| 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) |
| 2026-07-29 00:00 |
18:44:48.13 |
+20:38:03.5 |
HIP 92043 |
13.16 |
| 2026-07-29 12:00 |
18:44:32.70 |
+20:36:49.1 |
HIP 91916 |
15.83 |
| 2026-07-30 00:00 |
18:44:17.35 |
+20:35:33.7 |
HIP 91916 |
16.74 |
| 2026-07-30 12:00 |
18:44:02.06 |
+20:34:17.3 |
HIP 91770 |
18.37 |
| 2026-07-31 00:00 |
18:43:46.85 |
+20:33:00.1 |
HIP 91770 |
15.67 |
| 2026-07-31 12:00 |
18:43:31.72 |
+20:31:41.9 |
HIP 91770 |
13.53 |
| 2026-08-01 00:00 |
18:43:16.66 |
+20:30:22.8 |
HIP 91770 |
12.22 |
| 2026-08-01 12:00 |
18:43:01.68 |
+20:29:02.7 |
HIP 91770 |
12.02 |
| 2026-08-02 00:00 |
18:42:46.77 |
+20:27:41.8 |
HIP 91770 |
12.97 |
| 2026-08-02 12:00 |
18:42:31.95 |
+20:26:20.0 |
HIP 91770 |
14.84 |
| 2026-08-03 00:00 |
18:42:17.20 |
+20:24:57.3 |
HIP 91770 |
17.32 |
| 2026-08-03 12:00 |
18:42:02.54 |
+20:23:33.8 |
HIP 91770 |
20.19 |
| 2026-08-04 00:00 |
18:41:47.96 |
+20:22:09.3 |
HIP 91770 |
23.30 |
| 2026-08-04 12:00 |
18:41:33.46 |
+20:20:44.1 |
HIP 91770 |
26.55 |
| 2026-08-05 00:00 |
18:41:19.05 |
+20:19:17.9 |
HIP 91522 |
25.43 |
| 2026-08-05 12:00 |
18:41:04.72 |
+20:17:51.0 |
HIP 91522 |
21.87 |
| 2026-08-06 00:00 |
18:40:50.47 |
+20:16:23.2 |
HIP 91522 |
18.35 |
| 2026-08-06 12:00 |
18:40:36.31 |
+20:14:54.6 |
HIP 91522 |
14.90 |
| 2026-08-07 00:00 |
18:40:22.24 |
+20:13:25.1 |
HIP 91522 |
11.57 |
| 2026-08-07 12:00 |
18:40:08.26 |
+20:11:54.9 |
HIP 91522 |
8.47 |
| 2026-08-08 00:00 |
18:39:54.36 |
+20:10:23.9 |
HIP 91522 |
5.97 |
| 2026-08-08 12:00 |
18:39:40.56 |
+20:08:52.1 |
HIP 91522 |
5.02 |
| 2026-08-09 00:00 |
18:39:26.85 |
+20:07:19.6 |
HIP 91522 |
6.33 |
| 2026-08-09 12:00 |
18:39:13.23 |
+20:05:46.2 |
HIP 91522 |
8.95 |
| 2026-08-10 00:00 |
18:38:59.70 |
+20:04:12.1 |
HIP 91522 |
12.04 |
| 2026-08-10 12:00 |
18:38:46.27 |
+20:02:37.3 |
HIP 91350 |
13.86 |
| 2026-08-11 00:00 |
18:38:32.93 |
+20:01:01.8 |
HIP 91350 |
12.35 |
| 2026-08-11 12:00 |
18:38:19.68 |
+19:59:25.5 |
HIP 91350 |
11.75 |
| 2026-08-12 00:00 |
18:38:06.53 |
+19:57:48.5 |
HIP 91350 |
12.18 |
| 2026-08-12 12:00 |
18:37:53.48 |
+19:56:10.9 |
HIP 91350 |
13.54 |
| 2026-08-13 00:00 |
18:37:40.53 |
+19:54:32.5 |
HIP 91350 |
15.58 |
| 2026-08-13 12:00 |
18:37:27.67 |
+19:52:53.5 |
HIP 91205 |
17.49 |
| 2026-08-14 00:00 |
18:37:14.92 |
+19:51:13.8 |
HIP 91205 |
15.75 |
| 2026-08-14 12:00 |
18:37:02.26 |
+19:49:33.4 |
HIP 91205 |
14.64 |
| 2026-08-15 00:00 |
18:36:49.71 |
+19:47:52.4 |
HIP 91169 |
13.21 |
| 2026-08-15 12:00 |
18:36:37.25 |
+19:46:10.8 |
HIP 91169 |
11.49 |
| 2026-08-16 00:00 |
18:36:24.90 |
+19:44:28.6 |
HIP 91169 |
10.63 |
| 2026-08-16 12:00 |
18:36:12.65 |
+19:42:45.7 |
HIP 91169 |
10.81 |
| 2026-08-17 00:00 |
18:36:00.50 |
+19:41:02.3 |
HIP 91169 |
11.98 |
| 2026-08-17 12:00 |
18:35:48.46 |
+19:39:18.3 |
HIP 91169 |
13.87 |
| 2026-08-18 00:00 |
18:35:36.52 |
+19:37:33.7 |
HIP 91169 |
16.24 |
| 2026-08-18 12:00 |
18:35:24.69 |
+19:35:48.5 |
HIP 91169 |
18.89 |
| 2026-08-19 00:00 |
18:35:12.96 |
+19:34:02.8 |
HIP 91169 |
21.71 |