| 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 |
-0.999 |
| 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) |
| 2026-03-26 00:00 |
18:53:33.22 |
+05:26:51.9 |
HIP 92724 |
2.30 |
| 2026-03-26 12:00 |
18:53:34.08 |
+05:27:49.9 |
HIP 92724 |
1.84 |
| 2026-03-27 00:00 |
18:53:34.87 |
+05:28:47.9 |
HIP 92724 |
1.88 |
| 2026-03-27 12:00 |
18:53:35.61 |
+05:29:45.9 |
HIP 92724 |
2.37 |
| 2026-03-28 00:00 |
18:53:36.29 |
+05:30:43.9 |
HIP 92724 |
3.11 |
| 2026-03-28 12:00 |
18:53:36.92 |
+05:31:41.9 |
HIP 92724 |
3.97 |
| 2026-03-29 00:00 |
18:53:37.49 |
+05:32:39.9 |
HIP 92724 |
4.87 |
| 2026-03-29 12:00 |
18:53:38.00 |
+05:33:37.9 |
HIP 92724 |
5.80 |
| 2026-03-30 00:00 |
18:53:38.45 |
+05:34:35.8 |
HIP 92724 |
6.74 |
| 2026-03-30 12:00 |
18:53:38.85 |
+05:35:33.8 |
HIP 92724 |
7.70 |
| 2026-03-31 00:00 |
18:53:39.18 |
+05:36:31.7 |
HIP 92724 |
8.65 |
| 2026-03-31 12:00 |
18:53:39.47 |
+05:37:29.7 |
HIP 92724 |
9.61 |
| 2026-04-01 00:00 |
18:53:39.69 |
+05:38:27.6 |
HIP 92724 |
10.57 |
| 2026-04-01 12:00 |
18:53:39.86 |
+05:39:25.4 |
HIP 92724 |
11.54 |
| 2026-04-02 00:00 |
18:53:39.96 |
+05:40:23.3 |
HIP 92724 |
12.50 |
| 2026-04-02 12:00 |
18:53:40.02 |
+05:41:21.1 |
HIP 92724 |
13.46 |
| 2026-04-03 00:00 |
18:53:40.01 |
+05:42:18.9 |
HIP 92724 |
14.42 |
| 2026-04-03 12:00 |
18:53:39.95 |
+05:43:16.6 |
HIP 92724 |
15.39 |
| 2026-04-04 00:00 |
18:53:39.82 |
+05:44:14.3 |
HIP 92706 |
14.56 |
| 2026-04-04 12:00 |
18:53:39.64 |
+05:45:12.0 |
HIP 92706 |
13.62 |
| 2026-04-05 00:00 |
18:53:39.41 |
+05:46:09.6 |
HIP 92706 |
12.68 |
| 2026-04-05 12:00 |
18:53:39.11 |
+05:47:07.1 |
HIP 92706 |
11.75 |
| 2026-04-06 00:00 |
18:53:38.76 |
+05:48:04.6 |
HIP 92706 |
10.81 |
| 2026-04-06 12:00 |
18:53:38.35 |
+05:49:02.0 |
HIP 92706 |
9.88 |
| 2026-04-07 00:00 |
18:53:37.88 |
+05:49:59.4 |
HIP 92706 |
8.94 |
| 2026-04-07 12:00 |
18:53:37.35 |
+05:50:56.7 |
HIP 92706 |
8.01 |
| 2026-04-08 00:00 |
18:53:36.77 |
+05:51:53.9 |
HIP 92706 |
7.08 |
| 2026-04-08 12:00 |
18:53:36.13 |
+05:52:51.1 |
HIP 92706 |
6.16 |
| 2026-04-09 00:00 |
18:53:35.43 |
+05:53:48.2 |
HIP 92706 |
5.25 |
| 2026-04-09 12:00 |
18:53:34.67 |
+05:54:45.2 |
HIP 92706 |
4.35 |
| 2026-04-10 00:00 |
18:53:33.85 |
+05:55:42.1 |
HIP 92706 |
3.48 |
| 2026-04-10 12:00 |
18:53:32.98 |
+05:56:38.9 |
HIP 92706 |
2.68 |
| 2026-04-11 00:00 |
18:53:32.04 |
+05:57:35.6 |
HIP 92706 |
2.01 |
| 2026-04-11 12:00 |
18:53:31.05 |
+05:58:32.3 |
HIP 92706 |
1.65 |
| 2026-04-12 00:00 |
18:53:30.00 |
+05:59:28.8 |
HIP 92706 |
1.82 |
| 2026-04-12 12:00 |
18:53:28.90 |
+06:00:25.2 |
HIP 92706 |
2.40 |
| 2026-04-13 00:00 |
18:53:27.73 |
+06:01:21.6 |
HIP 92706 |
3.18 |
| 2026-04-13 12:00 |
18:53:26.51 |
+06:02:17.8 |
HIP 92706 |
4.04 |
| 2026-04-14 00:00 |
18:53:25.23 |
+06:03:13.9 |
HIP 92706 |
4.95 |
| 2026-04-14 12:00 |
18:53:23.89 |
+06:04:09.9 |
HIP 92706 |
5.88 |
| 2026-04-15 00:00 |
18:53:22.49 |
+06:05:05.7 |
HIP 92706 |
6.82 |
| 2026-04-15 12:00 |
18:53:21.04 |
+06:06:01.5 |
HIP 92706 |
7.78 |
| 2026-04-16 00:00 |
18:53:19.53 |
+06:06:57.1 |
HIP 92706 |
8.75 |