| 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 |
-0.501 |
| 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) |
| 2026-07-29 00:00 |
22:27:58.07 |
-02:03:04.6 |
HIP 110820 |
12.97 |
| 2026-07-29 12:00 |
22:27:52.64 |
-02:03:34.3 |
HIP 110820 |
11.56 |
| 2026-07-30 00:00 |
22:27:47.18 |
-02:04:04.2 |
HIP 110820 |
10.16 |
| 2026-07-30 12:00 |
22:27:41.68 |
-02:04:34.5 |
HIP 110820 |
8.76 |
| 2026-07-31 00:00 |
22:27:36.15 |
-02:05:05.0 |
HIP 110820 |
7.38 |
| 2026-07-31 12:00 |
22:27:30.59 |
-02:05:35.9 |
HIP 110820 |
6.03 |
| 2026-08-01 00:00 |
22:27:25.00 |
-02:06:07.0 |
HIP 110820 |
4.76 |
| 2026-08-01 12:00 |
22:27:19.38 |
-02:06:38.4 |
HIP 110820 |
3.66 |
| 2026-08-02 00:00 |
22:27:13.74 |
-02:07:10.1 |
HIP 110820 |
2.93 |
| 2026-08-02 12:00 |
22:27:08.06 |
-02:07:42.1 |
HIP 110820 |
2.88 |
| 2026-08-03 00:00 |
22:27:02.36 |
-02:08:14.4 |
HIP 110820 |
3.56 |
| 2026-08-03 12:00 |
22:26:56.63 |
-02:08:46.9 |
HIP 110820 |
4.67 |
| 2026-08-04 00:00 |
22:26:50.87 |
-02:09:19.7 |
HIP 110820 |
5.97 |
| 2026-08-04 12:00 |
22:26:45.08 |
-02:09:52.8 |
HIP 110820 |
7.37 |
| 2026-08-05 00:00 |
22:26:39.27 |
-02:10:26.2 |
HIP 110820 |
8.83 |
| 2026-08-05 12:00 |
22:26:33.43 |
-02:10:59.8 |
HIP 110820 |
10.33 |
| 2026-08-06 00:00 |
22:26:27.57 |
-02:11:33.7 |
HIP 110820 |
11.85 |
| 2026-08-06 12:00 |
22:26:21.68 |
-02:12:07.9 |
HIP 110820 |
13.39 |
| 2026-08-07 00:00 |
22:26:15.77 |
-02:12:42.3 |
HIP 110820 |
14.94 |
| 2026-08-07 12:00 |
22:26:09.84 |
-02:13:17.0 |
HIP 110820 |
16.51 |
| 2026-08-08 00:00 |
22:26:03.88 |
-02:13:52.0 |
HIP 110820 |
18.09 |
| 2026-08-08 12:00 |
22:25:57.90 |
-02:14:27.2 |
HIP 110820 |
19.68 |
| 2026-08-09 00:00 |
22:25:51.90 |
-02:15:02.6 |
HIP 110820 |
21.28 |
| 2026-08-09 12:00 |
22:25:45.88 |
-02:15:38.4 |
HIP 110820 |
22.88 |
| 2026-08-10 00:00 |
22:25:39.83 |
-02:16:14.3 |
HIP 110820 |
24.50 |
| 2026-08-10 12:00 |
22:25:33.77 |
-02:16:50.5 |
HIP 110582 |
24.62 |
| 2026-08-11 00:00 |
22:25:27.69 |
-02:17:26.9 |
HIP 110582 |
23.69 |
| 2026-08-11 12:00 |
22:25:21.59 |
-02:18:03.6 |
HIP 110582 |
22.85 |
| 2026-08-12 00:00 |
22:25:15.47 |
-02:18:40.5 |
HIP 110582 |
22.09 |
| 2026-08-12 12:00 |
22:25:09.33 |
-02:19:17.6 |
HIP 110582 |
21.43 |
| 2026-08-13 00:00 |
22:25:03.18 |
-02:19:55.0 |
HIP 110582 |
20.89 |
| 2026-08-13 12:00 |
22:24:57.01 |
-02:20:32.5 |
HIP 110582 |
20.46 |
| 2026-08-14 00:00 |
22:24:50.82 |
-02:21:10.3 |
HIP 110536 |
19.69 |
| 2026-08-14 12:00 |
22:24:44.62 |
-02:21:48.3 |
HIP 110536 |
18.28 |
| 2026-08-15 00:00 |
22:24:38.41 |
-02:22:26.5 |
HIP 110536 |
16.91 |
| 2026-08-15 12:00 |
22:24:32.18 |
-02:23:05.0 |
HIP 110536 |
15.61 |
| 2026-08-16 00:00 |
22:24:25.94 |
-02:23:43.6 |
HIP 110536 |
14.38 |
| 2026-08-16 12:00 |
22:24:19.68 |
-02:24:22.4 |
HIP 110536 |
13.25 |
| 2026-08-17 00:00 |
22:24:13.42 |
-02:25:01.4 |
HIP 110536 |
12.25 |
| 2026-08-17 12:00 |
22:24:07.14 |
-02:25:40.7 |
HIP 110536 |
11.42 |
| 2026-08-18 00:00 |
22:24:00.85 |
-02:26:20.1 |
HIP 110536 |
10.79 |
| 2026-08-18 12:00 |
22:23:54.56 |
-02:26:59.7 |
HIP 110536 |
10.41 |
| 2026-08-19 00:00 |
22:23:48.25 |
-02:27:39.4 |
HIP 110536 |
10.30 |