C/1940 R2 (Cunningham)
| Parameter |
Value |
| Designation |
C/1940 R2 (Cunningham) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1941-01-16T05:36:57.600000Z |
| Orbit solution date (soln_date, UTC) |
- |
| Obs used |
189 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1941-01-06.0000000 |
| e |
1.00048500 |
| q (au) |
0.367751 |
| a (au) |
-758.249484 |
| i (deg) |
49.894200 |
| Ω (om, deg) |
296.590500 |
| ω (w, deg) |
199.569000 |
| M (ma, deg) |
-0.000483 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.846 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.846 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
1.000 |
| δ90 |
1.000 |
| 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 |
20:19:59.83 |
-09:42:46.9 |
HIP 100138 |
20.50 |
| 2026-02-03 12:00 |
20:20:00.88 |
-09:42:42.7 |
HIP 100138 |
20.75 |
| 2026-02-04 00:00 |
20:20:01.93 |
-09:42:38.5 |
HIP 100138 |
21.01 |
| 2026-02-04 12:00 |
20:20:02.98 |
-09:42:34.3 |
HIP 100138 |
21.27 |
| 2026-02-05 00:00 |
20:20:04.02 |
-09:42:30.0 |
HIP 100138 |
21.53 |
| 2026-02-05 12:00 |
20:20:05.06 |
-09:42:25.8 |
HIP 100138 |
21.79 |
| 2026-02-06 00:00 |
20:20:06.10 |
-09:42:21.5 |
HIP 100138 |
22.05 |
| 2026-02-06 12:00 |
20:20:07.14 |
-09:42:17.2 |
HIP 100138 |
22.31 |
| 2026-02-07 00:00 |
20:20:08.17 |
-09:42:12.8 |
HIP 100138 |
22.56 |
| 2026-02-07 12:00 |
20:20:09.21 |
-09:42:08.5 |
HIP 100138 |
22.82 |
| 2026-02-08 00:00 |
20:20:10.24 |
-09:42:04.2 |
HIP 100138 |
23.08 |
| 2026-02-08 12:00 |
20:20:11.26 |
-09:41:59.8 |
HIP 100138 |
23.34 |
| 2026-02-09 00:00 |
20:20:12.29 |
-09:41:55.4 |
HIP 100138 |
23.59 |
| 2026-02-09 12:00 |
20:20:13.31 |
-09:41:51.0 |
HIP 100138 |
23.85 |
| 2026-02-10 00:00 |
20:20:14.33 |
-09:41:46.6 |
HIP 100138 |
24.11 |
| 2026-02-10 12:00 |
20:20:15.35 |
-09:41:42.2 |
HIP 100138 |
24.36 |
| 2026-02-11 00:00 |
20:20:16.36 |
-09:41:37.8 |
HIP 100138 |
24.62 |
| 2026-02-11 12:00 |
20:20:17.37 |
-09:41:33.3 |
HIP 100138 |
24.87 |
| 2026-02-12 00:00 |
20:20:18.38 |
-09:41:28.9 |
HIP 100138 |
25.13 |
| 2026-02-12 12:00 |
20:20:19.39 |
-09:41:24.4 |
HIP 100138 |
25.38 |
| 2026-02-13 00:00 |
20:20:20.39 |
-09:41:19.9 |
HIP 100138 |
25.63 |
| 2026-02-13 12:00 |
20:20:21.39 |
-09:41:15.4 |
HIP 100138 |
25.89 |
| 2026-02-14 00:00 |
20:20:22.38 |
-09:41:10.9 |
HIP 100138 |
26.14 |
| 2026-02-14 12:00 |
20:20:23.37 |
-09:41:06.4 |
HIP 100138 |
26.39 |
| 2026-02-15 00:00 |
20:20:24.36 |
-09:41:01.9 |
HIP 100138 |
26.64 |
| 2026-02-15 12:00 |
20:20:25.35 |
-09:40:57.3 |
HIP 100138 |
26.89 |
| 2026-02-16 00:00 |
20:20:26.33 |
-09:40:52.8 |
HIP 100138 |
27.14 |
| 2026-02-16 12:00 |
20:20:27.30 |
-09:40:48.2 |
HIP 100138 |
27.39 |
| 2026-02-17 00:00 |
20:20:28.28 |
-09:40:43.7 |
HIP 100138 |
27.64 |
| 2026-02-17 12:00 |
20:20:29.25 |
-09:40:39.1 |
HIP 100138 |
27.89 |
| 2026-02-18 00:00 |
20:20:30.21 |
-09:40:34.5 |
HIP 100138 |
28.13 |
| 2026-02-18 12:00 |
20:20:31.17 |
-09:40:29.9 |
HIP 100138 |
28.38 |
| 2026-02-19 00:00 |
20:20:32.13 |
-09:40:25.3 |
HIP 100138 |
28.63 |
| 2026-02-19 12:00 |
20:20:33.08 |
-09:40:20.7 |
HIP 100138 |
28.87 |
| 2026-02-20 00:00 |
20:20:34.03 |
-09:40:16.1 |
HIP 100138 |
29.11 |
| 2026-02-20 12:00 |
20:20:34.98 |
-09:40:11.5 |
HIP 100138 |
29.36 |
| 2026-02-21 00:00 |
20:20:35.91 |
-09:40:06.8 |
HIP 100138 |
29.60 |
| 2026-02-21 12:00 |
20:20:36.85 |
-09:40:02.2 |
HIP 100138 |
29.84 |
| 2026-02-22 00:00 |
20:20:37.78 |
-09:39:57.6 |
HIP 100138 |
30.08 |
| 2026-02-22 12:00 |
20:20:38.71 |
-09:39:52.9 |
HIP 100138 |
30.32 |
| 2026-02-23 00:00 |
20:20:39.63 |
-09:39:48.3 |
HIP 100138 |
30.56 |
| 2026-02-23 12:00 |
20:20:40.54 |
-09:39:43.6 |
HIP 100138 |
30.79 |
| 2026-02-24 00:00 |
20:20:41.46 |
-09:39:39.0 |
HIP 100138 |
31.03 |