| 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) |
| 2026-09-20 00:00 |
07:15:05.23 |
-71:11:13.6 |
HIP 35308 |
15.02 |
| 2026-09-20 12:00 |
07:15:06.85 |
-71:11:37.9 |
HIP 35308 |
14.68 |
| 2026-09-21 00:00 |
07:15:08.44 |
-71:12:02.2 |
HIP 35308 |
14.34 |
| 2026-09-21 12:00 |
07:15:09.98 |
-71:12:26.7 |
HIP 35308 |
14.01 |
| 2026-09-22 00:00 |
07:15:11.49 |
-71:12:51.2 |
HIP 35308 |
13.69 |
| 2026-09-22 12:00 |
07:15:12.95 |
-71:13:15.8 |
HIP 35308 |
13.38 |
| 2026-09-23 00:00 |
07:15:14.37 |
-71:13:40.4 |
HIP 35308 |
13.07 |
| 2026-09-23 12:00 |
07:15:15.74 |
-71:14:05.1 |
HIP 35308 |
12.78 |
| 2026-09-24 00:00 |
07:15:17.08 |
-71:14:29.9 |
HIP 35308 |
12.49 |
| 2026-09-24 12:00 |
07:15:18.38 |
-71:14:54.7 |
HIP 35308 |
12.21 |
| 2026-09-25 00:00 |
07:15:19.63 |
-71:15:19.6 |
HIP 35308 |
11.95 |
| 2026-09-25 12:00 |
07:15:20.84 |
-71:15:44.6 |
HIP 35308 |
11.70 |
| 2026-09-26 00:00 |
07:15:22.01 |
-71:16:09.6 |
HIP 35308 |
11.46 |
| 2026-09-26 12:00 |
07:15:23.13 |
-71:16:34.6 |
HIP 35308 |
11.24 |
| 2026-09-27 00:00 |
07:15:24.22 |
-71:16:59.7 |
HIP 35308 |
11.03 |
| 2026-09-27 12:00 |
07:15:25.26 |
-71:17:24.9 |
HIP 35308 |
10.84 |
| 2026-09-28 00:00 |
07:15:26.26 |
-71:17:50.1 |
HIP 35308 |
10.66 |
| 2026-09-28 12:00 |
07:15:27.21 |
-71:18:15.4 |
HIP 35308 |
10.51 |
| 2026-09-29 00:00 |
07:15:28.12 |
-71:18:40.7 |
HIP 35308 |
10.37 |
| 2026-09-29 12:00 |
07:15:28.99 |
-71:19:06.0 |
HIP 35308 |
10.25 |
| 2026-09-30 00:00 |
07:15:29.82 |
-71:19:31.4 |
HIP 35308 |
10.15 |
| 2026-09-30 12:00 |
07:15:30.60 |
-71:19:56.9 |
HIP 35308 |
10.07 |
| 2026-10-01 00:00 |
07:15:31.34 |
-71:20:22.4 |
HIP 35308 |
10.02 |
| 2026-10-01 12:00 |
07:15:32.03 |
-71:20:47.9 |
HIP 35308 |
9.98 |
| 2026-10-02 00:00 |
07:15:32.69 |
-71:21:13.4 |
HIP 35308 |
9.97 |
| 2026-10-02 12:00 |
07:15:33.29 |
-71:21:39.0 |
HIP 35308 |
9.98 |
| 2026-10-03 00:00 |
07:15:33.86 |
-71:22:04.6 |
HIP 35308 |
10.01 |
| 2026-10-03 12:00 |
07:15:34.37 |
-71:22:30.3 |
HIP 35308 |
10.06 |
| 2026-10-04 00:00 |
07:15:34.85 |
-71:22:56.0 |
HIP 35308 |
10.13 |
| 2026-10-04 12:00 |
07:15:35.28 |
-71:23:21.7 |
HIP 35308 |
10.23 |
| 2026-10-05 00:00 |
07:15:35.66 |
-71:23:47.4 |
HIP 35308 |
10.35 |
| 2026-10-05 12:00 |
07:15:36.00 |
-71:24:13.2 |
HIP 35308 |
10.48 |
| 2026-10-06 00:00 |
07:15:36.30 |
-71:24:39.0 |
HIP 35308 |
10.64 |
| 2026-10-06 12:00 |
07:15:36.54 |
-71:25:04.8 |
HIP 35308 |
10.81 |
| 2026-10-07 00:00 |
07:15:36.75 |
-71:25:30.6 |
HIP 35308 |
11.00 |
| 2026-10-07 12:00 |
07:15:36.91 |
-71:25:56.5 |
HIP 35308 |
11.21 |
| 2026-10-08 00:00 |
07:15:37.02 |
-71:26:22.3 |
HIP 35308 |
11.43 |
| 2026-10-08 12:00 |
07:15:37.09 |
-71:26:48.2 |
HIP 35308 |
11.67 |
| 2026-10-09 00:00 |
07:15:37.11 |
-71:27:14.1 |
HIP 35308 |
11.92 |
| 2026-10-09 12:00 |
07:15:37.09 |
-71:27:40.0 |
HIP 35308 |
12.18 |
| 2026-10-10 00:00 |
07:15:37.02 |
-71:28:05.9 |
HIP 35308 |
12.46 |
| 2026-10-10 12:00 |
07:15:36.90 |
-71:28:31.8 |
HIP 35308 |
12.75 |
| 2026-10-11 00:00 |
07:15:36.74 |
-71:28:57.7 |
HIP 35308 |
13.05 |