| Parameter |
Value |
| Designation |
C/2015 A2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-08-30T11:44:29.256000Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:05Z |
| Obs used |
23 |
| NEO |
- |
| M1 |
14.300 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-01-10.0000000 |
| e |
1.01374666 |
| q (au) |
5.266785 |
| a (au) |
-383.131941 |
| i (deg) |
108.899105 |
| Ω (om, deg) |
258.474274 |
| ω (w, deg) |
212.370407 |
| M (ma, deg) |
-0.030555 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.672 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.672 |
| n |
6.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
17:33:51.42 |
-47:14:02.9 |
HIP 86002 |
9.72 |
| 2026-07-29 12:00 |
17:33:45.64 |
-47:13:29.5 |
HIP 86002 |
10.84 |
| 2026-07-30 00:00 |
17:33:39.91 |
-47:12:55.9 |
HIP 86002 |
11.96 |
| 2026-07-30 12:00 |
17:33:34.23 |
-47:12:22.1 |
HIP 86002 |
13.07 |
| 2026-07-31 00:00 |
17:33:28.60 |
-47:11:48.2 |
HIP 86002 |
14.18 |
| 2026-07-31 12:00 |
17:33:23.02 |
-47:11:14.1 |
HIP 86002 |
15.29 |
| 2026-08-01 00:00 |
17:33:17.49 |
-47:10:39.8 |
HIP 86002 |
16.38 |
| 2026-08-01 12:00 |
17:33:12.00 |
-47:10:05.4 |
HIP 86002 |
17.48 |
| 2026-08-02 00:00 |
17:33:06.57 |
-47:09:30.9 |
HIP 86002 |
18.57 |
| 2026-08-02 12:00 |
17:33:01.18 |
-47:08:56.1 |
HIP 86002 |
19.65 |
| 2026-08-03 00:00 |
17:32:55.85 |
-47:08:21.3 |
HIP 86002 |
20.73 |
| 2026-08-03 12:00 |
17:32:50.57 |
-47:07:46.2 |
HIP 86002 |
21.80 |
| 2026-08-04 00:00 |
17:32:45.33 |
-47:07:11.1 |
HIP 85907 |
22.10 |
| 2026-08-04 12:00 |
17:32:40.15 |
-47:06:35.7 |
HIP 85907 |
21.79 |
| 2026-08-05 00:00 |
17:32:35.02 |
-47:06:00.3 |
HIP 85907 |
21.52 |
| 2026-08-05 12:00 |
17:32:29.95 |
-47:05:24.7 |
HIP 85907 |
21.30 |
| 2026-08-06 00:00 |
17:32:24.92 |
-47:04:48.9 |
HIP 85907 |
21.11 |
| 2026-08-06 12:00 |
17:32:19.95 |
-47:04:13.0 |
HIP 85907 |
20.98 |
| 2026-08-07 00:00 |
17:32:15.04 |
-47:03:37.0 |
HIP 85907 |
20.88 |
| 2026-08-07 12:00 |
17:32:10.17 |
-47:03:00.9 |
HIP 85907 |
20.83 |
| 2026-08-08 00:00 |
17:32:05.36 |
-47:02:24.6 |
HIP 85907 |
20.83 |
| 2026-08-08 12:00 |
17:32:00.61 |
-47:01:48.2 |
HIP 85907 |
20.87 |
| 2026-08-09 00:00 |
17:31:55.90 |
-47:01:11.6 |
HIP 85629 |
20.76 |
| 2026-08-09 12:00 |
17:31:51.26 |
-47:00:35.0 |
HIP 85629 |
19.95 |
| 2026-08-10 00:00 |
17:31:46.67 |
-46:59:58.2 |
HIP 85629 |
19.17 |
| 2026-08-10 12:00 |
17:31:42.13 |
-46:59:21.3 |
HIP 85629 |
18.43 |
| 2026-08-11 00:00 |
17:31:37.65 |
-46:58:44.4 |
HIP 85629 |
17.71 |
| 2026-08-11 12:00 |
17:31:33.23 |
-46:58:07.2 |
HIP 85629 |
17.03 |
| 2026-08-12 00:00 |
17:31:28.86 |
-46:57:30.0 |
HIP 85629 |
16.40 |
| 2026-08-12 12:00 |
17:31:24.55 |
-46:56:52.7 |
HIP 85629 |
15.80 |
| 2026-08-13 00:00 |
17:31:20.29 |
-46:56:15.3 |
HIP 85629 |
15.25 |
| 2026-08-13 12:00 |
17:31:16.10 |
-46:55:37.8 |
HIP 85629 |
14.75 |
| 2026-08-14 00:00 |
17:31:11.96 |
-46:55:00.1 |
HIP 85629 |
14.31 |
| 2026-08-14 12:00 |
17:31:07.88 |
-46:54:22.4 |
HIP 85629 |
13.93 |
| 2026-08-15 00:00 |
17:31:03.85 |
-46:53:44.6 |
HIP 85629 |
13.61 |
| 2026-08-15 12:00 |
17:30:59.89 |
-46:53:06.7 |
HIP 85629 |
13.36 |
| 2026-08-16 00:00 |
17:30:55.98 |
-46:52:28.7 |
HIP 85629 |
13.17 |
| 2026-08-16 12:00 |
17:30:52.13 |
-46:51:50.7 |
HIP 85629 |
13.06 |
| 2026-08-17 00:00 |
17:30:48.34 |
-46:51:12.5 |
HIP 85629 |
13.02 |
| 2026-08-17 12:00 |
17:30:44.61 |
-46:50:34.3 |
HIP 85629 |
13.05 |
| 2026-08-18 00:00 |
17:30:40.94 |
-46:49:56.0 |
HIP 85629 |
13.14 |
| 2026-08-18 12:00 |
17:30:37.32 |
-46:49:17.6 |
HIP 85629 |
13.31 |
| 2026-08-19 00:00 |
17:30:33.77 |
-46:48:39.2 |
HIP 85629 |
13.53 |