| Parameter |
Value |
| Designation |
C/2017 T2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-05-04T22:47:59.723520Z |
| Orbit solution date (soln_date, UTC) |
2026-07-28T14:12:17Z |
| Obs used |
6929 |
| NEO |
- |
| M1 |
10.200 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-12-14.0000000 |
| e |
0.99967660 |
| q (au) |
1.615096 |
| a (au) |
4994.082846 |
| i (deg) |
57.231424 |
| Ω (om, deg) |
64.378772 |
| ω (w, deg) |
92.993313 |
| M (ma, deg) |
359.999601 |
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 |
1.000 |
| 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) |
| 2026-07-29 00:00 |
19:45:35.86 |
-69:49:44.6 |
HIP 97185 |
11.45 |
| 2026-07-29 12:00 |
19:45:18.54 |
-69:49:43.8 |
HIP 97185 |
11.28 |
| 2026-07-30 00:00 |
19:45:01.26 |
-69:49:42.3 |
HIP 97185 |
11.31 |
| 2026-07-30 12:00 |
19:44:44.02 |
-69:49:40.0 |
HIP 97185 |
11.54 |
| 2026-07-31 00:00 |
19:44:26.83 |
-69:49:37.0 |
HIP 97185 |
11.97 |
| 2026-07-31 12:00 |
19:44:09.70 |
-69:49:33.2 |
HIP 97185 |
12.56 |
| 2026-08-01 00:00 |
19:43:52.61 |
-69:49:28.7 |
HIP 97185 |
13.30 |
| 2026-08-01 12:00 |
19:43:35.58 |
-69:49:23.4 |
HIP 97185 |
14.17 |
| 2026-08-02 00:00 |
19:43:18.60 |
-69:49:17.3 |
HIP 97185 |
15.13 |
| 2026-08-02 12:00 |
19:43:01.68 |
-69:49:10.5 |
HIP 97185 |
16.17 |
| 2026-08-03 00:00 |
19:42:44.82 |
-69:49:02.9 |
HIP 97185 |
17.28 |
| 2026-08-03 12:00 |
19:42:28.02 |
-69:48:54.6 |
HIP 97185 |
18.44 |
| 2026-08-04 00:00 |
19:42:11.28 |
-69:48:45.5 |
HIP 96708 |
18.53 |
| 2026-08-04 12:00 |
19:41:54.61 |
-69:48:35.7 |
HIP 96708 |
17.38 |
| 2026-08-05 00:00 |
19:41:38.00 |
-69:48:25.2 |
HIP 96708 |
16.28 |
| 2026-08-05 12:00 |
19:41:21.46 |
-69:48:13.9 |
HIP 96708 |
15.22 |
| 2026-08-06 00:00 |
19:41:04.99 |
-69:48:01.8 |
HIP 96708 |
14.23 |
| 2026-08-06 12:00 |
19:40:48.60 |
-69:47:49.1 |
HIP 96708 |
13.31 |
| 2026-08-07 00:00 |
19:40:32.27 |
-69:47:35.6 |
HIP 96708 |
12.49 |
| 2026-08-07 12:00 |
19:40:16.02 |
-69:47:21.3 |
HIP 96708 |
11.77 |
| 2026-08-08 00:00 |
19:39:59.85 |
-69:47:06.4 |
HIP 96708 |
11.18 |
| 2026-08-08 12:00 |
19:39:43.76 |
-69:46:50.7 |
HIP 96708 |
10.73 |
| 2026-08-09 00:00 |
19:39:27.75 |
-69:46:34.3 |
HIP 96708 |
10.44 |
| 2026-08-09 12:00 |
19:39:11.82 |
-69:46:17.2 |
HIP 96708 |
10.33 |
| 2026-08-10 00:00 |
19:38:55.98 |
-69:45:59.3 |
HIP 96708 |
10.40 |
| 2026-08-10 12:00 |
19:38:40.22 |
-69:45:40.8 |
HIP 96487 |
9.71 |
| 2026-08-11 00:00 |
19:38:24.55 |
-69:45:21.5 |
HIP 96487 |
8.59 |
| 2026-08-11 12:00 |
19:38:08.97 |
-69:45:01.6 |
HIP 96487 |
7.56 |
| 2026-08-12 00:00 |
19:37:53.49 |
-69:44:40.9 |
HIP 96487 |
6.68 |
| 2026-08-12 12:00 |
19:37:38.09 |
-69:44:19.5 |
HIP 96487 |
6.00 |
| 2026-08-13 00:00 |
19:37:22.79 |
-69:43:57.5 |
HIP 96487 |
5.61 |
| 2026-08-13 12:00 |
19:37:07.59 |
-69:43:34.7 |
HIP 96487 |
5.54 |
| 2026-08-14 00:00 |
19:36:52.49 |
-69:43:11.3 |
HIP 96487 |
5.82 |
| 2026-08-14 12:00 |
19:36:37.48 |
-69:42:47.2 |
HIP 96487 |
6.39 |
| 2026-08-15 00:00 |
19:36:22.58 |
-69:42:22.4 |
HIP 96487 |
7.18 |
| 2026-08-15 12:00 |
19:36:07.78 |
-69:41:56.9 |
HIP 96487 |
8.13 |
| 2026-08-16 00:00 |
19:35:53.09 |
-69:41:30.8 |
HIP 96487 |
9.19 |
| 2026-08-16 12:00 |
19:35:38.50 |
-69:41:04.0 |
HIP 96487 |
10.31 |
| 2026-08-17 00:00 |
19:35:24.02 |
-69:40:36.5 |
HIP 96487 |
11.48 |
| 2026-08-17 12:00 |
19:35:09.65 |
-69:40:08.4 |
HIP 96487 |
12.69 |
| 2026-08-18 00:00 |
19:34:55.39 |
-69:39:39.7 |
HIP 96487 |
13.92 |
| 2026-08-18 12:00 |
19:34:41.24 |
-69:39:10.3 |
HIP 96487 |
15.16 |
| 2026-08-19 00:00 |
19:34:27.21 |
-69:38:40.3 |
HIP 96487 |
16.42 |