| Parameter |
Value |
| Designation |
P/2021 Q5 (ATLAS) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-08-30T10:00:46.546560Z |
| Orbit solution date (soln_date, UTC) |
2025-01-14T17:42:18Z |
| Obs used |
274 |
| NEO |
Yes |
| M1 |
15.800 |
| K1 |
4.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-08-29T14:33:45.619200Z |
| Discovery magnitude (MPC) |
17.59 o |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-09-20.0000000 |
| e |
0.62395172 |
| q (au) |
1.234397 |
| a (au) |
3.282550 |
| i (deg) |
10.733839 |
| Ω (om, deg) |
239.770616 |
| ω (w, deg) |
180.879852 |
| M (ma, deg) |
3.411076 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.774 + 2.320\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.774 |
| n |
2.320 |
| gf |
1.000 |
| gb |
-0.998 |
| k |
1.000 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
18:14:42.87 |
-14:09:01.8 |
HIP 89519 |
21.38 |
| 2026-09-20 12:00 |
18:14:51.07 |
-14:09:49.5 |
HIP 89519 |
19.25 |
| 2026-09-21 00:00 |
18:14:59.58 |
-14:10:36.9 |
HIP 89519 |
17.05 |
| 2026-09-21 12:00 |
18:15:08.39 |
-14:11:24.2 |
HIP 89519 |
14.79 |
| 2026-09-22 00:00 |
18:15:17.51 |
-14:12:11.2 |
HIP 89519 |
12.48 |
| 2026-09-22 12:00 |
18:15:26.94 |
-14:12:58.0 |
HIP 89519 |
10.12 |
| 2026-09-23 00:00 |
18:15:36.67 |
-14:13:44.5 |
HIP 89519 |
7.73 |
| 2026-09-23 12:00 |
18:15:46.70 |
-14:14:30.8 |
HIP 89519 |
5.39 |
| 2026-09-24 00:00 |
18:15:57.03 |
-14:15:16.9 |
HIP 89519 |
3.33 |
| 2026-09-24 12:00 |
18:16:07.66 |
-14:16:02.7 |
HIP 89519 |
2.65 |
| 2026-09-25 00:00 |
18:16:18.59 |
-14:16:48.2 |
HIP 89519 |
4.24 |
| 2026-09-25 12:00 |
18:16:29.82 |
-14:17:33.5 |
HIP 89519 |
6.72 |
| 2026-09-26 00:00 |
18:16:41.34 |
-14:18:18.5 |
HIP 89519 |
9.46 |
| 2026-09-26 12:00 |
18:16:53.16 |
-14:19:03.2 |
HIP 89634 |
12.25 |
| 2026-09-27 00:00 |
18:17:05.28 |
-14:19:47.6 |
HIP 89634 |
9.66 |
| 2026-09-27 12:00 |
18:17:17.68 |
-14:20:31.7 |
HIP 89634 |
7.38 |
| 2026-09-28 00:00 |
18:17:30.38 |
-14:21:15.5 |
HIP 89634 |
5.89 |
| 2026-09-28 12:00 |
18:17:43.37 |
-14:21:59.0 |
HIP 89634 |
5.96 |
| 2026-09-29 00:00 |
18:17:56.65 |
-14:22:42.2 |
HIP 89634 |
7.61 |
| 2026-09-29 12:00 |
18:18:10.22 |
-14:23:25.0 |
HIP 89634 |
10.17 |
| 2026-09-30 00:00 |
18:18:24.07 |
-14:24:07.5 |
HIP 89634 |
13.17 |
| 2026-09-30 12:00 |
18:18:38.21 |
-14:24:49.7 |
HIP 89634 |
16.41 |
| 2026-10-01 00:00 |
18:18:52.64 |
-14:25:31.5 |
HIP 89634 |
19.80 |
| 2026-10-01 12:00 |
18:19:07.35 |
-14:26:12.9 |
HIP 89892 |
20.81 |
| 2026-10-02 00:00 |
18:19:22.34 |
-14:26:54.0 |
HIP 89892 |
17.48 |
| 2026-10-02 12:00 |
18:19:37.62 |
-14:27:34.7 |
HIP 89892 |
14.26 |
| 2026-10-03 00:00 |
18:19:53.18 |
-14:28:15.0 |
HIP 89892 |
11.32 |
| 2026-10-03 12:00 |
18:20:09.02 |
-14:28:54.9 |
HIP 89892 |
9.02 |
| 2026-10-04 00:00 |
18:20:25.14 |
-14:29:34.4 |
HIP 89892 |
8.04 |
| 2026-10-04 12:00 |
18:20:41.54 |
-14:30:13.5 |
HIP 89892 |
8.92 |
| 2026-10-05 00:00 |
18:20:58.21 |
-14:30:52.2 |
HIP 89892 |
11.29 |
| 2026-10-05 12:00 |
18:21:15.16 |
-14:31:30.5 |
HIP 89892 |
14.50 |
| 2026-10-06 00:00 |
18:21:32.39 |
-14:32:08.3 |
HIP 90034 |
13.75 |
| 2026-10-06 12:00 |
18:21:49.90 |
-14:32:45.7 |
HIP 90034 |
11.36 |
| 2026-10-07 00:00 |
18:22:07.67 |
-14:33:22.6 |
HIP 90034 |
10.25 |
| 2026-10-07 12:00 |
18:22:25.72 |
-14:33:59.1 |
HIP 90034 |
10.92 |
| 2026-10-08 00:00 |
18:22:44.04 |
-14:34:35.1 |
HIP 90062 |
12.78 |
| 2026-10-08 12:00 |
18:23:02.63 |
-14:35:10.6 |
HIP 90062 |
14.05 |
| 2026-10-09 00:00 |
18:23:21.49 |
-14:35:45.6 |
HIP 90062 |
16.55 |
| 2026-10-09 12:00 |
18:23:40.61 |
-14:36:20.1 |
HIP 90062 |
19.85 |
| 2026-10-10 00:00 |
18:24:00.01 |
-14:36:54.2 |
HIP 90267 |
16.14 |
| 2026-10-10 12:00 |
18:24:19.67 |
-14:37:27.7 |
HIP 90267 |
11.35 |
| 2026-10-11 00:00 |
18:24:39.59 |
-14:38:00.7 |
HIP 90267 |
6.50 |