| 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) |
| 2026-07-29 00:00 |
09:19:32.61 |
-59:29:16.4 |
HIP 45749 |
1.60 |
| 2026-07-29 12:00 |
09:19:36.58 |
-59:29:10.8 |
HIP 45749 |
1.10 |
| 2026-07-30 00:00 |
09:19:40.56 |
-59:29:05.4 |
HIP 45749 |
0.64 |
| 2026-07-30 12:00 |
09:19:44.54 |
-59:29:00.3 |
HIP 45749 |
0.36 |
| 2026-07-31 00:00 |
09:19:48.52 |
-59:28:55.4 |
HIP 45749 |
0.61 |
| 2026-07-31 12:00 |
09:19:52.51 |
-59:28:50.8 |
HIP 45749 |
1.07 |
| 2026-08-01 00:00 |
09:19:56.50 |
-59:28:46.5 |
HIP 45749 |
1.56 |
| 2026-08-01 12:00 |
09:20:00.50 |
-59:28:42.3 |
HIP 45749 |
2.07 |
| 2026-08-02 00:00 |
09:20:04.51 |
-59:28:38.5 |
HIP 45749 |
2.58 |
| 2026-08-02 12:00 |
09:20:08.51 |
-59:28:34.9 |
HIP 45749 |
3.09 |
| 2026-08-03 00:00 |
09:20:12.52 |
-59:28:31.5 |
HIP 45749 |
3.60 |
| 2026-08-03 12:00 |
09:20:16.54 |
-59:28:28.4 |
HIP 45749 |
4.11 |
| 2026-08-04 00:00 |
09:20:20.56 |
-59:28:25.6 |
HIP 45749 |
4.62 |
| 2026-08-04 12:00 |
09:20:24.58 |
-59:28:23.0 |
HIP 45749 |
5.13 |
| 2026-08-05 00:00 |
09:20:28.60 |
-59:28:20.6 |
HIP 45749 |
5.64 |
| 2026-08-05 12:00 |
09:20:32.63 |
-59:28:18.5 |
HIP 45749 |
6.16 |
| 2026-08-06 00:00 |
09:20:36.66 |
-59:28:16.7 |
HIP 45749 |
6.67 |
| 2026-08-06 12:00 |
09:20:40.69 |
-59:28:15.1 |
HIP 45749 |
7.18 |
| 2026-08-07 00:00 |
09:20:44.72 |
-59:28:13.8 |
HIP 45749 |
7.69 |
| 2026-08-07 12:00 |
09:20:48.75 |
-59:28:12.7 |
HIP 45749 |
8.21 |
| 2026-08-08 00:00 |
09:20:52.79 |
-59:28:11.9 |
HIP 45749 |
8.72 |
| 2026-08-08 12:00 |
09:20:56.83 |
-59:28:11.3 |
HIP 45749 |
9.23 |
| 2026-08-09 00:00 |
09:21:00.86 |
-59:28:11.0 |
HIP 45749 |
9.74 |
| 2026-08-09 12:00 |
09:21:04.90 |
-59:28:11.0 |
HIP 45749 |
10.26 |
| 2026-08-10 00:00 |
09:21:08.94 |
-59:28:11.2 |
HIP 45749 |
10.77 |
| 2026-08-10 12:00 |
09:21:12.98 |
-59:28:11.6 |
HIP 45749 |
11.28 |
| 2026-08-11 00:00 |
09:21:17.02 |
-59:28:12.3 |
HIP 45749 |
11.79 |
| 2026-08-11 12:00 |
09:21:21.05 |
-59:28:13.3 |
HIP 45749 |
12.30 |
| 2026-08-12 00:00 |
09:21:25.09 |
-59:28:14.5 |
HIP 45749 |
12.82 |
| 2026-08-12 12:00 |
09:21:29.13 |
-59:28:16.0 |
HIP 46014 |
13.06 |
| 2026-08-13 00:00 |
09:21:33.16 |
-59:28:17.7 |
HIP 46014 |
12.58 |
| 2026-08-13 12:00 |
09:21:37.19 |
-59:28:19.7 |
HIP 46014 |
12.10 |
| 2026-08-14 00:00 |
09:21:41.23 |
-59:28:21.9 |
HIP 46014 |
11.62 |
| 2026-08-14 12:00 |
09:21:45.25 |
-59:28:24.4 |
HIP 46014 |
11.14 |
| 2026-08-15 00:00 |
09:21:49.28 |
-59:28:27.1 |
HIP 46014 |
10.67 |
| 2026-08-15 12:00 |
09:21:53.30 |
-59:28:30.1 |
HIP 46014 |
10.19 |
| 2026-08-16 00:00 |
09:21:57.32 |
-59:28:33.4 |
HIP 46014 |
9.72 |
| 2026-08-16 12:00 |
09:22:01.34 |
-59:28:36.8 |
HIP 46014 |
9.25 |
| 2026-08-17 00:00 |
09:22:05.36 |
-59:28:40.6 |
HIP 46014 |
8.79 |
| 2026-08-17 12:00 |
09:22:09.37 |
-59:28:44.6 |
HIP 46014 |
8.32 |
| 2026-08-18 00:00 |
09:22:13.37 |
-59:28:48.8 |
HIP 46014 |
7.87 |
| 2026-08-18 12:00 |
09:22:17.37 |
-59:28:53.3 |
HIP 46014 |
7.41 |
| 2026-08-19 00:00 |
09:22:21.37 |
-59:28:58.0 |
HIP 46014 |
6.97 |