| 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) |
| 2026-05-12 00:00 |
09:12:50.04 |
-60:27:12.8 |
HIP 45311 |
10.66 |
| 2026-05-12 12:00 |
09:12:50.47 |
-60:26:39.4 |
HIP 45311 |
10.88 |
| 2026-05-13 00:00 |
09:12:50.93 |
-60:26:06.0 |
HIP 45311 |
11.13 |
| 2026-05-13 12:00 |
09:12:51.43 |
-60:25:32.7 |
HIP 45311 |
11.39 |
| 2026-05-14 00:00 |
09:12:51.96 |
-60:24:59.5 |
HIP 45311 |
11.67 |
| 2026-05-14 12:00 |
09:12:52.53 |
-60:24:26.3 |
HIP 45311 |
11.96 |
| 2026-05-15 00:00 |
09:12:53.14 |
-60:23:53.2 |
HIP 45311 |
12.27 |
| 2026-05-15 12:00 |
09:12:53.77 |
-60:23:20.1 |
HIP 45311 |
12.59 |
| 2026-05-16 00:00 |
09:12:54.45 |
-60:22:47.1 |
HIP 45256 |
12.36 |
| 2026-05-16 12:00 |
09:12:55.16 |
-60:22:14.1 |
HIP 45256 |
11.81 |
| 2026-05-17 00:00 |
09:12:55.90 |
-60:21:41.3 |
HIP 45256 |
11.26 |
| 2026-05-17 12:00 |
09:12:56.68 |
-60:21:08.5 |
HIP 45256 |
10.71 |
| 2026-05-18 00:00 |
09:12:57.49 |
-60:20:35.7 |
HIP 45256 |
10.16 |
| 2026-05-18 12:00 |
09:12:58.33 |
-60:20:03.1 |
HIP 45256 |
9.61 |
| 2026-05-19 00:00 |
09:12:59.21 |
-60:19:30.5 |
HIP 45256 |
9.07 |
| 2026-05-19 12:00 |
09:13:00.13 |
-60:18:58.0 |
HIP 45256 |
8.52 |
| 2026-05-20 00:00 |
09:13:01.08 |
-60:18:25.6 |
HIP 45256 |
7.97 |
| 2026-05-20 12:00 |
09:13:02.06 |
-60:17:53.3 |
HIP 45256 |
7.43 |
| 2026-05-21 00:00 |
09:13:03.07 |
-60:17:21.0 |
HIP 45256 |
6.88 |
| 2026-05-21 12:00 |
09:13:04.12 |
-60:16:48.9 |
HIP 45256 |
6.34 |
| 2026-05-22 00:00 |
09:13:05.21 |
-60:16:16.8 |
HIP 45256 |
5.80 |
| 2026-05-22 12:00 |
09:13:06.32 |
-60:15:44.8 |
HIP 45256 |
5.26 |
| 2026-05-23 00:00 |
09:13:07.47 |
-60:15:12.9 |
HIP 45256 |
4.72 |
| 2026-05-23 12:00 |
09:13:08.66 |
-60:14:41.1 |
HIP 45256 |
4.18 |
| 2026-05-24 00:00 |
09:13:09.87 |
-60:14:09.5 |
HIP 45256 |
3.64 |
| 2026-05-24 12:00 |
09:13:11.12 |
-60:13:37.9 |
HIP 45256 |
3.11 |
| 2026-05-25 00:00 |
09:13:12.40 |
-60:13:06.4 |
HIP 45256 |
2.59 |
| 2026-05-25 12:00 |
09:13:13.71 |
-60:12:35.0 |
HIP 45256 |
2.08 |
| 2026-05-26 00:00 |
09:13:15.06 |
-60:12:03.7 |
HIP 45256 |
1.59 |
| 2026-05-26 12:00 |
09:13:16.44 |
-60:11:32.6 |
HIP 45256 |
1.15 |
| 2026-05-27 00:00 |
09:13:17.85 |
-60:11:01.5 |
HIP 45256 |
0.84 |
| 2026-05-27 12:00 |
09:13:19.29 |
-60:10:30.6 |
HIP 45256 |
0.83 |
| 2026-05-28 00:00 |
09:13:20.76 |
-60:09:59.7 |
HIP 45256 |
1.12 |
| 2026-05-28 12:00 |
09:13:22.27 |
-60:09:29.0 |
HIP 45256 |
1.55 |
| 2026-05-29 00:00 |
09:13:23.80 |
-60:08:58.4 |
HIP 45256 |
2.04 |
| 2026-05-29 12:00 |
09:13:25.37 |
-60:08:27.9 |
HIP 45256 |
2.54 |
| 2026-05-30 00:00 |
09:13:26.97 |
-60:07:57.6 |
HIP 45256 |
3.06 |
| 2026-05-30 12:00 |
09:13:28.60 |
-60:07:27.3 |
HIP 45256 |
3.59 |
| 2026-05-31 00:00 |
09:13:30.26 |
-60:06:57.2 |
HIP 45256 |
4.11 |
| 2026-05-31 12:00 |
09:13:31.95 |
-60:06:27.2 |
HIP 45256 |
4.64 |
| 2026-06-01 00:00 |
09:13:33.68 |
-60:05:57.4 |
HIP 45256 |
5.18 |
| 2026-06-01 12:00 |
09:13:35.43 |
-60:05:27.6 |
HIP 45256 |
5.71 |
| 2026-06-02 00:00 |
09:13:37.21 |
-60:04:58.0 |
HIP 45256 |
6.24 |