| 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) |
| 2026-03-26 00:00 |
17:32:55.86 |
+11:01:54.4 |
HIP 85901 |
25.69 |
| 2026-03-26 12:00 |
17:32:53.74 |
+11:02:34.5 |
HIP 85901 |
26.44 |
| 2026-03-27 00:00 |
17:32:51.56 |
+11:03:14.5 |
HIP 85776 |
26.49 |
| 2026-03-27 12:00 |
17:32:49.32 |
+11:03:54.5 |
HIP 85776 |
25.63 |
| 2026-03-28 00:00 |
17:32:47.04 |
+11:04:34.5 |
HIP 85776 |
24.76 |
| 2026-03-28 12:00 |
17:32:44.69 |
+11:05:14.3 |
HIP 85776 |
23.88 |
| 2026-03-29 00:00 |
17:32:42.30 |
+11:05:54.1 |
HIP 85776 |
22.99 |
| 2026-03-29 12:00 |
17:32:39.85 |
+11:06:33.9 |
HIP 85776 |
22.10 |
| 2026-03-30 00:00 |
17:32:37.35 |
+11:07:13.6 |
HIP 85776 |
21.20 |
| 2026-03-30 12:00 |
17:32:34.79 |
+11:07:53.2 |
HIP 85776 |
20.29 |
| 2026-03-31 00:00 |
17:32:32.18 |
+11:08:32.7 |
HIP 85776 |
19.37 |
| 2026-03-31 12:00 |
17:32:29.52 |
+11:09:12.2 |
HIP 85776 |
18.44 |
| 2026-04-01 00:00 |
17:32:26.81 |
+11:09:51.6 |
HIP 85776 |
17.51 |
| 2026-04-01 12:00 |
17:32:24.04 |
+11:10:30.9 |
HIP 85776 |
16.57 |
| 2026-04-02 00:00 |
17:32:21.22 |
+11:11:10.1 |
HIP 85776 |
15.62 |
| 2026-04-02 12:00 |
17:32:18.34 |
+11:11:49.2 |
HIP 85776 |
14.66 |
| 2026-04-03 00:00 |
17:32:15.42 |
+11:12:28.2 |
HIP 85776 |
13.70 |
| 2026-04-03 12:00 |
17:32:12.44 |
+11:13:07.1 |
HIP 85776 |
12.73 |
| 2026-04-04 00:00 |
17:32:09.41 |
+11:13:45.9 |
HIP 85776 |
11.76 |
| 2026-04-04 12:00 |
17:32:06.32 |
+11:14:24.6 |
HIP 85776 |
10.78 |
| 2026-04-05 00:00 |
17:32:03.19 |
+11:15:03.2 |
HIP 85776 |
9.80 |
| 2026-04-05 12:00 |
17:32:00.00 |
+11:15:41.6 |
HIP 85776 |
8.82 |
| 2026-04-06 00:00 |
17:31:56.76 |
+11:16:20.0 |
HIP 85776 |
7.84 |
| 2026-04-06 12:00 |
17:31:53.47 |
+11:16:58.2 |
HIP 85776 |
6.87 |
| 2026-04-07 00:00 |
17:31:50.13 |
+11:17:36.3 |
HIP 85776 |
5.91 |
| 2026-04-07 12:00 |
17:31:46.73 |
+11:18:14.2 |
HIP 85776 |
4.98 |
| 2026-04-08 00:00 |
17:31:43.29 |
+11:18:52.1 |
HIP 85776 |
4.10 |
| 2026-04-08 12:00 |
17:31:39.79 |
+11:19:29.8 |
HIP 85776 |
3.33 |
| 2026-04-09 00:00 |
17:31:36.24 |
+11:20:07.3 |
HIP 85776 |
2.76 |
| 2026-04-09 12:00 |
17:31:32.65 |
+11:20:44.7 |
HIP 85776 |
2.56 |
| 2026-04-10 00:00 |
17:31:29.00 |
+11:21:21.9 |
HIP 85776 |
2.80 |
| 2026-04-10 12:00 |
17:31:25.30 |
+11:21:59.0 |
HIP 85776 |
3.41 |
| 2026-04-11 00:00 |
17:31:21.55 |
+11:22:35.9 |
HIP 85776 |
4.23 |
| 2026-04-11 12:00 |
17:31:17.75 |
+11:23:12.7 |
HIP 85776 |
5.17 |
| 2026-04-12 00:00 |
17:31:13.90 |
+11:23:49.3 |
HIP 85776 |
6.18 |
| 2026-04-12 12:00 |
17:31:10.00 |
+11:24:25.7 |
HIP 85776 |
7.23 |
| 2026-04-13 00:00 |
17:31:06.05 |
+11:25:01.9 |
HIP 85776 |
8.32 |
| 2026-04-13 12:00 |
17:31:02.05 |
+11:25:38.0 |
HIP 85776 |
9.43 |
| 2026-04-14 00:00 |
17:30:58.00 |
+11:26:13.9 |
HIP 85776 |
10.56 |
| 2026-04-14 12:00 |
17:30:53.91 |
+11:26:49.6 |
HIP 85776 |
11.70 |
| 2026-04-15 00:00 |
17:30:49.76 |
+11:27:25.1 |
HIP 85776 |
12.86 |
| 2026-04-15 12:00 |
17:30:45.57 |
+11:28:00.4 |
HIP 85776 |
14.03 |
| 2026-04-16 00:00 |
17:30:41.33 |
+11:28:35.5 |
HIP 85776 |
15.22 |