:00.96 |
+54:24:36.8 |
HIP 16888 |
8.60 |
| 2026-04-04 00:00 |
03:37:02.92 |
+54:24:30.9 |
HIP 16888 |
8.61 |
| 2026-04-04 12:00 |
03:37:04.89 |
+54:24:25.2 |
HIP 16888 |
8.62 |
| 2026-04-05 00:00 |
03:37:06.88 |
+54:24:19.6 |
HIP 16888 |
8.65 |
| 2026-04-05 12:00 |
03:37:08.88 |
+54:24:14.0 |
HIP 16888 |
8.68 |
| 2026-04-06 00:00 |
03:37:10.90 |
+54:24:08.6 |
HIP 16888 |
8.72 |
| 2026-04-06 12:00 |
03:37:12.93 |
+54:24:03.4 |
HIP 16888 |
8.77 |
| 2026-04-07 00:00 |
03:37:14.98 |
+54:23:58.2 |
HIP 16888 |
8.83 |
| 2026-04-07 12:00 |
03:37:17.04 |
+54:23:53.1 |
HIP 16888 |
8.90 |
| 2026-04-08 00:00 |
03:37:19.11 |
+54:23:48.2 |
HIP 16888 |
8.97 |
| 2026-04-08 12:00 |
03:37:21.20 |
+54:23:43.3 |
HIP 16888 |
9.06 |
| 2026-04-09 00:00 |
03:37:23.31 |
+54:23:38.6 |
HIP 16888 |
9.15 |
| 2026-04-09 12:00 |
03:37:25.42 |
+54:23:34.0 |
HIP 16888 |
9.25 |
| 2026-04-10 00:00 |
03:37:27.55 |
+54:23:29.5 |
HIP 16888 |
9.36 |
| 2026-04-10 12:00 |
03:37:29.69 |
+54:23:25.2 |
HIP 16888 |
9.47 |
| 2026-04-11 00:00 |
03:37:31.85 |
+54:23:20.9 |
HIP 16888 |
9.60 |
| 2026-04-11 12:00 |
03:37:34.02 |
+54:23:16.8 |
HIP 16888 |
9.73 |
| 2026-04-12 00:00 |
03:37:36.20 |
+54:23:12.7 |
HIP 16888 |
9.87 |
| 2026-04-12 12:00 |
03:37:38.39 |
+54:23:08.8 |
HIP 16888 |
10.01 |
| 2026-04-13 00:00 |
03:37:40.60 |
+54:23:05.0 |
HIP 16888 |
10.17 |
| 2026-04-13 12:00 |
03:37:42.81 |
+54:23:01.4 |
HIP 16888 |
10.33 |
| 2026-04-14 00:00 |
03:37:45.05 |
+54:22:57.8 |
HIP 16888 |
10.49 |
| 2026-04-14 12:00 |
03:37:47.29 |
+54:22:54.4 |
HIP 16888 |
10.67 |
| 2026-04-15 00:00 |
03:37:49.54 |
+54:22:51.0 |
HIP 16888 |
10.84 |
| 2026-04-15 12:00 |
03:37:51.81 |
+54:22:47.8 |
HIP 16888 |
11.03 |
| 2026-04-16 00:00 |
03:37:54.09 |
+54:22:44.7 |
HIP 16888 |
11.22 |