| Parameter |
Value |
| Designation |
C/1980 Y2 (Panther) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1981-01-27T07:35:59.709120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:29Z |
| Obs used |
200 |
| NEO |
- |
| M1 |
6.800 |
| K1 |
6.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1981-02-26.0000000 |
| e |
0.99865714 |
| q (au) |
1.657187 |
| a (au) |
1234.075622 |
| i (deg) |
82.646128 |
| Ω (om, deg) |
332.000700 |
| ω (w, deg) |
105.597962 |
| M (ma, deg) |
0.000675 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.548 + 4.217\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.548 |
| n |
4.217 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.863 |
| δ90 |
1.000 |
| 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 |
| 1980-10-27 |
1981-01-26 |
+21.4786 |
-4.799 |
| 1981-01-27 |
1981-06-03 |
-0.3491 |
+0.057 |
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 |
06:59:58.84 |
-70:45:05.6 |
HIP 33860 |
14.22 |
| 2026-06-01 12:00 |
07:00:02.97 |
-70:44:51.9 |
HIP 33860 |
13.83 |
| 2026-06-02 00:00 |
07:00:07.12 |
-70:44:38.3 |
HIP 33860 |
13.44 |
| 2026-06-02 12:00 |
07:00:11.30 |
-70:44:25.0 |
HIP 33860 |
13.05 |
| 2026-06-03 00:00 |
07:00:15.49 |
-70:44:11.8 |
HIP 33860 |
12.67 |
| 2026-06-03 12:00 |
07:00:19.71 |
-70:43:58.7 |
HIP 33860 |
12.29 |
| 2026-06-04 00:00 |
07:00:23.94 |
-70:43:45.9 |
HIP 33860 |
11.91 |
| 2026-06-04 12:00 |
07:00:28.20 |
-70:43:33.2 |
HIP 33860 |
11.54 |
| 2026-06-05 00:00 |
07:00:32.47 |
-70:43:20.7 |
HIP 33860 |
11.17 |
| 2026-06-05 12:00 |
07:00:36.77 |
-70:43:08.4 |
HIP 33860 |
10.81 |
| 2026-06-06 00:00 |
07:00:41.08 |
-70:42:56.3 |
HIP 33860 |
10.45 |
| 2026-06-06 12:00 |
07:00:45.42 |
-70:42:44.3 |
HIP 33860 |
10.09 |
| 2026-06-07 00:00 |
07:00:49.77 |
-70:42:32.5 |
HIP 33860 |
9.75 |
| 2026-06-07 12:00 |
07:00:54.14 |
-70:42:20.9 |
HIP 33860 |
9.40 |
| 2026-06-08 00:00 |
07:00:58.54 |
-70:42:09.5 |
HIP 33860 |
9.07 |
| 2026-06-08 12:00 |
07:01:02.94 |
-70:41:58.3 |
HIP 33860 |
8.75 |
| 2026-06-09 00:00 |
07:01:07.37 |
-70:41:47.3 |
HIP 33860 |
8.43 |
| 2026-06-09 12:00 |
07:01:11.82 |
-70:41:36.4 |
HIP 33860 |
8.13 |
| 2026-06-10 00:00 |
07:01:16.28 |
-70:41:25.7 |
HIP 33860 |
7.84 |
| 2026-06-10 12:00 |
07:01:20.76 |
-70:41:15.2 |
HIP 33860 |
7.56 |
| 2026-06-11 00:00 |
07:01:25.25 |
-70:41:04.9 |
HIP 33860 |
7.30 |
| 2026-06-11 12:00 |
07:01:29.77 |
-70:40:54.8 |
HIP 33860 |
7.06 |
| 2026-06-12 00:00 |
07:01:34.29 |
-70:40:44.9 |
HIP 33860 |
6.83 |
| 2026-06-12 12:00 |
07:01:38.84 |
-70:40:35.1 |
HIP 33860 |
6.63 |
| 2026-06-13 00:00 |
07:01:43.40 |
-70:40:25.6 |
HIP 33860 |
6.44 |
| 2026-06-13 12:00 |
07:01:47.97 |
-70:40:16.2 |
HIP 33860 |
6.29 |
| 2026-06-14 00:00 |
07:01:52.56 |
-70:40:07.1 |
HIP 33860 |
6.16 |
| 2026-06-14 12:00 |
07:01:57.17 |
-70:39:58.1 |
HIP 33860 |
6.05 |
| 2026-06-15 00:00 |
07:02:01.78 |
-70:39:49.3 |
HIP 33860 |
5.98 |
| 2026-06-15 12:00 |
07:02:06.42 |
-70:39:40.8 |
HIP 33860 |
5.94 |
| 2026-06-16 00:00 |
07:02:11.06 |
-70:39:32.4 |
HIP 33860 |
5.93 |
| 2026-06-16 12:00 |
07:02:15.72 |
-70:39:24.2 |
HIP 33860 |
5.95 |
| 2026-06-17 00:00 |
07:02:20.39 |
-70:39:16.2 |
HIP 33860 |
6.00 |
| 2026-06-17 12:00 |
07:02:25.08 |
-70:39:08.4 |
HIP 33860 |
6.09 |
| 2026-06-18 00:00 |
07:02:29.77 |
-70:39:00.8 |
HIP 33860 |
6.20 |
| 2026-06-18 12:00 |
07:02:34.48 |
-70:38:53.3 |
HIP 33860 |
6.34 |
| 2026-06-19 00:00 |
07:02:39.20 |
-70:38:46.1 |
HIP 33860 |
6.51 |
| 2026-06-19 12:00 |
07:02:43.93 |
-70:38:39.1 |
HIP 33990 |
6.53 |
| 2026-06-20 00:00 |
07:02:48.67 |
-70:38:32.3 |
HIP 33990 |
6.30 |
| 2026-06-20 12:00 |
07:02:53.43 |
-70:38:25.7 |
HIP 33990 |
6.09 |
| 2026-06-21 00:00 |
07:02:58.19 |
-70:38:19.2 |
HIP 33990 |
5.91 |
| 2026-06-21 12:00 |
07:03:02.96 |
-70:38:13.0 |
HIP 33990 |
5.75 |
| 2026-06-22 00:00 |
07:03:07.74 |
-70:38:07.0 |
HIP 33990 |
5.62 |