| Parameter |
Value |
| Designation |
38P/Stephan-Oterma |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2018-11-10T23:41:26.018880Z |
| Orbit solution date (soln_date, UTC) |
2024-12-04T09:13:02Z |
| Obs used |
3293 |
| NEO |
- |
| M1 |
11.600 |
| K1 |
9.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-05-28.0000000 |
| e |
0.85928734 |
| q (au) |
1.588509 |
| a (au) |
11.289028 |
| i (deg) |
18.352950 |
| Ω (om, deg) |
78.000299 |
| ω (w, deg) |
359.588512 |
| M (ma, deg) |
355.660875 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.431 + 3.907\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.431 |
| n |
3.907 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2017-06-24 |
2018-11-10 |
+2.8190 |
-1.701 |
| 2018-11-11 |
2020-05-21 |
+1.0455 |
-0.769 |
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 |
15:40:04.30 |
-13:12:08.0 |
HIP 76622 |
21.25 |
| 2026-07-29 12:00 |
15:40:02.38 |
-13:12:17.2 |
HIP 76622 |
20.95 |
| 2026-07-30 00:00 |
15:40:00.53 |
-13:12:26.5 |
HIP 76622 |
20.67 |
| 2026-07-30 12:00 |
15:39:58.74 |
-13:12:36.1 |
HIP 76622 |
20.41 |
| 2026-07-31 00:00 |
15:39:57.01 |
-13:12:46.0 |
HIP 76622 |
20.17 |
| 2026-07-31 12:00 |
15:39:55.34 |
-13:12:56.0 |
HIP 76622 |
19.95 |
| 2026-08-01 00:00 |
15:39:53.73 |
-13:13:06.3 |
HIP 76622 |
19.76 |
| 2026-08-01 12:00 |
15:39:52.19 |
-13:13:16.8 |
HIP 76622 |
19.59 |
| 2026-08-02 00:00 |
15:39:50.71 |
-13:13:27.5 |
HIP 76622 |
19.43 |
| 2026-08-02 12:00 |
15:39:49.29 |
-13:13:38.5 |
HIP 76622 |
19.30 |
| 2026-08-03 00:00 |
15:39:47.93 |
-13:13:49.7 |
HIP 76622 |
19.19 |
| 2026-08-03 12:00 |
15:39:46.64 |
-13:14:01.1 |
HIP 76622 |
19.10 |
| 2026-08-04 00:00 |
15:39:45.41 |
-13:14:12.7 |
HIP 76622 |
19.03 |
| 2026-08-04 12:00 |
15:39:44.24 |
-13:14:24.6 |
HIP 76622 |
18.98 |
| 2026-08-05 00:00 |
15:39:43.14 |
-13:14:36.7 |
HIP 76622 |
18.95 |
| 2026-08-05 12:00 |
15:39:42.09 |
-13:14:49.0 |
HIP 76622 |
18.94 |
| 2026-08-06 00:00 |
15:39:41.12 |
-13:15:01.5 |
HIP 76622 |
18.94 |
| 2026-08-06 12:00 |
15:39:40.20 |
-13:15:14.2 |
HIP 76622 |
18.96 |
| 2026-08-07 00:00 |
15:39:39.35 |
-13:15:27.2 |
HIP 76622 |
19.00 |
| 2026-08-07 12:00 |
15:39:38.56 |
-13:15:40.4 |
HIP 76622 |
19.06 |
| 2026-08-08 00:00 |
15:39:37.83 |
-13:15:53.8 |
HIP 76622 |
19.13 |
| 2026-08-08 12:00 |
15:39:37.17 |
-13:16:07.4 |
HIP 76622 |
19.22 |
| 2026-08-09 00:00 |
15:39:36.57 |
-13:16:21.3 |
HIP 76622 |
19.33 |
| 2026-08-09 12:00 |
15:39:36.03 |
-13:16:35.3 |
HIP 76622 |
19.45 |
| 2026-08-10 00:00 |
15:39:35.56 |
-13:16:49.6 |
HIP 76622 |
19.58 |
| 2026-08-10 12:00 |
15:39:35.15 |
-13:17:04.1 |
HIP 76622 |
19.73 |
| 2026-08-11 00:00 |
15:39:34.80 |
-13:17:18.8 |
HIP 76622 |
19.89 |
| 2026-08-11 12:00 |
15:39:34.52 |
-13:17:33.8 |
HIP 76622 |
20.07 |
| 2026-08-12 00:00 |
15:39:34.30 |
-13:17:48.9 |
HIP 76622 |
20.26 |
| 2026-08-12 12:00 |
15:39:34.15 |
-13:18:04.2 |
HIP 76622 |
20.46 |
| 2026-08-13 00:00 |
15:39:34.06 |
-13:18:19.8 |
HIP 76622 |
20.67 |
| 2026-08-13 12:00 |
15:39:34.03 |
-13:18:35.6 |
HIP 76622 |
20.89 |
| 2026-08-14 00:00 |
15:39:34.06 |
-13:18:51.6 |
HIP 76622 |
21.13 |
| 2026-08-14 12:00 |
15:39:34.16 |
-13:19:07.7 |
HIP 76622 |
21.38 |
| 2026-08-15 00:00 |
15:39:34.33 |
-13:19:24.1 |
HIP 76622 |
21.63 |
| 2026-08-15 12:00 |
15:39:34.55 |
-13:19:40.7 |
HIP 76622 |
21.90 |
| 2026-08-16 00:00 |
15:39:34.84 |
-13:19:57.5 |
HIP 76622 |
22.18 |
| 2026-08-16 12:00 |
15:39:35.19 |
-13:20:14.5 |
HIP 76622 |
22.47 |
| 2026-08-17 00:00 |
15:39:35.61 |
-13:20:31.8 |
HIP 76622 |
22.77 |
| 2026-08-17 12:00 |
15:39:36.08 |
-13:20:49.2 |
HIP 76622 |
23.08 |
| 2026-08-18 00:00 |
15:39:36.62 |
-13:21:06.8 |
HIP 76622 |
23.40 |
| 2026-08-18 12:00 |
15:39:37.23 |
-13:21:24.6 |
HIP 76622 |
23.73 |
| 2026-08-19 00:00 |
15:39:37.89 |
-13:21:42.6 |
HIP 76622 |
24.08 |