| Parameter |
Value |
| Designation |
C/2021 T2 (Fuls) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-06-07T21:34:39.907200Z |
| Orbit solution date (soln_date, UTC) |
2023-01-14T00:13:00Z |
| Obs used |
183 |
| NEO |
- |
| M1 |
15.300 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-10-02T09:01:40.224000Z |
| Discovery magnitude (MPC) |
19.87 G |
| Discovery observatory (MPC) |
G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-11-13.0000000 |
| e |
1.00014284 |
| q (au) |
1.247719 |
| a (au) |
-8734.775296 |
| i (deg) |
117.526989 |
| Ω (om, deg) |
223.231185 |
| ω (w, deg) |
263.592510 |
| M (ma, deg) |
-0.000250 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.173 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.173 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.684 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2021-10-02 |
2021-12-19 |
-4.4532 |
+2.177 |
| 2021-12-19 |
2022-02-25 |
-13.3606 |
+5.458 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
13:57:20.95 |
+30:11:20.7 |
HIP 68188 |
20.07 |
| 2026-09-20 12:00 |
13:57:28.22 |
+30:10:24.1 |
HIP 68188 |
18.96 |
| 2026-09-21 00:00 |
13:57:35.52 |
+30:09:28.0 |
HIP 68188 |
17.99 |
| 2026-09-21 12:00 |
13:57:42.86 |
+30:08:32.4 |
HIP 68188 |
17.17 |
| 2026-09-22 00:00 |
13:57:50.23 |
+30:07:37.2 |
HIP 68188 |
16.51 |
| 2026-09-22 12:00 |
13:57:57.64 |
+30:06:42.4 |
HIP 68188 |
16.06 |
| 2026-09-23 00:00 |
13:58:05.07 |
+30:05:48.1 |
HIP 68188 |
15.82 |
| 2026-09-23 12:00 |
13:58:12.54 |
+30:04:54.3 |
HIP 68188 |
15.80 |
| 2026-09-24 00:00 |
13:58:20.05 |
+30:04:01.0 |
HIP 68188 |
16.01 |
| 2026-09-24 12:00 |
13:58:27.58 |
+30:03:08.1 |
HIP 68188 |
16.44 |
| 2026-09-25 00:00 |
13:58:35.15 |
+30:02:15.6 |
HIP 68188 |
17.07 |
| 2026-09-25 12:00 |
13:58:42.75 |
+30:01:23.7 |
HIP 68313 |
17.53 |
| 2026-09-26 00:00 |
13:58:50.37 |
+30:00:32.2 |
HIP 68313 |
16.39 |
| 2026-09-26 12:00 |
13:58:58.03 |
+29:59:41.3 |
HIP 68313 |
15.40 |
| 2026-09-27 00:00 |
13:59:05.72 |
+29:58:50.8 |
HIP 68313 |
14.59 |
| 2026-09-27 12:00 |
13:59:13.43 |
+29:58:00.8 |
HIP 68313 |
14.00 |
| 2026-09-28 00:00 |
13:59:21.18 |
+29:57:11.3 |
HIP 68313 |
13.65 |
| 2026-09-28 12:00 |
13:59:28.95 |
+29:56:22.2 |
HIP 68313 |
13.56 |
| 2026-09-29 00:00 |
13:59:36.75 |
+29:55:33.7 |
HIP 68313 |
13.74 |
| 2026-09-29 12:00 |
13:59:44.58 |
+29:54:45.7 |
HIP 68313 |
14.18 |
| 2026-09-30 00:00 |
13:59:52.44 |
+29:53:58.2 |
HIP 68313 |
14.85 |
| 2026-09-30 12:00 |
14:00:00.32 |
+29:53:11.2 |
HIP 68313 |
15.73 |
| 2026-10-01 00:00 |
14:00:08.23 |
+29:52:24.7 |
HIP 68313 |
16.79 |
| 2026-10-01 12:00 |
14:00:16.16 |
+29:51:38.7 |
HIP 68313 |
17.99 |
| 2026-10-02 00:00 |
14:00:24.12 |
+29:50:53.3 |
HIP 68313 |
19.30 |
| 2026-10-02 12:00 |
14:00:32.10 |
+29:50:08.3 |
HIP 68313 |
20.72 |
| 2026-10-03 00:00 |
14:00:40.11 |
+29:49:23.9 |
HIP 68526 |
21.39 |
| 2026-10-03 12:00 |
14:00:48.14 |
+29:48:40.1 |
HIP 68526 |
20.90 |
| 2026-10-04 00:00 |
14:00:56.19 |
+29:47:56.7 |
HIP 68526 |
20.56 |
| 2026-10-04 12:00 |
14:01:04.27 |
+29:47:13.9 |
HIP 68526 |
20.38 |
| 2026-10-05 00:00 |
14:01:12.37 |
+29:46:31.7 |
HIP 68526 |
20.37 |
| 2026-10-05 12:00 |
14:01:20.49 |
+29:45:49.9 |
HIP 68526 |
20.51 |
| 2026-10-06 00:00 |
14:01:28.64 |
+29:45:08.8 |
HIP 68526 |
20.82 |
| 2026-10-06 12:00 |
14:01:36.80 |
+29:44:28.2 |
HIP 68526 |
21.29 |
| 2026-10-07 00:00 |
14:01:44.98 |
+29:43:48.1 |
HIP 68526 |
21.90 |
| 2026-10-07 12:00 |
14:01:53.19 |
+29:43:08.6 |
HIP 68526 |
22.64 |
| 2026-10-08 00:00 |
14:02:01.41 |
+29:42:29.7 |
HIP 68526 |
23.51 |
| 2026-10-08 12:00 |
14:02:09.65 |
+29:41:51.3 |
HIP 68526 |
24.48 |
| 2026-10-09 00:00 |
14:02:17.92 |
+29:41:13.6 |
HIP 68526 |
25.55 |
| 2026-10-09 12:00 |
14:02:26.19 |
+29:40:36.4 |
HIP 68526 |
26.70 |
| 2026-10-10 00:00 |
14:02:34.49 |
+29:39:59.7 |
HIP 68526 |
27.93 |
| 2026-10-10 12:00 |
14:02:42.80 |
+29:39:23.7 |
HIP 68526 |
29.22 |
| 2026-10-11 00:00 |
14:02:51.13 |
+29:38:48.2 |
HIP 68526 |
30.57 |