| 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) |
| 2026-07-29 00:00 |
17:08:58.35 |
+11:16:58.1 |
HIP 84050 |
35.42 |
| 2026-07-29 12:00 |
17:08:53.48 |
+11:16:12.9 |
HIP 84050 |
36.84 |
| 2026-07-30 00:00 |
17:08:48.66 |
+11:15:27.3 |
HIP 84050 |
38.24 |
| 2026-07-30 12:00 |
17:08:43.87 |
+11:14:41.5 |
HIP 84050 |
39.64 |
| 2026-07-31 00:00 |
17:08:39.13 |
+11:13:55.5 |
HIP 84060 |
40.74 |
| 2026-07-31 12:00 |
17:08:34.43 |
+11:13:09.1 |
HIP 83831 |
40.18 |
| 2026-08-01 00:00 |
17:08:29.78 |
+11:12:22.4 |
HIP 83831 |
39.18 |
| 2026-08-01 12:00 |
17:08:25.17 |
+11:11:35.5 |
HIP 83831 |
38.21 |
| 2026-08-02 00:00 |
17:08:20.60 |
+11:10:48.2 |
HIP 83831 |
37.26 |
| 2026-08-02 12:00 |
17:08:16.07 |
+11:10:00.7 |
HIP 83831 |
36.34 |
| 2026-08-03 00:00 |
17:08:11.59 |
+11:09:13.0 |
HIP 83831 |
35.44 |
| 2026-08-03 12:00 |
17:08:07.16 |
+11:08:24.9 |
HIP 83831 |
34.56 |
| 2026-08-04 00:00 |
17:08:02.77 |
+11:07:36.6 |
HIP 83831 |
33.71 |
| 2026-08-04 12:00 |
17:07:58.42 |
+11:06:48.1 |
HIP 83831 |
32.90 |
| 2026-08-05 00:00 |
17:07:54.12 |
+11:05:59.2 |
HIP 83831 |
32.11 |
| 2026-08-05 12:00 |
17:07:49.86 |
+11:05:10.1 |
HIP 83831 |
31.35 |
| 2026-08-06 00:00 |
17:07:45.66 |
+11:04:20.8 |
HIP 83831 |
30.63 |
| 2026-08-06 12:00 |
17:07:41.49 |
+11:03:31.2 |
HIP 83831 |
29.94 |
| 2026-08-07 00:00 |
17:07:37.37 |
+11:02:41.3 |
HIP 83831 |
29.29 |
| 2026-08-07 12:00 |
17:07:33.30 |
+11:01:51.2 |
HIP 83831 |
28.67 |
| 2026-08-08 00:00 |
17:07:29.28 |
+11:01:00.9 |
HIP 83831 |
28.10 |
| 2026-08-08 12:00 |
17:07:25.30 |
+11:00:10.3 |
HIP 83831 |
27.57 |
| 2026-08-09 00:00 |
17:07:21.37 |
+10:59:19.5 |
HIP 83636 |
26.61 |
| 2026-08-09 12:00 |
17:07:17.49 |
+10:58:28.5 |
HIP 83636 |
25.68 |
| 2026-08-10 00:00 |
17:07:13.65 |
+10:57:37.2 |
HIP 83636 |
24.80 |
| 2026-08-10 12:00 |
17:07:09.86 |
+10:56:45.7 |
HIP 83636 |
23.96 |
| 2026-08-11 00:00 |
17:07:06.12 |
+10:55:54.0 |
HIP 83636 |
23.18 |
| 2026-08-11 12:00 |
17:07:02.43 |
+10:55:02.0 |
HIP 83636 |
22.45 |
| 2026-08-12 00:00 |
17:06:58.79 |
+10:54:09.9 |
HIP 83636 |
21.78 |
| 2026-08-12 12:00 |
17:06:55.19 |
+10:53:17.5 |
HIP 83636 |
21.17 |
| 2026-08-13 00:00 |
17:06:51.64 |
+10:52:24.9 |
HIP 83636 |
20.64 |
| 2026-08-13 12:00 |
17:06:48.15 |
+10:51:32.2 |
HIP 83636 |
20.18 |
| 2026-08-14 00:00 |
17:06:44.70 |
+10:50:39.2 |
HIP 83636 |
19.79 |
| 2026-08-14 12:00 |
17:06:41.30 |
+10:49:46.0 |
HIP 83636 |
19.49 |
| 2026-08-15 00:00 |
17:06:37.95 |
+10:48:52.6 |
HIP 83636 |
19.27 |
| 2026-08-15 12:00 |
17:06:34.65 |
+10:47:59.1 |
HIP 83636 |
19.14 |
| 2026-08-16 00:00 |
17:06:31.40 |
+10:47:05.3 |
HIP 83636 |
19.09 |
| 2026-08-16 12:00 |
17:06:28.20 |
+10:46:11.4 |
HIP 83636 |
19.13 |
| 2026-08-17 00:00 |
17:06:25.04 |
+10:45:17.3 |
HIP 83634 |
18.05 |
| 2026-08-17 12:00 |
17:06:21.94 |
+10:44:23.0 |
HIP 83634 |
16.88 |
| 2026-08-18 00:00 |
17:06:18.89 |
+10:43:28.6 |
HIP 83634 |
15.71 |
| 2026-08-18 12:00 |
17:06:15.89 |
+10:42:33.9 |
HIP 83634 |
14.55 |
| 2026-08-19 00:00 |
17:06:12.94 |
+10:41:39.2 |
HIP 83634 |
13.40 |