| Parameter |
Value |
| Designation |
C/2017 G3 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-04-15T00:45:00.587520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:33Z |
| Obs used |
155 |
| NEO |
- |
| M1 |
14.500 |
| K1 |
9.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-05-26.0000000 |
| e |
0.99105792 |
| q (au) |
2.590476 |
| a (au) |
289.694902 |
| i (deg) |
159.051707 |
| Ω (om, deg) |
279.473026 |
| ω (w, deg) |
73.096573 |
| M (ma, deg) |
0.008189 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.149 + 3.830\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.149 |
| n |
3.830 |
| gf |
0.994 |
| gb |
-0.606 |
| k |
0.905 |
| δ90 |
7.745 |
| 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) |
| 2026-09-25 00:00 |
04:38:26.77 |
+10:11:26.3 |
HIP 21663 |
15.49 |
| 2026-09-25 12:00 |
04:38:24.25 |
+10:11:03.4 |
HIP 21663 |
16.17 |
| 2026-09-26 00:00 |
04:38:21.69 |
+10:10:40.5 |
HIP 21663 |
16.85 |
| 2026-09-26 12:00 |
04:38:19.09 |
+10:10:17.6 |
HIP 21663 |
17.55 |
| 2026-09-27 00:00 |
04:38:16.44 |
+10:09:54.5 |
HIP 21663 |
18.26 |
| 2026-09-27 12:00 |
04:38:13.76 |
+10:09:31.5 |
HIP 21663 |
18.98 |
| 2026-09-28 00:00 |
04:38:11.02 |
+10:09:08.4 |
HIP 21663 |
19.71 |
| 2026-09-28 12:00 |
04:38:08.25 |
+10:08:45.2 |
HIP 21663 |
20.46 |
| 2026-09-29 00:00 |
04:38:05.43 |
+10:08:22.0 |
HIP 21663 |
21.21 |
| 2026-09-29 12:00 |
04:38:02.57 |
+10:07:58.8 |
HIP 21663 |
21.97 |
| 2026-09-30 00:00 |
04:37:59.66 |
+10:07:35.5 |
HIP 21663 |
22.75 |
| 2026-09-30 12:00 |
04:37:56.72 |
+10:07:12.2 |
HIP 21663 |
23.53 |
| 2026-10-01 00:00 |
04:37:53.73 |
+10:06:48.9 |
HIP 21663 |
24.33 |
| 2026-10-01 12:00 |
04:37:50.70 |
+10:06:25.5 |
HIP 21663 |
25.13 |
| 2026-10-02 00:00 |
04:37:47.62 |
+10:06:02.1 |
HIP 21663 |
25.95 |
| 2026-10-02 12:00 |
04:37:44.51 |
+10:05:38.7 |
HIP 21663 |
26.77 |
| 2026-10-03 00:00 |
04:37:41.35 |
+10:05:15.2 |
HIP 21663 |
27.61 |
| 2026-10-03 12:00 |
04:37:38.15 |
+10:04:51.7 |
HIP 21663 |
28.46 |
| 2026-10-04 00:00 |
04:37:34.90 |
+10:04:28.2 |
HIP 21402 |
28.94 |
| 2026-10-04 12:00 |
04:37:31.62 |
+10:04:04.7 |
HIP 21402 |
28.22 |
| 2026-10-05 00:00 |
04:37:28.29 |
+10:03:41.1 |
HIP 21402 |
27.50 |
| 2026-10-05 12:00 |
04:37:24.93 |
+10:03:17.5 |
HIP 21402 |
26.78 |
| 2026-10-06 00:00 |
04:37:21.52 |
+10:02:53.9 |
HIP 21402 |
26.07 |
| 2026-10-06 12:00 |
04:37:18.07 |
+10:02:30.3 |
HIP 21402 |
25.36 |
| 2026-10-07 00:00 |
04:37:14.58 |
+10:02:06.6 |
HIP 21402 |
24.65 |
| 2026-10-07 12:00 |
04:37:11.05 |
+10:01:43.0 |
HIP 21402 |
23.95 |
| 2026-10-08 00:00 |
04:37:07.48 |
+10:01:19.3 |
HIP 21402 |
23.26 |
| 2026-10-08 12:00 |
04:37:03.87 |
+10:00:55.6 |
HIP 21402 |
22.59 |
| 2026-10-09 00:00 |
04:37:00.21 |
+10:00:31.9 |
HIP 21402 |
21.92 |
| 2026-10-09 12:00 |
04:36:56.52 |
+10:00:08.2 |
HIP 21402 |
21.27 |
| 2026-10-10 00:00 |
04:36:52.79 |
+09:59:44.5 |
HIP 21402 |
20.64 |
| 2026-10-10 12:00 |
04:36:49.02 |
+09:59:20.7 |
HIP 21402 |
20.03 |
| 2026-10-11 00:00 |
04:36:45.21 |
+09:58:57.0 |
HIP 21402 |
19.45 |
| 2026-10-11 12:00 |
04:36:41.36 |
+09:58:33.3 |
HIP 21402 |
18.90 |
| 2026-10-12 00:00 |
04:36:37.48 |
+09:58:09.6 |
HIP 21402 |
18.38 |
| 2026-10-12 12:00 |
04:36:33.55 |
+09:57:45.8 |
HIP 21402 |
17.89 |
| 2026-10-13 00:00 |
04:36:29.59 |
+09:57:22.1 |
HIP 21402 |
17.45 |
| 2026-10-13 12:00 |
04:36:25.59 |
+09:56:58.4 |
HIP 21402 |
17.06 |
| 2026-10-14 00:00 |
04:36:21.55 |
+09:56:34.7 |
HIP 21402 |
16.72 |
| 2026-10-14 12:00 |
04:36:17.47 |
+09:56:11.0 |
HIP 21402 |
16.43 |
| 2026-10-15 00:00 |
04:36:13.36 |
+09:55:47.3 |
HIP 21402 |
16.21 |
| 2026-10-15 12:00 |
04:36:09.21 |
+09:55:23.6 |
HIP 21402 |
16.06 |
| 2026-10-16 00:00 |
04:36:05.02 |
+09:55:00.0 |
HIP 21402 |
15.97 |