C/2021 Q4 (Fuls)
| Parameter |
Value |
| Designation |
C/2021 Q4 (Fuls) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-06-10T10:47:21.906240Z |
| Orbit solution date (soln_date, UTC) |
2025-10-03T14:42:16Z |
| Obs used |
558 |
| NEO |
- |
| M1 |
6.800 |
| K1 |
9.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-08-26T07:09:57.139200Z |
| Discovery magnitude (MPC) |
20.07 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-04-14.0000000 |
| e |
1.00316029 |
| q (au) |
7.564703 |
| a (au) |
-2393.669779 |
| i (deg) |
71.474447 |
| Ω (om, deg) |
183.332460 |
| ω (w, deg) |
146.998903 |
| M (ma, deg) |
-0.000483 |
Magnitude
Scatter + Global Linear
$$
M_a = (0.695 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
0.695 |
| n |
6.000 |
| gf |
0.998 |
| gb |
-1.000 |
| k |
1.000 |
| 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 |
00:52:28.93 |
-15:43:09.9 |
HIP 3970 |
32.50 |
| 2026-02-03 12:00 |
00:52:37.96 |
-15:42:34.1 |
HIP 3970 |
34.36 |
| 2026-02-04 00:00 |
00:52:47.07 |
-15:41:58.3 |
HIP 4240 |
34.39 |
| 2026-02-04 12:00 |
00:52:56.24 |
-15:41:22.2 |
HIP 4240 |
33.73 |
| 2026-02-05 00:00 |
00:53:05.49 |
-15:40:46.0 |
HIP 4240 |
33.21 |
| 2026-02-05 12:00 |
00:53:14.80 |
-15:40:09.6 |
HIP 4240 |
32.83 |
| 2026-02-06 00:00 |
00:53:24.18 |
-15:39:33.1 |
HIP 4240 |
32.62 |
| 2026-02-06 12:00 |
00:53:33.62 |
-15:38:56.5 |
HIP 4240 |
32.57 |
| 2026-02-07 00:00 |
00:53:43.14 |
-15:38:19.7 |
HIP 4240 |
32.69 |
| 2026-02-07 12:00 |
00:53:52.72 |
-15:37:42.8 |
HIP 4240 |
32.98 |
| 2026-02-08 00:00 |
00:54:02.36 |
-15:37:05.8 |
HIP 4240 |
33.44 |
| 2026-02-08 12:00 |
00:54:12.08 |
-15:36:28.7 |
HIP 4240 |
34.06 |
| 2026-02-09 00:00 |
00:54:21.85 |
-15:35:51.4 |
HIP 4240 |
34.85 |
| 2026-02-09 12:00 |
00:54:31.69 |
-15:35:14.1 |
HIP 4426 |
33.55 |
| 2026-02-10 00:00 |
00:54:41.60 |
-15:34:36.6 |
HIP 4426 |
31.56 |
| 2026-02-10 12:00 |
00:54:51.57 |
-15:33:59.0 |
HIP 4426 |
29.64 |
| 2026-02-11 00:00 |
00:55:01.60 |
-15:33:21.4 |
HIP 4426 |
27.79 |
| 2026-02-11 12:00 |
00:55:11.69 |
-15:32:43.7 |
HIP 4426 |
26.04 |
| 2026-02-12 00:00 |
00:55:21.85 |
-15:32:05.9 |
HIP 4426 |
24.40 |
| 2026-02-12 12:00 |
00:55:32.06 |
-15:31:28.0 |
HIP 4426 |
22.92 |
| 2026-02-13 00:00 |
00:55:42.34 |
-15:30:50.1 |
HIP 4426 |
21.63 |
| 2026-02-13 12:00 |
00:55:52.68 |
-15:30:12.1 |
HIP 4426 |
20.56 |
| 2026-02-14 00:00 |
00:56:03.08 |
-15:29:34.1 |
HIP 4426 |
19.77 |
| 2026-02-14 12:00 |
00:56:13.54 |
-15:28:56.0 |
HIP 4426 |
19.29 |
| 2026-02-15 00:00 |
00:56:24.05 |
-15:28:17.9 |
HIP 4426 |
19.15 |
| 2026-02-15 12:00 |
00:56:34.63 |
-15:27:39.8 |
HIP 4426 |
19.36 |
| 2026-02-16 00:00 |
00:56:45.26 |
-15:27:01.6 |
HIP 4426 |
19.92 |
| 2026-02-16 12:00 |
00:56:55.95 |
-15:26:23.4 |
HIP 4521 |
19.56 |
| 2026-02-17 00:00 |
00:57:06.69 |
-15:25:45.2 |
HIP 4521 |
17.29 |
| 2026-02-17 12:00 |
00:57:17.49 |
-15:25:07.0 |
HIP 4521 |
15.14 |
| 2026-02-18 00:00 |
00:57:28.35 |
-15:24:28.7 |
HIP 4521 |
13.17 |
| 2026-02-18 12:00 |
00:57:39.26 |
-15:23:50.5 |
HIP 4521 |
11.51 |
| 2026-02-19 00:00 |
00:57:50.23 |
-15:23:12.3 |
HIP 4521 |
10.29 |
| 2026-02-19 12:00 |
00:58:01.25 |
-15:22:34.1 |
HIP 4521 |
9.70 |
| 2026-02-20 00:00 |
00:58:12.32 |
-15:21:56.0 |
HIP 4521 |
9.88 |
| 2026-02-20 12:00 |
00:58:23.45 |
-15:21:17.8 |
HIP 4521 |
10.78 |
| 2026-02-21 00:00 |
00:58:34.62 |
-15:20:39.7 |
HIP 4597 |
11.90 |
| 2026-02-21 12:00 |
00:58:45.85 |
-15:20:01.7 |
HIP 4597 |
10.66 |
| 2026-02-22 00:00 |
00:58:57.13 |
-15:19:23.7 |
HIP 4597 |
10.05 |
| 2026-02-22 12:00 |
00:59:08.46 |
-15:18:45.7 |
HIP 4597 |
10.21 |
| 2026-02-23 00:00 |
00:59:19.84 |
-15:18:07.8 |
HIP 4597 |
11.10 |
| 2026-02-23 12:00 |
00:59:31.26 |
-15:17:30.0 |
HIP 4597 |
12.59 |
| 2026-02-24 00:00 |
00:59:42.74 |
-15:16:52.2 |
HIP 4597 |
14.49 |