C/2021 X1 (Maury-Attard)
| 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 |
0.988 |
| gb |
-0.977 |
| k |
1.000 |
| δ90 |
9.948 |
| 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 |
+4.7011 |
-3.916 |
| 2022-11-02 |
2023-03-19 |
-16.6535 |
+8.611 |
| 2023-06-17 |
2024-09-27 |
+1.8795 |
-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) |
| 2026-02-03 00:00 |
19:27:11.22 |
+14:07:14.1 |
HIP 95649 |
8.40 |
| 2026-02-03 12:00 |
19:27:19.09 |
+14:08:22.2 |
HIP 95649 |
9.10 |
| 2026-02-04 00:00 |
19:27:26.91 |
+14:09:31.2 |
HIP 95664 |
7.62 |
| 2026-02-04 12:00 |
19:27:34.69 |
+14:10:41.0 |
HIP 95664 |
6.27 |
| 2026-02-05 00:00 |
19:27:42.41 |
+14:11:51.5 |
HIP 95664 |
5.49 |
| 2026-02-05 12:00 |
19:27:50.09 |
+14:13:02.7 |
HIP 95664 |
5.53 |
| 2026-02-06 00:00 |
19:27:57.72 |
+14:14:14.7 |
HIP 95664 |
6.37 |
| 2026-02-06 12:00 |
19:28:05.31 |
+14:15:27.5 |
HIP 95664 |
7.75 |
| 2026-02-07 00:00 |
19:28:12.84 |
+14:16:41.0 |
HIP 95664 |
9.44 |
| 2026-02-07 12:00 |
19:28:20.32 |
+14:17:55.3 |
HIP 95664 |
11.29 |
| 2026-02-08 00:00 |
19:28:27.75 |
+14:19:10.3 |
HIP 95664 |
13.23 |
| 2026-02-08 12:00 |
19:28:35.13 |
+14:20:26.1 |
HIP 95794 |
14.94 |
| 2026-02-09 00:00 |
19:28:42.45 |
+14:21:42.6 |
HIP 95794 |
13.06 |
| 2026-02-09 12:00 |
19:28:49.72 |
+14:22:59.8 |
HIP 95794 |
11.28 |
| 2026-02-10 00:00 |
19:28:56.94 |
+14:24:17.7 |
HIP 95794 |
9.66 |
| 2026-02-10 12:00 |
19:29:04.10 |
+14:25:36.4 |
HIP 95794 |
8.28 |
| 2026-02-11 00:00 |
19:29:11.21 |
+14:26:55.8 |
HIP 95794 |
7.28 |
| 2026-02-11 12:00 |
19:29:18.26 |
+14:28:15.9 |
HIP 95794 |
6.83 |
| 2026-02-12 00:00 |
19:29:25.25 |
+14:29:36.7 |
HIP 95822 |
6.20 |
| 2026-02-12 12:00 |
19:29:32.19 |
+14:30:58.2 |
HIP 95822 |
5.38 |
| 2026-02-13 00:00 |
19:29:39.06 |
+14:32:20.5 |
HIP 95822 |
5.34 |
| 2026-02-13 12:00 |
19:29:45.88 |
+14:33:43.4 |
HIP 95822 |
6.10 |
| 2026-02-14 00:00 |
19:29:52.63 |
+14:35:07.0 |
HIP 95822 |
7.41 |
| 2026-02-14 12:00 |
19:29:59.33 |
+14:36:31.3 |
HIP 95822 |
9.03 |
| 2026-02-15 00:00 |
19:30:05.96 |
+14:37:56.3 |
HIP 95822 |
10.83 |
| 2026-02-15 12:00 |
19:30:12.53 |
+14:39:22.0 |
HIP 95822 |
12.71 |
| 2026-02-16 00:00 |
19:30:19.04 |
+14:40:48.3 |
HIP 95822 |
14.66 |
| 2026-02-16 12:00 |
19:30:25.48 |
+14:42:15.3 |
HIP 95822 |
16.64 |
| 2026-02-17 00:00 |
19:30:31.86 |
+14:43:43.0 |
HIP 95822 |
18.65 |
| 2026-02-17 12:00 |
19:30:38.17 |
+14:45:11.4 |
HIP 95822 |
20.67 |
| 2026-02-18 00:00 |
19:30:44.42 |
+14:46:40.3 |
HIP 96057 |
20.28 |
| 2026-02-18 12:00 |
19:30:50.60 |
+14:48:10.0 |
HIP 96057 |
18.21 |
| 2026-02-19 00:00 |
19:30:56.71 |
+14:49:40.3 |
HIP 96057 |
16.15 |
| 2026-02-19 12:00 |
19:31:02.75 |
+14:51:11.2 |
HIP 96057 |
14.12 |
| 2026-02-20 00:00 |
19:31:08.73 |
+14:52:42.7 |
HIP 96057 |
12.13 |
| 2026-02-20 12:00 |
19:31:14.63 |
+14:54:14.9 |
HIP 96057 |
10.19 |
| 2026-02-21 00:00 |
19:31:20.47 |
+14:55:47.7 |
HIP 96057 |
8.35 |
| 2026-02-21 12:00 |
19:31:26.23 |
+14:57:21.1 |
HIP 96057 |
6.67 |
| 2026-02-22 00:00 |
19:31:31.92 |
+14:58:55.1 |
HIP 96057 |
5.30 |
| 2026-02-22 12:00 |
19:31:37.54 |
+15:00:29.7 |
HIP 96057 |
4.55 |
| 2026-02-23 00:00 |
19:31:43.08 |
+15:02:04.9 |
HIP 96057 |
4.70 |
| 2026-02-23 12:00 |
19:31:48.55 |
+15:03:40.7 |
HIP 96057 |
5.67 |
| 2026-02-24 00:00 |
19:31:53.95 |
+15:05:17.1 |
HIP 96057 |
7.15 |