| 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
$$
M_a = (15.161 + 3.830\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.161 |
| n |
3.830 |
| gf |
0.963 |
| gb |
-0.606 |
| k |
0.903 |
| δ90 |
7.076 |
| 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) |
| 2026-05-12 00:00 |
04:27:50.79 |
+10:40:38.0 |
HIP 20751 |
19.28 |
| 2026-05-12 12:00 |
04:27:55.20 |
+10:40:50.0 |
HIP 20751 |
20.04 |
| 2026-05-13 00:00 |
04:27:59.63 |
+10:41:01.9 |
HIP 20751 |
20.83 |
| 2026-05-13 12:00 |
04:28:04.07 |
+10:41:13.7 |
HIP 20751 |
21.66 |
| 2026-05-14 00:00 |
04:28:08.52 |
+10:41:25.4 |
HIP 20751 |
22.51 |
| 2026-05-14 12:00 |
04:28:12.98 |
+10:41:37.0 |
HIP 20751 |
23.39 |
| 2026-05-15 00:00 |
04:28:17.45 |
+10:41:48.5 |
HIP 20963 |
23.47 |
| 2026-05-15 12:00 |
04:28:21.93 |
+10:42:00.0 |
HIP 20963 |
22.58 |
| 2026-05-16 00:00 |
04:28:26.42 |
+10:42:11.2 |
HIP 20963 |
21.70 |
| 2026-05-16 12:00 |
04:28:30.92 |
+10:42:22.4 |
HIP 20963 |
20.85 |
| 2026-05-17 00:00 |
04:28:35.43 |
+10:42:33.5 |
HIP 20963 |
20.03 |
| 2026-05-17 12:00 |
04:28:39.94 |
+10:42:44.5 |
HIP 20963 |
19.23 |
| 2026-05-18 00:00 |
04:28:44.47 |
+10:42:55.4 |
HIP 20963 |
18.46 |
| 2026-05-18 12:00 |
04:28:49.00 |
+10:43:06.1 |
HIP 20963 |
17.72 |
| 2026-05-19 00:00 |
04:28:53.54 |
+10:43:16.8 |
HIP 20963 |
17.03 |
| 2026-05-19 12:00 |
04:28:58.09 |
+10:43:27.3 |
HIP 20963 |
16.39 |
| 2026-05-20 00:00 |
04:29:02.64 |
+10:43:37.7 |
HIP 20963 |
15.79 |
| 2026-05-20 12:00 |
04:29:07.20 |
+10:43:48.0 |
HIP 20963 |
15.26 |
| 2026-05-21 00:00 |
04:29:11.76 |
+10:43:58.2 |
HIP 20963 |
14.79 |
| 2026-05-21 12:00 |
04:29:16.33 |
+10:44:08.3 |
HIP 20963 |
14.39 |
| 2026-05-22 00:00 |
04:29:20.91 |
+10:44:18.3 |
HIP 20963 |
14.07 |
| 2026-05-22 12:00 |
04:29:25.49 |
+10:44:28.1 |
HIP 20963 |
13.83 |
| 2026-05-23 00:00 |
04:29:30.08 |
+10:44:37.8 |
HIP 20963 |
13.68 |
| 2026-05-23 12:00 |
04:29:34.67 |
+10:44:47.5 |
HIP 20963 |
13.63 |
| 2026-05-24 00:00 |
04:29:39.26 |
+10:44:56.9 |
HIP 20963 |
13.67 |
| 2026-05-24 12:00 |
04:29:43.86 |
+10:45:06.3 |
HIP 20963 |
13.80 |
| 2026-05-25 00:00 |
04:29:48.46 |
+10:45:15.6 |
HIP 20963 |
14.02 |
| 2026-05-25 12:00 |
04:29:53.06 |
+10:45:24.7 |
HIP 20963 |
14.32 |
| 2026-05-26 00:00 |
04:29:57.66 |
+10:45:33.7 |
HIP 21066 |
14.61 |
| 2026-05-26 12:00 |
04:30:02.27 |
+10:45:42.6 |
HIP 21066 |
13.48 |
| 2026-05-27 00:00 |
04:30:06.88 |
+10:45:51.4 |
HIP 21066 |
12.36 |
| 2026-05-27 12:00 |
04:30:11.49 |
+10:46:00.0 |
HIP 21066 |
11.24 |
| 2026-05-28 00:00 |
04:30:16.11 |
+10:46:08.5 |
HIP 21066 |
10.12 |
| 2026-05-28 12:00 |
04:30:20.72 |
+10:46:16.9 |
HIP 21066 |
9.01 |
| 2026-05-29 00:00 |
04:30:25.34 |
+10:46:25.2 |
HIP 21066 |
7.91 |
| 2026-05-29 12:00 |
04:30:29.95 |
+10:46:33.3 |
HIP 21066 |
6.83 |
| 2026-05-30 00:00 |
04:30:34.57 |
+10:46:41.3 |
HIP 21066 |
5.76 |
| 2026-05-30 12:00 |
04:30:39.18 |
+10:46:49.2 |
HIP 21066 |
4.72 |
| 2026-05-31 00:00 |
04:30:43.80 |
+10:46:57.0 |
HIP 21066 |
3.75 |
| 2026-05-31 12:00 |
04:30:48.41 |
+10:47:04.6 |
HIP 21066 |
2.91 |
| 2026-06-01 00:00 |
04:30:53.02 |
+10:47:12.1 |
HIP 21066 |
2.32 |
| 2026-06-01 12:00 |
04:30:57.64 |
+10:47:19.5 |
HIP 21066 |
2.22 |
| 2026-06-02 00:00 |
04:31:02.25 |
+10:47:26.7 |
HIP 21066 |
2.66 |