| Parameter |
Value |
| Designation |
C/2013 US10 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-11-15T17:19:09.851520Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T14:42:53Z |
| Obs used |
4397 |
| NEO |
- |
| M1 |
8.500 |
| K1 |
6.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-11-23.0000000 |
| e |
1.00028014 |
| q (au) |
0.822969 |
| a (au) |
-2937.712795 |
| i (deg) |
148.878297 |
| Ω (om, deg) |
186.144580 |
| ω (w, deg) |
340.358754 |
| M (ma, deg) |
0.000045 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.879 + 3.465\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.879 |
| n |
3.465 |
| gf |
1.000 |
| gb |
-0.500 |
| 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 |
| 2013-11-16 |
2014-09-02 |
+6.3490 |
-5.168 |
| 2014-09-02 |
2015-05-09 |
-1.8469 |
+1.075 |
| 2015-05-09 |
2015-07-22 |
+1.9657 |
-0.856 |
| 2015-07-22 |
2015-09-04 |
+7.2007 |
-2.686 |
| 2015-09-04 |
2015-10-16 |
-7.7697 |
+0.128 |
| 2015-11-22 |
2016-09-01 |
+1.0099 |
+0.081 |
| 2016-09-01 |
2017-10-24 |
-1.4000 |
+1.815 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
02:12:42.19 |
+33:15:44.0 |
HIP 10373 |
20.74 |
| 2026-05-12 12:00 |
02:12:46.71 |
+33:16:07.2 |
HIP 10373 |
20.53 |
| 2026-05-13 00:00 |
02:12:51.21 |
+33:16:30.5 |
HIP 10373 |
20.37 |
| 2026-05-13 12:00 |
02:12:55.70 |
+33:16:53.9 |
HIP 10373 |
20.26 |
| 2026-05-14 00:00 |
02:13:00.18 |
+33:17:17.4 |
HIP 10373 |
20.21 |
| 2026-05-14 12:00 |
02:13:04.65 |
+33:17:41.1 |
HIP 10450 |
19.94 |
| 2026-05-15 00:00 |
02:13:09.10 |
+33:18:04.9 |
HIP 10450 |
18.99 |
| 2026-05-15 12:00 |
02:13:13.55 |
+33:18:28.8 |
HIP 10450 |
18.04 |
| 2026-05-16 00:00 |
02:13:17.98 |
+33:18:52.7 |
HIP 10450 |
17.11 |
| 2026-05-16 12:00 |
02:13:22.39 |
+33:19:16.9 |
HIP 10450 |
16.19 |
| 2026-05-17 00:00 |
02:13:26.80 |
+33:19:41.1 |
HIP 10450 |
15.29 |
| 2026-05-17 12:00 |
02:13:31.19 |
+33:20:05.4 |
HIP 10450 |
14.40 |
| 2026-05-18 00:00 |
02:13:35.56 |
+33:20:29.8 |
HIP 10450 |
13.53 |
| 2026-05-18 12:00 |
02:13:39.92 |
+33:20:54.4 |
HIP 10450 |
12.68 |
| 2026-05-19 00:00 |
02:13:44.27 |
+33:21:19.0 |
HIP 10450 |
11.86 |
| 2026-05-19 12:00 |
02:13:48.60 |
+33:21:43.7 |
HIP 10450 |
11.07 |
| 2026-05-20 00:00 |
02:13:52.91 |
+33:22:08.6 |
HIP 10450 |
10.32 |
| 2026-05-20 12:00 |
02:13:57.21 |
+33:22:33.5 |
HIP 10450 |
9.62 |
| 2026-05-21 00:00 |
02:14:01.50 |
+33:22:58.5 |
HIP 10450 |
8.98 |
| 2026-05-21 12:00 |
02:14:05.77 |
+33:23:23.6 |
HIP 10450 |
8.40 |
| 2026-05-22 00:00 |
02:14:10.02 |
+33:23:48.8 |
HIP 10450 |
7.92 |
| 2026-05-22 12:00 |
02:14:14.25 |
+33:24:14.1 |
HIP 10450 |
7.53 |
| 2026-05-23 00:00 |
02:14:18.47 |
+33:24:39.5 |
HIP 10450 |
7.26 |
| 2026-05-23 12:00 |
02:14:22.67 |
+33:25:04.9 |
HIP 10450 |
7.12 |
| 2026-05-24 00:00 |
02:14:26.85 |
+33:25:30.5 |
HIP 10450 |
7.11 |
| 2026-05-24 12:00 |
02:14:31.01 |
+33:25:56.1 |
HIP 10450 |
7.24 |
| 2026-05-25 00:00 |
02:14:35.16 |
+33:26:21.8 |
HIP 10450 |
7.49 |
| 2026-05-25 12:00 |
02:14:39.29 |
+33:26:47.6 |
HIP 10450 |
7.86 |
| 2026-05-26 00:00 |
02:14:43.39 |
+33:27:13.4 |
HIP 10450 |
8.32 |
| 2026-05-26 12:00 |
02:14:47.48 |
+33:27:39.4 |
HIP 10450 |
8.86 |
| 2026-05-27 00:00 |
02:14:51.56 |
+33:28:05.4 |
HIP 10450 |
9.47 |
| 2026-05-27 12:00 |
02:14:55.61 |
+33:28:31.4 |
HIP 10450 |
10.13 |
| 2026-05-28 00:00 |
02:14:59.64 |
+33:28:57.6 |
HIP 10450 |
10.84 |
| 2026-05-28 12:00 |
02:15:03.65 |
+33:29:23.8 |
HIP 10450 |
11.58 |
| 2026-05-29 00:00 |
02:15:07.64 |
+33:29:50.1 |
HIP 10450 |
12.34 |
| 2026-05-29 12:00 |
02:15:11.61 |
+33:30:16.4 |
HIP 10559 |
12.78 |
| 2026-05-30 00:00 |
02:15:15.56 |
+33:30:42.8 |
HIP 10559 |
12.51 |
| 2026-05-30 12:00 |
02:15:19.49 |
+33:31:09.3 |
HIP 10559 |
12.31 |
| 2026-05-31 00:00 |
02:15:23.40 |
+33:31:35.8 |
HIP 10559 |
12.18 |
| 2026-05-31 12:00 |
02:15:27.28 |
+33:32:02.4 |
HIP 10559 |
12.12 |
| 2026-06-01 00:00 |
02:15:31.15 |
+33:32:29.1 |
HIP 10559 |
12.14 |
| 2026-06-01 12:00 |
02:15:34.99 |
+33:32:55.8 |
HIP 10559 |
12.23 |
| 2026-06-02 00:00 |
02:15:38.81 |
+33:33:22.5 |
HIP 10559 |
12.39 |