| 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) |
| 2026-03-26 00:00 |
00:23:50.11 |
+29:02:51.1 |
HIP 1878 |
21.27 |
| 2026-03-26 12:00 |
00:23:51.81 |
+29:02:59.6 |
HIP 1878 |
21.15 |
| 2026-03-27 00:00 |
00:23:53.51 |
+29:03:08.3 |
HIP 1878 |
21.05 |
| 2026-03-27 12:00 |
00:23:55.21 |
+29:03:17.1 |
HIP 1878 |
20.95 |
| 2026-03-28 00:00 |
00:23:56.91 |
+29:03:25.9 |
HIP 1878 |
20.85 |
| 2026-03-28 12:00 |
00:23:58.61 |
+29:03:34.8 |
HIP 1878 |
20.76 |
| 2026-03-29 00:00 |
00:24:00.31 |
+29:03:43.9 |
HIP 1878 |
20.68 |
| 2026-03-29 12:00 |
00:24:02.01 |
+29:03:53.0 |
HIP 1878 |
20.60 |
| 2026-03-30 00:00 |
00:24:03.70 |
+29:04:02.2 |
HIP 1878 |
20.53 |
| 2026-03-30 12:00 |
00:24:05.40 |
+29:04:11.4 |
HIP 1878 |
20.46 |
| 2026-03-31 00:00 |
00:24:07.10 |
+29:04:20.8 |
HIP 1878 |
20.40 |
| 2026-03-31 12:00 |
00:24:08.80 |
+29:04:30.3 |
HIP 1878 |
20.35 |
| 2026-04-01 00:00 |
00:24:10.49 |
+29:04:39.8 |
HIP 1878 |
20.30 |
| 2026-04-01 12:00 |
00:24:12.19 |
+29:04:49.4 |
HIP 1878 |
20.26 |
| 2026-04-02 00:00 |
00:24:13.88 |
+29:04:59.1 |
HIP 1878 |
20.22 |
| 2026-04-02 12:00 |
00:24:15.57 |
+29:05:08.9 |
HIP 1878 |
20.20 |
| 2026-04-03 00:00 |
00:24:17.26 |
+29:05:18.8 |
HIP 1878 |
20.18 |
| 2026-04-03 12:00 |
00:24:18.95 |
+29:05:28.7 |
HIP 1878 |
20.16 |
| 2026-04-04 00:00 |
00:24:20.63 |
+29:05:38.8 |
HIP 1878 |
20.16 |
| 2026-04-04 12:00 |
00:24:22.32 |
+29:05:48.9 |
HIP 1878 |
20.15 |
| 2026-04-05 00:00 |
00:24:24.00 |
+29:05:59.1 |
HIP 1878 |
20.16 |
| 2026-04-05 12:00 |
00:24:25.68 |
+29:06:09.3 |
HIP 1878 |
20.17 |
| 2026-04-06 00:00 |
00:24:27.36 |
+29:06:19.7 |
HIP 1878 |
20.19 |
| 2026-04-06 12:00 |
00:24:29.04 |
+29:06:30.1 |
HIP 1878 |
20.22 |
| 2026-04-07 00:00 |
00:24:30.71 |
+29:06:40.6 |
HIP 1878 |
20.25 |
| 2026-04-07 12:00 |
00:24:32.39 |
+29:06:51.2 |
HIP 1878 |
20.29 |
| 2026-04-08 00:00 |
00:24:34.06 |
+29:07:01.8 |
HIP 1878 |
20.34 |
| 2026-04-08 12:00 |
00:24:35.72 |
+29:07:12.6 |
HIP 1878 |
20.39 |
| 2026-04-09 00:00 |
00:24:37.39 |
+29:07:23.4 |
HIP 1878 |
20.45 |
| 2026-04-09 12:00 |
00:24:39.05 |
+29:07:34.2 |
HIP 1878 |
20.52 |
| 2026-04-10 00:00 |
00:24:40.70 |
+29:07:45.2 |
HIP 1878 |
20.59 |
| 2026-04-10 12:00 |
00:24:42.36 |
+29:07:56.2 |
HIP 1878 |
20.67 |
| 2026-04-11 00:00 |
00:24:44.01 |
+29:08:07.3 |
HIP 1878 |
20.75 |
| 2026-04-11 12:00 |
00:24:45.66 |
+29:08:18.4 |
HIP 2055 |
20.61 |
| 2026-04-12 00:00 |
00:24:47.30 |
+29:08:29.7 |
HIP 2055 |
20.42 |
| 2026-04-12 12:00 |
00:24:48.95 |
+29:08:41.0 |
HIP 2055 |
20.25 |
| 2026-04-13 00:00 |
00:24:50.58 |
+29:08:52.3 |
HIP 2055 |
20.08 |
| 2026-04-13 12:00 |
00:24:52.22 |
+29:09:03.8 |
HIP 2055 |
19.92 |
| 2026-04-14 00:00 |
00:24:53.85 |
+29:09:15.2 |
HIP 2055 |
19.77 |
| 2026-04-14 12:00 |
00:24:55.47 |
+29:09:26.8 |
HIP 2055 |
19.63 |
| 2026-04-15 00:00 |
00:24:57.09 |
+29:09:38.4 |
HIP 2055 |
19.50 |
| 2026-04-15 12:00 |
00:24:58.71 |
+29:09:50.1 |
HIP 2055 |
19.37 |
| 2026-04-16 00:00 |
00:25:00.32 |
+29:10:01.9 |
HIP 2055 |
19.26 |