| Parameter |
Value |
| Designation |
C/1978 H1 (Meier) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1978-11-11T09:49:21.498240Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:26Z |
| Obs used |
276 |
| NEO |
- |
| M1 |
5.100 |
| K1 |
7.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1978-12-13.0000000 |
| e |
1.00084968 |
| q (au) |
1.136526 |
| a (au) |
-1337.595649 |
| i (deg) |
43.761381 |
| Ω (om, deg) |
349.344795 |
| ω (w, deg) |
231.402033 |
| M (ma, deg) |
0.000636 |
Magnitude
Scatter + Global Linear
$$
M_a = (1.696 + 4.508\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
1.696 |
| n |
4.508 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 1978-04-27 |
1978-11-09 |
-2.4267 |
+0.754 |
| 1978-11-13 |
1979-12-21 |
-2.6793 |
+1.685 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
00:26:56.23 |
+29:30:33.5 |
HIP 2133 |
26.86 |
| 2026-06-01 12:00 |
00:26:57.01 |
+29:30:47.2 |
HIP 2133 |
27.08 |
| 2026-06-02 00:00 |
00:26:57.78 |
+29:31:00.9 |
HIP 2133 |
27.30 |
| 2026-06-02 12:00 |
00:26:58.54 |
+29:31:14.6 |
HIP 2133 |
27.52 |
| 2026-06-03 00:00 |
00:26:59.28 |
+29:31:28.2 |
HIP 2133 |
27.74 |
| 2026-06-03 12:00 |
00:27:00.02 |
+29:31:41.9 |
HIP 2133 |
27.96 |
| 2026-06-04 00:00 |
00:27:00.74 |
+29:31:55.5 |
HIP 2133 |
28.18 |
| 2026-06-04 12:00 |
00:27:01.44 |
+29:32:09.0 |
HIP 2133 |
28.41 |
| 2026-06-05 00:00 |
00:27:02.14 |
+29:32:22.6 |
HIP 2133 |
28.63 |
| 2026-06-05 12:00 |
00:27:02.82 |
+29:32:36.1 |
HIP 2133 |
28.85 |
| 2026-06-06 00:00 |
00:27:03.49 |
+29:32:49.6 |
HIP 2133 |
29.08 |
| 2026-06-06 12:00 |
00:27:04.14 |
+29:33:03.0 |
HIP 2133 |
29.30 |
| 2026-06-07 00:00 |
00:27:04.79 |
+29:33:16.5 |
HIP 2133 |
29.52 |
| 2026-06-07 12:00 |
00:27:05.42 |
+29:33:29.9 |
HIP 2133 |
29.75 |
| 2026-06-08 00:00 |
00:27:06.03 |
+29:33:43.2 |
HIP 2133 |
29.97 |
| 2026-06-08 12:00 |
00:27:06.64 |
+29:33:56.6 |
HIP 2133 |
30.20 |
| 2026-06-09 00:00 |
00:27:07.23 |
+29:34:09.9 |
HIP 2133 |
30.42 |
| 2026-06-09 12:00 |
00:27:07.80 |
+29:34:23.1 |
HIP 2133 |
30.65 |
| 2026-06-10 00:00 |
00:27:08.37 |
+29:34:36.3 |
HIP 2133 |
30.87 |
| 2026-06-10 12:00 |
00:27:08.92 |
+29:34:49.5 |
HIP 2133 |
31.09 |
| 2026-06-11 00:00 |
00:27:09.46 |
+29:35:02.7 |
HIP 2133 |
31.32 |
| 2026-06-11 12:00 |
00:27:09.98 |
+29:35:15.8 |
HIP 1980 |
31.33 |
| 2026-06-12 00:00 |
00:27:10.49 |
+29:35:28.9 |
HIP 1980 |
31.32 |
| 2026-06-12 12:00 |
00:27:10.99 |
+29:35:41.9 |
HIP 1980 |
31.31 |
| 2026-06-13 00:00 |
00:27:11.47 |
+29:35:54.9 |
HIP 1980 |
31.29 |
| 2026-06-13 12:00 |
00:27:11.94 |
+29:36:07.9 |
HIP 1980 |
31.28 |
| 2026-06-14 00:00 |
00:27:12.40 |
+29:36:20.8 |
HIP 1980 |
31.27 |
| 2026-06-14 12:00 |
00:27:12.84 |
+29:36:33.7 |
HIP 1980 |
31.25 |
| 2026-06-15 00:00 |
00:27:13.27 |
+29:36:46.5 |
HIP 1980 |
31.24 |
| 2026-06-15 12:00 |
00:27:13.69 |
+29:36:59.3 |
HIP 1980 |
31.22 |
| 2026-06-16 00:00 |
00:27:14.09 |
+29:37:12.0 |
HIP 1980 |
31.21 |
| 2026-06-16 12:00 |
00:27:14.48 |
+29:37:24.7 |
HIP 1980 |
31.19 |
| 2026-06-17 00:00 |
00:27:14.85 |
+29:37:37.3 |
HIP 1980 |
31.18 |
| 2026-06-17 12:00 |
00:27:15.21 |
+29:37:49.9 |
HIP 1980 |
31.16 |
| 2026-06-18 00:00 |
00:27:15.56 |
+29:38:02.4 |
HIP 1980 |
31.14 |
| 2026-06-18 12:00 |
00:27:15.89 |
+29:38:14.9 |
HIP 1980 |
31.12 |
| 2026-06-19 00:00 |
00:27:16.21 |
+29:38:27.4 |
HIP 1980 |
31.10 |
| 2026-06-19 12:00 |
00:27:16.51 |
+29:38:39.7 |
HIP 1980 |
31.08 |
| 2026-06-20 00:00 |
00:27:16.80 |
+29:38:52.1 |
HIP 1980 |
31.06 |
| 2026-06-20 12:00 |
00:27:17.08 |
+29:39:04.3 |
HIP 1980 |
31.03 |
| 2026-06-21 00:00 |
00:27:17.34 |
+29:39:16.6 |
HIP 1980 |
31.01 |
| 2026-06-21 12:00 |
00:27:17.59 |
+29:39:28.7 |
HIP 1980 |
30.98 |
| 2026-06-22 00:00 |
00:27:17.83 |
+29:39:40.8 |
HIP 1980 |
30.96 |