| 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
$$
M_a = (8.191 + 3.897\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.191 |
| n |
3.897 |
| gf |
0.822 |
| gb |
-0.613 |
| k |
0.994 |
| δ90 |
4.869 |
| 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 |
+14.6991 |
-8.562 |
| 2008-02-05 |
2008-07-29 |
+6.0207 |
-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) |
| 2026-07-29 00:00 |
17:26:25.10 |
-10:35:29.6 |
HIP 85331 |
24.16 |
| 2026-07-29 12:00 |
17:26:22.43 |
-10:35:36.2 |
HIP 85331 |
24.01 |
| 2026-07-30 00:00 |
17:26:19.78 |
-10:35:42.8 |
HIP 85331 |
23.87 |
| 2026-07-30 12:00 |
17:26:17.14 |
-10:35:49.6 |
HIP 85331 |
23.75 |
| 2026-07-31 00:00 |
17:26:14.53 |
-10:35:56.4 |
HIP 85331 |
23.65 |
| 2026-07-31 12:00 |
17:26:11.94 |
-10:36:03.3 |
HIP 85331 |
23.56 |
| 2026-08-01 00:00 |
17:26:09.37 |
-10:36:10.3 |
HIP 85331 |
23.49 |
| 2026-08-01 12:00 |
17:26:06.83 |
-10:36:17.4 |
HIP 85331 |
23.43 |
| 2026-08-02 00:00 |
17:26:04.30 |
-10:36:24.5 |
HIP 85331 |
23.39 |
| 2026-08-02 12:00 |
17:26:01.80 |
-10:36:31.7 |
HIP 85331 |
23.36 |
| 2026-08-03 00:00 |
17:25:59.32 |
-10:36:39.0 |
HIP 85331 |
23.35 |
| 2026-08-03 12:00 |
17:25:56.86 |
-10:36:46.4 |
HIP 85331 |
23.35 |
| 2026-08-04 00:00 |
17:25:54.43 |
-10:36:53.8 |
HIP 85331 |
23.37 |
| 2026-08-04 12:00 |
17:25:52.02 |
-10:37:01.3 |
HIP 85331 |
23.40 |
| 2026-08-05 00:00 |
17:25:49.63 |
-10:37:08.9 |
HIP 85331 |
23.44 |
| 2026-08-05 12:00 |
17:25:47.26 |
-10:37:16.6 |
HIP 85331 |
23.49 |
| 2026-08-06 00:00 |
17:25:44.92 |
-10:37:24.3 |
HIP 85331 |
23.56 |
| 2026-08-06 12:00 |
17:25:42.60 |
-10:37:32.1 |
HIP 85331 |
23.64 |
| 2026-08-07 00:00 |
17:25:40.30 |
-10:37:40.0 |
HIP 85331 |
23.73 |
| 2026-08-07 12:00 |
17:25:38.03 |
-10:37:48.0 |
HIP 85331 |
23.82 |
| 2026-08-08 00:00 |
17:25:35.78 |
-10:37:56.0 |
HIP 85331 |
23.93 |
| 2026-08-08 12:00 |
17:25:33.55 |
-10:38:04.1 |
HIP 85331 |
24.05 |
| 2026-08-09 00:00 |
17:25:31.35 |
-10:38:12.2 |
HIP 85331 |
24.18 |
| 2026-08-09 12:00 |
17:25:29.17 |
-10:38:20.5 |
HIP 85331 |
24.31 |
| 2026-08-10 00:00 |
17:25:27.02 |
-10:38:28.8 |
HIP 85331 |
24.45 |
| 2026-08-10 12:00 |
17:25:24.89 |
-10:38:37.1 |
HIP 85331 |
24.60 |
| 2026-08-11 00:00 |
17:25:22.79 |
-10:38:45.6 |
HIP 85331 |
24.76 |
| 2026-08-11 12:00 |
17:25:20.71 |
-10:38:54.1 |
HIP 85331 |
24.92 |
| 2026-08-12 00:00 |
17:25:18.66 |
-10:39:02.7 |
HIP 85331 |
25.09 |
| 2026-08-12 12:00 |
17:25:16.63 |
-10:39:11.3 |
HIP 85331 |
25.26 |
| 2026-08-13 00:00 |
17:25:14.63 |
-10:39:20.0 |
HIP 85331 |
25.44 |
| 2026-08-13 12:00 |
17:25:12.65 |
-10:39:28.8 |
HIP 85331 |
25.62 |
| 2026-08-14 00:00 |
17:25:10.70 |
-10:39:37.6 |
HIP 85331 |
25.80 |
| 2026-08-14 12:00 |
17:25:08.78 |
-10:39:46.5 |
HIP 85331 |
25.99 |
| 2026-08-15 00:00 |
17:25:06.88 |
-10:39:55.5 |
HIP 85331 |
26.19 |
| 2026-08-15 12:00 |
17:25:05.00 |
-10:40:04.5 |
HIP 85331 |
26.38 |
| 2026-08-16 00:00 |
17:25:03.15 |
-10:40:13.6 |
HIP 85331 |
26.58 |
| 2026-08-16 12:00 |
17:25:01.33 |
-10:40:22.8 |
HIP 85331 |
26.78 |
| 2026-08-17 00:00 |
17:24:59.54 |
-10:40:32.0 |
HIP 85331 |
26.98 |
| 2026-08-17 12:00 |
17:24:57.77 |
-10:40:41.2 |
HIP 85331 |
27.18 |
| 2026-08-18 00:00 |
17:24:56.03 |
-10:40:50.6 |
HIP 85331 |
27.38 |
| 2026-08-18 12:00 |
17:24:54.31 |
-10:41:00.0 |
HIP 85331 |
27.58 |
| 2026-08-19 00:00 |
17:24:52.62 |
-10:41:09.4 |
HIP 85331 |
27.79 |