| Parameter |
Value |
| Designation |
C/1978 A1 (West) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1977-07-21T10:46:21.555840Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:26Z |
| Obs used |
60 |
| NEO |
- |
| M1 |
6.000 |
| K1 |
8.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1978-03-26.0000000 |
| e |
1.00269511 |
| q (au) |
5.606239 |
| a (au) |
-2080.153011 |
| i (deg) |
116.921045 |
| Ω (om, deg) |
211.624226 |
| ω (w, deg) |
343.273891 |
| M (ma, deg) |
0.002572 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.758 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.758 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.507 |
| 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) |
| 2026-06-01 00:00 |
02:43:14.93 |
+60:36:22.9 |
HIP 12729 |
2.74 |
| 2026-06-01 12:00 |
02:43:17.75 |
+60:36:34.3 |
HIP 12729 |
2.39 |
| 2026-06-02 00:00 |
02:43:20.56 |
+60:36:45.8 |
HIP 12729 |
2.06 |
| 2026-06-02 12:00 |
02:43:23.35 |
+60:36:57.4 |
HIP 12729 |
1.76 |
| 2026-06-03 00:00 |
02:43:26.13 |
+60:37:09.1 |
HIP 12729 |
1.51 |
| 2026-06-03 12:00 |
02:43:28.90 |
+60:37:20.9 |
HIP 12729 |
1.33 |
| 2026-06-04 00:00 |
02:43:31.66 |
+60:37:32.8 |
HIP 12729 |
1.25 |
| 2026-06-04 12:00 |
02:43:34.40 |
+60:37:44.8 |
HIP 12729 |
1.29 |
| 2026-06-05 00:00 |
02:43:37.13 |
+60:37:56.9 |
HIP 12729 |
1.45 |
| 2026-06-05 12:00 |
02:43:39.85 |
+60:38:09.2 |
HIP 12729 |
1.68 |
| 2026-06-06 00:00 |
02:43:42.56 |
+60:38:21.5 |
HIP 12729 |
1.97 |
| 2026-06-06 12:00 |
02:43:45.25 |
+60:38:33.9 |
HIP 12729 |
2.28 |
| 2026-06-07 00:00 |
02:43:47.93 |
+60:38:46.4 |
HIP 12729 |
2.62 |
| 2026-06-07 12:00 |
02:43:50.59 |
+60:38:59.0 |
HIP 12729 |
2.97 |
| 2026-06-08 00:00 |
02:43:53.24 |
+60:39:11.8 |
HIP 12729 |
3.33 |
| 2026-06-08 12:00 |
02:43:55.87 |
+60:39:24.6 |
HIP 12729 |
3.70 |
| 2026-06-09 00:00 |
02:43:58.50 |
+60:39:37.5 |
HIP 12729 |
4.07 |
| 2026-06-09 12:00 |
02:44:01.10 |
+60:39:50.5 |
HIP 12729 |
4.44 |
| 2026-06-10 00:00 |
02:44:03.69 |
+60:40:03.6 |
HIP 12729 |
4.81 |
| 2026-06-10 12:00 |
02:44:06.27 |
+60:40:16.7 |
HIP 12729 |
5.19 |
| 2026-06-11 00:00 |
02:44:08.83 |
+60:40:30.0 |
HIP 12729 |
5.57 |
| 2026-06-11 12:00 |
02:44:11.38 |
+60:40:43.4 |
HIP 12729 |
5.94 |
| 2026-06-12 00:00 |
02:44:13.91 |
+60:40:56.8 |
HIP 12729 |
6.32 |
| 2026-06-12 12:00 |
02:44:16.42 |
+60:41:10.4 |
HIP 12729 |
6.70 |
| 2026-06-13 00:00 |
02:44:18.92 |
+60:41:24.0 |
HIP 12729 |
7.08 |
| 2026-06-13 12:00 |
02:44:21.41 |
+60:41:37.7 |
HIP 12729 |
7.46 |
| 2026-06-14 00:00 |
02:44:23.87 |
+60:41:51.5 |
HIP 12729 |
7.83 |
| 2026-06-14 12:00 |
02:44:26.32 |
+60:42:05.4 |
HIP 12729 |
8.21 |
| 2026-06-15 00:00 |
02:44:28.75 |
+60:42:19.4 |
HIP 12729 |
8.59 |
| 2026-06-15 12:00 |
02:44:31.17 |
+60:42:33.5 |
HIP 12729 |
8.96 |
| 2026-06-16 00:00 |
02:44:33.57 |
+60:42:47.6 |
HIP 12729 |
9.34 |
| 2026-06-16 12:00 |
02:44:35.95 |
+60:43:01.8 |
HIP 12729 |
9.71 |
| 2026-06-17 00:00 |
02:44:38.32 |
+60:43:16.1 |
HIP 12729 |
10.09 |
| 2026-06-17 12:00 |
02:44:40.66 |
+60:43:30.5 |
HIP 12729 |
10.46 |
| 2026-06-18 00:00 |
02:44:42.99 |
+60:43:44.9 |
HIP 12729 |
10.83 |
| 2026-06-18 12:00 |
02:44:45.30 |
+60:43:59.5 |
HIP 12729 |
11.21 |
| 2026-06-19 00:00 |
02:44:47.60 |
+60:44:14.1 |
HIP 12729 |
11.58 |
| 2026-06-19 12:00 |
02:44:49.87 |
+60:44:28.7 |
HIP 12729 |
11.95 |
| 2026-06-20 00:00 |
02:44:52.13 |
+60:44:43.5 |
HIP 12729 |
12.32 |
| 2026-06-20 12:00 |
02:44:54.37 |
+60:44:58.3 |
HIP 12729 |
12.68 |
| 2026-06-21 00:00 |
02:44:56.58 |
+60:45:13.2 |
HIP 12729 |
13.05 |
| 2026-06-21 12:00 |
02:44:58.78 |
+60:45:28.2 |
HIP 12729 |
13.42 |
| 2026-06-22 00:00 |
02:45:00.96 |
+60:45:43.2 |
HIP 12729 |
13.78 |