| Parameter |
Value |
| Designation |
C/2017 T2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-05-04T22:47:55.688640Z |
| Orbit solution date (soln_date, UTC) |
2024-07-30T14:57:25Z |
| Obs used |
6922 |
| NEO |
- |
| M1 |
10.200 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-12-13.0000000 |
| e |
0.99967750 |
| q (au) |
1.615095 |
| a (au) |
5008.050241 |
| i (deg) |
57.231440 |
| Ω (om, deg) |
64.378780 |
| ω (w, deg) |
92.993316 |
| M (ma, deg) |
359.999600 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.827 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.827 |
| n |
2.000 |
| gf |
0.999 |
| gb |
-0.653 |
| k |
0.800 |
| δ90 |
10.000 |
| 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 |
| 2017-09-15 |
2019-08-05 |
+4.1328 |
-3.262 |
| 2019-08-05 |
2020-01-09 |
-1.8797 |
+0.423 |
| 2020-01-09 |
2020-05-04 |
+5.4565 |
-2.847 |
| 2020-05-05 |
2020-08-08 |
+15.7863 |
-4.493 |
| 2020-08-08 |
2021-10-04 |
+3.9198 |
-1.129 |
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 |
20:15:28.71 |
-65:36:24.3 |
HIP 100117 |
24.35 |
| 2026-03-26 12:00 |
20:15:37.69 |
-65:37:28.1 |
HIP 100117 |
22.96 |
| 2026-03-27 00:00 |
20:15:46.56 |
-65:38:32.3 |
HIP 100117 |
21.58 |
| 2026-03-27 12:00 |
20:15:55.31 |
-65:39:36.9 |
HIP 100117 |
20.22 |
| 2026-03-28 00:00 |
20:16:03.95 |
-65:40:41.9 |
HIP 100117 |
18.86 |
| 2026-03-28 12:00 |
20:16:12.47 |
-65:41:47.3 |
HIP 100117 |
17.52 |
| 2026-03-29 00:00 |
20:16:20.88 |
-65:42:53.1 |
HIP 100117 |
16.20 |
| 2026-03-29 12:00 |
20:16:29.18 |
-65:43:59.2 |
HIP 100117 |
14.90 |
| 2026-03-30 00:00 |
20:16:37.36 |
-65:45:05.8 |
HIP 100117 |
13.63 |
| 2026-03-30 12:00 |
20:16:45.42 |
-65:46:12.7 |
HIP 100117 |
12.39 |
| 2026-03-31 00:00 |
20:16:53.37 |
-65:47:20.0 |
HIP 100117 |
11.20 |
| 2026-03-31 12:00 |
20:17:01.20 |
-65:48:27.6 |
HIP 100117 |
10.06 |
| 2026-04-01 00:00 |
20:17:08.91 |
-65:49:35.7 |
HIP 100117 |
9.01 |
| 2026-04-01 12:00 |
20:17:16.50 |
-65:50:44.0 |
HIP 100117 |
8.07 |
| 2026-04-02 00:00 |
20:17:23.97 |
-65:51:52.8 |
HIP 100117 |
7.29 |
| 2026-04-02 12:00 |
20:17:31.32 |
-65:53:01.9 |
HIP 100117 |
6.71 |
| 2026-04-03 00:00 |
20:17:38.56 |
-65:54:11.3 |
HIP 100117 |
6.40 |
| 2026-04-03 12:00 |
20:17:45.67 |
-65:55:21.2 |
HIP 100117 |
6.39 |
| 2026-04-04 00:00 |
20:17:52.66 |
-65:56:31.3 |
HIP 100117 |
6.68 |
| 2026-04-04 12:00 |
20:17:59.52 |
-65:57:41.8 |
HIP 100117 |
7.24 |
| 2026-04-05 00:00 |
20:18:06.27 |
-65:58:52.7 |
HIP 100117 |
8.00 |
| 2026-04-05 12:00 |
20:18:12.89 |
-66:00:03.8 |
HIP 100117 |
8.92 |
| 2026-04-06 00:00 |
20:18:19.38 |
-66:01:15.4 |
HIP 100117 |
9.95 |
| 2026-04-06 12:00 |
20:18:25.76 |
-66:02:27.2 |
HIP 100117 |
11.06 |
| 2026-04-07 00:00 |
20:18:32.00 |
-66:03:39.4 |
HIP 100117 |
12.22 |
| 2026-04-07 12:00 |
20:18:38.12 |
-66:04:51.9 |
HIP 100117 |
13.43 |
| 2026-04-08 00:00 |
20:18:44.11 |
-66:06:04.7 |
HIP 100117 |
14.67 |
| 2026-04-08 12:00 |
20:18:49.98 |
-66:07:17.8 |
HIP 100117 |
15.93 |
| 2026-04-09 00:00 |
20:18:55.72 |
-66:08:31.3 |
HIP 100117 |
17.21 |
| 2026-04-09 12:00 |
20:19:01.33 |
-66:09:45.0 |
HIP 100117 |
18.51 |
| 2026-04-10 00:00 |
20:19:06.80 |
-66:10:59.1 |
HIP 100318 |
19.77 |
| 2026-04-10 12:00 |
20:19:12.15 |
-66:12:13.4 |
HIP 100318 |
18.43 |
| 2026-04-11 00:00 |
20:19:17.37 |
-66:13:28.1 |
HIP 100318 |
17.09 |
| 2026-04-11 12:00 |
20:19:22.46 |
-66:14:43.0 |
HIP 100318 |
15.75 |
| 2026-04-12 00:00 |
20:19:27.41 |
-66:15:58.3 |
HIP 100318 |
14.42 |
| 2026-04-12 12:00 |
20:19:32.24 |
-66:17:13.8 |
HIP 100318 |
13.09 |
| 2026-04-13 00:00 |
20:19:36.92 |
-66:18:29.6 |
HIP 100318 |
11.78 |
| 2026-04-13 12:00 |
20:19:41.48 |
-66:19:45.6 |
HIP 100318 |
10.47 |
| 2026-04-14 00:00 |
20:19:45.90 |
-66:21:02.0 |
HIP 100318 |
9.19 |
| 2026-04-14 12:00 |
20:19:50.18 |
-66:22:18.6 |
HIP 100318 |
7.93 |
| 2026-04-15 00:00 |
20:19:54.33 |
-66:23:35.5 |
HIP 100318 |
6.72 |
| 2026-04-15 12:00 |
20:19:58.35 |
-66:24:52.6 |
HIP 100318 |
5.57 |
| 2026-04-16 00:00 |
20:20:02.22 |
-66:26:10.0 |
HIP 100318 |
4.55 |