C/2015 T2 (PANSTARRS)
| 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 |
0.986 |
| gb |
-0.998 |
| k |
1.000 |
| δ90 |
9.980 |
| 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) |
| 2026-02-03 00:00 |
17:31:54.76 |
+10:01:42.7 |
HIP 85823 |
4.99 |
| 2026-02-03 12:00 |
17:31:57.79 |
+10:02:07.5 |
HIP 85823 |
4.14 |
| 2026-02-04 00:00 |
17:32:00.77 |
+10:02:32.7 |
HIP 85823 |
3.30 |
| 2026-02-04 12:00 |
17:32:03.72 |
+10:02:58.1 |
HIP 85823 |
2.47 |
| 2026-02-05 00:00 |
17:32:06.62 |
+10:03:23.9 |
HIP 85823 |
1.66 |
| 2026-02-05 12:00 |
17:32:09.49 |
+10:03:49.9 |
HIP 85823 |
0.91 |
| 2026-02-06 00:00 |
17:32:12.31 |
+10:04:16.3 |
HIP 85823 |
0.53 |
| 2026-02-06 12:00 |
17:32:15.09 |
+10:04:42.9 |
HIP 85823 |
1.03 |
| 2026-02-07 00:00 |
17:32:17.83 |
+10:05:09.9 |
HIP 85823 |
1.78 |
| 2026-02-07 12:00 |
17:32:20.52 |
+10:05:37.1 |
HIP 85823 |
2.57 |
| 2026-02-08 00:00 |
17:32:23.18 |
+10:06:04.7 |
HIP 85823 |
3.36 |
| 2026-02-08 12:00 |
17:32:25.79 |
+10:06:32.5 |
HIP 85823 |
4.14 |
| 2026-02-09 00:00 |
17:32:28.35 |
+10:07:00.6 |
HIP 85823 |
4.93 |
| 2026-02-09 12:00 |
17:32:30.88 |
+10:07:29.0 |
HIP 85823 |
5.71 |
| 2026-02-10 00:00 |
17:32:33.36 |
+10:07:57.6 |
HIP 85823 |
6.48 |
| 2026-02-10 12:00 |
17:32:35.79 |
+10:08:26.6 |
HIP 85823 |
7.25 |
| 2026-02-11 00:00 |
17:32:38.18 |
+10:08:55.8 |
HIP 85823 |
8.01 |
| 2026-02-11 12:00 |
17:32:40.53 |
+10:09:25.3 |
HIP 85823 |
8.77 |
| 2026-02-12 00:00 |
17:32:42.83 |
+10:09:55.1 |
HIP 85823 |
9.53 |
| 2026-02-12 12:00 |
17:32:45.09 |
+10:10:25.1 |
HIP 85823 |
10.27 |
| 2026-02-13 00:00 |
17:32:47.30 |
+10:10:55.4 |
HIP 85823 |
11.01 |
| 2026-02-13 12:00 |
17:32:49.46 |
+10:11:25.9 |
HIP 85823 |
11.75 |
| 2026-02-14 00:00 |
17:32:51.58 |
+10:11:56.8 |
HIP 85823 |
12.48 |
| 2026-02-14 12:00 |
17:32:53.66 |
+10:12:27.8 |
HIP 85823 |
13.20 |
| 2026-02-15 00:00 |
17:32:55.68 |
+10:12:59.1 |
HIP 85823 |
13.92 |
| 2026-02-15 12:00 |
17:32:57.66 |
+10:13:30.7 |
HIP 85823 |
14.64 |
| 2026-02-16 00:00 |
17:32:59.59 |
+10:14:02.5 |
HIP 85823 |
15.34 |
| 2026-02-16 12:00 |
17:33:01.48 |
+10:14:34.6 |
HIP 85823 |
16.05 |
| 2026-02-17 00:00 |
17:33:03.31 |
+10:15:06.9 |
HIP 85823 |
16.74 |
| 2026-02-17 12:00 |
17:33:05.10 |
+10:15:39.4 |
HIP 85823 |
17.43 |
| 2026-02-18 00:00 |
17:33:06.84 |
+10:16:12.2 |
HIP 85823 |
18.12 |
| 2026-02-18 12:00 |
17:33:08.54 |
+10:16:45.1 |
HIP 85823 |
18.80 |
| 2026-02-19 00:00 |
17:33:10.18 |
+10:17:18.4 |
HIP 85901 |
19.30 |
| 2026-02-19 12:00 |
17:33:11.77 |
+10:17:51.8 |
HIP 85901 |
18.73 |
| 2026-02-20 00:00 |
17:33:13.32 |
+10:18:25.5 |
HIP 85901 |
18.16 |
| 2026-02-20 12:00 |
17:33:14.82 |
+10:18:59.3 |
HIP 85901 |
17.60 |
| 2026-02-21 00:00 |
17:33:16.26 |
+10:19:33.4 |
HIP 85901 |
17.04 |
| 2026-02-21 12:00 |
17:33:17.66 |
+10:20:07.7 |
HIP 85901 |
16.49 |
| 2026-02-22 00:00 |
17:33:19.01 |
+10:20:42.2 |
HIP 85901 |
15.94 |
| 2026-02-22 12:00 |
17:33:20.31 |
+10:21:16.9 |
HIP 85901 |
15.39 |
| 2026-02-23 00:00 |
17:33:21.55 |
+10:21:51.8 |
HIP 85901 |
14.85 |
| 2026-02-23 12:00 |
17:33:22.75 |
+10:22:26.9 |
HIP 85901 |
14.32 |
| 2026-02-24 00:00 |
17:33:23.90 |
+10:23:02.2 |
HIP 85901 |
13.79 |