| Parameter |
Value |
| Designation |
C/2019 A9 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-07-26T12:36:17.003520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:51Z |
| Obs used |
199 |
| NEO |
- |
| M1 |
10.300 |
| K1 |
17.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2019-01-14T06:23:34.368000Z |
| Discovery magnitude (MPC) |
20.30 i |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-03-25.0000000 |
| e |
0.96326067 |
| q (au) |
1.426376 |
| a (au) |
38.824214 |
| i (deg) |
84.341078 |
| Ω (om, deg) |
278.368440 |
| ω (w, deg) |
237.802336 |
| M (ma, deg) |
359.496725 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.529 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.529 |
| 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 |
| 2018-12-18 |
2019-04-22 |
+6.0772 |
-2.366 |
| 2019-08-05 |
2020-06-16 |
+2.0655 |
-3.527 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
18:47:18.99 |
+07:15:20.9 |
HIP 92055 |
23.07 |
| 2026-06-01 12:00 |
18:47:13.09 |
+07:15:50.2 |
HIP 92055 |
21.66 |
| 2026-06-02 00:00 |
18:47:07.15 |
+07:16:19.0 |
HIP 92055 |
20.27 |
| 2026-06-02 12:00 |
18:47:01.19 |
+07:16:47.5 |
HIP 92055 |
18.90 |
| 2026-06-03 00:00 |
18:46:55.20 |
+07:17:15.5 |
HIP 92055 |
17.54 |
| 2026-06-03 12:00 |
18:46:49.18 |
+07:17:43.1 |
HIP 92055 |
16.21 |
| 2026-06-04 00:00 |
18:46:43.13 |
+07:18:10.3 |
HIP 92055 |
14.92 |
| 2026-06-04 12:00 |
18:46:37.05 |
+07:18:37.1 |
HIP 92055 |
13.68 |
| 2026-06-05 00:00 |
18:46:30.94 |
+07:19:03.5 |
HIP 92055 |
12.51 |
| 2026-06-05 12:00 |
18:46:24.81 |
+07:19:29.5 |
HIP 92055 |
11.42 |
| 2026-06-06 00:00 |
18:46:18.65 |
+07:19:55.1 |
HIP 92055 |
10.45 |
| 2026-06-06 12:00 |
18:46:12.47 |
+07:20:20.2 |
HIP 92055 |
9.63 |
| 2026-06-07 00:00 |
18:46:06.25 |
+07:20:44.9 |
HIP 92055 |
9.01 |
| 2026-06-07 12:00 |
18:46:00.02 |
+07:21:09.2 |
HIP 92055 |
8.64 |
| 2026-06-08 00:00 |
18:45:53.75 |
+07:21:33.0 |
HIP 92055 |
8.54 |
| 2026-06-08 12:00 |
18:45:47.47 |
+07:21:56.5 |
HIP 92055 |
8.74 |
| 2026-06-09 00:00 |
18:45:41.16 |
+07:22:19.5 |
HIP 92055 |
9.21 |
| 2026-06-09 12:00 |
18:45:34.82 |
+07:22:42.0 |
HIP 92055 |
9.92 |
| 2026-06-10 00:00 |
18:45:28.47 |
+07:23:04.2 |
HIP 92055 |
10.82 |
| 2026-06-10 12:00 |
18:45:22.09 |
+07:23:25.9 |
HIP 92055 |
11.87 |
| 2026-06-11 00:00 |
18:45:15.68 |
+07:23:47.2 |
HIP 91944 |
12.14 |
| 2026-06-11 12:00 |
18:45:09.26 |
+07:24:08.0 |
HIP 91944 |
10.57 |
| 2026-06-12 00:00 |
18:45:02.82 |
+07:24:28.4 |
HIP 91944 |
9.02 |
| 2026-06-12 12:00 |
18:44:56.35 |
+07:24:48.4 |
HIP 91944 |
7.51 |
| 2026-06-13 00:00 |
18:44:49.87 |
+07:25:07.9 |
HIP 91944 |
6.06 |
| 2026-06-13 12:00 |
18:44:43.37 |
+07:25:27.0 |
HIP 91944 |
4.75 |
| 2026-06-14 00:00 |
18:44:36.85 |
+07:25:45.6 |
HIP 91944 |
3.71 |
| 2026-06-14 12:00 |
18:44:30.31 |
+07:26:03.8 |
HIP 91944 |
3.23 |
| 2026-06-15 00:00 |
18:44:23.75 |
+07:26:21.5 |
HIP 91944 |
3.55 |
| 2026-06-15 12:00 |
18:44:17.17 |
+07:26:38.8 |
HIP 91944 |
4.51 |
| 2026-06-16 00:00 |
18:44:10.58 |
+07:26:55.7 |
HIP 91944 |
5.79 |
| 2026-06-16 12:00 |
18:44:03.98 |
+07:27:12.1 |
HIP 91944 |
7.24 |
| 2026-06-17 00:00 |
18:43:57.36 |
+07:27:28.0 |
HIP 91944 |
8.77 |
| 2026-06-17 12:00 |
18:43:50.72 |
+07:27:43.5 |
HIP 91944 |
10.34 |
| 2026-06-18 00:00 |
18:43:44.07 |
+07:27:58.6 |
HIP 91944 |
11.94 |
| 2026-06-18 12:00 |
18:43:37.41 |
+07:28:13.2 |
HIP 91944 |
13.56 |
| 2026-06-19 00:00 |
18:43:30.73 |
+07:28:27.3 |
HIP 91803 |
13.49 |
| 2026-06-19 12:00 |
18:43:24.05 |
+07:28:41.0 |
HIP 91803 |
13.03 |
| 2026-06-20 00:00 |
18:43:17.35 |
+07:28:54.3 |
HIP 91803 |
12.78 |
| 2026-06-20 12:00 |
18:43:10.64 |
+07:29:07.1 |
HIP 91803 |
12.73 |
| 2026-06-21 00:00 |
18:43:03.92 |
+07:29:19.5 |
HIP 91801 |
12.78 |
| 2026-06-21 12:00 |
18:42:57.18 |
+07:29:31.4 |
HIP 91801 |
12.74 |
| 2026-06-22 00:00 |
18:42:50.44 |
+07:29:42.8 |
HIP 91801 |
12.94 |