| Parameter |
Value |
| Designation |
C/2019 F2 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-09-08T21:26:06.544320Z |
| Orbit solution date (soln_date, UTC) |
2025-09-09T12:42:31Z |
| Obs used |
683 |
| NEO |
- |
| M1 |
5.300 |
| K1 |
24.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2019-03-26T07:21:56.332800Z |
| Discovery magnitude (MPC) |
17.58 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-05-07.0000000 |
| e |
0.86507120 |
| q (au) |
2.232882 |
| a (au) |
16.548594 |
| i (deg) |
19.188643 |
| Ω (om, deg) |
175.867930 |
| ω (w, deg) |
10.953986 |
| M (ma, deg) |
358.171475 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.336 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.336 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2019-02-26 |
2019-04-23 |
+11.7951 |
-5.190 |
| 2019-04-23 |
2019-06-26 |
+19.2752 |
-8.502 |
| 2019-12-28 |
2020-07-20 |
+5.9715 |
-2.763 |
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 |
22:32:03.70 |
-01:58:32.6 |
HIP 111394 |
38.31 |
| 2026-05-12 12:00 |
22:32:06.51 |
-01:58:07.4 |
HIP 111394 |
37.50 |
| 2026-05-13 00:00 |
22:32:09.27 |
-01:57:42.4 |
HIP 111394 |
36.70 |
| 2026-05-13 12:00 |
22:32:11.97 |
-01:57:17.8 |
HIP 111394 |
35.92 |
| 2026-05-14 00:00 |
22:32:14.62 |
-01:56:53.5 |
HIP 111394 |
35.15 |
| 2026-05-14 12:00 |
22:32:17.21 |
-01:56:29.4 |
HIP 111394 |
34.40 |
| 2026-05-15 00:00 |
22:32:19.75 |
-01:56:05.6 |
HIP 111394 |
33.66 |
| 2026-05-15 12:00 |
22:32:22.22 |
-01:55:42.2 |
HIP 111394 |
32.93 |
| 2026-05-16 00:00 |
22:32:24.65 |
-01:55:19.0 |
HIP 111394 |
32.22 |
| 2026-05-16 12:00 |
22:32:27.01 |
-01:54:56.2 |
HIP 111394 |
31.52 |
| 2026-05-17 00:00 |
22:32:29.32 |
-01:54:33.6 |
HIP 111394 |
30.84 |
| 2026-05-17 12:00 |
22:32:31.57 |
-01:54:11.4 |
HIP 111394 |
30.17 |
| 2026-05-18 00:00 |
22:32:33.76 |
-01:53:49.5 |
HIP 111394 |
29.52 |
| 2026-05-18 12:00 |
22:32:35.90 |
-01:53:27.8 |
HIP 111394 |
28.88 |
| 2026-05-19 00:00 |
22:32:37.98 |
-01:53:06.5 |
HIP 111394 |
28.25 |
| 2026-05-19 12:00 |
22:32:40.00 |
-01:52:45.6 |
HIP 111394 |
27.64 |
| 2026-05-20 00:00 |
22:32:41.96 |
-01:52:24.9 |
HIP 111394 |
27.05 |
| 2026-05-20 12:00 |
22:32:43.87 |
-01:52:04.5 |
HIP 111394 |
26.47 |
| 2026-05-21 00:00 |
22:32:45.72 |
-01:51:44.5 |
HIP 111394 |
25.90 |
| 2026-05-21 12:00 |
22:32:47.51 |
-01:51:24.8 |
HIP 111394 |
25.35 |
| 2026-05-22 00:00 |
22:32:49.24 |
-01:51:05.4 |
HIP 111394 |
24.81 |
| 2026-05-22 12:00 |
22:32:50.91 |
-01:50:46.3 |
HIP 111394 |
24.29 |
| 2026-05-23 00:00 |
22:32:52.53 |
-01:50:27.6 |
HIP 111394 |
23.78 |
| 2026-05-23 12:00 |
22:32:54.08 |
-01:50:09.2 |
HIP 111394 |
23.28 |
| 2026-05-24 00:00 |
22:32:55.58 |
-01:49:51.1 |
HIP 111394 |
22.80 |
| 2026-05-24 12:00 |
22:32:57.02 |
-01:49:33.3 |
HIP 111394 |
22.34 |
| 2026-05-25 00:00 |
22:32:58.41 |
-01:49:15.9 |
HIP 111394 |
21.89 |
| 2026-05-25 12:00 |
22:32:59.73 |
-01:48:58.8 |
HIP 111394 |
21.45 |
| 2026-05-26 00:00 |
22:33:00.99 |
-01:48:42.1 |
HIP 111394 |
21.03 |
| 2026-05-26 12:00 |
22:33:02.20 |
-01:48:25.6 |
HIP 111394 |
20.62 |
| 2026-05-27 00:00 |
22:33:03.35 |
-01:48:09.5 |
HIP 111394 |
20.23 |
| 2026-05-27 12:00 |
22:33:04.44 |
-01:47:53.8 |
HIP 111394 |
19.85 |
| 2026-05-28 00:00 |
22:33:05.47 |
-01:47:38.4 |
HIP 111394 |
19.49 |
| 2026-05-28 12:00 |
22:33:06.44 |
-01:47:23.3 |
HIP 111394 |
19.14 |
| 2026-05-29 00:00 |
22:33:07.36 |
-01:47:08.6 |
HIP 111394 |
18.81 |
| 2026-05-29 12:00 |
22:33:08.21 |
-01:46:54.2 |
HIP 111394 |
18.49 |
| 2026-05-30 00:00 |
22:33:09.01 |
-01:46:40.1 |
HIP 111394 |
18.18 |
| 2026-05-30 12:00 |
22:33:09.74 |
-01:46:26.4 |
HIP 111394 |
17.89 |
| 2026-05-31 00:00 |
22:33:10.42 |
-01:46:13.0 |
HIP 111394 |
17.62 |
| 2026-05-31 12:00 |
22:33:11.04 |
-01:46:00.0 |
HIP 111394 |
17.36 |
| 2026-06-01 00:00 |
22:33:11.60 |
-01:45:47.4 |
HIP 111394 |
17.11 |
| 2026-06-01 12:00 |
22:33:12.10 |
-01:45:35.0 |
HIP 111394 |
16.88 |
| 2026-06-02 00:00 |
22:33:12.54 |
-01:45:23.1 |
HIP 111394 |
16.67 |