C/1919 Q2 (Metcalf)
| 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 |
0.999 |
| 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) |
| 2026-02-03 00:00 |
07:59:23.79 |
+16:54:47.7 |
HIP 39046 |
5.83 |
| 2026-02-03 12:00 |
07:59:22.84 |
+16:54:50.8 |
HIP 39046 |
5.83 |
| 2026-02-04 00:00 |
07:59:21.90 |
+16:54:53.9 |
HIP 39046 |
5.84 |
| 2026-02-04 12:00 |
07:59:20.96 |
+16:54:57.0 |
HIP 39046 |
5.85 |
| 2026-02-05 00:00 |
07:59:20.02 |
+16:55:00.1 |
HIP 39046 |
5.88 |
| 2026-02-05 12:00 |
07:59:19.08 |
+16:55:03.3 |
HIP 39046 |
5.92 |
| 2026-02-06 00:00 |
07:59:18.15 |
+16:55:06.4 |
HIP 39046 |
5.96 |
| 2026-02-06 12:00 |
07:59:17.22 |
+16:55:09.5 |
HIP 39046 |
6.01 |
| 2026-02-07 00:00 |
07:59:16.29 |
+16:55:12.6 |
HIP 39046 |
6.07 |
| 2026-02-07 12:00 |
07:59:15.36 |
+16:55:15.7 |
HIP 39046 |
6.14 |
| 2026-02-08 00:00 |
07:59:14.44 |
+16:55:18.9 |
HIP 39046 |
6.22 |
| 2026-02-08 12:00 |
07:59:13.52 |
+16:55:22.0 |
HIP 39046 |
6.30 |
| 2026-02-09 00:00 |
07:59:12.61 |
+16:55:25.1 |
HIP 39046 |
6.39 |
| 2026-02-09 12:00 |
07:59:11.70 |
+16:55:28.2 |
HIP 39046 |
6.49 |
| 2026-02-10 00:00 |
07:59:10.79 |
+16:55:31.3 |
HIP 39046 |
6.59 |
| 2026-02-10 12:00 |
07:59:09.88 |
+16:55:34.4 |
HIP 39046 |
6.70 |
| 2026-02-11 00:00 |
07:59:08.98 |
+16:55:37.5 |
HIP 39046 |
6.81 |
| 2026-02-11 12:00 |
07:59:08.08 |
+16:55:40.6 |
HIP 39046 |
6.93 |
| 2026-02-12 00:00 |
07:59:07.18 |
+16:55:43.7 |
HIP 39046 |
7.05 |
| 2026-02-12 12:00 |
07:59:06.29 |
+16:55:46.8 |
HIP 39046 |
7.18 |
| 2026-02-13 00:00 |
07:59:05.41 |
+16:55:49.9 |
HIP 39046 |
7.31 |
| 2026-02-13 12:00 |
07:59:04.52 |
+16:55:53.0 |
HIP 39046 |
7.44 |
| 2026-02-14 00:00 |
07:59:03.64 |
+16:55:56.1 |
HIP 39046 |
7.58 |
| 2026-02-14 12:00 |
07:59:02.77 |
+16:55:59.1 |
HIP 39046 |
7.72 |
| 2026-02-15 00:00 |
07:59:01.90 |
+16:56:02.2 |
HIP 39046 |
7.86 |
| 2026-02-15 12:00 |
07:59:01.03 |
+16:56:05.3 |
HIP 39046 |
8.01 |
| 2026-02-16 00:00 |
07:59:00.17 |
+16:56:08.3 |
HIP 39046 |
8.16 |
| 2026-02-16 12:00 |
07:58:59.31 |
+16:56:11.4 |
HIP 39046 |
8.31 |
| 2026-02-17 00:00 |
07:58:58.45 |
+16:56:14.4 |
HIP 39046 |
8.46 |
| 2026-02-17 12:00 |
07:58:57.60 |
+16:56:17.5 |
HIP 39046 |
8.62 |
| 2026-02-18 00:00 |
07:58:56.76 |
+16:56:20.5 |
HIP 39046 |
8.77 |
| 2026-02-18 12:00 |
07:58:55.92 |
+16:56:23.5 |
HIP 39046 |
8.93 |
| 2026-02-19 00:00 |
07:58:55.08 |
+16:56:26.6 |
HIP 39046 |
9.09 |
| 2026-02-19 12:00 |
07:58:54.25 |
+16:56:29.6 |
HIP 39046 |
9.25 |
| 2026-02-20 00:00 |
07:58:53.42 |
+16:56:32.6 |
HIP 39046 |
9.41 |
| 2026-02-20 12:00 |
07:58:52.60 |
+16:56:35.6 |
HIP 39046 |
9.57 |
| 2026-02-21 00:00 |
07:58:51.78 |
+16:56:38.6 |
HIP 39046 |
9.73 |
| 2026-02-21 12:00 |
07:58:50.97 |
+16:56:41.6 |
HIP 39046 |
9.90 |
| 2026-02-22 00:00 |
07:58:50.16 |
+16:56:44.6 |
HIP 39046 |
10.06 |
| 2026-02-22 12:00 |
07:58:49.36 |
+16:56:47.5 |
HIP 39046 |
10.22 |
| 2026-02-23 00:00 |
07:58:48.57 |
+16:56:50.5 |
HIP 39046 |
10.39 |
| 2026-02-23 12:00 |
07:58:47.77 |
+16:56:53.4 |
HIP 39046 |
10.55 |
| 2026-02-24 00:00 |
07:58:46.99 |
+16:56:56.4 |
HIP 39046 |
10.72 |