| Parameter |
Value |
| Designation |
250P/Larson |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2018-02-01T20:31:02.945280Z |
| Orbit solution date (soln_date, UTC) |
2026-05-28T12:12:25Z |
| Obs used |
571 |
| NEO |
- |
| M1 |
14.600 |
| K1 |
10.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-08-24.0000000 |
| e |
0.40736973 |
| q (au) |
2.212476 |
| a (au) |
3.733316 |
| i (deg) |
13.289115 |
| Ω (om, deg) |
73.709887 |
| ω (w, deg) |
45.028545 |
| M (ma, deg) |
238.004787 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.845 + 3.530\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.845 |
| n |
3.530 |
| gf |
0.982 |
| gb |
-0.684 |
| k |
0.800 |
| δ90 |
4.965 |
| 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) |
| 2026-09-20 00:00 |
14:39:43.86 |
-11:11:25.5 |
HIP 71646 |
25.19 |
| 2026-09-20 12:00 |
14:40:14.60 |
-11:14:50.3 |
HIP 71808 |
17.28 |
| 2026-09-21 00:00 |
14:40:45.40 |
-11:18:14.8 |
HIP 71808 |
8.99 |
| 2026-09-21 12:00 |
14:41:16.28 |
-11:21:39.0 |
HIP 71808 |
0.70 |
| 2026-09-22 00:00 |
14:41:47.23 |
-11:25:02.9 |
HIP 71808 |
7.62 |
| 2026-09-22 12:00 |
14:42:18.25 |
-11:28:26.5 |
HIP 71808 |
15.94 |
| 2026-09-23 00:00 |
14:42:49.33 |
-11:31:49.8 |
HIP 72053 |
22.06 |
| 2026-09-23 12:00 |
14:43:20.48 |
-11:35:12.8 |
HIP 72053 |
13.93 |
| 2026-09-24 00:00 |
14:43:51.70 |
-11:38:35.5 |
HIP 72053 |
6.36 |
| 2026-09-24 12:00 |
14:44:22.98 |
-11:41:57.8 |
HIP 72053 |
5.15 |
| 2026-09-25 00:00 |
14:44:54.33 |
-11:45:19.9 |
HIP 72053 |
12.37 |
| 2026-09-25 12:00 |
14:45:25.75 |
-11:48:41.6 |
HIP 72053 |
20.50 |
| 2026-09-26 00:00 |
14:45:57.23 |
-11:52:03.0 |
HIP 72301 |
25.33 |
| 2026-09-26 12:00 |
14:46:28.77 |
-11:55:24.0 |
HIP 72301 |
24.10 |
| 2026-09-27 00:00 |
14:47:00.38 |
-11:58:44.7 |
HIP 72301 |
25.71 |
| 2026-09-27 12:00 |
14:47:32.05 |
-12:02:05.1 |
HIP 72301 |
29.72 |
| 2026-09-28 00:00 |
14:48:03.78 |
-12:05:25.2 |
HIP 72301 |
35.33 |
| 2026-09-28 12:00 |
14:48:35.57 |
-12:08:44.9 |
HIP 72596 |
30.47 |
| 2026-09-29 00:00 |
14:49:07.43 |
-12:12:04.2 |
HIP 72596 |
24.32 |
| 2026-09-29 12:00 |
14:49:39.34 |
-12:15:23.2 |
HIP 72596 |
19.94 |
| 2026-09-30 00:00 |
14:50:11.32 |
-12:18:41.9 |
HIP 72596 |
18.63 |
| 2026-09-30 12:00 |
14:50:43.35 |
-12:22:00.2 |
HIP 72596 |
20.98 |
| 2026-10-01 00:00 |
14:51:15.45 |
-12:25:18.2 |
HIP 72804 |
23.92 |
| 2026-10-01 12:00 |
14:51:47.60 |
-12:28:35.8 |
HIP 72804 |
16.91 |
| 2026-10-02 00:00 |
14:52:19.82 |
-12:31:53.0 |
HIP 72811 |
10.90 |
| 2026-10-02 12:00 |
14:52:52.09 |
-12:35:09.9 |
HIP 72811 |
3.54 |
| 2026-10-03 00:00 |
14:53:24.42 |
-12:38:26.3 |
HIP 72811 |
7.21 |
| 2026-10-03 12:00 |
14:53:56.80 |
-12:41:42.5 |
HIP 72811 |
15.41 |
| 2026-10-04 00:00 |
14:54:29.25 |
-12:44:58.2 |
HIP 73044 |
18.84 |
| 2026-10-04 12:00 |
14:55:01.74 |
-12:48:13.6 |
HIP 73044 |
13.71 |
| 2026-10-05 00:00 |
14:55:34.30 |
-12:51:28.6 |
HIP 73044 |
12.94 |
| 2026-10-05 12:00 |
14:56:06.91 |
-12:54:43.2 |
HIP 73044 |
17.15 |
| 2026-10-06 00:00 |
14:56:39.57 |
-12:57:57.4 |
HIP 73055 |
19.23 |
| 2026-10-06 12:00 |
14:57:12.29 |
-13:01:11.2 |
HIP 73055 |
23.52 |
| 2026-10-07 00:00 |
14:57:45.06 |
-13:04:24.7 |
HIP 73291 |
23.07 |
| 2026-10-07 12:00 |
14:58:17.88 |
-13:07:37.7 |
HIP 73291 |
22.36 |
| 2026-10-08 00:00 |
14:58:50.76 |
-13:10:50.3 |
HIP 73291 |
24.81 |
| 2026-10-08 12:00 |
14:59:23.69 |
-13:14:02.5 |
HIP 73291 |
29.67 |
| 2026-10-09 00:00 |
14:59:56.66 |
-13:17:14.3 |
HIP 73516 |
23.67 |
| 2026-10-09 12:00 |
15:00:29.69 |
-13:20:25.7 |
HIP 73516 |
15.49 |
| 2026-10-10 00:00 |
15:01:02.77 |
-13:23:36.7 |
HIP 73516 |
8.29 |
| 2026-10-10 12:00 |
15:01:35.90 |
-13:26:47.2 |
HIP 73516 |
6.88 |
| 2026-10-11 00:00 |
15:02:09.07 |
-13:29:57.3 |
HIP 73516 |
13.26 |