| 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) |
| 2026-05-12 00:00 |
23:35:28.59 |
-52:52:55.2 |
HIP 116500 |
27.67 |
| 2026-05-12 12:00 |
23:35:31.70 |
-52:53:32.0 |
HIP 116500 |
28.11 |
| 2026-05-13 00:00 |
23:35:34.76 |
-52:54:09.1 |
HIP 116500 |
28.57 |
| 2026-05-13 12:00 |
23:35:37.79 |
-52:54:46.5 |
HIP 116500 |
29.04 |
| 2026-05-14 00:00 |
23:35:40.77 |
-52:55:24.2 |
HIP 116500 |
29.54 |
| 2026-05-14 12:00 |
23:35:43.71 |
-52:56:02.3 |
HIP 116500 |
30.06 |
| 2026-05-15 00:00 |
23:35:46.60 |
-52:56:40.7 |
HIP 116500 |
30.59 |
| 2026-05-15 12:00 |
23:35:49.45 |
-52:57:19.4 |
HIP 116500 |
31.14 |
| 2026-05-16 00:00 |
23:35:52.26 |
-52:57:58.5 |
HIP 116500 |
31.71 |
| 2026-05-16 12:00 |
23:35:55.02 |
-52:58:37.8 |
HIP 116500 |
32.29 |
| 2026-05-17 00:00 |
23:35:57.73 |
-52:59:17.5 |
HIP 116500 |
32.88 |
| 2026-05-17 12:00 |
23:36:00.41 |
-52:59:57.5 |
HIP 116500 |
33.49 |
| 2026-05-18 00:00 |
23:36:03.03 |
-53:00:37.7 |
HIP 116500 |
34.11 |
| 2026-05-18 12:00 |
23:36:05.61 |
-53:01:18.3 |
HIP 116500 |
34.75 |
| 2026-05-19 00:00 |
23:36:08.15 |
-53:01:59.2 |
HIP 116500 |
35.39 |
| 2026-05-19 12:00 |
23:36:10.64 |
-53:02:40.4 |
HIP 116729 |
35.33 |
| 2026-05-20 00:00 |
23:36:13.08 |
-53:03:21.9 |
HIP 116729 |
34.62 |
| 2026-05-20 12:00 |
23:36:15.48 |
-53:04:03.7 |
HIP 116729 |
33.93 |
| 2026-05-21 00:00 |
23:36:17.83 |
-53:04:45.8 |
HIP 116729 |
33.24 |
| 2026-05-21 12:00 |
23:36:20.13 |
-53:05:28.2 |
HIP 116729 |
32.56 |
| 2026-05-22 00:00 |
23:36:22.39 |
-53:06:10.8 |
HIP 116729 |
31.89 |
| 2026-05-22 12:00 |
23:36:24.60 |
-53:06:53.8 |
HIP 116729 |
31.23 |
| 2026-05-23 00:00 |
23:36:26.76 |
-53:07:37.0 |
HIP 116729 |
30.58 |
| 2026-05-23 12:00 |
23:36:28.87 |
-53:08:20.5 |
HIP 116729 |
29.93 |
| 2026-05-24 00:00 |
23:36:30.94 |
-53:09:04.3 |
HIP 116729 |
29.30 |
| 2026-05-24 12:00 |
23:36:32.96 |
-53:09:48.4 |
HIP 116729 |
28.69 |
| 2026-05-25 00:00 |
23:36:34.93 |
-53:10:32.7 |
HIP 116729 |
28.08 |
| 2026-05-25 12:00 |
23:36:36.85 |
-53:11:17.3 |
HIP 116729 |
27.49 |
| 2026-05-26 00:00 |
23:36:38.73 |
-53:12:02.2 |
HIP 116729 |
26.92 |
| 2026-05-26 12:00 |
23:36:40.55 |
-53:12:47.3 |
HIP 116729 |
26.36 |
| 2026-05-27 00:00 |
23:36:42.33 |
-53:13:32.7 |
HIP 116729 |
25.82 |
| 2026-05-27 12:00 |
23:36:44.06 |
-53:14:18.3 |
HIP 116729 |
25.30 |
| 2026-05-28 00:00 |
23:36:45.74 |
-53:15:04.2 |
HIP 116729 |
24.80 |
| 2026-05-28 12:00 |
23:36:47.37 |
-53:15:50.4 |
HIP 116729 |
24.32 |
| 2026-05-29 00:00 |
23:36:48.95 |
-53:16:36.8 |
HIP 116729 |
23.87 |
| 2026-05-29 12:00 |
23:36:50.48 |
-53:17:23.5 |
HIP 116729 |
23.44 |
| 2026-05-30 00:00 |
23:36:51.96 |
-53:18:10.4 |
HIP 116729 |
23.04 |
| 2026-05-30 12:00 |
23:36:53.39 |
-53:18:57.5 |
HIP 116729 |
22.66 |
| 2026-05-31 00:00 |
23:36:54.78 |
-53:19:44.9 |
HIP 116729 |
22.32 |
| 2026-05-31 12:00 |
23:36:56.11 |
-53:20:32.5 |
HIP 116729 |
22.01 |
| 2026-06-01 00:00 |
23:36:57.39 |
-53:21:20.3 |
HIP 116729 |
21.73 |
| 2026-06-01 12:00 |
23:36:58.62 |
-53:22:08.4 |
HIP 116729 |
21.49 |
| 2026-06-02 00:00 |
23:36:59.80 |
-53:22:56.7 |
HIP 116729 |
21.29 |