C/2015 A2 (PANSTARRS)
| 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
$$
M_a = (5.673 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.673 |
| n |
6.000 |
| gf |
0.982 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.908 |
| 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) |
| 2026-02-03 00:00 |
17:55:37.26 |
-46:51:38.9 |
HIP 87770 |
4.53 |
| 2026-02-03 12:00 |
17:55:42.14 |
-46:51:50.8 |
HIP 87770 |
4.49 |
| 2026-02-04 00:00 |
17:55:46.97 |
-46:52:03.0 |
HIP 87770 |
4.61 |
| 2026-02-04 12:00 |
17:55:51.75 |
-46:52:15.2 |
HIP 87770 |
4.89 |
| 2026-02-05 00:00 |
17:55:56.49 |
-46:52:27.7 |
HIP 87770 |
5.28 |
| 2026-02-05 12:00 |
17:56:01.19 |
-46:52:40.3 |
HIP 87770 |
5.77 |
| 2026-02-06 00:00 |
17:56:05.84 |
-46:52:53.1 |
HIP 87770 |
6.33 |
| 2026-02-06 12:00 |
17:56:10.44 |
-46:53:06.1 |
HIP 87770 |
6.95 |
| 2026-02-07 00:00 |
17:56:15.00 |
-46:53:19.2 |
HIP 87770 |
7.59 |
| 2026-02-07 12:00 |
17:56:19.51 |
-46:53:32.5 |
HIP 87770 |
8.26 |
| 2026-02-08 00:00 |
17:56:23.97 |
-46:53:46.0 |
HIP 87770 |
8.95 |
| 2026-02-08 12:00 |
17:56:28.39 |
-46:53:59.6 |
HIP 87770 |
9.65 |
| 2026-02-09 00:00 |
17:56:32.76 |
-46:54:13.4 |
HIP 87770 |
10.36 |
| 2026-02-09 12:00 |
17:56:37.08 |
-46:54:27.3 |
HIP 87770 |
11.08 |
| 2026-02-10 00:00 |
17:56:41.35 |
-46:54:41.4 |
HIP 87770 |
11.80 |
| 2026-02-10 12:00 |
17:56:45.58 |
-46:54:55.7 |
HIP 87770 |
12.51 |
| 2026-02-11 00:00 |
17:56:49.75 |
-46:55:10.1 |
HIP 87770 |
13.23 |
| 2026-02-11 12:00 |
17:56:53.88 |
-46:55:24.7 |
HIP 87770 |
13.95 |
| 2026-02-12 00:00 |
17:56:57.95 |
-46:55:39.4 |
HIP 87770 |
14.66 |
| 2026-02-12 12:00 |
17:57:01.98 |
-46:55:54.3 |
HIP 87770 |
15.37 |
| 2026-02-13 00:00 |
17:57:05.95 |
-46:56:09.3 |
HIP 87770 |
16.07 |
| 2026-02-13 12:00 |
17:57:09.88 |
-46:56:24.5 |
HIP 87770 |
16.78 |
| 2026-02-14 00:00 |
17:57:13.75 |
-46:56:39.8 |
HIP 87770 |
17.47 |
| 2026-02-14 12:00 |
17:57:17.57 |
-46:56:55.3 |
HIP 87770 |
18.16 |
| 2026-02-15 00:00 |
17:57:21.33 |
-46:57:10.9 |
HIP 87770 |
18.85 |
| 2026-02-15 12:00 |
17:57:25.05 |
-46:57:26.7 |
HIP 87770 |
19.53 |
| 2026-02-16 00:00 |
17:57:28.71 |
-46:57:42.6 |
HIP 87770 |
20.20 |
| 2026-02-16 12:00 |
17:57:32.32 |
-46:57:58.7 |
HIP 87805 |
20.82 |
| 2026-02-17 00:00 |
17:57:35.88 |
-46:58:14.9 |
HIP 87805 |
21.42 |
| 2026-02-17 12:00 |
17:57:39.38 |
-46:58:31.2 |
HIP 87805 |
22.02 |
| 2026-02-18 00:00 |
17:57:42.83 |
-46:58:47.6 |
HIP 87805 |
22.62 |
| 2026-02-18 12:00 |
17:57:46.22 |
-46:59:04.2 |
HIP 87805 |
23.22 |
| 2026-02-19 00:00 |
17:57:49.56 |
-46:59:21.0 |
HIP 87805 |
23.81 |
| 2026-02-19 12:00 |
17:57:52.84 |
-46:59:37.8 |
HIP 87805 |
24.40 |
| 2026-02-20 00:00 |
17:57:56.07 |
-46:59:54.8 |
HIP 87805 |
24.99 |
| 2026-02-20 12:00 |
17:57:59.24 |
-47:00:11.9 |
HIP 87805 |
25.57 |
| 2026-02-21 00:00 |
17:58:02.35 |
-47:00:29.1 |
HIP 87805 |
26.15 |
| 2026-02-21 12:00 |
17:58:05.41 |
-47:00:46.5 |
HIP 87805 |
26.73 |
| 2026-02-22 00:00 |
17:58:08.41 |
-47:01:04.0 |
HIP 87805 |
27.30 |
| 2026-02-22 12:00 |
17:58:11.36 |
-47:01:21.6 |
HIP 87805 |
27.87 |
| 2026-02-23 00:00 |
17:58:14.25 |
-47:01:39.3 |
HIP 87805 |
28.43 |
| 2026-02-23 12:00 |
17:58:17.08 |
-47:01:57.1 |
HIP 87805 |
28.98 |
| 2026-02-24 00:00 |
17:58:19.85 |
-47:02:15.1 |
HIP 87805 |
29.53 |