| Parameter |
Value |
| Designation |
C/2015 V1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-12-17T19:17:15.800640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:16Z |
| Obs used |
2145 |
| NEO |
- |
| M1 |
8.300 |
| K1 |
8.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-06-28.0000000 |
| e |
1.00055464 |
| q (au) |
4.266704 |
| a (au) |
-7692.742203 |
| i (deg) |
139.230487 |
| Ω (om, deg) |
197.193756 |
| ω (w, deg) |
179.649665 |
| M (ma, deg) |
-0.000252 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.400 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.400 |
| n |
2.000 |
| gf |
0.821 |
| gb |
-0.500 |
| k |
0.901 |
| δ90 |
1.000 |
| 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 |
| 2015-11-02 |
2016-09-21 |
+10.7844 |
-8.539 |
| 2016-09-21 |
2017-03-03 |
+2.3776 |
-2.080 |
| 2017-03-03 |
2017-12-17 |
-9.8282 |
+6.267 |
| 2017-12-17 |
2019-06-11 |
+7.0878 |
-4.329 |
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 |
15:16:12.35 |
-50:58:38.0 |
HIP 74766 |
7.26 |
| 2026-09-20 12:00 |
15:16:16.70 |
-50:58:03.7 |
HIP 74766 |
7.09 |
| 2026-09-21 00:00 |
15:16:21.10 |
-50:57:29.8 |
HIP 74766 |
7.02 |
| 2026-09-21 12:00 |
15:16:25.56 |
-50:56:56.3 |
HIP 74766 |
7.05 |
| 2026-09-22 00:00 |
15:16:30.07 |
-50:56:23.2 |
HIP 74766 |
7.18 |
| 2026-09-22 12:00 |
15:16:34.64 |
-50:55:50.5 |
HIP 74766 |
7.41 |
| 2026-09-23 00:00 |
15:16:39.26 |
-50:55:18.1 |
HIP 74766 |
7.74 |
| 2026-09-23 12:00 |
15:16:43.93 |
-50:54:46.2 |
HIP 74766 |
8.14 |
| 2026-09-24 00:00 |
15:16:48.65 |
-50:54:14.6 |
HIP 74766 |
8.61 |
| 2026-09-24 12:00 |
15:16:53.43 |
-50:53:43.4 |
HIP 74766 |
9.15 |
| 2026-09-25 00:00 |
15:16:58.25 |
-50:53:12.6 |
HIP 74766 |
9.73 |
| 2026-09-25 12:00 |
15:17:03.13 |
-50:52:42.1 |
HIP 74766 |
10.36 |
| 2026-09-26 00:00 |
15:17:08.06 |
-50:52:12.1 |
HIP 74766 |
11.03 |
| 2026-09-26 12:00 |
15:17:13.03 |
-50:51:42.4 |
HIP 74766 |
11.73 |
| 2026-09-27 00:00 |
15:17:18.06 |
-50:51:13.2 |
HIP 74766 |
12.45 |
| 2026-09-27 12:00 |
15:17:23.14 |
-50:50:44.3 |
HIP 74766 |
13.20 |
| 2026-09-28 00:00 |
15:17:28.26 |
-50:50:15.8 |
HIP 74766 |
13.96 |
| 2026-09-28 12:00 |
15:17:33.43 |
-50:49:47.7 |
HIP 74766 |
14.75 |
| 2026-09-29 00:00 |
15:17:38.65 |
-50:49:19.9 |
HIP 74766 |
15.55 |
| 2026-09-29 12:00 |
15:17:43.92 |
-50:48:52.6 |
HIP 74766 |
16.36 |
| 2026-09-30 00:00 |
15:17:49.23 |
-50:48:25.7 |
HIP 74766 |
17.19 |
| 2026-09-30 12:00 |
15:17:54.59 |
-50:47:59.1 |
HIP 74994 |
17.20 |
| 2026-10-01 00:00 |
15:18:00.00 |
-50:47:33.0 |
HIP 74994 |
16.72 |
| 2026-10-01 12:00 |
15:18:05.45 |
-50:47:07.2 |
HIP 74994 |
16.28 |
| 2026-10-02 00:00 |
15:18:10.95 |
-50:46:41.8 |
HIP 74994 |
15.87 |
| 2026-10-02 12:00 |
15:18:16.50 |
-50:46:16.8 |
HIP 74994 |
15.50 |
| 2026-10-03 00:00 |
15:18:22.08 |
-50:45:52.2 |
HIP 74994 |
15.18 |
| 2026-10-03 12:00 |
15:18:27.72 |
-50:45:28.1 |
HIP 74994 |
14.90 |
| 2026-10-04 00:00 |
15:18:33.39 |
-50:45:04.3 |
HIP 74994 |
14.68 |
| 2026-10-04 12:00 |
15:18:39.11 |
-50:44:40.9 |
HIP 74994 |
14.50 |
| 2026-10-05 00:00 |
15:18:44.87 |
-50:44:17.9 |
HIP 74994 |
14.39 |
| 2026-10-05 12:00 |
15:18:50.68 |
-50:43:55.2 |
HIP 74994 |
14.33 |
| 2026-10-06 00:00 |
15:18:56.53 |
-50:43:33.0 |
HIP 74994 |
14.33 |
| 2026-10-06 12:00 |
15:19:02.42 |
-50:43:11.2 |
HIP 74994 |
14.39 |
| 2026-10-07 00:00 |
15:19:08.35 |
-50:42:49.8 |
HIP 74994 |
14.51 |
| 2026-10-07 12:00 |
15:19:14.32 |
-50:42:28.8 |
HIP 74994 |
14.69 |
| 2026-10-08 00:00 |
15:19:20.33 |
-50:42:08.2 |
HIP 74994 |
14.93 |
| 2026-10-08 12:00 |
15:19:26.38 |
-50:41:48.0 |
HIP 74994 |
15.23 |
| 2026-10-09 00:00 |
15:19:32.47 |
-50:41:28.1 |
HIP 74994 |
15.58 |
| 2026-10-09 12:00 |
15:19:38.60 |
-50:41:08.7 |
HIP 74994 |
15.98 |
| 2026-10-10 00:00 |
15:19:44.76 |
-50:40:49.7 |
HIP 74994 |
16.43 |
| 2026-10-10 12:00 |
15:19:50.97 |
-50:40:31.1 |
HIP 74994 |
16.92 |
| 2026-10-11 00:00 |
15:19:57.21 |
-50:40:12.9 |
HIP 74994 |
17.46 |