| Parameter |
Value |
| Designation |
C/2015 D2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-09-27T14:47:50.671680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:07Z |
| Obs used |
68 |
| NEO |
- |
| M1 |
7.100 |
| K1 |
12.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-03-24.0000000 |
| e |
0.56825603 |
| q (au) |
5.606049 |
| a (au) |
12.984662 |
| i (deg) |
31.834348 |
| Ω (om, deg) |
162.858947 |
| ω (w, deg) |
291.923116 |
| M (ma, deg) |
11.425219 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.637 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.637 |
| n |
6.000 |
| gf |
0.948 |
| gb |
-0.640 |
| k |
0.800 |
| δ90 |
8.992 |
| 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 |
16:31:47.83 |
+11:54:39.5 |
HIP 80903 |
8.98 |
| 2026-05-12 12:00 |
16:31:42.19 |
+11:55:10.0 |
HIP 80903 |
7.57 |
| 2026-05-13 00:00 |
16:31:36.52 |
+11:55:40.0 |
HIP 80903 |
6.19 |
| 2026-05-13 12:00 |
16:31:30.84 |
+11:56:09.6 |
HIP 80903 |
4.87 |
| 2026-05-14 00:00 |
16:31:25.14 |
+11:56:38.7 |
HIP 80903 |
3.67 |
| 2026-05-14 12:00 |
16:31:19.41 |
+11:57:07.4 |
HIP 80903 |
2.77 |
| 2026-05-15 00:00 |
16:31:13.67 |
+11:57:35.5 |
HIP 80903 |
2.51 |
| 2026-05-15 12:00 |
16:31:07.92 |
+11:58:03.2 |
HIP 80903 |
3.06 |
| 2026-05-16 00:00 |
16:31:02.14 |
+11:58:30.5 |
HIP 80903 |
4.10 |
| 2026-05-16 12:00 |
16:30:56.35 |
+11:58:57.2 |
HIP 80903 |
5.36 |
| 2026-05-17 00:00 |
16:30:50.54 |
+11:59:23.5 |
HIP 80903 |
6.72 |
| 2026-05-17 12:00 |
16:30:44.72 |
+11:59:49.3 |
HIP 80903 |
8.13 |
| 2026-05-18 00:00 |
16:30:38.88 |
+12:00:14.6 |
HIP 80903 |
9.56 |
| 2026-05-18 12:00 |
16:30:33.03 |
+12:00:39.4 |
HIP 80903 |
11.01 |
| 2026-05-19 00:00 |
16:30:27.17 |
+12:01:03.7 |
HIP 80903 |
12.48 |
| 2026-05-19 12:00 |
16:30:21.29 |
+12:01:27.5 |
HIP 80773 |
13.03 |
| 2026-05-20 00:00 |
16:30:15.40 |
+12:01:50.8 |
HIP 80773 |
11.90 |
| 2026-05-20 12:00 |
16:30:09.50 |
+12:02:13.6 |
HIP 80773 |
10.85 |
| 2026-05-21 00:00 |
16:30:03.59 |
+12:02:36.0 |
HIP 80773 |
9.91 |
| 2026-05-21 12:00 |
16:29:57.66 |
+12:02:57.8 |
HIP 80773 |
9.10 |
| 2026-05-22 00:00 |
16:29:51.73 |
+12:03:19.1 |
HIP 80773 |
8.48 |
| 2026-05-22 12:00 |
16:29:45.79 |
+12:03:40.0 |
HIP 80773 |
8.08 |
| 2026-05-23 00:00 |
16:29:39.84 |
+12:04:00.3 |
HIP 80773 |
7.93 |
| 2026-05-23 12:00 |
16:29:33.89 |
+12:04:20.1 |
HIP 80773 |
8.06 |
| 2026-05-24 00:00 |
16:29:27.92 |
+12:04:39.4 |
HIP 80773 |
8.44 |
| 2026-05-24 12:00 |
16:29:21.96 |
+12:04:58.2 |
HIP 80773 |
9.05 |
| 2026-05-25 00:00 |
16:29:15.98 |
+12:05:16.5 |
HIP 80773 |
9.84 |
| 2026-05-25 12:00 |
16:29:10.00 |
+12:05:34.3 |
HIP 80773 |
10.78 |
| 2026-05-26 00:00 |
16:29:04.01 |
+12:05:51.6 |
HIP 80773 |
11.82 |
| 2026-05-26 12:00 |
16:28:58.02 |
+12:06:08.3 |
HIP 80773 |
12.95 |
| 2026-05-27 00:00 |
16:28:52.03 |
+12:06:24.6 |
HIP 80773 |
14.14 |
| 2026-05-27 12:00 |
16:28:46.03 |
+12:06:40.3 |
HIP 80773 |
15.37 |
| 2026-05-28 00:00 |
16:28:40.03 |
+12:06:55.5 |
HIP 80773 |
16.64 |
| 2026-05-28 12:00 |
16:28:34.03 |
+12:07:10.2 |
HIP 80773 |
17.94 |
| 2026-05-29 00:00 |
16:28:28.03 |
+12:07:24.4 |
HIP 80773 |
19.27 |
| 2026-05-29 12:00 |
16:28:22.03 |
+12:07:38.1 |
HIP 80773 |
20.61 |
| 2026-05-30 00:00 |
16:28:16.03 |
+12:07:51.2 |
HIP 80773 |
21.96 |
| 2026-05-30 12:00 |
16:28:10.02 |
+12:08:03.8 |
HIP 80553 |
20.87 |
| 2026-05-31 00:00 |
16:28:04.02 |
+12:08:15.9 |
HIP 80553 |
19.50 |
| 2026-05-31 12:00 |
16:27:58.02 |
+12:08:27.5 |
HIP 80553 |
18.14 |
| 2026-06-01 00:00 |
16:27:52.02 |
+12:08:38.6 |
HIP 80553 |
16.79 |
| 2026-06-01 12:00 |
16:27:46.03 |
+12:08:49.1 |
HIP 80553 |
15.47 |
| 2026-06-02 00:00 |
16:27:40.04 |
+12:08:59.2 |
HIP 80553 |
14.18 |