D/1977 C1 (Skiff-Kosai)
| Parameter |
Value |
| Designation |
D/1977 C1 (Skiff-Kosai) |
| Type |
D |
| Perihelion (tp_cal, UTC) |
1976-08-03T23:51:26.127360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:24Z |
| Obs used |
8 |
| NEO |
- |
| M1 |
8.500 |
| K1 |
15.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1977-02-23.0000000 |
| e |
0.25917112 |
| q (au) |
2.849755 |
| a (au) |
3.846712 |
| i (deg) |
3.201388 |
| Ω (om, deg) |
80.768376 |
| ω (w, deg) |
26.550778 |
| M (ma, deg) |
26.520292 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.449 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.449 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.502 |
| 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) |
| 2026-02-03 00:00 |
20:48:38.30 |
-19:51:24.3 |
HIP 102660 |
36.26 |
| 2026-02-03 12:00 |
20:49:08.38 |
-19:49:32.0 |
HIP 102660 |
36.29 |
| 2026-02-04 00:00 |
20:49:38.44 |
-19:47:39.5 |
HIP 102660 |
37.76 |
| 2026-02-04 12:00 |
20:50:08.49 |
-19:45:46.8 |
HIP 103018 |
30.88 |
| 2026-02-05 00:00 |
20:50:38.52 |
-19:43:53.9 |
HIP 103018 |
23.57 |
| 2026-02-05 12:00 |
20:51:08.53 |
-19:42:00.8 |
HIP 103018 |
16.26 |
| 2026-02-06 00:00 |
20:51:38.53 |
-19:40:07.5 |
HIP 103018 |
8.97 |
| 2026-02-06 12:00 |
20:52:08.52 |
-19:38:14.0 |
HIP 103018 |
1.82 |
| 2026-02-07 00:00 |
20:52:38.48 |
-19:36:20.3 |
HIP 103032 |
5.23 |
| 2026-02-07 12:00 |
20:53:08.42 |
-19:34:26.4 |
HIP 103032 |
10.00 |
| 2026-02-08 00:00 |
20:53:38.35 |
-19:32:32.3 |
HIP 103032 |
16.71 |
| 2026-02-08 12:00 |
20:54:08.26 |
-19:30:38.1 |
HIP 103032 |
23.77 |
| 2026-02-09 00:00 |
20:54:38.14 |
-19:28:43.7 |
HIP 103114 |
26.87 |
| 2026-02-09 12:00 |
20:55:08.01 |
-19:26:49.2 |
HIP 103332 |
28.26 |
| 2026-02-10 00:00 |
20:55:37.85 |
-19:24:54.4 |
HIP 103332 |
23.81 |
| 2026-02-10 12:00 |
20:56:07.67 |
-19:22:59.5 |
HIP 103332 |
21.02 |
| 2026-02-11 00:00 |
20:56:37.47 |
-19:21:04.5 |
HIP 103332 |
20.57 |
| 2026-02-11 12:00 |
20:57:07.24 |
-19:19:09.3 |
HIP 103332 |
22.59 |
| 2026-02-12 00:00 |
20:57:36.99 |
-19:17:14.0 |
HIP 103332 |
26.53 |
| 2026-02-12 12:00 |
20:58:06.71 |
-19:15:18.5 |
HIP 103566 |
24.23 |
| 2026-02-13 00:00 |
20:58:36.41 |
-19:13:22.8 |
HIP 103616 |
18.05 |
| 2026-02-13 12:00 |
20:59:06.08 |
-19:11:27.1 |
HIP 103616 |
11.73 |
| 2026-02-14 00:00 |
20:59:35.72 |
-19:09:31.2 |
HIP 103616 |
7.41 |
| 2026-02-14 12:00 |
21:00:05.34 |
-19:07:35.2 |
HIP 103616 |
8.81 |
| 2026-02-15 00:00 |
21:00:34.93 |
-19:05:39.0 |
HIP 103616 |
14.33 |
| 2026-02-15 12:00 |
21:01:04.48 |
-19:03:42.8 |
HIP 103751 |
10.10 |
| 2026-02-16 00:00 |
21:01:34.01 |
-19:01:46.4 |
HIP 103751 |
6.96 |
| 2026-02-16 12:00 |
21:02:03.50 |
-18:59:49.9 |
HIP 103751 |
9.99 |
| 2026-02-17 00:00 |
21:02:32.97 |
-18:57:53.3 |
HIP 103751 |
15.99 |
| 2026-02-17 12:00 |
21:03:02.40 |
-18:55:56.6 |
HIP 103865 |
19.41 |
| 2026-02-18 00:00 |
21:03:31.79 |
-18:53:59.9 |
HIP 103865 |
23.65 |
| 2026-02-18 12:00 |
21:04:01.16 |
-18:52:03.0 |
HIP 103997 |
20.86 |
| 2026-02-19 00:00 |
21:04:30.48 |
-18:50:06.1 |
HIP 103997 |
19.13 |
| 2026-02-19 12:00 |
21:04:59.78 |
-18:48:09.0 |
HIP 103997 |
20.01 |
| 2026-02-20 00:00 |
21:05:29.03 |
-18:46:12.0 |
HIP 103997 |
23.21 |
| 2026-02-20 12:00 |
21:05:58.25 |
-18:44:14.8 |
HIP 104230 |
16.32 |
| 2026-02-21 00:00 |
21:06:27.43 |
-18:42:17.6 |
HIP 104230 |
9.27 |
| 2026-02-21 12:00 |
21:06:56.57 |
-18:40:20.3 |
HIP 104230 |
2.94 |
| 2026-02-22 00:00 |
21:07:25.68 |
-18:38:22.9 |
HIP 104230 |
5.85 |
| 2026-02-22 12:00 |
21:07:54.74 |
-18:36:25.5 |
HIP 104230 |
12.74 |
| 2026-02-23 00:00 |
21:08:23.76 |
-18:34:28.1 |
HIP 104387 |
11.06 |
| 2026-02-23 12:00 |
21:08:52.74 |
-18:32:30.6 |
HIP 104387 |
11.14 |
| 2026-02-24 00:00 |
21:09:21.68 |
-18:30:33.1 |
HIP 104387 |
15.09 |