C/1991 R1 (McNaught-Russell)
| 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) |
| 2026-02-03 00:00 |
09:21:26.07 |
-61:44:33.2 |
HIP 45733 |
14.47 |
| 2026-02-03 12:00 |
09:21:21.69 |
-61:44:31.1 |
HIP 45733 |
13.95 |
| 2026-02-04 00:00 |
09:21:17.30 |
-61:44:28.7 |
HIP 45733 |
13.43 |
| 2026-02-04 12:00 |
09:21:12.91 |
-61:44:26.0 |
HIP 45733 |
12.91 |
| 2026-02-05 00:00 |
09:21:08.51 |
-61:44:23.0 |
HIP 45733 |
12.39 |
| 2026-02-05 12:00 |
09:21:04.12 |
-61:44:19.7 |
HIP 45733 |
11.87 |
| 2026-02-06 00:00 |
09:20:59.72 |
-61:44:16.1 |
HIP 45733 |
11.35 |
| 2026-02-06 12:00 |
09:20:55.33 |
-61:44:12.3 |
HIP 45733 |
10.83 |
| 2026-02-07 00:00 |
09:20:50.93 |
-61:44:08.1 |
HIP 45733 |
10.31 |
| 2026-02-07 12:00 |
09:20:46.53 |
-61:44:03.7 |
HIP 45733 |
9.79 |
| 2026-02-08 00:00 |
09:20:42.14 |
-61:43:58.9 |
HIP 45733 |
9.27 |
| 2026-02-08 12:00 |
09:20:37.74 |
-61:43:53.9 |
HIP 45733 |
8.75 |
| 2026-02-09 00:00 |
09:20:33.35 |
-61:43:48.6 |
HIP 45733 |
8.24 |
| 2026-02-09 12:00 |
09:20:28.96 |
-61:43:43.0 |
HIP 45733 |
7.72 |
| 2026-02-10 00:00 |
09:20:24.57 |
-61:43:37.0 |
HIP 45733 |
7.21 |
| 2026-02-10 12:00 |
09:20:20.18 |
-61:43:30.8 |
HIP 45733 |
6.70 |
| 2026-02-11 00:00 |
09:20:15.79 |
-61:43:24.4 |
HIP 45733 |
6.20 |
| 2026-02-11 12:00 |
09:20:11.41 |
-61:43:17.6 |
HIP 45733 |
5.71 |
| 2026-02-12 00:00 |
09:20:07.03 |
-61:43:10.5 |
HIP 45733 |
5.22 |
| 2026-02-12 12:00 |
09:20:02.66 |
-61:43:03.2 |
HIP 45733 |
4.74 |
| 2026-02-13 00:00 |
09:19:58.28 |
-61:42:55.5 |
HIP 45733 |
4.28 |
| 2026-02-13 12:00 |
09:19:53.92 |
-61:42:47.6 |
HIP 45733 |
3.84 |
| 2026-02-14 00:00 |
09:19:49.56 |
-61:42:39.3 |
HIP 45733 |
3.43 |
| 2026-02-14 12:00 |
09:19:45.20 |
-61:42:30.8 |
HIP 45733 |
3.06 |
| 2026-02-15 00:00 |
09:19:40.85 |
-61:42:22.0 |
HIP 45733 |
2.75 |
| 2026-02-15 12:00 |
09:19:36.51 |
-61:42:12.9 |
HIP 45733 |
2.52 |
| 2026-02-16 00:00 |
09:19:32.17 |
-61:42:03.6 |
HIP 45733 |
2.39 |
| 2026-02-16 12:00 |
09:19:27.84 |
-61:41:53.9 |
HIP 45733 |
2.39 |
| 2026-02-17 00:00 |
09:19:23.52 |
-61:41:44.0 |
HIP 45733 |
2.51 |
| 2026-02-17 12:00 |
09:19:19.20 |
-61:41:33.7 |
HIP 45733 |
2.73 |
| 2026-02-18 00:00 |
09:19:14.90 |
-61:41:23.2 |
HIP 45733 |
3.04 |
| 2026-02-18 12:00 |
09:19:10.60 |
-61:41:12.4 |
HIP 45733 |
3.42 |
| 2026-02-19 00:00 |
09:19:06.31 |
-61:41:01.3 |
HIP 45733 |
3.83 |
| 2026-02-19 12:00 |
09:19:02.03 |
-61:40:50.0 |
HIP 45733 |
4.28 |
| 2026-02-20 00:00 |
09:18:57.76 |
-61:40:38.3 |
HIP 45733 |
4.75 |
| 2026-02-20 12:00 |
09:18:53.50 |
-61:40:26.4 |
HIP 45639 |
5.21 |
| 2026-02-21 00:00 |
09:18:49.25 |
-61:40:14.2 |
HIP 45639 |
4.72 |
| 2026-02-21 12:00 |
09:18:45.01 |
-61:40:01.8 |
HIP 45639 |
4.25 |
| 2026-02-22 00:00 |
09:18:40.79 |
-61:39:49.0 |
HIP 45639 |
3.81 |
| 2026-02-22 12:00 |
09:18:36.57 |
-61:39:36.0 |
HIP 45639 |
3.39 |
| 2026-02-23 00:00 |
09:18:32.37 |
-61:39:22.7 |
HIP 45639 |
3.02 |
| 2026-02-23 12:00 |
09:18:28.18 |
-61:39:09.1 |
HIP 45639 |
2.71 |
| 2026-02-24 00:00 |
09:18:24.00 |
-61:38:55.3 |
HIP 45639 |
2.49 |