| Parameter |
Value |
| Designation |
C/2015 T2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-05-20T14:34:53.685120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:15Z |
| Obs used |
214 |
| NEO |
- |
| M1 |
7.000 |
| K1 |
10.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-12-20.0000000 |
| e |
1.00038904 |
| q (au) |
6.935284 |
| a (au) |
-17826.537165 |
| i (deg) |
124.543195 |
| Ω (om, deg) |
51.058229 |
| ω (w, deg) |
30.773308 |
| M (ma, deg) |
-0.000063 |
Magnitude
Scatter + Global Linear
$$
M_a = (1.916 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
1.916 |
| n |
6.000 |
| gf |
0.978 |
| gb |
-0.997 |
| k |
1.000 |
| δ90 |
9.999 |
| 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 |
| 2015-10-09 |
2017-01-24 |
+9.5885 |
-8.057 |
| 2017-08-17 |
2019-09-26 |
-6.8397 |
+5.422 |
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 |
17:04:50.04 |
+09:40:12.0 |
HIP 83677 |
19.99 |
| 2026-09-20 12:00 |
17:04:50.39 |
+09:39:14.1 |
HIP 83677 |
20.11 |
| 2026-09-21 00:00 |
17:04:50.78 |
+09:38:16.2 |
HIP 83677 |
20.27 |
| 2026-09-21 12:00 |
17:04:51.23 |
+09:37:18.3 |
HIP 83677 |
20.46 |
| 2026-09-22 00:00 |
17:04:51.73 |
+09:36:20.5 |
HIP 83677 |
20.68 |
| 2026-09-22 12:00 |
17:04:52.27 |
+09:35:22.8 |
HIP 83677 |
20.94 |
| 2026-09-23 00:00 |
17:04:52.86 |
+09:34:25.2 |
HIP 83677 |
21.22 |
| 2026-09-23 12:00 |
17:04:53.50 |
+09:33:27.7 |
HIP 83677 |
21.54 |
| 2026-09-24 00:00 |
17:04:54.19 |
+09:32:30.2 |
HIP 83677 |
21.88 |
| 2026-09-24 12:00 |
17:04:54.93 |
+09:31:32.8 |
HIP 83677 |
22.25 |
| 2026-09-25 00:00 |
17:04:55.71 |
+09:30:35.5 |
HIP 83677 |
22.64 |
| 2026-09-25 12:00 |
17:04:56.54 |
+09:29:38.3 |
HIP 83677 |
23.06 |
| 2026-09-26 00:00 |
17:04:57.41 |
+09:28:41.2 |
HIP 83677 |
23.50 |
| 2026-09-26 12:00 |
17:04:58.34 |
+09:27:44.2 |
HIP 83677 |
23.97 |
| 2026-09-27 00:00 |
17:04:59.31 |
+09:26:47.3 |
HIP 83677 |
24.45 |
| 2026-09-27 12:00 |
17:05:00.33 |
+09:25:50.5 |
HIP 83677 |
24.96 |
| 2026-09-28 00:00 |
17:05:01.39 |
+09:24:53.8 |
HIP 83677 |
25.48 |
| 2026-09-28 12:00 |
17:05:02.50 |
+09:23:57.2 |
HIP 83677 |
26.02 |
| 2026-09-29 00:00 |
17:05:03.66 |
+09:23:00.8 |
HIP 83677 |
26.58 |
| 2026-09-29 12:00 |
17:05:04.86 |
+09:22:04.4 |
HIP 83677 |
27.15 |
| 2026-09-30 00:00 |
17:05:06.11 |
+09:21:08.2 |
HIP 83677 |
27.74 |
| 2026-09-30 12:00 |
17:05:07.40 |
+09:20:12.0 |
HIP 83677 |
28.34 |
| 2026-10-01 00:00 |
17:05:08.74 |
+09:19:16.0 |
HIP 83677 |
28.96 |
| 2026-10-01 12:00 |
17:05:10.12 |
+09:18:20.2 |
HIP 83677 |
29.59 |
| 2026-10-02 00:00 |
17:05:11.55 |
+09:17:24.4 |
HIP 83677 |
30.23 |
| 2026-10-02 12:00 |
17:05:13.03 |
+09:16:28.8 |
HIP 83458 |
30.48 |
| 2026-10-03 00:00 |
17:05:14.55 |
+09:15:33.3 |
HIP 83458 |
30.37 |
| 2026-10-03 12:00 |
17:05:16.11 |
+09:14:38.0 |
HIP 83458 |
30.30 |
| 2026-10-04 00:00 |
17:05:17.72 |
+09:13:42.7 |
HIP 83458 |
30.27 |
| 2026-10-04 12:00 |
17:05:19.37 |
+09:12:47.7 |
HIP 83764 |
29.63 |
| 2026-10-05 00:00 |
17:05:21.07 |
+09:11:52.8 |
HIP 83764 |
28.87 |
| 2026-10-05 12:00 |
17:05:22.81 |
+09:10:58.0 |
HIP 83764 |
28.13 |
| 2026-10-06 00:00 |
17:05:24.60 |
+09:10:03.4 |
HIP 83764 |
27.39 |
| 2026-10-06 12:00 |
17:05:26.42 |
+09:09:08.9 |
HIP 83764 |
26.66 |
| 2026-10-07 00:00 |
17:05:28.30 |
+09:08:14.6 |
HIP 83764 |
25.94 |
| 2026-10-07 12:00 |
17:05:30.21 |
+09:07:20.4 |
HIP 83764 |
25.23 |
| 2026-10-08 00:00 |
17:05:32.17 |
+09:06:26.5 |
HIP 83764 |
24.54 |
| 2026-10-08 12:00 |
17:05:34.17 |
+09:05:32.7 |
HIP 83764 |
23.85 |
| 2026-10-09 00:00 |
17:05:36.21 |
+09:04:39.0 |
HIP 83764 |
23.19 |
| 2026-10-09 12:00 |
17:05:38.30 |
+09:03:45.5 |
HIP 83764 |
22.54 |
| 2026-10-10 00:00 |
17:05:40.43 |
+09:02:52.3 |
HIP 83764 |
21.90 |
| 2026-10-10 12:00 |
17:05:42.60 |
+09:01:59.1 |
HIP 83764 |
21.29 |
| 2026-10-11 00:00 |
17:05:44.81 |
+09:01:06.2 |
HIP 83764 |
20.71 |