| 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) |
| 2026-07-29 00:00 |
20:19:31.34 |
-09:33:11.5 |
HIP 100138 |
22.62 |
| 2026-07-29 12:00 |
20:19:30.30 |
-09:33:15.1 |
HIP 100138 |
22.44 |
| 2026-07-30 00:00 |
20:19:29.25 |
-09:33:18.8 |
HIP 100138 |
22.27 |
| 2026-07-30 12:00 |
20:19:28.21 |
-09:33:22.4 |
HIP 100138 |
22.10 |
| 2026-07-31 00:00 |
20:19:27.17 |
-09:33:26.1 |
HIP 100138 |
21.93 |
| 2026-07-31 12:00 |
20:19:26.13 |
-09:33:29.8 |
HIP 100138 |
21.76 |
| 2026-08-01 00:00 |
20:19:25.09 |
-09:33:33.6 |
HIP 100138 |
21.60 |
| 2026-08-01 12:00 |
20:19:24.05 |
-09:33:37.3 |
HIP 100138 |
21.43 |
| 2026-08-02 00:00 |
20:19:23.02 |
-09:33:41.1 |
HIP 100138 |
21.27 |
| 2026-08-02 12:00 |
20:19:21.98 |
-09:33:44.9 |
HIP 100138 |
21.11 |
| 2026-08-03 00:00 |
20:19:20.94 |
-09:33:48.7 |
HIP 100138 |
20.95 |
| 2026-08-03 12:00 |
20:19:19.91 |
-09:33:52.5 |
HIP 100138 |
20.80 |
| 2026-08-04 00:00 |
20:19:18.88 |
-09:33:56.3 |
HIP 100138 |
20.64 |
| 2026-08-04 12:00 |
20:19:17.85 |
-09:34:00.2 |
HIP 100138 |
20.49 |
| 2026-08-05 00:00 |
20:19:16.82 |
-09:34:04.1 |
HIP 100138 |
20.34 |
| 2026-08-05 12:00 |
20:19:15.79 |
-09:34:08.0 |
HIP 100138 |
20.19 |
| 2026-08-06 00:00 |
20:19:14.76 |
-09:34:11.9 |
HIP 100138 |
20.05 |
| 2026-08-06 12:00 |
20:19:13.73 |
-09:34:15.8 |
HIP 100138 |
19.90 |
| 2026-08-07 00:00 |
20:19:12.71 |
-09:34:19.8 |
HIP 100138 |
19.76 |
| 2026-08-07 12:00 |
20:19:11.69 |
-09:34:23.7 |
HIP 100138 |
19.62 |
| 2026-08-08 00:00 |
20:19:10.67 |
-09:34:27.7 |
HIP 100138 |
19.49 |
| 2026-08-08 12:00 |
20:19:09.65 |
-09:34:31.7 |
HIP 100138 |
19.35 |
| 2026-08-09 00:00 |
20:19:08.63 |
-09:34:35.8 |
HIP 100138 |
19.22 |
| 2026-08-09 12:00 |
20:19:07.62 |
-09:34:39.8 |
HIP 100138 |
19.09 |
| 2026-08-10 00:00 |
20:19:06.61 |
-09:34:43.8 |
HIP 100138 |
18.96 |
| 2026-08-10 12:00 |
20:19:05.60 |
-09:34:47.9 |
HIP 100138 |
18.84 |
| 2026-08-11 00:00 |
20:19:04.59 |
-09:34:52.0 |
HIP 100138 |
18.72 |
| 2026-08-11 12:00 |
20:19:03.59 |
-09:34:56.1 |
HIP 100138 |
18.60 |
| 2026-08-12 00:00 |
20:19:02.59 |
-09:35:00.2 |
HIP 100138 |
18.48 |
| 2026-08-12 12:00 |
20:19:01.59 |
-09:35:04.3 |
HIP 100138 |
18.37 |
| 2026-08-13 00:00 |
20:19:00.59 |
-09:35:08.4 |
HIP 100138 |
18.26 |
| 2026-08-13 12:00 |
20:18:59.59 |
-09:35:12.6 |
HIP 100138 |
18.15 |
| 2026-08-14 00:00 |
20:18:58.60 |
-09:35:16.7 |
HIP 100138 |
18.04 |
| 2026-08-14 12:00 |
20:18:57.61 |
-09:35:20.9 |
HIP 100138 |
17.94 |
| 2026-08-15 00:00 |
20:18:56.63 |
-09:35:25.1 |
HIP 100138 |
17.84 |
| 2026-08-15 12:00 |
20:18:55.65 |
-09:35:29.3 |
HIP 100138 |
17.74 |
| 2026-08-16 00:00 |
20:18:54.67 |
-09:35:33.5 |
HIP 100138 |
17.65 |
| 2026-08-16 12:00 |
20:18:53.69 |
-09:35:37.7 |
HIP 100138 |
17.56 |
| 2026-08-17 00:00 |
20:18:52.72 |
-09:35:41.9 |
HIP 100138 |
17.47 |
| 2026-08-17 12:00 |
20:18:51.75 |
-09:35:46.2 |
HIP 100138 |
17.39 |
| 2026-08-18 00:00 |
20:18:50.78 |
-09:35:50.4 |
HIP 100138 |
17.30 |
| 2026-08-18 12:00 |
20:18:49.82 |
-09:35:54.7 |
HIP 100138 |
17.23 |
| 2026-08-19 00:00 |
20:18:48.86 |
-09:35:58.9 |
HIP 100138 |
17.15 |