| 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) |
| 2026-07-29 00:00 |
13:18:00.51 |
+01:34:50.6 |
HIP 64930 |
21.25 |
| 2026-07-29 12:00 |
13:18:06.73 |
+01:33:13.7 |
HIP 64930 |
19.24 |
| 2026-07-30 00:00 |
13:18:13.05 |
+01:31:36.4 |
HIP 64930 |
17.26 |
| 2026-07-30 12:00 |
13:18:19.47 |
+01:29:58.7 |
HIP 64930 |
15.36 |
| 2026-07-31 00:00 |
13:18:26.00 |
+01:28:20.4 |
HIP 64930 |
13.56 |
| 2026-07-31 12:00 |
13:18:32.63 |
+01:26:41.8 |
HIP 64930 |
11.94 |
| 2026-08-01 00:00 |
13:18:39.36 |
+01:25:02.7 |
HIP 64930 |
10.58 |
| 2026-08-01 12:00 |
13:18:46.20 |
+01:23:23.2 |
HIP 64930 |
9.63 |
| 2026-08-02 00:00 |
13:18:53.14 |
+01:21:43.3 |
HIP 64930 |
9.22 |
| 2026-08-02 12:00 |
13:19:00.18 |
+01:20:02.9 |
HIP 64930 |
9.44 |
| 2026-08-03 00:00 |
13:19:07.32 |
+01:18:22.1 |
HIP 64930 |
10.28 |
| 2026-08-03 12:00 |
13:19:14.57 |
+01:16:40.9 |
HIP 64930 |
11.60 |
| 2026-08-04 00:00 |
13:19:21.91 |
+01:14:59.3 |
HIP 64930 |
13.28 |
| 2026-08-04 12:00 |
13:19:29.35 |
+01:13:17.3 |
HIP 64930 |
15.22 |
| 2026-08-05 00:00 |
13:19:36.90 |
+01:11:34.9 |
HIP 64930 |
17.33 |
| 2026-08-05 12:00 |
13:19:44.54 |
+01:09:52.0 |
HIP 64930 |
19.57 |
| 2026-08-06 00:00 |
13:19:52.28 |
+01:08:08.8 |
HIP 64930 |
21.91 |
| 2026-08-06 12:00 |
13:20:00.13 |
+01:06:25.2 |
HIP 64930 |
24.32 |
| 2026-08-07 00:00 |
13:20:08.07 |
+01:04:41.2 |
HIP 64930 |
26.80 |
| 2026-08-07 12:00 |
13:20:16.10 |
+01:02:56.8 |
HIP 64930 |
29.33 |
| 2026-08-08 00:00 |
13:20:24.24 |
+01:01:12.1 |
HIP 65211 |
31.18 |
| 2026-08-08 12:00 |
13:20:32.47 |
+00:59:26.9 |
HIP 65211 |
31.14 |
| 2026-08-09 00:00 |
13:20:40.80 |
+00:57:41.4 |
HIP 65211 |
31.32 |
| 2026-08-09 12:00 |
13:20:49.22 |
+00:55:55.5 |
HIP 65211 |
31.74 |
| 2026-08-10 00:00 |
13:20:57.74 |
+00:54:09.3 |
HIP 65211 |
32.37 |
| 2026-08-10 12:00 |
13:21:06.36 |
+00:52:22.7 |
HIP 65211 |
33.23 |
| 2026-08-11 00:00 |
13:21:15.07 |
+00:50:35.7 |
HIP 65211 |
34.29 |
| 2026-08-11 12:00 |
13:21:23.88 |
+00:48:48.4 |
HIP 65211 |
35.55 |
| 2026-08-12 00:00 |
13:21:32.77 |
+00:47:00.7 |
HIP 65211 |
36.98 |
| 2026-08-12 12:00 |
13:21:41.77 |
+00:45:12.7 |
HIP 65211 |
38.57 |
| 2026-08-13 00:00 |
13:21:50.85 |
+00:43:24.4 |
HIP 65211 |
40.32 |
| 2026-08-13 12:00 |
13:22:00.03 |
+00:41:35.7 |
HIP 65211 |
42.20 |
| 2026-08-14 00:00 |
13:22:09.30 |
+00:39:46.7 |
HIP 65238 |
43.85 |
| 2026-08-14 12:00 |
13:22:18.66 |
+00:37:57.4 |
HIP 65238 |
42.11 |
| 2026-08-15 00:00 |
13:22:28.11 |
+00:36:07.7 |
HIP 65238 |
40.52 |
| 2026-08-15 12:00 |
13:22:37.65 |
+00:34:17.8 |
HIP 65238 |
39.08 |
| 2026-08-16 00:00 |
13:22:47.28 |
+00:32:27.5 |
HIP 65238 |
37.84 |
| 2026-08-16 12:00 |
13:22:56.99 |
+00:30:36.9 |
HIP 65238 |
36.80 |
| 2026-08-17 00:00 |
13:23:06.80 |
+00:28:46.1 |
HIP 65238 |
36.00 |
| 2026-08-17 12:00 |
13:23:16.69 |
+00:26:54.9 |
HIP 65238 |
35.45 |
| 2026-08-18 00:00 |
13:23:26.67 |
+00:25:03.5 |
HIP 65238 |
35.18 |
| 2026-08-18 12:00 |
13:23:36.74 |
+00:23:11.7 |
HIP 65238 |
35.19 |
| 2026-08-19 00:00 |
13:23:46.89 |
+00:21:19.7 |
HIP 65238 |
35.48 |