| Parameter |
Value |
| Designation |
C/1991 R1 (McNaught-Russell) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1990-11-10T22:00:23.633280Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:41Z |
| Obs used |
41 |
| NEO |
- |
| M1 |
4.400 |
| K1 |
11.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1993-05-02.0000000 |
| e |
0.99985167 |
| q (au) |
6.981918 |
| a (au) |
47069.984909 |
| i (deg) |
104.522092 |
| Ω (om, deg) |
150.114710 |
| ω (w, deg) |
149.130210 |
| M (ma, deg) |
0.000087 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.517 + 4.076\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.517 |
| n |
4.076 |
| gf |
0.931 |
| gb |
-0.999 |
| k |
1.000 |
| δ90 |
9.878 |
| 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) |
| 2026-09-20 00:00 |
09:26:16.61 |
-59:42:06.1 |
HIP 46274 |
2.99 |
| 2026-09-20 12:00 |
09:26:19.79 |
-59:42:25.3 |
HIP 46274 |
2.97 |
| 2026-09-21 00:00 |
09:26:22.95 |
-59:42:44.8 |
HIP 46274 |
3.03 |
| 2026-09-21 12:00 |
09:26:26.09 |
-59:43:04.4 |
HIP 46274 |
3.18 |
| 2026-09-22 00:00 |
09:26:29.20 |
-59:43:24.2 |
HIP 46274 |
3.39 |
| 2026-09-22 12:00 |
09:26:32.30 |
-59:43:44.2 |
HIP 46274 |
3.66 |
| 2026-09-23 00:00 |
09:26:35.37 |
-59:44:04.4 |
HIP 46274 |
3.97 |
| 2026-09-23 12:00 |
09:26:38.43 |
-59:44:24.7 |
HIP 46274 |
4.32 |
| 2026-09-24 00:00 |
09:26:41.46 |
-59:44:45.3 |
HIP 46274 |
4.70 |
| 2026-09-24 12:00 |
09:26:44.47 |
-59:45:06.0 |
HIP 46274 |
5.10 |
| 2026-09-25 00:00 |
09:26:47.46 |
-59:45:26.8 |
HIP 46274 |
5.51 |
| 2026-09-25 12:00 |
09:26:50.42 |
-59:45:47.9 |
HIP 46274 |
5.94 |
| 2026-09-26 00:00 |
09:26:53.36 |
-59:46:09.1 |
HIP 46274 |
6.38 |
| 2026-09-26 12:00 |
09:26:56.28 |
-59:46:30.5 |
HIP 46274 |
6.82 |
| 2026-09-27 00:00 |
09:26:59.18 |
-59:46:52.1 |
HIP 46274 |
7.27 |
| 2026-09-27 12:00 |
09:27:02.06 |
-59:47:13.8 |
HIP 46274 |
7.73 |
| 2026-09-28 00:00 |
09:27:04.91 |
-59:47:35.7 |
HIP 46274 |
8.19 |
| 2026-09-28 12:00 |
09:27:07.73 |
-59:47:57.8 |
HIP 46274 |
8.66 |
| 2026-09-29 00:00 |
09:27:10.54 |
-59:48:20.0 |
HIP 46274 |
9.13 |
| 2026-09-29 12:00 |
09:27:13.32 |
-59:48:42.4 |
HIP 46274 |
9.60 |
| 2026-09-30 00:00 |
09:27:16.07 |
-59:49:05.0 |
HIP 46274 |
10.08 |
| 2026-09-30 12:00 |
09:27:18.81 |
-59:49:27.7 |
HIP 46274 |
10.55 |
| 2026-10-01 00:00 |
09:27:21.51 |
-59:49:50.6 |
HIP 46274 |
11.03 |
| 2026-10-01 12:00 |
09:27:24.19 |
-59:50:13.6 |
HIP 46274 |
11.51 |
| 2026-10-02 00:00 |
09:27:26.85 |
-59:50:36.8 |
HIP 46274 |
11.99 |
| 2026-10-02 12:00 |
09:27:29.48 |
-59:51:00.1 |
HIP 46274 |
12.47 |
| 2026-10-03 00:00 |
09:27:32.09 |
-59:51:23.6 |
HIP 46467 |
12.22 |
| 2026-10-03 12:00 |
09:27:34.67 |
-59:51:47.3 |
HIP 46467 |
11.71 |
| 2026-10-04 00:00 |
09:27:37.23 |
-59:52:11.0 |
HIP 46467 |
11.20 |
| 2026-10-04 12:00 |
09:27:39.76 |
-59:52:35.0 |
HIP 46467 |
10.69 |
| 2026-10-05 00:00 |
09:27:42.26 |
-59:52:59.1 |
HIP 46467 |
10.19 |
| 2026-10-05 12:00 |
09:27:44.74 |
-59:53:23.3 |
HIP 46467 |
9.68 |
| 2026-10-06 00:00 |
09:27:47.19 |
-59:53:47.7 |
HIP 46467 |
9.17 |
| 2026-10-06 12:00 |
09:27:49.61 |
-59:54:12.2 |
HIP 46467 |
8.66 |
| 2026-10-07 00:00 |
09:27:52.01 |
-59:54:36.8 |
HIP 46467 |
8.16 |
| 2026-10-07 12:00 |
09:27:54.38 |
-59:55:01.6 |
HIP 46467 |
7.65 |
| 2026-10-08 00:00 |
09:27:56.72 |
-59:55:26.5 |
HIP 46467 |
7.15 |
| 2026-10-08 12:00 |
09:27:59.03 |
-59:55:51.6 |
HIP 46467 |
6.65 |
| 2026-10-09 00:00 |
09:28:01.32 |
-59:56:16.8 |
HIP 46467 |
6.15 |
| 2026-10-09 12:00 |
09:28:03.58 |
-59:56:42.1 |
HIP 46467 |
5.65 |
| 2026-10-10 00:00 |
09:28:05.81 |
-59:57:07.5 |
HIP 46467 |
5.16 |
| 2026-10-10 12:00 |
09:28:08.01 |
-59:57:33.1 |
HIP 46467 |
4.67 |
| 2026-10-11 00:00 |
09:28:10.18 |
-59:57:58.8 |
HIP 46467 |
4.19 |