| Parameter |
Value |
| Designation |
C/2016 A1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-11-23T08:54:05.518080Z |
| Orbit solution date (soln_date, UTC) |
2022-07-19T01:12:15Z |
| Obs used |
2143 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
9.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-11-13.0000000 |
| e |
1.00196775 |
| q (au) |
5.327762 |
| a (au) |
-2707.536844 |
| i (deg) |
121.185405 |
| Ω (om, deg) |
128.174457 |
| ω (w, deg) |
10.320070 |
| M (ma, deg) |
-0.000073 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.402 + 3.724\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.402 |
| n |
3.724 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
1.000 |
| 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 |
| 2016-01-01 |
2017-11-22 |
-2.3519 |
+1.891 |
| 2017-11-26 |
2019-03-10 |
-2.2345 |
+1.488 |
| 2019-03-10 |
2020-02-15 |
+16.2456 |
-13.536 |
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 |
21:34:39.47 |
+33:01:13.2 |
HIP 106473 |
13.11 |
| 2026-09-20 12:00 |
21:34:33.64 |
+33:00:02.2 |
HIP 106473 |
11.41 |
| 2026-09-21 00:00 |
21:34:27.86 |
+32:58:51.0 |
HIP 106473 |
9.71 |
| 2026-09-21 12:00 |
21:34:22.11 |
+32:57:39.3 |
HIP 106473 |
8.01 |
| 2026-09-22 00:00 |
21:34:16.41 |
+32:56:27.4 |
HIP 106473 |
6.32 |
| 2026-09-22 12:00 |
21:34:10.74 |
+32:55:15.1 |
HIP 106473 |
4.63 |
| 2026-09-23 00:00 |
21:34:05.12 |
+32:54:02.5 |
HIP 106473 |
2.95 |
| 2026-09-23 12:00 |
21:33:59.54 |
+32:52:49.5 |
HIP 106473 |
1.28 |
| 2026-09-24 00:00 |
21:33:54.00 |
+32:51:36.2 |
HIP 106473 |
0.57 |
| 2026-09-24 12:00 |
21:33:48.51 |
+32:50:22.6 |
HIP 106473 |
2.16 |
| 2026-09-25 00:00 |
21:33:43.05 |
+32:49:08.8 |
HIP 106473 |
3.83 |
| 2026-09-25 12:00 |
21:33:37.65 |
+32:47:54.6 |
HIP 106473 |
5.51 |
| 2026-09-26 00:00 |
21:33:32.28 |
+32:46:40.1 |
HIP 106473 |
7.18 |
| 2026-09-26 12:00 |
21:33:26.96 |
+32:45:25.3 |
HIP 106388 |
7.70 |
| 2026-09-27 00:00 |
21:33:21.68 |
+32:44:10.2 |
HIP 106388 |
6.94 |
| 2026-09-27 12:00 |
21:33:16.45 |
+32:42:54.8 |
HIP 106388 |
6.54 |
| 2026-09-28 00:00 |
21:33:11.26 |
+32:41:39.2 |
HIP 106388 |
6.56 |
| 2026-09-28 12:00 |
21:33:06.12 |
+32:40:23.3 |
HIP 106388 |
7.00 |
| 2026-09-29 00:00 |
21:33:01.02 |
+32:39:07.1 |
HIP 106388 |
7.79 |
| 2026-09-29 12:00 |
21:32:55.97 |
+32:37:50.7 |
HIP 106388 |
8.82 |
| 2026-09-30 00:00 |
21:32:50.97 |
+32:36:34.0 |
HIP 106388 |
10.03 |
| 2026-09-30 12:00 |
21:32:46.01 |
+32:35:17.0 |
HIP 106388 |
11.36 |
| 2026-10-01 00:00 |
21:32:41.10 |
+32:33:59.8 |
HIP 106388 |
12.77 |
| 2026-10-01 12:00 |
21:32:36.24 |
+32:32:42.4 |
HIP 106388 |
14.23 |
| 2026-10-02 00:00 |
21:32:31.42 |
+32:31:24.7 |
HIP 106388 |
15.73 |
| 2026-10-02 12:00 |
21:32:26.65 |
+32:30:06.8 |
HIP 106388 |
17.25 |
| 2026-10-03 00:00 |
21:32:21.94 |
+32:28:48.7 |
HIP 106388 |
18.80 |
| 2026-10-03 12:00 |
21:32:17.27 |
+32:27:30.3 |
HIP 106388 |
20.36 |
| 2026-10-04 00:00 |
21:32:12.65 |
+32:26:11.7 |
HIP 106388 |
21.93 |
| 2026-10-04 12:00 |
21:32:08.07 |
+32:24:53.0 |
HIP 106388 |
23.51 |
| 2026-10-05 00:00 |
21:32:03.55 |
+32:23:34.0 |
HIP 106388 |
25.09 |
| 2026-10-05 12:00 |
21:31:59.08 |
+32:22:14.8 |
HIP 106388 |
26.68 |
| 2026-10-06 00:00 |
21:31:54.66 |
+32:20:55.4 |
HIP 106215 |
27.31 |
| 2026-10-06 12:00 |
21:31:50.29 |
+32:19:35.9 |
HIP 106215 |
25.70 |
| 2026-10-07 00:00 |
21:31:45.97 |
+32:18:16.1 |
HIP 106215 |
24.09 |
| 2026-10-07 12:00 |
21:31:41.70 |
+32:16:56.2 |
HIP 106215 |
22.49 |
| 2026-10-08 00:00 |
21:31:37.49 |
+32:15:36.1 |
HIP 106215 |
20.89 |
| 2026-10-08 12:00 |
21:31:33.33 |
+32:14:15.9 |
HIP 106215 |
19.29 |
| 2026-10-09 00:00 |
21:31:29.21 |
+32:12:55.4 |
HIP 106215 |
17.70 |
| 2026-10-09 12:00 |
21:31:25.15 |
+32:11:34.9 |
HIP 106215 |
16.11 |
| 2026-10-10 00:00 |
21:31:21.15 |
+32:10:14.2 |
HIP 106215 |
14.52 |
| 2026-10-10 12:00 |
21:31:17.20 |
+32:08:53.4 |
HIP 106215 |
12.94 |
| 2026-10-11 00:00 |
21:31:13.30 |
+32:07:32.4 |
HIP 106215 |
11.36 |