| 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) |
| 2026-07-29 00:00 |
10:11:25.10 |
+11:55:17.7 |
HIP 49925 |
7.33 |
| 2026-07-29 12:00 |
10:11:54.64 |
+11:52:45.0 |
HIP 49925 |
10.55 |
| 2026-07-30 00:00 |
10:12:24.20 |
+11:50:11.9 |
HIP 49925 |
16.93 |
| 2026-07-30 12:00 |
10:12:53.77 |
+11:47:38.5 |
HIP 50072 |
22.37 |
| 2026-07-31 00:00 |
10:13:23.36 |
+11:45:04.8 |
HIP 50072 |
23.68 |
| 2026-07-31 12:00 |
10:13:52.96 |
+11:42:30.8 |
HIP 50225 |
21.54 |
| 2026-08-01 00:00 |
10:14:22.57 |
+11:39:56.5 |
HIP 50225 |
17.35 |
| 2026-08-01 12:00 |
10:14:52.19 |
+11:37:21.9 |
HIP 50225 |
16.00 |
| 2026-08-02 00:00 |
10:15:21.83 |
+11:34:47.0 |
HIP 50297 |
12.98 |
| 2026-08-02 12:00 |
10:15:51.48 |
+11:32:11.8 |
HIP 50297 |
9.13 |
| 2026-08-03 00:00 |
10:16:21.14 |
+11:29:36.4 |
HIP 50297 |
10.81 |
| 2026-08-03 12:00 |
10:16:50.81 |
+11:27:00.6 |
HIP 50297 |
16.42 |
| 2026-08-04 00:00 |
10:17:20.49 |
+11:24:24.6 |
HIP 50424 |
9.62 |
| 2026-08-04 12:00 |
10:17:50.18 |
+11:21:48.3 |
HIP 50424 |
4.92 |
| 2026-08-05 00:00 |
10:18:19.89 |
+11:19:11.7 |
HIP 50424 |
8.68 |
| 2026-08-05 12:00 |
10:18:49.60 |
+11:16:34.8 |
HIP 50424 |
15.69 |
| 2026-08-06 00:00 |
10:19:19.32 |
+11:13:57.7 |
HIP 50623 |
17.97 |
| 2026-08-06 12:00 |
10:19:49.05 |
+11:11:20.3 |
HIP 50623 |
13.45 |
| 2026-08-07 00:00 |
10:20:18.78 |
+11:08:42.6 |
HIP 50623 |
12.60 |
| 2026-08-07 12:00 |
10:20:48.53 |
+11:06:04.7 |
HIP 50729 |
10.11 |
| 2026-08-08 00:00 |
10:21:18.28 |
+11:03:26.6 |
HIP 50729 |
2.99 |
| 2026-08-08 12:00 |
10:21:48.03 |
+11:00:48.2 |
HIP 50729 |
6.01 |
| 2026-08-09 00:00 |
10:22:17.80 |
+10:58:09.5 |
HIP 50729 |
13.56 |
| 2026-08-09 12:00 |
10:22:47.57 |
+10:55:30.6 |
HIP 50845 |
18.94 |
| 2026-08-10 00:00 |
10:23:17.34 |
+10:52:51.4 |
HIP 50845 |
21.99 |
| 2026-08-10 12:00 |
10:23:47.12 |
+10:50:12.1 |
HIP 50950 |
16.93 |
| 2026-08-11 00:00 |
10:24:16.90 |
+10:47:32.5 |
HIP 50950 |
12.29 |
| 2026-08-11 12:00 |
10:24:46.68 |
+10:44:52.7 |
HIP 50950 |
11.70 |
| 2026-08-12 00:00 |
10:25:16.47 |
+10:42:12.6 |
HIP 50950 |
15.61 |
| 2026-08-12 12:00 |
10:25:46.26 |
+10:39:32.4 |
HIP 51105 |
13.62 |
| 2026-08-13 00:00 |
10:26:16.05 |
+10:36:51.9 |
HIP 51105 |
7.16 |
| 2026-08-13 12:00 |
10:26:45.84 |
+10:34:11.2 |
HIP 51105 |
6.21 |
| 2026-08-14 00:00 |
10:27:15.63 |
+10:31:30.4 |
HIP 51168 |
5.33 |
| 2026-08-14 12:00 |
10:27:45.42 |
+10:28:49.3 |
HIP 51168 |
9.97 |
| 2026-08-15 00:00 |
10:28:15.20 |
+10:26:08.1 |
HIP 51351 |
16.90 |
| 2026-08-15 12:00 |
10:28:44.99 |
+10:23:26.6 |
HIP 51351 |
11.90 |
| 2026-08-16 00:00 |
10:29:14.77 |
+10:20:45.0 |
HIP 51351 |
10.92 |
| 2026-08-16 12:00 |
10:29:44.55 |
+10:18:03.3 |
HIP 51351 |
14.79 |
| 2026-08-17 00:00 |
10:30:14.33 |
+10:15:21.3 |
HIP 51520 |
20.68 |
| 2026-08-17 12:00 |
10:30:44.10 |
+10:12:39.2 |
HIP 51520 |
13.37 |
| 2026-08-18 00:00 |
10:31:13.87 |
+10:09:56.9 |
HIP 51520 |
7.21 |
| 2026-08-18 12:00 |
10:31:43.64 |
+10:07:14.5 |
HIP 51520 |
6.85 |
| 2026-08-19 00:00 |
10:32:13.39 |
+10:04:31.9 |
HIP 51520 |
12.80 |