| Parameter |
Value |
| Designation |
C/2015 A1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-03-13T01:22:02.553600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:05Z |
| Obs used |
60 |
| NEO |
- |
| M1 |
7.300 |
| K1 |
32.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-03-29.0000000 |
| e |
0.90081449 |
| q (au) |
1.995505 |
| a (au) |
20.118914 |
| i (deg) |
80.365746 |
| Ω (om, deg) |
341.085968 |
| ω (w, deg) |
244.879299 |
| M (ma, deg) |
0.174128 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.204 + 4.454\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.204 |
| n |
4.454 |
| gf |
1.000 |
| gb |
-0.664 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
22:15:15.50 |
+35:23:05.3 |
HIP 109916 |
12.09 |
| 2026-07-29 12:00 |
22:15:09.79 |
+35:23:19.0 |
HIP 109916 |
12.47 |
| 2026-07-30 00:00 |
22:15:04.04 |
+35:23:32.1 |
HIP 109916 |
12.95 |
| 2026-07-30 12:00 |
22:14:58.28 |
+35:23:44.8 |
HIP 109916 |
13.54 |
| 2026-07-31 00:00 |
22:14:52.49 |
+35:23:56.8 |
HIP 109916 |
14.20 |
| 2026-07-31 12:00 |
22:14:46.68 |
+35:24:08.4 |
HIP 109827 |
13.90 |
| 2026-08-01 00:00 |
22:14:40.85 |
+35:24:19.4 |
HIP 109827 |
13.65 |
| 2026-08-01 12:00 |
22:14:34.99 |
+35:24:29.9 |
HIP 109827 |
13.51 |
| 2026-08-02 00:00 |
22:14:29.11 |
+35:24:39.8 |
HIP 109827 |
13.49 |
| 2026-08-02 12:00 |
22:14:23.21 |
+35:24:49.3 |
HIP 109827 |
13.58 |
| 2026-08-03 00:00 |
22:14:17.29 |
+35:24:58.1 |
HIP 109827 |
13.79 |
| 2026-08-03 12:00 |
22:14:11.34 |
+35:25:06.5 |
HIP 109827 |
14.11 |
| 2026-08-04 00:00 |
22:14:05.38 |
+35:25:14.3 |
HIP 109827 |
14.54 |
| 2026-08-04 12:00 |
22:13:59.40 |
+35:25:21.6 |
HIP 109827 |
15.07 |
| 2026-08-05 00:00 |
22:13:53.39 |
+35:25:28.3 |
HIP 109827 |
15.68 |
| 2026-08-05 12:00 |
22:13:47.37 |
+35:25:34.5 |
HIP 109827 |
16.37 |
| 2026-08-06 00:00 |
22:13:41.33 |
+35:25:40.1 |
HIP 109827 |
17.13 |
| 2026-08-06 12:00 |
22:13:35.27 |
+35:25:45.2 |
HIP 109827 |
17.95 |
| 2026-08-07 00:00 |
22:13:29.20 |
+35:25:49.8 |
HIP 109827 |
18.82 |
| 2026-08-07 12:00 |
22:13:23.10 |
+35:25:53.8 |
HIP 109827 |
19.75 |
| 2026-08-08 00:00 |
22:13:16.99 |
+35:25:57.3 |
HIP 109827 |
20.71 |
| 2026-08-08 12:00 |
22:13:10.87 |
+35:26:00.2 |
HIP 109827 |
21.71 |
| 2026-08-09 00:00 |
22:13:04.72 |
+35:26:02.6 |
HIP 109827 |
22.74 |
| 2026-08-09 12:00 |
22:12:58.57 |
+35:26:04.5 |
HIP 109827 |
23.80 |
| 2026-08-10 00:00 |
22:12:52.39 |
+35:26:05.8 |
HIP 109827 |
24.89 |
| 2026-08-10 12:00 |
22:12:46.21 |
+35:26:06.5 |
HIP 109645 |
24.90 |
| 2026-08-11 00:00 |
22:12:40.01 |
+35:26:06.7 |
HIP 109645 |
24.89 |
| 2026-08-11 12:00 |
22:12:33.79 |
+35:26:06.4 |
HIP 109645 |
24.94 |
| 2026-08-12 00:00 |
22:12:27.57 |
+35:26:05.5 |
HIP 109645 |
25.03 |
| 2026-08-12 12:00 |
22:12:21.33 |
+35:26:04.1 |
HIP 109645 |
25.19 |
| 2026-08-13 00:00 |
22:12:15.08 |
+35:26:02.1 |
HIP 109645 |
25.40 |
| 2026-08-13 12:00 |
22:12:08.82 |
+35:25:59.6 |
HIP 109645 |
25.66 |
| 2026-08-14 00:00 |
22:12:02.55 |
+35:25:56.5 |
HIP 109645 |
25.98 |
| 2026-08-14 12:00 |
22:11:56.27 |
+35:25:52.9 |
HIP 109418 |
25.90 |
| 2026-08-15 00:00 |
22:11:49.98 |
+35:25:48.7 |
HIP 109418 |
24.77 |
| 2026-08-15 12:00 |
22:11:43.68 |
+35:25:44.0 |
HIP 109418 |
23.64 |
| 2026-08-16 00:00 |
22:11:37.37 |
+35:25:38.8 |
HIP 109418 |
22.52 |
| 2026-08-16 12:00 |
22:11:31.05 |
+35:25:33.0 |
HIP 109418 |
21.42 |
| 2026-08-17 00:00 |
22:11:24.73 |
+35:25:26.7 |
HIP 109418 |
20.33 |
| 2026-08-17 12:00 |
22:11:18.40 |
+35:25:19.8 |
HIP 109418 |
19.26 |
| 2026-08-18 00:00 |
22:11:12.07 |
+35:25:12.4 |
HIP 109418 |
18.21 |
| 2026-08-18 12:00 |
22:11:05.73 |
+35:25:04.4 |
HIP 109418 |
17.19 |
| 2026-08-19 00:00 |
22:10:59.38 |
+35:24:56.0 |
HIP 109418 |
16.20 |