| Parameter |
Value |
| Designation |
C/2021 G2 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2024-09-09T04:30:12.493440Z |
| Orbit solution date (soln_date, UTC) |
2026-05-08T13:42:11Z |
| Obs used |
4076 |
| NEO |
- |
| M1 |
7.800 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2024-10-16.0000000 |
| e |
1.00032725 |
| q (au) |
4.982440 |
| a (au) |
-15225.386839 |
| i (deg) |
48.472763 |
| Ω (om, deg) |
221.095192 |
| ω (w, deg) |
343.275113 |
| M (ma, deg) |
0.000019 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.320 + 2.839\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.320 |
| n |
2.839 |
| gf |
0.884 |
| gb |
-0.940 |
| k |
1.000 |
| δ90 |
7.178 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
17:24:50.62 |
+13:21:29.2 |
HIP 85227 |
1.61 |
| 2026-05-12 12:00 |
17:24:41.15 |
+13:24:18.4 |
HIP 85227 |
5.23 |
| 2026-05-13 00:00 |
17:24:31.58 |
+13:27:06.3 |
HIP 85227 |
8.86 |
| 2026-05-13 12:00 |
17:24:21.93 |
+13:29:53.1 |
HIP 85109 |
12.28 |
| 2026-05-14 00:00 |
17:24:12.18 |
+13:32:38.6 |
HIP 85109 |
12.11 |
| 2026-05-14 12:00 |
17:24:02.35 |
+13:35:22.9 |
HIP 85109 |
12.97 |
| 2026-05-15 00:00 |
17:23:52.43 |
+13:38:05.9 |
HIP 85109 |
14.67 |
| 2026-05-15 12:00 |
17:23:42.43 |
+13:40:47.7 |
HIP 85109 |
16.97 |
| 2026-05-16 00:00 |
17:23:32.34 |
+13:43:28.1 |
HIP 85109 |
19.66 |
| 2026-05-16 12:00 |
17:23:22.18 |
+13:46:07.3 |
HIP 85109 |
22.59 |
| 2026-05-17 00:00 |
17:23:11.93 |
+13:48:45.1 |
HIP 85109 |
25.68 |
| 2026-05-17 12:00 |
17:23:01.60 |
+13:51:21.6 |
HIP 84927 |
27.94 |
| 2026-05-18 00:00 |
17:22:51.20 |
+13:53:56.8 |
HIP 84927 |
27.21 |
| 2026-05-18 12:00 |
17:22:40.72 |
+13:56:30.6 |
HIP 84927 |
26.91 |
| 2026-05-19 00:00 |
17:22:30.17 |
+13:59:03.1 |
HIP 84921 |
26.26 |
| 2026-05-19 12:00 |
17:22:19.55 |
+14:01:34.2 |
HIP 84921 |
22.67 |
| 2026-05-20 00:00 |
17:22:08.86 |
+14:04:03.9 |
HIP 84921 |
19.09 |
| 2026-05-20 12:00 |
17:21:58.10 |
+14:06:32.2 |
HIP 84921 |
15.52 |
| 2026-05-21 00:00 |
17:21:47.28 |
+14:08:59.1 |
HIP 84921 |
11.98 |
| 2026-05-21 12:00 |
17:21:36.39 |
+14:11:24.7 |
HIP 84921 |
8.50 |
| 2026-05-22 00:00 |
17:21:25.45 |
+14:13:48.8 |
HIP 84921 |
5.17 |
| 2026-05-22 12:00 |
17:21:14.44 |
+14:16:11.4 |
HIP 84921 |
2.64 |
| 2026-05-23 00:00 |
17:21:03.37 |
+14:18:32.6 |
HIP 84921 |
3.58 |
| 2026-05-23 12:00 |
17:20:52.24 |
+14:20:52.4 |
HIP 84921 |
6.65 |
| 2026-05-24 00:00 |
17:20:41.06 |
+14:23:10.8 |
HIP 84921 |
10.05 |
| 2026-05-24 12:00 |
17:20:29.83 |
+14:25:27.6 |
HIP 84921 |
13.53 |
| 2026-05-25 00:00 |
17:20:18.54 |
+14:27:43.0 |
HIP 84921 |
17.04 |
| 2026-05-25 12:00 |
17:20:07.21 |
+14:29:57.0 |
HIP 84921 |
20.55 |
| 2026-05-26 00:00 |
17:19:55.83 |
+14:32:09.4 |
HIP 84921 |
24.07 |
| 2026-05-26 12:00 |
17:19:44.40 |
+14:34:20.4 |
HIP 84682 |
23.84 |
| 2026-05-27 00:00 |
17:19:32.92 |
+14:36:29.8 |
HIP 84682 |
20.43 |
| 2026-05-27 12:00 |
17:19:21.40 |
+14:38:37.8 |
HIP 84682 |
17.09 |
| 2026-05-28 00:00 |
17:19:09.85 |
+14:40:44.3 |
HIP 84682 |
13.84 |
| 2026-05-28 12:00 |
17:18:58.25 |
+14:42:49.2 |
HIP 84682 |
10.77 |
| 2026-05-29 00:00 |
17:18:46.61 |
+14:44:52.6 |
HIP 84682 |
8.07 |
| 2026-05-29 12:00 |
17:18:34.94 |
+14:46:54.5 |
HIP 84682 |
6.25 |
| 2026-05-30 00:00 |
17:18:23.23 |
+14:48:54.8 |
HIP 84682 |
6.11 |
| 2026-05-30 12:00 |
17:18:11.49 |
+14:50:53.7 |
HIP 84682 |
7.74 |
| 2026-05-31 00:00 |
17:17:59.72 |
+14:52:50.9 |
HIP 84682 |
10.32 |
| 2026-05-31 12:00 |
17:17:47.93 |
+14:54:46.6 |
HIP 84682 |
13.31 |
| 2026-06-01 00:00 |
17:17:36.10 |
+14:56:40.8 |
HIP 84568 |
14.98 |
| 2026-06-01 12:00 |
17:17:24.25 |
+14:58:33.4 |
HIP 84568 |
12.48 |
| 2026-06-02 00:00 |
17:17:12.37 |
+15:00:24.4 |
HIP 84568 |
10.55 |