| Parameter |
Value |
| Designation |
C/2015 R1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-06-25T18:24:22.605120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:14Z |
| Obs used |
257 |
| NEO |
- |
| M1 |
13.500 |
| K1 |
10.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-10-18.0000000 |
| e |
0.63286160 |
| q (au) |
2.165459 |
| a (au) |
5.898208 |
| i (deg) |
22.668327 |
| Ω (om, deg) |
48.514080 |
| ω (w, deg) |
300.537706 |
| M (ma, deg) |
7.859878 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.789 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.789 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.680 |
| k |
0.800 |
| 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 |
13:25:35.11 |
+03:32:04.4 |
HIP 65320 |
36.69 |
| 2026-05-12 12:00 |
13:25:23.85 |
+03:32:21.4 |
HIP 65320 |
33.95 |
| 2026-05-13 00:00 |
13:25:12.66 |
+03:32:37.5 |
HIP 65320 |
31.24 |
| 2026-05-13 12:00 |
13:25:01.54 |
+03:32:52.8 |
HIP 65320 |
28.56 |
| 2026-05-14 00:00 |
13:24:50.50 |
+03:33:07.3 |
HIP 65320 |
25.94 |
| 2026-05-14 12:00 |
13:24:39.54 |
+03:33:20.9 |
HIP 65320 |
23.37 |
| 2026-05-15 00:00 |
13:24:28.66 |
+03:33:33.7 |
HIP 65320 |
20.87 |
| 2026-05-15 12:00 |
13:24:17.85 |
+03:33:45.7 |
HIP 65320 |
18.46 |
| 2026-05-16 00:00 |
13:24:07.13 |
+03:33:56.9 |
HIP 65320 |
16.16 |
| 2026-05-16 12:00 |
13:23:56.49 |
+03:34:07.1 |
HIP 65320 |
14.03 |
| 2026-05-17 00:00 |
13:23:45.93 |
+03:34:16.6 |
HIP 65320 |
12.13 |
| 2026-05-17 12:00 |
13:23:35.46 |
+03:34:25.2 |
HIP 65320 |
10.58 |
| 2026-05-18 00:00 |
13:23:25.08 |
+03:34:32.9 |
HIP 65320 |
9.53 |
| 2026-05-18 12:00 |
13:23:14.78 |
+03:34:39.8 |
HIP 65320 |
9.13 |
| 2026-05-19 00:00 |
13:23:04.57 |
+03:34:45.9 |
HIP 65320 |
9.44 |
| 2026-05-19 12:00 |
13:22:54.45 |
+03:34:51.0 |
HIP 65320 |
10.39 |
| 2026-05-20 00:00 |
13:22:44.42 |
+03:34:55.4 |
HIP 65320 |
11.82 |
| 2026-05-20 12:00 |
13:22:34.48 |
+03:34:58.8 |
HIP 65320 |
13.55 |
| 2026-05-21 00:00 |
13:22:24.63 |
+03:35:01.4 |
HIP 65320 |
15.47 |
| 2026-05-21 12:00 |
13:22:14.88 |
+03:35:03.2 |
HIP 65320 |
17.51 |
| 2026-05-22 00:00 |
13:22:05.22 |
+03:35:04.0 |
HIP 65320 |
19.63 |
| 2026-05-22 12:00 |
13:21:55.65 |
+03:35:04.1 |
HIP 65320 |
21.80 |
| 2026-05-23 00:00 |
13:21:46.19 |
+03:35:03.2 |
HIP 65320 |
23.99 |
| 2026-05-23 12:00 |
13:21:36.82 |
+03:35:01.5 |
HIP 65320 |
26.19 |
| 2026-05-24 00:00 |
13:21:27.54 |
+03:34:58.9 |
HIP 65067 |
25.39 |
| 2026-05-24 12:00 |
13:21:18.37 |
+03:34:55.5 |
HIP 65067 |
23.77 |
| 2026-05-25 00:00 |
13:21:09.29 |
+03:34:51.2 |
HIP 65067 |
22.26 |
| 2026-05-25 12:00 |
13:21:00.32 |
+03:34:46.1 |
HIP 65067 |
20.89 |
| 2026-05-26 00:00 |
13:20:51.44 |
+03:34:40.0 |
HIP 65067 |
19.68 |
| 2026-05-26 12:00 |
13:20:42.67 |
+03:34:33.2 |
HIP 65067 |
18.66 |
| 2026-05-27 00:00 |
13:20:34.00 |
+03:34:25.4 |
HIP 65067 |
17.83 |
| 2026-05-27 12:00 |
13:20:25.44 |
+03:34:16.8 |
HIP 65067 |
17.24 |
| 2026-05-28 00:00 |
13:20:16.97 |
+03:34:07.4 |
HIP 65067 |
16.88 |
| 2026-05-28 12:00 |
13:20:08.62 |
+03:33:57.0 |
HIP 65067 |
16.77 |
| 2026-05-29 00:00 |
13:20:00.36 |
+03:33:45.9 |
HIP 64983 |
16.48 |
| 2026-05-29 12:00 |
13:19:52.22 |
+03:33:33.8 |
HIP 64983 |
15.00 |
| 2026-05-30 00:00 |
13:19:44.17 |
+03:33:20.9 |
HIP 64983 |
13.71 |
| 2026-05-30 12:00 |
13:19:36.24 |
+03:33:07.2 |
HIP 64983 |
12.63 |
| 2026-05-31 00:00 |
13:19:28.42 |
+03:32:52.6 |
HIP 64983 |
11.81 |
| 2026-05-31 12:00 |
13:19:20.70 |
+03:32:37.1 |
HIP 64983 |
11.31 |
| 2026-06-01 00:00 |
13:19:13.09 |
+03:32:20.8 |
HIP 64954 |
10.46 |
| 2026-06-01 12:00 |
13:19:05.59 |
+03:32:03.6 |
HIP 64954 |
9.88 |
| 2026-06-02 00:00 |
13:18:58.20 |
+03:31:45.6 |
HIP 64954 |
9.66 |