| Parameter |
Value |
| Designation |
C/2012 A2 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2012-11-05T02:25:12.688320Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:59Z |
| Obs used |
2643 |
| NEO |
- |
| M1 |
10.600 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-12-02.0000000 |
| e |
0.99638777 |
| q (au) |
3.537475 |
| a (au) |
979.305586 |
| i (deg) |
125.868477 |
| Ω (om, deg) |
191.404772 |
| ω (w, deg) |
101.672043 |
| M (ma, deg) |
0.000865 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.126 + 3.455\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.126 |
| n |
3.455 |
| gf |
1.000 |
| gb |
-0.897 |
| k |
0.999 |
| 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 |
| 2011-04-02 |
2012-11-04 |
+17.9825 |
-10.877 |
| 2012-11-06 |
2013-09-27 |
-3.7538 |
+1.934 |
| 2013-09-27 |
2014-04-15 |
-2.2574 |
+1.298 |
| 2014-04-15 |
2014-10-23 |
+11.5349 |
-9.101 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
23:22:12.12 |
-56:05:44.3 |
HIP 115486 |
12.06 |
| 2026-09-20 12:00 |
23:22:05.16 |
-56:05:56.9 |
HIP 115486 |
13.04 |
| 2026-09-21 00:00 |
23:21:58.20 |
-56:06:09.1 |
HIP 115486 |
14.01 |
| 2026-09-21 12:00 |
23:21:51.25 |
-56:06:20.8 |
HIP 115295 |
13.57 |
| 2026-09-22 00:00 |
23:21:44.31 |
-56:06:32.0 |
HIP 115295 |
12.96 |
| 2026-09-22 12:00 |
23:21:37.39 |
-56:06:42.8 |
HIP 115295 |
12.40 |
| 2026-09-23 00:00 |
23:21:30.47 |
-56:06:53.1 |
HIP 115295 |
11.90 |
| 2026-09-23 12:00 |
23:21:23.57 |
-56:07:03.0 |
HIP 115295 |
11.47 |
| 2026-09-24 00:00 |
23:21:16.68 |
-56:07:12.4 |
HIP 115295 |
11.12 |
| 2026-09-24 12:00 |
23:21:09.80 |
-56:07:21.3 |
HIP 115295 |
10.85 |
| 2026-09-25 00:00 |
23:21:02.94 |
-56:07:29.8 |
HIP 115295 |
10.67 |
| 2026-09-25 12:00 |
23:20:56.09 |
-56:07:37.9 |
HIP 115295 |
10.59 |
| 2026-09-26 00:00 |
23:20:49.26 |
-56:07:45.4 |
HIP 115295 |
10.59 |
| 2026-09-26 12:00 |
23:20:42.44 |
-56:07:52.6 |
HIP 115295 |
10.70 |
| 2026-09-27 00:00 |
23:20:35.63 |
-56:07:59.2 |
HIP 115295 |
10.89 |
| 2026-09-27 12:00 |
23:20:28.85 |
-56:08:05.4 |
HIP 115295 |
11.16 |
| 2026-09-28 00:00 |
23:20:22.08 |
-56:08:11.1 |
HIP 115295 |
11.51 |
| 2026-09-28 12:00 |
23:20:15.33 |
-56:08:16.4 |
HIP 115295 |
11.93 |
| 2026-09-29 00:00 |
23:20:08.59 |
-56:08:21.2 |
HIP 115295 |
12.42 |
| 2026-09-29 12:00 |
23:20:01.88 |
-56:08:25.6 |
HIP 115295 |
12.96 |
| 2026-09-30 00:00 |
23:19:55.18 |
-56:08:29.5 |
HIP 115295 |
13.54 |
| 2026-09-30 12:00 |
23:19:48.51 |
-56:08:33.0 |
HIP 115295 |
14.17 |
| 2026-10-01 00:00 |
23:19:41.85 |
-56:08:36.0 |
HIP 115295 |
14.83 |
| 2026-10-01 12:00 |
23:19:35.22 |
-56:08:38.5 |
HIP 115295 |
15.51 |
| 2026-10-02 00:00 |
23:19:28.60 |
-56:08:40.6 |
HIP 115295 |
16.23 |
| 2026-10-02 12:00 |
23:19:22.01 |
-56:08:42.2 |
HIP 115295 |
16.97 |
| 2026-10-03 00:00 |
23:19:15.44 |
-56:08:43.4 |
HIP 115295 |
17.72 |
| 2026-10-03 12:00 |
23:19:08.90 |
-56:08:44.1 |
HIP 115295 |
18.49 |
| 2026-10-04 00:00 |
23:19:02.37 |
-56:08:44.3 |
HIP 115295 |
19.27 |
| 2026-10-04 12:00 |
23:18:55.87 |
-56:08:44.1 |
HIP 115295 |
20.07 |
| 2026-10-05 00:00 |
23:18:49.40 |
-56:08:43.5 |
HIP 115295 |
20.87 |
| 2026-10-05 12:00 |
23:18:42.95 |
-56:08:42.4 |
HIP 115295 |
21.68 |
| 2026-10-06 00:00 |
23:18:36.53 |
-56:08:40.8 |
HIP 115295 |
22.50 |
| 2026-10-06 12:00 |
23:18:30.13 |
-56:08:38.8 |
HIP 115295 |
23.32 |
| 2026-10-07 00:00 |
23:18:23.76 |
-56:08:36.3 |
HIP 115295 |
24.15 |
| 2026-10-07 12:00 |
23:18:17.42 |
-56:08:33.4 |
HIP 115295 |
24.98 |
| 2026-10-08 00:00 |
23:18:11.10 |
-56:08:30.0 |
HIP 115295 |
25.81 |
| 2026-10-08 12:00 |
23:18:04.82 |
-56:08:26.2 |
HIP 115295 |
26.65 |
| 2026-10-09 00:00 |
23:17:58.56 |
-56:08:21.9 |
HIP 115295 |
27.49 |
| 2026-10-09 12:00 |
23:17:52.33 |
-56:08:17.2 |
HIP 115295 |
28.33 |
| 2026-10-10 00:00 |
23:17:46.14 |
-56:08:12.0 |
HIP 115295 |
29.16 |
| 2026-10-10 12:00 |
23:17:39.97 |
-56:08:06.4 |
HIP 115295 |
30.00 |
| 2026-10-11 00:00 |
23:17:33.84 |
-56:08:00.3 |
HIP 115295 |
30.84 |