| 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) |
| 2026-09-20 00:00 |
22:04:25.96 |
+34:58:33.5 |
HIP 108838 |
25.14 |
| 2026-09-20 12:00 |
22:04:20.37 |
+34:57:54.3 |
HIP 108838 |
24.75 |
| 2026-09-21 00:00 |
22:04:14.82 |
+34:57:14.6 |
HIP 108932 |
24.21 |
| 2026-09-21 12:00 |
22:04:09.29 |
+34:56:34.6 |
HIP 108932 |
23.49 |
| 2026-09-22 00:00 |
22:04:03.79 |
+34:55:54.3 |
HIP 108932 |
22.81 |
| 2026-09-22 12:00 |
22:03:58.33 |
+34:55:13.5 |
HIP 108932 |
22.19 |
| 2026-09-23 00:00 |
22:03:52.89 |
+34:54:32.4 |
HIP 108932 |
21.62 |
| 2026-09-23 12:00 |
22:03:47.48 |
+34:53:51.0 |
HIP 108932 |
21.11 |
| 2026-09-24 00:00 |
22:03:42.10 |
+34:53:09.2 |
HIP 108932 |
20.67 |
| 2026-09-24 12:00 |
22:03:36.76 |
+34:52:27.0 |
HIP 108932 |
20.29 |
| 2026-09-25 00:00 |
22:03:31.44 |
+34:51:44.6 |
HIP 108932 |
19.98 |
| 2026-09-25 12:00 |
22:03:26.16 |
+34:51:01.7 |
HIP 108932 |
19.75 |
| 2026-09-26 00:00 |
22:03:20.91 |
+34:50:18.6 |
HIP 108932 |
19.59 |
| 2026-09-26 12:00 |
22:03:15.69 |
+34:49:35.1 |
HIP 108932 |
19.51 |
| 2026-09-27 00:00 |
22:03:10.51 |
+34:48:51.3 |
HIP 108932 |
19.50 |
| 2026-09-27 12:00 |
22:03:05.35 |
+34:48:07.2 |
HIP 108932 |
19.57 |
| 2026-09-28 00:00 |
22:03:00.24 |
+34:47:22.7 |
HIP 108932 |
19.72 |
| 2026-09-28 12:00 |
22:02:55.15 |
+34:46:37.9 |
HIP 108932 |
19.94 |
| 2026-09-29 00:00 |
22:02:50.10 |
+34:45:52.9 |
HIP 108932 |
20.24 |
| 2026-09-29 12:00 |
22:02:45.09 |
+34:45:07.5 |
HIP 108932 |
20.60 |
| 2026-09-30 00:00 |
22:02:40.11 |
+34:44:21.8 |
HIP 108932 |
21.02 |
| 2026-09-30 12:00 |
22:02:35.17 |
+34:43:35.8 |
HIP 108796 |
20.96 |
| 2026-10-01 00:00 |
22:02:30.26 |
+34:42:49.5 |
HIP 108796 |
20.12 |
| 2026-10-01 12:00 |
22:02:25.39 |
+34:42:03.0 |
HIP 108796 |
19.33 |
| 2026-10-02 00:00 |
22:02:20.56 |
+34:41:16.1 |
HIP 108796 |
18.58 |
| 2026-10-02 12:00 |
22:02:15.76 |
+34:40:29.0 |
HIP 108796 |
17.89 |
| 2026-10-03 00:00 |
22:02:11.00 |
+34:39:41.6 |
HIP 108796 |
17.25 |
| 2026-10-03 12:00 |
22:02:06.28 |
+34:38:53.9 |
HIP 108796 |
16.68 |
| 2026-10-04 00:00 |
22:02:01.59 |
+34:38:05.9 |
HIP 108796 |
16.19 |
| 2026-10-04 12:00 |
22:01:56.95 |
+34:37:17.7 |
HIP 108796 |
15.76 |
| 2026-10-05 00:00 |
22:01:52.35 |
+34:36:29.3 |
HIP 108796 |
15.43 |
| 2026-10-05 12:00 |
22:01:47.78 |
+34:35:40.5 |
HIP 108796 |
15.17 |
| 2026-10-06 00:00 |
22:01:43.25 |
+34:34:51.6 |
HIP 108796 |
15.01 |
| 2026-10-06 12:00 |
22:01:38.77 |
+34:34:02.3 |
HIP 108796 |
14.95 |
| 2026-10-07 00:00 |
22:01:34.32 |
+34:33:12.9 |
HIP 108796 |
14.97 |
| 2026-10-07 12:00 |
22:01:29.92 |
+34:32:23.2 |
HIP 108796 |
15.09 |
| 2026-10-08 00:00 |
22:01:25.56 |
+34:31:33.2 |
HIP 108796 |
15.30 |
| 2026-10-08 12:00 |
22:01:21.24 |
+34:30:43.1 |
HIP 108621 |
14.97 |
| 2026-10-09 00:00 |
22:01:16.96 |
+34:29:52.7 |
HIP 108621 |
14.64 |
| 2026-10-09 12:00 |
22:01:12.72 |
+34:29:02.1 |
HIP 108621 |
14.41 |
| 2026-10-10 00:00 |
22:01:08.53 |
+34:28:11.3 |
HIP 108621 |
14.29 |
| 2026-10-10 12:00 |
22:01:04.38 |
+34:27:20.3 |
HIP 108621 |
14.27 |
| 2026-10-11 00:00 |
22:01:00.27 |
+34:26:29.1 |
HIP 108621 |
14.37 |