| 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 |
-0.500 |
| 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) |
| 2026-05-12 00:00 |
22:21:54.15 |
+33:24:32.2 |
HIP 110486 |
16.15 |
| 2026-05-12 12:00 |
22:21:55.30 |
+33:25:36.4 |
HIP 110486 |
15.25 |
| 2026-05-13 00:00 |
22:21:56.40 |
+33:26:40.6 |
HIP 110486 |
14.38 |
| 2026-05-13 12:00 |
22:21:57.46 |
+33:27:44.7 |
HIP 110486 |
13.55 |
| 2026-05-14 00:00 |
22:21:58.47 |
+33:28:48.8 |
HIP 110486 |
12.77 |
| 2026-05-14 12:00 |
22:21:59.42 |
+33:29:52.8 |
HIP 110486 |
12.05 |
| 2026-05-15 00:00 |
22:22:00.34 |
+33:30:56.7 |
HIP 110486 |
11.39 |
| 2026-05-15 12:00 |
22:22:01.20 |
+33:32:00.6 |
HIP 110486 |
10.82 |
| 2026-05-16 00:00 |
22:22:02.01 |
+33:33:04.4 |
HIP 110486 |
10.33 |
| 2026-05-16 12:00 |
22:22:02.77 |
+33:34:08.1 |
HIP 110486 |
9.95 |
| 2026-05-17 00:00 |
22:22:03.49 |
+33:35:11.7 |
HIP 110486 |
9.68 |
| 2026-05-17 12:00 |
22:22:04.15 |
+33:36:15.3 |
HIP 110486 |
9.54 |
| 2026-05-18 00:00 |
22:22:04.77 |
+33:37:18.7 |
HIP 110486 |
9.53 |
| 2026-05-18 12:00 |
22:22:05.34 |
+33:38:22.1 |
HIP 110486 |
9.64 |
| 2026-05-19 00:00 |
22:22:05.85 |
+33:39:25.3 |
HIP 110486 |
9.88 |
| 2026-05-19 12:00 |
22:22:06.32 |
+33:40:28.5 |
HIP 110486 |
10.23 |
| 2026-05-20 00:00 |
22:22:06.74 |
+33:41:31.5 |
HIP 110486 |
10.68 |
| 2026-05-20 12:00 |
22:22:07.11 |
+33:42:34.5 |
HIP 110486 |
11.22 |
| 2026-05-21 00:00 |
22:22:07.43 |
+33:43:37.3 |
HIP 110486 |
11.83 |
| 2026-05-21 12:00 |
22:22:07.70 |
+33:44:40.0 |
HIP 110389 |
12.06 |
| 2026-05-22 00:00 |
22:22:07.92 |
+33:45:42.5 |
HIP 110389 |
11.26 |
| 2026-05-22 12:00 |
22:22:08.09 |
+33:46:45.0 |
HIP 110389 |
10.50 |
| 2026-05-23 00:00 |
22:22:08.21 |
+33:47:47.3 |
HIP 110389 |
9.78 |
| 2026-05-23 12:00 |
22:22:08.28 |
+33:48:49.5 |
HIP 110389 |
9.12 |
| 2026-05-24 00:00 |
22:22:08.30 |
+33:49:51.5 |
HIP 110389 |
8.53 |
| 2026-05-24 12:00 |
22:22:08.27 |
+33:50:53.4 |
HIP 110389 |
8.01 |
| 2026-05-25 00:00 |
22:22:08.19 |
+33:51:55.2 |
HIP 110389 |
7.60 |
| 2026-05-25 12:00 |
22:22:08.06 |
+33:52:56.8 |
HIP 110389 |
7.30 |
| 2026-05-26 00:00 |
22:22:07.88 |
+33:53:58.2 |
HIP 110389 |
7.13 |
| 2026-05-26 12:00 |
22:22:07.65 |
+33:54:59.5 |
HIP 110389 |
7.09 |
| 2026-05-27 00:00 |
22:22:07.37 |
+33:56:00.6 |
HIP 110389 |
7.18 |
| 2026-05-27 12:00 |
22:22:07.04 |
+33:57:01.6 |
HIP 110389 |
7.41 |
| 2026-05-28 00:00 |
22:22:06.66 |
+33:58:02.4 |
HIP 110389 |
7.75 |
| 2026-05-28 12:00 |
22:22:06.22 |
+33:59:03.0 |
HIP 110389 |
8.20 |
| 2026-05-29 00:00 |
22:22:05.74 |
+34:00:03.5 |
HIP 110389 |
8.73 |
| 2026-05-29 12:00 |
22:22:05.21 |
+34:01:03.8 |
HIP 110389 |
9.33 |
| 2026-05-30 00:00 |
22:22:04.63 |
+34:02:03.9 |
HIP 110389 |
9.99 |
| 2026-05-30 12:00 |
22:22:04.00 |
+34:03:03.8 |
HIP 110389 |
10.69 |
| 2026-05-31 00:00 |
22:22:03.32 |
+34:04:03.5 |
HIP 110389 |
11.43 |
| 2026-05-31 12:00 |
22:22:02.59 |
+34:05:03.0 |
HIP 110389 |
12.21 |
| 2026-06-01 00:00 |
22:22:01.80 |
+34:06:02.3 |
HIP 110389 |
13.00 |
| 2026-06-01 12:00 |
22:22:00.97 |
+34:07:01.5 |
HIP 110389 |
13.82 |
| 2026-06-02 00:00 |
22:22:00.09 |
+34:08:00.4 |
HIP 110389 |
14.65 |