| 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) |
| 2026-03-26 00:00 |
13:45:15.45 |
+02:18:18.5 |
HIP 67086 |
13.19 |
| 2026-03-26 12:00 |
13:45:03.89 |
+02:19:23.6 |
HIP 67086 |
13.87 |
| 2026-03-27 00:00 |
13:44:52.27 |
+02:20:28.5 |
HIP 67086 |
15.16 |
| 2026-03-27 12:00 |
13:44:40.57 |
+02:21:33.4 |
HIP 67086 |
16.93 |
| 2026-03-28 00:00 |
13:44:28.81 |
+02:22:38.1 |
HIP 67086 |
19.06 |
| 2026-03-28 12:00 |
13:44:16.99 |
+02:23:42.7 |
HIP 67086 |
21.43 |
| 2026-03-29 00:00 |
13:44:05.10 |
+02:24:47.2 |
HIP 67086 |
24.00 |
| 2026-03-29 12:00 |
13:43:53.16 |
+02:25:51.5 |
HIP 67086 |
26.70 |
| 2026-03-30 00:00 |
13:43:41.15 |
+02:26:55.7 |
HIP 66858 |
27.88 |
| 2026-03-30 12:00 |
13:43:29.09 |
+02:27:59.7 |
HIP 66858 |
26.10 |
| 2026-03-31 00:00 |
13:43:16.97 |
+02:29:03.5 |
HIP 66858 |
24.60 |
| 2026-03-31 12:00 |
13:43:04.79 |
+02:30:07.1 |
HIP 66858 |
23.44 |
| 2026-04-01 00:00 |
13:42:52.57 |
+02:31:10.5 |
HIP 66858 |
22.66 |
| 2026-04-01 12:00 |
13:42:40.29 |
+02:32:13.7 |
HIP 66858 |
22.33 |
| 2026-04-02 00:00 |
13:42:27.95 |
+02:33:16.7 |
HIP 66858 |
22.45 |
| 2026-04-02 12:00 |
13:42:15.57 |
+02:34:19.4 |
HIP 66858 |
23.04 |
| 2026-04-03 00:00 |
13:42:03.14 |
+02:35:21.9 |
HIP 66858 |
24.05 |
| 2026-04-03 12:00 |
13:41:50.67 |
+02:36:24.2 |
HIP 66858 |
25.45 |
| 2026-04-04 00:00 |
13:41:38.15 |
+02:37:26.2 |
HIP 66858 |
27.17 |
| 2026-04-04 12:00 |
13:41:25.58 |
+02:38:28.0 |
HIP 66858 |
29.17 |
| 2026-04-05 00:00 |
13:41:12.98 |
+02:39:29.5 |
HIP 66858 |
31.38 |
| 2026-04-05 12:00 |
13:41:00.33 |
+02:40:30.7 |
HIP 66708 |
32.47 |
| 2026-04-06 00:00 |
13:40:47.64 |
+02:41:31.6 |
HIP 66708 |
32.81 |
| 2026-04-06 12:00 |
13:40:34.92 |
+02:42:32.2 |
HIP 66708 |
33.47 |
| 2026-04-07 00:00 |
13:40:22.16 |
+02:43:32.5 |
HIP 66708 |
34.43 |
| 2026-04-07 12:00 |
13:40:09.36 |
+02:44:32.4 |
HIP 66708 |
35.68 |
| 2026-04-08 00:00 |
13:39:56.53 |
+02:45:32.1 |
HIP 66708 |
37.19 |
| 2026-04-08 12:00 |
13:39:43.67 |
+02:46:31.3 |
HIP 66477 |
37.82 |
| 2026-04-09 00:00 |
13:39:30.78 |
+02:47:30.3 |
HIP 66477 |
36.00 |
| 2026-04-09 12:00 |
13:39:17.86 |
+02:48:28.8 |
HIP 66444 |
33.08 |
| 2026-04-10 00:00 |
13:39:04.91 |
+02:49:27.0 |
HIP 66444 |
29.72 |
| 2026-04-10 12:00 |
13:38:51.94 |
+02:50:24.9 |
HIP 66444 |
26.37 |
| 2026-04-11 00:00 |
13:38:38.95 |
+02:51:22.3 |
HIP 66444 |
23.02 |
| 2026-04-11 12:00 |
13:38:25.93 |
+02:52:19.3 |
HIP 66444 |
19.69 |
| 2026-04-12 00:00 |
13:38:12.89 |
+02:53:15.9 |
HIP 66444 |
16.37 |
| 2026-04-12 12:00 |
13:37:59.84 |
+02:54:12.1 |
HIP 66444 |
13.09 |
| 2026-04-13 00:00 |
13:37:46.76 |
+02:55:07.9 |
HIP 66444 |
9.88 |
| 2026-04-13 12:00 |
13:37:33.67 |
+02:56:03.2 |
HIP 66444 |
6.86 |
| 2026-04-14 00:00 |
13:37:20.57 |
+02:56:58.1 |
HIP 66444 |
4.44 |
| 2026-04-14 12:00 |
13:37:07.45 |
+02:57:52.5 |
HIP 66444 |
3.93 |
| 2026-04-15 00:00 |
13:36:54.32 |
+02:58:46.4 |
HIP 66444 |
5.86 |
| 2026-04-15 12:00 |
13:36:41.19 |
+02:59:39.9 |
HIP 66444 |
8.74 |
| 2026-04-16 00:00 |
13:36:28.04 |
+03:00:32.9 |
HIP 66444 |
11.90 |