| Parameter |
Value |
| Designation |
253P/PANSTARRS |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2018-05-07T16:43:41.024640Z |
| Orbit solution date (soln_date, UTC) |
2025-10-28T16:12:55Z |
| Obs used |
936 |
| NEO |
- |
| M1 |
8.000 |
| K1 |
29.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-05-04.0000000 |
| e |
0.41304705 |
| q (au) |
2.036337 |
| a (au) |
3.469336 |
| i (deg) |
4.940807 |
| Ω (om, deg) |
146.875124 |
| ω (w, deg) |
230.708050 |
| M (ma, deg) |
55.106908 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.139 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.139 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.655 |
| k |
0.800 |
| 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 |
| 2024-05-08 |
2025-02-03 |
+31.1826 |
-9.791 |
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 |
08:53:33.91 |
+17:06:33.9 |
HIP 43635 |
16.41 |
| 2026-03-26 12:00 |
08:53:29.72 |
+17:07:16.5 |
HIP 43635 |
15.43 |
| 2026-03-27 00:00 |
08:53:25.81 |
+17:07:57.8 |
HIP 43635 |
14.53 |
| 2026-03-27 12:00 |
08:53:22.19 |
+17:08:37.8 |
HIP 43635 |
13.70 |
| 2026-03-28 00:00 |
08:53:18.85 |
+17:09:16.6 |
HIP 43635 |
12.95 |
| 2026-03-28 12:00 |
08:53:15.80 |
+17:09:54.1 |
HIP 43635 |
12.25 |
| 2026-03-29 00:00 |
08:53:13.02 |
+17:10:30.3 |
HIP 43635 |
11.62 |
| 2026-03-29 12:00 |
08:53:10.53 |
+17:11:05.3 |
HIP 43635 |
11.04 |
| 2026-03-30 00:00 |
08:53:08.32 |
+17:11:39.0 |
HIP 43635 |
10.51 |
| 2026-03-30 12:00 |
08:53:06.39 |
+17:12:11.5 |
HIP 43635 |
10.02 |
| 2026-03-31 00:00 |
08:53:04.73 |
+17:12:42.7 |
HIP 43635 |
9.57 |
| 2026-03-31 12:00 |
08:53:03.36 |
+17:13:12.7 |
HIP 43635 |
9.14 |
| 2026-04-01 00:00 |
08:53:02.26 |
+17:13:41.4 |
HIP 43635 |
8.74 |
| 2026-04-01 12:00 |
08:53:01.43 |
+17:14:08.9 |
HIP 43635 |
8.36 |
| 2026-04-02 00:00 |
08:53:00.89 |
+17:14:35.2 |
HIP 43635 |
7.99 |
| 2026-04-02 12:00 |
08:53:00.61 |
+17:15:00.3 |
HIP 43635 |
7.62 |
| 2026-04-03 00:00 |
08:53:00.61 |
+17:15:24.1 |
HIP 43635 |
7.25 |
| 2026-04-03 12:00 |
08:53:00.88 |
+17:15:46.8 |
HIP 43635 |
6.87 |
| 2026-04-04 00:00 |
08:53:01.43 |
+17:16:08.2 |
HIP 43635 |
6.49 |
| 2026-04-04 12:00 |
08:53:02.24 |
+17:16:28.4 |
HIP 43635 |
6.11 |
| 2026-04-05 00:00 |
08:53:03.32 |
+17:16:47.4 |
HIP 43635 |
5.72 |
| 2026-04-05 12:00 |
08:53:04.68 |
+17:17:05.2 |
HIP 43635 |
5.33 |
| 2026-04-06 00:00 |
08:53:06.30 |
+17:17:21.8 |
HIP 43635 |
4.95 |
| 2026-04-06 12:00 |
08:53:08.18 |
+17:17:37.3 |
HIP 43635 |
4.59 |
| 2026-04-07 00:00 |
08:53:10.34 |
+17:17:51.5 |
HIP 43635 |
4.28 |
| 2026-04-07 12:00 |
08:53:12.75 |
+17:18:04.5 |
HIP 43635 |
4.05 |
| 2026-04-08 00:00 |
08:53:15.43 |
+17:18:16.4 |
HIP 43635 |
3.93 |
| 2026-04-08 12:00 |
08:53:18.38 |
+17:18:27.1 |
HIP 43635 |
3.97 |
| 2026-04-09 00:00 |
08:53:21.58 |
+17:18:36.6 |
HIP 43635 |
4.19 |
| 2026-04-09 12:00 |
08:53:25.05 |
+17:18:45.0 |
HIP 43635 |
4.59 |
| 2026-04-10 00:00 |
08:53:28.77 |
+17:18:52.1 |
HIP 43635 |
5.15 |
| 2026-04-10 12:00 |
08:53:32.75 |
+17:18:58.1 |
HIP 43635 |
5.87 |
| 2026-04-11 00:00 |
08:53:36.99 |
+17:19:03.0 |
HIP 43635 |
6.70 |
| 2026-04-11 12:00 |
08:53:41.49 |
+17:19:06.7 |
HIP 43635 |
7.65 |
| 2026-04-12 00:00 |
08:53:46.24 |
+17:19:09.3 |
HIP 43635 |
8.69 |
| 2026-04-12 12:00 |
08:53:51.25 |
+17:19:10.7 |
HIP 43635 |
9.81 |
| 2026-04-13 00:00 |
08:53:56.50 |
+17:19:10.9 |
HIP 43635 |
11.02 |
| 2026-04-13 12:00 |
08:54:02.01 |
+17:19:10.0 |
HIP 43635 |
12.29 |
| 2026-04-14 00:00 |
08:54:07.77 |
+17:19:08.0 |
HIP 43635 |
13.64 |
| 2026-04-14 12:00 |
08:54:13.78 |
+17:19:04.9 |
HIP 43672 |
14.69 |
| 2026-04-15 00:00 |
08:54:20.04 |
+17:19:00.6 |
HIP 43672 |
15.38 |
| 2026-04-15 12:00 |
08:54:26.54 |
+17:18:55.2 |
HIP 43811 |
14.37 |
| 2026-04-16 00:00 |
08:54:33.29 |
+17:18:48.6 |
HIP 43811 |
12.83 |