| 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) |
| 2026-03-26 00:00 |
06:55:45.87 |
-71:33:32.1 |
HIP 33115 |
9.45 |
| 2026-03-26 12:00 |
06:55:44.98 |
-71:33:07.1 |
HIP 33115 |
9.49 |
| 2026-03-27 00:00 |
06:55:44.13 |
-71:32:42.1 |
HIP 33115 |
9.56 |
| 2026-03-27 12:00 |
06:55:43.33 |
-71:32:17.1 |
HIP 33115 |
9.64 |
| 2026-03-28 00:00 |
06:55:42.58 |
-71:31:52.0 |
HIP 33115 |
9.75 |
| 2026-03-28 12:00 |
06:55:41.87 |
-71:31:27.0 |
HIP 33115 |
9.88 |
| 2026-03-29 00:00 |
06:55:41.21 |
-71:31:01.9 |
HIP 33115 |
10.03 |
| 2026-03-29 12:00 |
06:55:40.60 |
-71:30:36.8 |
HIP 33115 |
10.19 |
| 2026-03-30 00:00 |
06:55:40.03 |
-71:30:11.7 |
HIP 33115 |
10.37 |
| 2026-03-30 12:00 |
06:55:39.51 |
-71:29:46.5 |
HIP 33115 |
10.58 |
| 2026-03-31 00:00 |
06:55:39.04 |
-71:29:21.4 |
HIP 33115 |
10.79 |
| 2026-03-31 12:00 |
06:55:38.61 |
-71:28:56.2 |
HIP 33115 |
11.02 |
| 2026-04-01 00:00 |
06:55:38.23 |
-71:28:31.1 |
HIP 33115 |
11.27 |
| 2026-04-01 12:00 |
06:55:37.89 |
-71:28:05.9 |
HIP 33115 |
11.52 |
| 2026-04-02 00:00 |
06:55:37.61 |
-71:27:40.7 |
HIP 33115 |
11.79 |
| 2026-04-02 12:00 |
06:55:37.36 |
-71:27:15.5 |
HIP 33115 |
12.07 |
| 2026-04-03 00:00 |
06:55:37.17 |
-71:26:50.3 |
HIP 33115 |
12.37 |
| 2026-04-03 12:00 |
06:55:37.02 |
-71:26:25.1 |
HIP 33115 |
12.67 |
| 2026-04-04 00:00 |
06:55:36.91 |
-71:26:00.0 |
HIP 33115 |
12.98 |
| 2026-04-04 12:00 |
06:55:36.86 |
-71:25:34.8 |
HIP 33115 |
13.30 |
| 2026-04-05 00:00 |
06:55:36.84 |
-71:25:09.6 |
HIP 33115 |
13.62 |
| 2026-04-05 12:00 |
06:55:36.88 |
-71:24:44.4 |
HIP 33115 |
13.95 |
| 2026-04-06 00:00 |
06:55:36.96 |
-71:24:19.2 |
HIP 33115 |
14.29 |
| 2026-04-06 12:00 |
06:55:37.08 |
-71:23:54.1 |
HIP 33115 |
14.64 |
| 2026-04-07 00:00 |
06:55:37.25 |
-71:23:28.9 |
HIP 33115 |
14.99 |
| 2026-04-07 12:00 |
06:55:37.47 |
-71:23:03.8 |
HIP 33115 |
15.35 |
| 2026-04-08 00:00 |
06:55:37.73 |
-71:22:38.7 |
HIP 33115 |
15.71 |
| 2026-04-08 12:00 |
06:55:38.04 |
-71:22:13.6 |
HIP 33115 |
16.08 |
| 2026-04-09 00:00 |
06:55:38.39 |
-71:21:48.5 |
HIP 33115 |
16.45 |
| 2026-04-09 12:00 |
06:55:38.79 |
-71:21:23.4 |
HIP 33115 |
16.82 |
| 2026-04-10 00:00 |
06:55:39.23 |
-71:20:58.4 |
HIP 33115 |
17.20 |
| 2026-04-10 12:00 |
06:55:39.72 |
-71:20:33.4 |
HIP 33115 |
17.58 |
| 2026-04-11 00:00 |
06:55:40.25 |
-71:20:08.4 |
HIP 33115 |
17.96 |
| 2026-04-11 12:00 |
06:55:40.83 |
-71:19:43.4 |
HIP 33115 |
18.35 |
| 2026-04-12 00:00 |
06:55:41.45 |
-71:19:18.5 |
HIP 33115 |
18.74 |
| 2026-04-12 12:00 |
06:55:42.12 |
-71:18:53.6 |
HIP 33115 |
19.13 |
| 2026-04-13 00:00 |
06:55:42.83 |
-71:18:28.7 |
HIP 33115 |
19.53 |
| 2026-04-13 12:00 |
06:55:43.59 |
-71:18:03.9 |
HIP 33115 |
19.92 |
| 2026-04-14 00:00 |
06:55:44.39 |
-71:17:39.1 |
HIP 33115 |
20.32 |
| 2026-04-14 12:00 |
06:55:45.23 |
-71:17:14.4 |
HIP 33115 |
20.72 |
| 2026-04-15 00:00 |
06:55:46.12 |
-71:16:49.6 |
HIP 33115 |
21.12 |
| 2026-04-15 12:00 |
06:55:47.06 |
-71:16:25.0 |
HIP 33115 |
21.52 |
| 2026-04-16 00:00 |
06:55:48.03 |
-71:16:00.4 |
HIP 33115 |
21.93 |