| Parameter |
Value |
| Designation |
491P/Spacewatch-PANSTARRS |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2024-09-06T20:24:15.223680Z |
| Orbit solution date (soln_date, UTC) |
2026-07-28T14:12:31Z |
| Obs used |
502 |
| NEO |
- |
| M1 |
10.900 |
| K1 |
8.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2024-05-30T08:01:15.830400Z |
| Discovery magnitude (MPC) |
21.20 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-06-24.0000000 |
| e |
0.25951471 |
| q (au) |
3.711257 |
| a (au) |
5.011925 |
| i (deg) |
9.371052 |
| Ω (om, deg) |
311.733911 |
| ω (w, deg) |
299.094577 |
| M (ma, deg) |
257.151363 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.212 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.212 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.965 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
23:10:18.43 |
+00:33:19.9 |
HIP 114458 |
11.86 |
| 2026-07-29 12:00 |
23:10:08.90 |
+00:33:19.3 |
HIP 114458 |
13.59 |
| 2026-07-30 00:00 |
23:09:59.19 |
+00:33:17.4 |
HIP 114458 |
15.51 |
| 2026-07-30 12:00 |
23:09:49.32 |
+00:33:14.3 |
HIP 114458 |
17.58 |
| 2026-07-31 00:00 |
23:09:39.28 |
+00:33:10.0 |
HIP 114458 |
19.78 |
| 2026-07-31 12:00 |
23:09:29.08 |
+00:33:04.4 |
HIP 114458 |
22.07 |
| 2026-08-01 00:00 |
23:09:18.71 |
+00:32:57.6 |
HIP 114458 |
24.45 |
| 2026-08-01 12:00 |
23:09:08.17 |
+00:32:49.6 |
HIP 114458 |
26.90 |
| 2026-08-02 00:00 |
23:08:57.48 |
+00:32:40.3 |
HIP 114458 |
29.41 |
| 2026-08-02 12:00 |
23:08:46.62 |
+00:32:29.9 |
HIP 114458 |
31.99 |
| 2026-08-03 00:00 |
23:08:35.60 |
+00:32:18.2 |
HIP 114458 |
34.62 |
| 2026-08-03 12:00 |
23:08:24.43 |
+00:32:05.4 |
HIP 114458 |
37.31 |
| 2026-08-04 00:00 |
23:08:13.10 |
+00:31:51.3 |
HIP 114458 |
40.04 |
| 2026-08-04 12:00 |
23:08:01.62 |
+00:31:36.0 |
HIP 114458 |
42.83 |
| 2026-08-05 00:00 |
23:07:49.98 |
+00:31:19.5 |
HIP 114458 |
45.66 |
| 2026-08-05 12:00 |
23:07:38.19 |
+00:31:01.9 |
HIP 114098 |
45.83 |
| 2026-08-06 00:00 |
23:07:26.25 |
+00:30:43.0 |
HIP 114098 |
44.55 |
| 2026-08-06 12:00 |
23:07:14.17 |
+00:30:23.0 |
HIP 114098 |
43.41 |
| 2026-08-07 00:00 |
23:07:01.93 |
+00:30:01.8 |
HIP 114098 |
42.43 |
| 2026-08-07 12:00 |
23:06:49.55 |
+00:29:39.4 |
HIP 114098 |
41.64 |
| 2026-08-08 00:00 |
23:06:37.03 |
+00:29:15.8 |
HIP 114098 |
41.04 |
| 2026-08-08 12:00 |
23:06:24.37 |
+00:28:51.1 |
HIP 114098 |
40.67 |
| 2026-08-09 00:00 |
23:06:11.57 |
+00:28:25.3 |
HIP 114098 |
40.53 |
| 2026-08-09 12:00 |
23:05:58.63 |
+00:27:58.3 |
HIP 114098 |
40.63 |
| 2026-08-10 00:00 |
23:05:45.56 |
+00:27:30.1 |
HIP 114098 |
40.99 |
| 2026-08-10 12:00 |
23:05:32.35 |
+00:27:00.9 |
HIP 114098 |
41.60 |
| 2026-08-11 00:00 |
23:05:19.02 |
+00:26:30.5 |
HIP 114098 |
42.46 |
| 2026-08-11 12:00 |
23:05:05.55 |
+00:25:59.0 |
HIP 113770 |
40.31 |
| 2026-08-12 00:00 |
23:04:51.96 |
+00:25:26.4 |
HIP 113770 |
36.92 |
| 2026-08-12 12:00 |
23:04:38.25 |
+00:24:52.7 |
HIP 113770 |
33.52 |
| 2026-08-13 00:00 |
23:04:24.41 |
+00:24:17.9 |
HIP 113770 |
30.09 |
| 2026-08-13 12:00 |
23:04:10.45 |
+00:23:42.1 |
HIP 113770 |
26.67 |
| 2026-08-14 00:00 |
23:03:56.38 |
+00:23:05.2 |
HIP 113770 |
23.25 |
| 2026-08-14 12:00 |
23:03:42.20 |
+00:22:27.2 |
HIP 113770 |
19.86 |
| 2026-08-15 00:00 |
23:03:27.90 |
+00:21:48.3 |
HIP 113770 |
16.54 |
| 2026-08-15 12:00 |
23:03:13.49 |
+00:21:08.2 |
HIP 113770 |
13.36 |
| 2026-08-16 00:00 |
23:02:58.98 |
+00:20:27.2 |
HIP 113770 |
10.48 |
| 2026-08-16 12:00 |
23:02:44.37 |
+00:19:45.2 |
HIP 113770 |
8.29 |
| 2026-08-17 00:00 |
23:02:29.65 |
+00:19:02.2 |
HIP 113770 |
7.44 |
| 2026-08-17 12:00 |
23:02:14.83 |
+00:18:18.2 |
HIP 113737 |
6.33 |
| 2026-08-18 00:00 |
23:01:59.92 |
+00:17:33.2 |
HIP 113737 |
6.42 |
| 2026-08-18 12:00 |
23:01:44.92 |
+00:16:47.3 |
HIP 113737 |
8.46 |
| 2026-08-19 00:00 |
23:01:29.82 |
+00:16:00.4 |
HIP 113672 |
8.89 |