| Parameter |
Value |
| Designation |
C/2023 E1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-07-01T02:34:44.604480Z |
| Orbit solution date (soln_date, UTC) |
2024-02-17T03:13:27Z |
| Obs used |
3004 |
| NEO |
Yes |
| M1 |
16.200 |
| K1 |
7.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2023-03-01T00:05:50.179200Z |
| Discovery magnitude (MPC) |
18.82 o |
| Discovery observatory (MPC) |
M22 · ATLAS South Africa, Sutherland |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-07-02.0000000 |
| e |
0.94690275 |
| q (au) |
1.026605 |
| a (au) |
19.334429 |
| i (deg) |
38.312983 |
| Ω (om, deg) |
164.574212 |
| ω (w, deg) |
105.894615 |
| M (ma, deg) |
0.010347 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.216 + 5.450\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.216 |
| n |
5.450 |
| gf |
0.997 |
| gb |
-0.697 |
| k |
0.942 |
| 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 |
| 2022-12-25 |
2023-06-30 |
+7.6115 |
-1.812 |
| 2023-07-01 |
2023-12-11 |
-0.5124 |
-1.544 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
03:54:42.96 |
-13:34:11.9 |
HIP 18410 |
24.09 |
| 2026-05-12 12:00 |
03:54:55.71 |
-13:33:29.7 |
HIP 18410 |
21.82 |
| 2026-05-13 00:00 |
03:55:08.48 |
-13:32:48.3 |
HIP 18428 |
19.48 |
| 2026-05-13 12:00 |
03:55:21.25 |
-13:32:07.6 |
HIP 18428 |
16.56 |
| 2026-05-14 00:00 |
03:55:34.02 |
-13:31:27.7 |
HIP 18428 |
13.75 |
| 2026-05-14 12:00 |
03:55:46.80 |
-13:30:48.4 |
HIP 18428 |
11.14 |
| 2026-05-15 00:00 |
03:55:59.59 |
-13:30:10.0 |
HIP 18428 |
8.88 |
| 2026-05-15 12:00 |
03:56:12.37 |
-13:29:32.2 |
HIP 18428 |
7.33 |
| 2026-05-16 00:00 |
03:56:25.17 |
-13:28:55.2 |
HIP 18428 |
6.96 |
| 2026-05-16 12:00 |
03:56:37.96 |
-13:28:18.9 |
HIP 18428 |
7.94 |
| 2026-05-17 00:00 |
03:56:50.75 |
-13:27:43.4 |
HIP 18428 |
9.88 |
| 2026-05-17 12:00 |
03:57:03.55 |
-13:27:08.6 |
HIP 18514 |
8.17 |
| 2026-05-18 00:00 |
03:57:16.35 |
-13:26:34.5 |
HIP 18514 |
5.45 |
| 2026-05-18 12:00 |
03:57:29.14 |
-13:26:01.2 |
HIP 18514 |
3.56 |
| 2026-05-19 00:00 |
03:57:41.94 |
-13:25:28.7 |
HIP 18514 |
3.96 |
| 2026-05-19 12:00 |
03:57:54.73 |
-13:24:56.9 |
HIP 18543 |
5.80 |
| 2026-05-20 00:00 |
03:58:07.52 |
-13:24:25.9 |
HIP 18543 |
6.23 |
| 2026-05-20 12:00 |
03:58:20.31 |
-13:23:55.6 |
HIP 18543 |
7.97 |
| 2026-05-21 00:00 |
03:58:33.10 |
-13:23:26.0 |
HIP 18543 |
10.39 |
| 2026-05-21 12:00 |
03:58:45.88 |
-13:22:57.2 |
HIP 18543 |
13.12 |
| 2026-05-22 00:00 |
03:58:58.66 |
-13:22:29.2 |
HIP 18543 |
15.99 |
| 2026-05-22 12:00 |
03:59:11.43 |
-13:22:01.9 |
HIP 18543 |
18.94 |
| 2026-05-23 00:00 |
03:59:24.20 |
-13:21:35.4 |
HIP 18543 |
21.94 |
| 2026-05-23 12:00 |
03:59:36.96 |
-13:21:09.6 |
HIP 18543 |
24.97 |
| 2026-05-24 00:00 |
03:59:49.72 |
-13:20:44.6 |
HIP 18543 |
28.01 |
| 2026-05-24 12:00 |
04:00:02.46 |
-13:20:20.3 |
HIP 18722 |
30.19 |
| 2026-05-25 00:00 |
04:00:15.20 |
-13:19:56.8 |
HIP 18722 |
29.02 |
| 2026-05-25 12:00 |
04:00:27.93 |
-13:19:34.1 |
HIP 18722 |
28.15 |
| 2026-05-26 00:00 |
04:00:40.66 |
-13:19:12.1 |
HIP 18722 |
27.63 |
| 2026-05-26 12:00 |
04:00:53.37 |
-13:18:50.9 |
HIP 18722 |
27.47 |
| 2026-05-27 00:00 |
04:01:06.07 |
-13:18:30.4 |
HIP 18722 |
27.67 |
| 2026-05-27 12:00 |
04:01:18.76 |
-13:18:10.6 |
HIP 18722 |
28.22 |
| 2026-05-28 00:00 |
04:01:31.44 |
-13:17:51.7 |
HIP 18722 |
29.11 |
| 2026-05-28 12:00 |
04:01:44.11 |
-13:17:33.5 |
HIP 18722 |
30.30 |
| 2026-05-29 00:00 |
04:01:56.77 |
-13:17:16.0 |
HIP 18722 |
31.76 |
| 2026-05-29 12:00 |
04:02:09.42 |
-13:16:59.3 |
HIP 18796 |
33.42 |
| 2026-05-30 00:00 |
04:02:22.05 |
-13:16:43.4 |
HIP 18796 |
34.51 |
| 2026-05-30 12:00 |
04:02:34.67 |
-13:16:28.2 |
HIP 18796 |
35.82 |
| 2026-05-31 00:00 |
04:02:47.27 |
-13:16:13.8 |
HIP 19011 |
36.92 |
| 2026-05-31 12:00 |
04:02:59.87 |
-13:16:00.2 |
HIP 19011 |
34.89 |
| 2026-06-01 00:00 |
04:03:12.44 |
-13:15:47.3 |
HIP 19011 |
33.03 |
| 2026-06-01 12:00 |
04:03:25.00 |
-13:15:35.2 |
HIP 19011 |
31.37 |
| 2026-06-02 00:00 |
04:03:37.55 |
-13:15:23.8 |
HIP 19011 |
29.95 |