| Parameter |
Value |
| Designation |
C/2007 U1 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2008-08-07T01:09:20.272320Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:13Z |
| Obs used |
871 |
| NEO |
- |
| M1 |
10.300 |
| K1 |
7.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2008-09-04.0000000 |
| e |
1.00142595 |
| q (au) |
3.329202 |
| a (au) |
-2334.730148 |
| i (deg) |
157.786616 |
| Ω (om, deg) |
50.043135 |
| ω (w, deg) |
0.927038 |
| M (ma, deg) |
0.000244 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.173 + 3.897\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.173 |
| n |
3.897 |
| gf |
0.830 |
| gb |
-0.613 |
| k |
0.994 |
| δ90 |
5.330 |
| 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 |
| 2007-10-19 |
2008-02-05 |
+14.6988 |
-8.562 |
| 2008-02-05 |
2008-07-29 |
+6.0203 |
-3.221 |
| 2008-08-07 |
2009-11-18 |
-1.6673 |
+0.718 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
17:38:31.30 |
-10:50:46.7 |
HIP 86370 |
6.33 |
| 2026-03-26 12:00 |
17:38:30.48 |
-10:50:36.6 |
HIP 86370 |
6.58 |
| 2026-03-27 00:00 |
17:38:29.63 |
-10:50:26.4 |
HIP 86370 |
6.84 |
| 2026-03-27 12:00 |
17:38:28.74 |
-10:50:16.3 |
HIP 86313 |
7.10 |
| 2026-03-28 00:00 |
17:38:27.83 |
-10:50:06.1 |
HIP 86313 |
7.08 |
| 2026-03-28 12:00 |
17:38:26.89 |
-10:49:56.0 |
HIP 86313 |
7.07 |
| 2026-03-29 00:00 |
17:38:25.92 |
-10:49:45.8 |
HIP 86313 |
7.07 |
| 2026-03-29 12:00 |
17:38:24.92 |
-10:49:35.6 |
HIP 86313 |
7.08 |
| 2026-03-30 00:00 |
17:38:23.89 |
-10:49:25.5 |
HIP 86313 |
7.09 |
| 2026-03-30 12:00 |
17:38:22.84 |
-10:49:15.3 |
HIP 86313 |
7.12 |
| 2026-03-31 00:00 |
17:38:21.75 |
-10:49:05.2 |
HIP 86313 |
7.15 |
| 2026-03-31 12:00 |
17:38:20.63 |
-10:48:55.1 |
HIP 86313 |
7.20 |
| 2026-04-01 00:00 |
17:38:19.49 |
-10:48:44.9 |
HIP 86313 |
7.25 |
| 2026-04-01 12:00 |
17:38:18.31 |
-10:48:34.8 |
HIP 86313 |
7.32 |
| 2026-04-02 00:00 |
17:38:17.11 |
-10:48:24.7 |
HIP 86313 |
7.40 |
| 2026-04-02 12:00 |
17:38:15.88 |
-10:48:14.6 |
HIP 86313 |
7.50 |
| 2026-04-03 00:00 |
17:38:14.62 |
-10:48:04.5 |
HIP 86313 |
7.60 |
| 2026-04-03 12:00 |
17:38:13.33 |
-10:47:54.4 |
HIP 86313 |
7.73 |
| 2026-04-04 00:00 |
17:38:12.01 |
-10:47:44.3 |
HIP 86313 |
7.86 |
| 2026-04-04 12:00 |
17:38:10.67 |
-10:47:34.2 |
HIP 86313 |
8.01 |
| 2026-04-05 00:00 |
17:38:09.29 |
-10:47:24.2 |
HIP 86313 |
8.17 |
| 2026-04-05 12:00 |
17:38:07.89 |
-10:47:14.1 |
HIP 86313 |
8.35 |
| 2026-04-06 00:00 |
17:38:06.46 |
-10:47:04.1 |
HIP 86313 |
8.54 |
| 2026-04-06 12:00 |
17:38:05.00 |
-10:46:54.1 |
HIP 86313 |
8.74 |
| 2026-04-07 00:00 |
17:38:03.51 |
-10:46:44.1 |
HIP 86313 |
8.96 |
| 2026-04-07 12:00 |
17:38:02.00 |
-10:46:34.1 |
HIP 86313 |
9.19 |
| 2026-04-08 00:00 |
17:38:00.45 |
-10:46:24.1 |
HIP 86313 |
9.44 |
| 2026-04-08 12:00 |
17:37:58.88 |
-10:46:14.2 |
HIP 86313 |
9.70 |
| 2026-04-09 00:00 |
17:37:57.28 |
-10:46:04.2 |
HIP 86313 |
9.97 |
| 2026-04-09 12:00 |
17:37:55.66 |
-10:45:54.3 |
HIP 86313 |
10.25 |
| 2026-04-10 00:00 |
17:37:54.00 |
-10:45:44.4 |
HIP 86313 |
10.55 |
| 2026-04-10 12:00 |
17:37:52.32 |
-10:45:34.5 |
HIP 86313 |
10.85 |
| 2026-04-11 00:00 |
17:37:50.61 |
-10:45:24.7 |
HIP 86313 |
11.17 |
| 2026-04-11 12:00 |
17:37:48.87 |
-10:45:14.9 |
HIP 86313 |
11.50 |
| 2026-04-12 00:00 |
17:37:47.11 |
-10:45:05.1 |
HIP 86313 |
11.85 |
| 2026-04-12 12:00 |
17:37:45.32 |
-10:44:55.3 |
HIP 86313 |
12.20 |
| 2026-04-13 00:00 |
17:37:43.50 |
-10:44:45.5 |
HIP 86313 |
12.56 |
| 2026-04-13 12:00 |
17:37:41.66 |
-10:44:35.8 |
HIP 86313 |
12.93 |
| 2026-04-14 00:00 |
17:37:39.78 |
-10:44:26.1 |
HIP 86313 |
13.32 |
| 2026-04-14 12:00 |
17:37:37.89 |
-10:44:16.4 |
HIP 86313 |
13.71 |
| 2026-04-15 00:00 |
17:37:35.96 |
-10:44:06.8 |
HIP 86313 |
14.12 |
| 2026-04-15 12:00 |
17:37:34.01 |
-10:43:57.1 |
HIP 86313 |
14.53 |
| 2026-04-16 00:00 |
17:37:32.03 |
-10:43:47.5 |
HIP 86313 |
14.95 |