| Parameter |
Value |
| Designation |
C/1919 Q2 (Metcalf) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1919-12-07T19:37:10.358400Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:02Z |
| Obs used |
18 |
| NEO |
- |
| M1 |
5.100 |
| K1 |
11.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1919-09-18.0000000 |
| e |
0.99977859 |
| q (au) |
1.115204 |
| a (au) |
5036.797426 |
| i (deg) |
46.383158 |
| Ω (om, deg) |
122.097279 |
| ω (w, deg) |
185.764445 |
| M (ma, deg) |
359.999777 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.671 + 5.125\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.671 |
| n |
5.125 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.800 |
| δ90 |
10.000 |
| 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) |
| 2026-06-01 00:00 |
07:58:32.66 |
+17:00:37.7 |
HIP 39046 |
15.75 |
| 2026-06-01 12:00 |
07:58:33.31 |
+17:00:36.6 |
HIP 39046 |
15.63 |
| 2026-06-02 00:00 |
07:58:33.97 |
+17:00:35.5 |
HIP 39046 |
15.51 |
| 2026-06-02 12:00 |
07:58:34.63 |
+17:00:34.3 |
HIP 39046 |
15.39 |
| 2026-06-03 00:00 |
07:58:35.30 |
+17:00:33.2 |
HIP 39046 |
15.27 |
| 2026-06-03 12:00 |
07:58:35.98 |
+17:00:32.0 |
HIP 39046 |
15.15 |
| 2026-06-04 00:00 |
07:58:36.66 |
+17:00:30.8 |
HIP 39046 |
15.02 |
| 2026-06-04 12:00 |
07:58:37.35 |
+17:00:29.6 |
HIP 39046 |
14.90 |
| 2026-06-05 00:00 |
07:58:38.04 |
+17:00:28.3 |
HIP 39046 |
14.78 |
| 2026-06-05 12:00 |
07:58:38.74 |
+17:00:27.0 |
HIP 39046 |
14.66 |
| 2026-06-06 00:00 |
07:58:39.44 |
+17:00:25.7 |
HIP 39046 |
14.53 |
| 2026-06-06 12:00 |
07:58:40.15 |
+17:00:24.4 |
HIP 39046 |
14.41 |
| 2026-06-07 00:00 |
07:58:40.87 |
+17:00:23.1 |
HIP 39046 |
14.29 |
| 2026-06-07 12:00 |
07:58:41.59 |
+17:00:21.8 |
HIP 39046 |
14.16 |
| 2026-06-08 00:00 |
07:58:42.31 |
+17:00:20.4 |
HIP 39046 |
14.04 |
| 2026-06-08 12:00 |
07:58:43.04 |
+17:00:19.0 |
HIP 39046 |
13.92 |
| 2026-06-09 00:00 |
07:58:43.78 |
+17:00:17.6 |
HIP 39046 |
13.79 |
| 2026-06-09 12:00 |
07:58:44.52 |
+17:00:16.1 |
HIP 39046 |
13.67 |
| 2026-06-10 00:00 |
07:58:45.26 |
+17:00:14.7 |
HIP 39046 |
13.55 |
| 2026-06-10 12:00 |
07:58:46.01 |
+17:00:13.2 |
HIP 39046 |
13.42 |
| 2026-06-11 00:00 |
07:58:46.77 |
+17:00:11.7 |
HIP 39046 |
13.30 |
| 2026-06-11 12:00 |
07:58:47.53 |
+17:00:10.2 |
HIP 39046 |
13.18 |
| 2026-06-12 00:00 |
07:58:48.29 |
+17:00:08.6 |
HIP 39046 |
13.06 |
| 2026-06-12 12:00 |
07:58:49.06 |
+17:00:07.1 |
HIP 39046 |
12.94 |
| 2026-06-13 00:00 |
07:58:49.84 |
+17:00:05.5 |
HIP 39046 |
12.82 |
| 2026-06-13 12:00 |
07:58:50.62 |
+17:00:03.9 |
HIP 39046 |
12.70 |
| 2026-06-14 00:00 |
07:58:51.40 |
+17:00:02.3 |
HIP 39046 |
12.58 |
| 2026-06-14 12:00 |
07:58:52.19 |
+17:00:00.6 |
HIP 39046 |
12.46 |
| 2026-06-15 00:00 |
07:58:52.98 |
+16:59:59.0 |
HIP 39046 |
12.35 |
| 2026-06-15 12:00 |
07:58:53.78 |
+16:59:57.3 |
HIP 39046 |
12.23 |
| 2026-06-16 00:00 |
07:58:54.58 |
+16:59:55.6 |
HIP 39046 |
12.12 |
| 2026-06-16 12:00 |
07:58:55.39 |
+16:59:53.9 |
HIP 39046 |
12.01 |
| 2026-06-17 00:00 |
07:58:56.20 |
+16:59:52.1 |
HIP 39046 |
11.90 |
| 2026-06-17 12:00 |
07:58:57.02 |
+16:59:50.4 |
HIP 39046 |
11.79 |
| 2026-06-18 00:00 |
07:58:57.83 |
+16:59:48.6 |
HIP 39046 |
11.68 |
| 2026-06-18 12:00 |
07:58:58.66 |
+16:59:46.8 |
HIP 39046 |
11.57 |
| 2026-06-19 00:00 |
07:58:59.48 |
+16:59:45.0 |
HIP 39046 |
11.47 |
| 2026-06-19 12:00 |
07:59:00.32 |
+16:59:43.2 |
HIP 39046 |
11.36 |
| 2026-06-20 00:00 |
07:59:01.15 |
+16:59:41.3 |
HIP 39046 |
11.26 |
| 2026-06-20 12:00 |
07:59:01.99 |
+16:59:39.5 |
HIP 39046 |
11.17 |
| 2026-06-21 00:00 |
07:59:02.83 |
+16:59:37.6 |
HIP 39046 |
11.07 |
| 2026-06-21 12:00 |
07:59:03.68 |
+16:59:35.7 |
HIP 39046 |
10.98 |
| 2026-06-22 00:00 |
07:59:04.53 |
+16:59:33.8 |
HIP 39046 |
10.89 |