| 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) |
| 2026-03-26 00:00 |
23:28:08.31 |
-52:23:01.3 |
HIP 115781 |
8.38 |
| 2026-03-26 12:00 |
23:28:14.06 |
-52:23:02.0 |
HIP 115781 |
9.12 |
| 2026-03-27 00:00 |
23:28:19.81 |
-52:23:03.0 |
HIP 115781 |
9.88 |
| 2026-03-27 12:00 |
23:28:25.53 |
-52:23:04.5 |
HIP 115781 |
10.66 |
| 2026-03-28 00:00 |
23:28:31.25 |
-52:23:06.4 |
HIP 115781 |
11.46 |
| 2026-03-28 12:00 |
23:28:36.95 |
-52:23:08.7 |
HIP 115781 |
12.27 |
| 2026-03-29 00:00 |
23:28:42.64 |
-52:23:11.3 |
HIP 115781 |
13.08 |
| 2026-03-29 12:00 |
23:28:48.31 |
-52:23:14.4 |
HIP 115781 |
13.91 |
| 2026-03-30 00:00 |
23:28:53.97 |
-52:23:17.9 |
HIP 115781 |
14.73 |
| 2026-03-30 12:00 |
23:28:59.61 |
-52:23:21.8 |
HIP 115781 |
15.57 |
| 2026-03-31 00:00 |
23:29:05.24 |
-52:23:26.1 |
HIP 115781 |
16.40 |
| 2026-03-31 12:00 |
23:29:10.85 |
-52:23:30.8 |
HIP 115781 |
17.24 |
| 2026-04-01 00:00 |
23:29:16.45 |
-52:23:35.9 |
HIP 115942 |
17.17 |
| 2026-04-01 12:00 |
23:29:22.03 |
-52:23:41.4 |
HIP 115942 |
17.03 |
| 2026-04-02 00:00 |
23:29:27.59 |
-52:23:47.3 |
HIP 115942 |
16.93 |
| 2026-04-02 12:00 |
23:29:33.14 |
-52:23:53.6 |
HIP 115942 |
16.86 |
| 2026-04-03 00:00 |
23:29:38.67 |
-52:24:00.3 |
HIP 115942 |
16.82 |
| 2026-04-03 12:00 |
23:29:44.18 |
-52:24:07.4 |
HIP 115942 |
16.82 |
| 2026-04-04 00:00 |
23:29:49.68 |
-52:24:14.9 |
HIP 115942 |
16.86 |
| 2026-04-04 12:00 |
23:29:55.15 |
-52:24:22.8 |
HIP 115942 |
16.93 |
| 2026-04-05 00:00 |
23:30:00.61 |
-52:24:31.2 |
HIP 115942 |
17.04 |
| 2026-04-05 12:00 |
23:30:06.05 |
-52:24:39.9 |
HIP 115942 |
17.18 |
| 2026-04-06 00:00 |
23:30:11.47 |
-52:24:49.0 |
HIP 115942 |
17.35 |
| 2026-04-06 12:00 |
23:30:16.87 |
-52:24:58.5 |
HIP 115942 |
17.55 |
| 2026-04-07 00:00 |
23:30:22.25 |
-52:25:08.5 |
HIP 115942 |
17.78 |
| 2026-04-07 12:00 |
23:30:27.61 |
-52:25:18.8 |
HIP 115942 |
18.04 |
| 2026-04-08 00:00 |
23:30:32.95 |
-52:25:29.6 |
HIP 115942 |
18.33 |
| 2026-04-08 12:00 |
23:30:38.26 |
-52:25:40.7 |
HIP 115942 |
18.64 |
| 2026-04-09 00:00 |
23:30:43.56 |
-52:25:52.3 |
HIP 115942 |
18.97 |
| 2026-04-09 12:00 |
23:30:48.83 |
-52:26:04.2 |
HIP 115942 |
19.33 |
| 2026-04-10 00:00 |
23:30:54.09 |
-52:26:16.6 |
HIP 115942 |
19.71 |
| 2026-04-10 12:00 |
23:30:59.32 |
-52:26:29.3 |
HIP 115942 |
20.11 |
| 2026-04-11 00:00 |
23:31:04.52 |
-52:26:42.5 |
HIP 115942 |
20.53 |
| 2026-04-11 12:00 |
23:31:09.71 |
-52:26:56.1 |
HIP 115942 |
20.96 |
| 2026-04-12 00:00 |
23:31:14.87 |
-52:27:10.0 |
HIP 115942 |
21.41 |
| 2026-04-12 12:00 |
23:31:20.00 |
-52:27:24.4 |
HIP 115942 |
21.87 |
| 2026-04-13 00:00 |
23:31:25.11 |
-52:27:39.2 |
HIP 115942 |
22.35 |
| 2026-04-13 12:00 |
23:31:30.20 |
-52:27:54.4 |
HIP 115942 |
22.83 |
| 2026-04-14 00:00 |
23:31:35.26 |
-52:28:09.9 |
HIP 115942 |
23.33 |
| 2026-04-14 12:00 |
23:31:40.30 |
-52:28:25.9 |
HIP 115942 |
23.84 |
| 2026-04-15 00:00 |
23:31:45.31 |
-52:28:42.3 |
HIP 115942 |
24.36 |
| 2026-04-15 12:00 |
23:31:50.30 |
-52:28:59.1 |
HIP 115942 |
24.89 |
| 2026-04-16 00:00 |
23:31:55.25 |
-52:29:16.3 |
HIP 115942 |
25.42 |