| Parameter |
Value |
| Designation |
C/2021 X1 (Maury-Attard) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-05-27T07:30:21.781440Z |
| Orbit solution date (soln_date, UTC) |
2024-10-05T23:12:24Z |
| Obs used |
2855 |
| NEO |
- |
| M1 |
8.800 |
| K1 |
8.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-12-02T07:46:33.600000Z |
| Discovery magnitude (MPC) |
19.00 G |
| Discovery observatory (MPC) |
W94 · MAPS, San Pedro de Atacama |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-07-16.0000000 |
| e |
1.00132476 |
| q (au) |
3.233578 |
| a (au) |
-2440.886866 |
| i (deg) |
140.111737 |
| Ω (om, deg) |
10.591202 |
| ω (w, deg) |
334.595699 |
| M (ma, deg) |
0.000406 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.700 + 3.519\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.700 |
| n |
3.519 |
| gf |
0.984 |
| gb |
-0.977 |
| k |
1.000 |
| δ90 |
9.941 |
| 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 |
| 2021-12-02 |
2022-11-02 |
+4.7012 |
-3.916 |
| 2022-11-02 |
2023-03-19 |
-16.6533 |
+8.611 |
| 2023-06-17 |
2024-09-27 |
+1.8796 |
-0.958 |
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 |
18:26:35.08 |
+17:30:22.8 |
HIP 90420 |
14.62 |
| 2026-09-20 12:00 |
18:26:30.72 |
+17:28:24.0 |
HIP 90420 |
16.85 |
| 2026-09-21 00:00 |
18:26:26.48 |
+17:26:25.3 |
HIP 90420 |
19.06 |
| 2026-09-21 12:00 |
18:26:22.35 |
+17:24:26.7 |
HIP 90420 |
21.26 |
| 2026-09-22 00:00 |
18:26:18.33 |
+17:22:28.3 |
HIP 90420 |
23.45 |
| 2026-09-22 12:00 |
18:26:14.43 |
+17:20:30.0 |
HIP 90420 |
25.63 |
| 2026-09-23 00:00 |
18:26:10.63 |
+17:18:32.0 |
HIP 90420 |
27.80 |
| 2026-09-23 12:00 |
18:26:06.95 |
+17:16:34.0 |
HIP 90420 |
29.95 |
| 2026-09-24 00:00 |
18:26:03.39 |
+17:14:36.3 |
HIP 90159 |
30.47 |
| 2026-09-24 12:00 |
18:25:59.93 |
+17:12:38.7 |
HIP 90159 |
29.68 |
| 2026-09-25 00:00 |
18:25:56.58 |
+17:10:41.4 |
HIP 90159 |
29.05 |
| 2026-09-25 12:00 |
18:25:53.35 |
+17:08:44.2 |
HIP 90159 |
28.59 |
| 2026-09-26 00:00 |
18:25:50.23 |
+17:06:47.3 |
HIP 90159 |
28.30 |
| 2026-09-26 12:00 |
18:25:47.21 |
+17:04:50.5 |
HIP 90159 |
28.18 |
| 2026-09-27 00:00 |
18:25:44.31 |
+17:02:54.0 |
HIP 90159 |
28.24 |
| 2026-09-27 12:00 |
18:25:41.52 |
+17:00:57.8 |
HIP 90142 |
28.46 |
| 2026-09-28 00:00 |
18:25:38.83 |
+16:59:01.7 |
HIP 90142 |
27.42 |
| 2026-09-28 12:00 |
18:25:36.26 |
+16:57:06.0 |
HIP 90142 |
26.52 |
| 2026-09-29 00:00 |
18:25:33.79 |
+16:55:10.4 |
HIP 90142 |
25.78 |
| 2026-09-29 12:00 |
18:25:31.43 |
+16:53:15.2 |
HIP 90142 |
25.20 |
| 2026-09-30 00:00 |
18:25:29.18 |
+16:51:20.2 |
HIP 90142 |
24.79 |
| 2026-09-30 12:00 |
18:25:27.04 |
+16:49:25.4 |
HIP 90317 |
23.74 |
| 2026-10-01 00:00 |
18:25:25.00 |
+16:47:31.0 |
HIP 90317 |
21.93 |
| 2026-10-01 12:00 |
18:25:23.08 |
+16:45:36.9 |
HIP 90317 |
20.15 |
| 2026-10-02 00:00 |
18:25:21.25 |
+16:43:43.0 |
HIP 90317 |
18.40 |
| 2026-10-02 12:00 |
18:25:19.54 |
+16:41:49.5 |
HIP 90317 |
16.70 |
| 2026-10-03 00:00 |
18:25:17.93 |
+16:39:56.3 |
HIP 90317 |
15.05 |
| 2026-10-03 12:00 |
18:25:16.43 |
+16:38:03.3 |
HIP 90317 |
13.46 |
| 2026-10-04 00:00 |
18:25:15.04 |
+16:36:10.8 |
HIP 90317 |
11.96 |
| 2026-10-04 12:00 |
18:25:13.75 |
+16:34:18.5 |
HIP 90317 |
10.59 |
| 2026-10-05 00:00 |
18:25:12.56 |
+16:32:26.6 |
HIP 90317 |
9.38 |
| 2026-10-05 12:00 |
18:25:11.48 |
+16:30:35.1 |
HIP 90317 |
8.41 |
| 2026-10-06 00:00 |
18:25:10.50 |
+16:28:43.9 |
HIP 90317 |
7.75 |
| 2026-10-06 12:00 |
18:25:09.63 |
+16:26:53.1 |
HIP 90317 |
7.49 |
| 2026-10-07 00:00 |
18:25:08.86 |
+16:25:02.6 |
HIP 90317 |
7.66 |
| 2026-10-07 12:00 |
18:25:08.20 |
+16:23:12.5 |
HIP 90317 |
8.23 |
| 2026-10-08 00:00 |
18:25:07.64 |
+16:21:22.8 |
HIP 90317 |
9.12 |
| 2026-10-08 12:00 |
18:25:07.18 |
+16:19:33.5 |
HIP 90317 |
10.23 |
| 2026-10-09 00:00 |
18:25:06.82 |
+16:17:44.7 |
HIP 90317 |
11.51 |
| 2026-10-09 12:00 |
18:25:06.56 |
+16:15:56.2 |
HIP 90252 |
11.38 |
| 2026-10-10 00:00 |
18:25:06.41 |
+16:14:08.1 |
HIP 90252 |
9.63 |
| 2026-10-10 12:00 |
18:25:06.35 |
+16:12:20.5 |
HIP 90252 |
7.92 |
| 2026-10-11 00:00 |
18:25:06.40 |
+16:10:33.3 |
HIP 90252 |
6.27 |