| 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) |
| 2026-07-29 00:00 |
18:34:44.20 |
+07:23:40.2 |
HIP 90924 |
28.41 |
| 2026-07-29 12:00 |
18:34:38.31 |
+07:23:20.1 |
HIP 90924 |
26.99 |
| 2026-07-30 00:00 |
18:34:32.45 |
+07:22:59.7 |
HIP 90924 |
25.59 |
| 2026-07-30 12:00 |
18:34:26.63 |
+07:22:39.0 |
HIP 90924 |
24.20 |
| 2026-07-31 00:00 |
18:34:20.83 |
+07:22:17.9 |
HIP 90924 |
22.84 |
| 2026-07-31 12:00 |
18:34:15.07 |
+07:21:56.4 |
HIP 90924 |
21.50 |
| 2026-08-01 00:00 |
18:34:09.34 |
+07:21:34.7 |
HIP 90924 |
20.19 |
| 2026-08-01 12:00 |
18:34:03.64 |
+07:21:12.5 |
HIP 90924 |
18.92 |
| 2026-08-02 00:00 |
18:33:57.98 |
+07:20:50.1 |
HIP 90924 |
17.68 |
| 2026-08-02 12:00 |
18:33:52.34 |
+07:20:27.3 |
HIP 90924 |
16.48 |
| 2026-08-03 00:00 |
18:33:46.75 |
+07:20:04.1 |
HIP 90924 |
15.34 |
| 2026-08-03 12:00 |
18:33:41.19 |
+07:19:40.7 |
HIP 90924 |
14.27 |
| 2026-08-04 00:00 |
18:33:35.66 |
+07:19:16.9 |
HIP 90924 |
13.27 |
| 2026-08-04 12:00 |
18:33:30.17 |
+07:18:52.8 |
HIP 90924 |
12.36 |
| 2026-08-05 00:00 |
18:33:24.71 |
+07:18:28.3 |
HIP 90924 |
11.57 |
| 2026-08-05 12:00 |
18:33:19.29 |
+07:18:03.6 |
HIP 90924 |
10.92 |
| 2026-08-06 00:00 |
18:33:13.91 |
+07:17:38.5 |
HIP 90924 |
10.43 |
| 2026-08-06 12:00 |
18:33:08.57 |
+07:17:13.1 |
HIP 90924 |
10.11 |
| 2026-08-07 00:00 |
18:33:03.26 |
+07:16:47.4 |
HIP 90924 |
9.99 |
| 2026-08-07 12:00 |
18:32:57.99 |
+07:16:21.4 |
HIP 90924 |
10.07 |
| 2026-08-08 00:00 |
18:32:52.76 |
+07:15:55.1 |
HIP 90924 |
10.33 |
| 2026-08-08 12:00 |
18:32:47.56 |
+07:15:28.5 |
HIP 90924 |
10.77 |
| 2026-08-09 00:00 |
18:32:42.41 |
+07:15:01.6 |
HIP 90924 |
11.36 |
| 2026-08-09 12:00 |
18:32:37.29 |
+07:14:34.4 |
HIP 90924 |
12.08 |
| 2026-08-10 00:00 |
18:32:32.22 |
+07:14:06.9 |
HIP 90826 |
12.20 |
| 2026-08-10 12:00 |
18:32:27.19 |
+07:13:39.1 |
HIP 90826 |
10.95 |
| 2026-08-11 00:00 |
18:32:22.19 |
+07:13:11.0 |
HIP 90826 |
9.73 |
| 2026-08-11 12:00 |
18:32:17.24 |
+07:12:42.7 |
HIP 90826 |
8.56 |
| 2026-08-12 00:00 |
18:32:12.33 |
+07:12:14.0 |
HIP 90826 |
7.45 |
| 2026-08-12 12:00 |
18:32:07.46 |
+07:11:45.1 |
HIP 90826 |
6.43 |
| 2026-08-13 00:00 |
18:32:02.64 |
+07:11:15.9 |
HIP 90826 |
5.53 |
| 2026-08-13 12:00 |
18:31:57.86 |
+07:10:46.5 |
HIP 90826 |
4.83 |
| 2026-08-14 00:00 |
18:31:53.12 |
+07:10:16.7 |
HIP 90826 |
4.40 |
| 2026-08-14 12:00 |
18:31:48.42 |
+07:09:46.7 |
HIP 90826 |
4.34 |
| 2026-08-15 00:00 |
18:31:43.77 |
+07:09:16.5 |
HIP 90826 |
4.63 |
| 2026-08-15 12:00 |
18:31:39.16 |
+07:08:46.0 |
HIP 90826 |
5.23 |
| 2026-08-16 00:00 |
18:31:34.60 |
+07:08:15.2 |
HIP 90826 |
6.03 |
| 2026-08-16 12:00 |
18:31:30.08 |
+07:07:44.2 |
HIP 90826 |
6.96 |
| 2026-08-17 00:00 |
18:31:25.61 |
+07:07:13.0 |
HIP 90826 |
7.97 |
| 2026-08-17 12:00 |
18:31:21.18 |
+07:06:41.5 |
HIP 90826 |
9.03 |
| 2026-08-18 00:00 |
18:31:16.80 |
+07:06:09.8 |
HIP 90826 |
10.12 |
| 2026-08-18 12:00 |
18:31:12.47 |
+07:05:37.8 |
HIP 90826 |
11.23 |
| 2026-08-19 00:00 |
18:31:08.18 |
+07:05:05.7 |
HIP 90826 |
12.35 |