| 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
$$
M_a = (4.641 + 4.023\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.641 |
| n |
4.023 |
| gf |
0.982 |
| gb |
-0.998 |
| k |
1.000 |
| δ90 |
9.986 |
| 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 |
09:14:48.33 |
-61:17:40.2 |
HIP 45296 |
6.83 |
| 2026-03-26 12:00 |
09:14:45.49 |
-61:17:12.6 |
HIP 45296 |
6.45 |
| 2026-03-27 00:00 |
09:14:42.70 |
-61:16:44.8 |
HIP 45296 |
6.10 |
| 2026-03-27 12:00 |
09:14:39.93 |
-61:16:16.8 |
HIP 45296 |
5.79 |
| 2026-03-28 00:00 |
09:14:37.19 |
-61:15:48.7 |
HIP 45296 |
5.52 |
| 2026-03-28 12:00 |
09:14:34.48 |
-61:15:20.4 |
HIP 45296 |
5.31 |
| 2026-03-29 00:00 |
09:14:31.80 |
-61:14:52.0 |
HIP 45296 |
5.16 |
| 2026-03-29 12:00 |
09:14:29.15 |
-61:14:23.4 |
HIP 45296 |
5.08 |
| 2026-03-30 00:00 |
09:14:26.54 |
-61:13:54.6 |
HIP 45296 |
5.06 |
| 2026-03-30 12:00 |
09:14:23.95 |
-61:13:25.7 |
HIP 45296 |
5.11 |
| 2026-03-31 00:00 |
09:14:21.40 |
-61:12:56.7 |
HIP 45296 |
5.23 |
| 2026-03-31 12:00 |
09:14:18.88 |
-61:12:27.4 |
HIP 45273 |
5.04 |
| 2026-04-01 00:00 |
09:14:16.39 |
-61:11:58.1 |
HIP 45273 |
4.88 |
| 2026-04-01 12:00 |
09:14:13.93 |
-61:11:28.6 |
HIP 45273 |
4.78 |
| 2026-04-02 00:00 |
09:14:11.50 |
-61:10:59.0 |
HIP 45273 |
4.76 |
| 2026-04-02 12:00 |
09:14:09.11 |
-61:10:29.2 |
HIP 45273 |
4.82 |
| 2026-04-03 00:00 |
09:14:06.75 |
-61:09:59.3 |
HIP 45273 |
4.94 |
| 2026-04-03 12:00 |
09:14:04.42 |
-61:09:29.2 |
HIP 45273 |
5.13 |
| 2026-04-04 00:00 |
09:14:02.12 |
-61:08:59.0 |
HIP 45273 |
5.38 |
| 2026-04-04 12:00 |
09:13:59.86 |
-61:08:28.7 |
HIP 45273 |
5.67 |
| 2026-04-05 00:00 |
09:13:57.63 |
-61:07:58.3 |
HIP 45273 |
6.02 |
| 2026-04-05 12:00 |
09:13:55.43 |
-61:07:27.7 |
HIP 45273 |
6.40 |
| 2026-04-06 00:00 |
09:13:53.27 |
-61:06:57.0 |
HIP 45273 |
6.81 |
| 2026-04-06 12:00 |
09:13:51.14 |
-61:06:26.2 |
HIP 45273 |
7.24 |
| 2026-04-07 00:00 |
09:13:49.04 |
-61:05:55.3 |
HIP 45273 |
7.70 |
| 2026-04-07 12:00 |
09:13:46.97 |
-61:05:24.2 |
HIP 45273 |
8.17 |
| 2026-04-08 00:00 |
09:13:44.94 |
-61:04:53.0 |
HIP 45273 |
8.66 |
| 2026-04-08 12:00 |
09:13:42.95 |
-61:04:21.8 |
HIP 45273 |
9.16 |
| 2026-04-09 00:00 |
09:13:40.98 |
-61:03:50.4 |
HIP 45273 |
9.67 |
| 2026-04-09 12:00 |
09:13:39.05 |
-61:03:18.8 |
HIP 45214 |
10.17 |
| 2026-04-10 00:00 |
09:13:37.16 |
-61:02:47.2 |
HIP 45214 |
9.61 |
| 2026-04-10 12:00 |
09:13:35.30 |
-61:02:15.5 |
HIP 45214 |
9.05 |
| 2026-04-11 00:00 |
09:13:33.47 |
-61:01:43.7 |
HIP 45214 |
8.49 |
| 2026-04-11 12:00 |
09:13:31.68 |
-61:01:11.8 |
HIP 45214 |
7.94 |
| 2026-04-12 00:00 |
09:13:29.92 |
-61:00:39.8 |
HIP 45214 |
7.40 |
| 2026-04-12 12:00 |
09:13:28.20 |
-61:00:07.6 |
HIP 45214 |
6.85 |
| 2026-04-13 00:00 |
09:13:26.51 |
-60:59:35.4 |
HIP 45214 |
6.32 |
| 2026-04-13 12:00 |
09:13:24.86 |
-60:59:03.1 |
HIP 45214 |
5.80 |
| 2026-04-14 00:00 |
09:13:23.25 |
-60:58:30.7 |
HIP 45214 |
5.29 |
| 2026-04-14 12:00 |
09:13:21.66 |
-60:57:58.3 |
HIP 45214 |
4.79 |
| 2026-04-15 00:00 |
09:13:20.12 |
-60:57:25.7 |
HIP 45214 |
4.32 |
| 2026-04-15 12:00 |
09:13:18.61 |
-60:56:53.1 |
HIP 45214 |
3.88 |
| 2026-04-16 00:00 |
09:13:17.13 |
-60:56:20.4 |
HIP 45214 |
3.48 |