| 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) |
| 2026-09-20 00:00 |
11:03:25.68 |
+07:08:59.5 |
HIP 54182 |
26.20 |
| 2026-09-20 12:00 |
11:03:54.09 |
+07:06:16.1 |
HIP 54182 |
21.69 |
| 2026-09-21 00:00 |
11:04:22.47 |
+07:03:32.9 |
HIP 54182 |
19.20 |
| 2026-09-21 12:00 |
11:04:50.80 |
+07:00:49.9 |
HIP 54268 |
19.05 |
| 2026-09-22 00:00 |
11:05:19.10 |
+06:58:07.0 |
HIP 54268 |
12.61 |
| 2026-09-22 12:00 |
11:05:47.36 |
+06:55:24.3 |
HIP 54268 |
8.28 |
| 2026-09-23 00:00 |
11:06:15.58 |
+06:52:41.8 |
HIP 54268 |
9.54 |
| 2026-09-23 12:00 |
11:06:43.76 |
+06:49:59.4 |
HIP 54331 |
8.34 |
| 2026-09-24 00:00 |
11:07:11.90 |
+06:47:17.2 |
HIP 54331 |
7.35 |
| 2026-09-24 12:00 |
11:07:40.00 |
+06:44:35.2 |
HIP 54331 |
12.27 |
| 2026-09-25 00:00 |
11:08:08.06 |
+06:41:53.3 |
HIP 54423 |
7.60 |
| 2026-09-25 12:00 |
11:08:36.08 |
+06:39:11.7 |
HIP 54423 |
7.36 |
| 2026-09-26 00:00 |
11:09:04.06 |
+06:36:30.2 |
HIP 54423 |
12.72 |
| 2026-09-26 12:00 |
11:09:31.99 |
+06:33:49.0 |
HIP 54423 |
19.49 |
| 2026-09-27 00:00 |
11:09:59.88 |
+06:31:07.9 |
HIP 54639 |
16.12 |
| 2026-09-27 12:00 |
11:10:27.73 |
+06:28:27.0 |
HIP 54639 |
8.70 |
| 2026-09-28 00:00 |
11:10:55.53 |
+06:25:46.4 |
HIP 54639 |
1.29 |
| 2026-09-28 12:00 |
11:11:23.30 |
+06:23:05.9 |
HIP 54639 |
6.10 |
| 2026-09-29 00:00 |
11:11:51.01 |
+06:20:25.7 |
HIP 54639 |
13.49 |
| 2026-09-29 12:00 |
11:12:18.68 |
+06:17:45.7 |
HIP 54639 |
20.86 |
| 2026-09-30 00:00 |
11:12:46.31 |
+06:15:05.9 |
HIP 54639 |
28.23 |
| 2026-09-30 12:00 |
11:13:13.89 |
+06:12:26.3 |
HIP 54887 |
21.73 |
| 2026-10-01 00:00 |
11:13:41.43 |
+06:09:47.0 |
HIP 54887 |
15.10 |
| 2026-10-01 12:00 |
11:14:08.91 |
+06:07:08.0 |
HIP 54887 |
9.57 |
| 2026-10-02 00:00 |
11:14:36.35 |
+06:04:29.1 |
HIP 54904 |
5.01 |
| 2026-10-02 12:00 |
11:15:03.75 |
+06:01:50.5 |
HIP 54904 |
8.08 |
| 2026-10-03 00:00 |
11:15:31.09 |
+05:59:12.2 |
HIP 54904 |
14.56 |
| 2026-10-03 12:00 |
11:15:58.39 |
+05:56:34.2 |
HIP 54904 |
21.55 |
| 2026-10-04 00:00 |
11:16:25.63 |
+05:53:56.4 |
HIP 54904 |
28.67 |
| 2026-10-04 12:00 |
11:16:52.83 |
+05:51:18.9 |
HIP 54904 |
35.84 |
| 2026-10-05 00:00 |
11:17:19.97 |
+05:48:41.6 |
HIP 55323 |
42.51 |
| 2026-10-05 12:00 |
11:17:47.07 |
+05:46:04.7 |
HIP 55323 |
38.66 |
| 2026-10-06 00:00 |
11:18:14.11 |
+05:43:28.0 |
HIP 55323 |
35.87 |
| 2026-10-06 12:00 |
11:18:41.10 |
+05:40:51.7 |
HIP 55232 |
33.54 |
| 2026-10-07 00:00 |
11:19:08.03 |
+05:38:15.6 |
HIP 55232 |
31.81 |
| 2026-10-07 12:00 |
11:19:34.91 |
+05:35:39.9 |
HIP 55321 |
28.88 |
| 2026-10-08 00:00 |
11:20:01.74 |
+05:33:04.4 |
HIP 55321 |
26.64 |
| 2026-10-08 12:00 |
11:20:28.51 |
+05:30:29.3 |
HIP 55321 |
26.23 |
| 2026-10-09 00:00 |
11:20:55.22 |
+05:27:54.6 |
HIP 55321 |
27.71 |
| 2026-10-09 12:00 |
11:21:21.88 |
+05:25:20.1 |
HIP 55321 |
30.81 |
| 2026-10-10 00:00 |
11:21:48.48 |
+05:22:46.0 |
HIP 55423 |
32.36 |
| 2026-10-10 12:00 |
11:22:15.02 |
+05:20:12.3 |
HIP 55575 |
32.78 |
| 2026-10-11 00:00 |
11:22:41.50 |
+05:17:38.9 |
HIP 55575 |
28.47 |