| 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) |
| 2026-07-29 00:00 |
23:33:25.95 |
-55:05:13.1 |
HIP 116373 |
13.40 |
| 2026-07-29 12:00 |
23:33:21.14 |
-55:06:03.9 |
HIP 116373 |
13.72 |
| 2026-07-30 00:00 |
23:33:16.29 |
-55:06:54.6 |
HIP 116373 |
14.14 |
| 2026-07-30 12:00 |
23:33:11.39 |
-55:07:45.0 |
HIP 116373 |
14.63 |
| 2026-07-31 00:00 |
23:33:06.45 |
-55:08:35.3 |
HIP 116373 |
15.18 |
| 2026-07-31 12:00 |
23:33:01.46 |
-55:09:25.3 |
HIP 116373 |
15.80 |
| 2026-08-01 00:00 |
23:32:56.43 |
-55:10:15.1 |
HIP 116373 |
16.48 |
| 2026-08-01 12:00 |
23:32:51.36 |
-55:11:04.7 |
HIP 116373 |
17.20 |
| 2026-08-02 00:00 |
23:32:46.25 |
-55:11:54.0 |
HIP 116373 |
17.97 |
| 2026-08-02 12:00 |
23:32:41.10 |
-55:12:43.1 |
HIP 116373 |
18.78 |
| 2026-08-03 00:00 |
23:32:35.91 |
-55:13:32.0 |
HIP 116373 |
19.62 |
| 2026-08-03 12:00 |
23:32:30.67 |
-55:14:20.7 |
HIP 116373 |
20.48 |
| 2026-08-04 00:00 |
23:32:25.39 |
-55:15:09.1 |
HIP 116373 |
21.38 |
| 2026-08-04 12:00 |
23:32:20.08 |
-55:15:57.3 |
HIP 116373 |
22.30 |
| 2026-08-05 00:00 |
23:32:14.72 |
-55:16:45.2 |
HIP 116373 |
23.23 |
| 2026-08-05 12:00 |
23:32:09.32 |
-55:17:32.9 |
HIP 116373 |
24.19 |
| 2026-08-06 00:00 |
23:32:03.89 |
-55:18:20.4 |
HIP 116373 |
25.16 |
| 2026-08-06 12:00 |
23:31:58.41 |
-55:19:07.5 |
HIP 116373 |
26.15 |
| 2026-08-07 00:00 |
23:31:52.90 |
-55:19:54.5 |
HIP 116373 |
27.15 |
| 2026-08-07 12:00 |
23:31:47.35 |
-55:20:41.1 |
HIP 116373 |
28.16 |
| 2026-08-08 00:00 |
23:31:41.76 |
-55:21:27.5 |
HIP 116373 |
29.18 |
| 2026-08-08 12:00 |
23:31:36.13 |
-55:22:13.6 |
HIP 116373 |
30.20 |
| 2026-08-09 00:00 |
23:31:30.46 |
-55:22:59.4 |
HIP 116373 |
31.24 |
| 2026-08-09 12:00 |
23:31:24.76 |
-55:23:45.0 |
HIP 116373 |
32.29 |
| 2026-08-10 00:00 |
23:31:19.02 |
-55:24:30.3 |
HIP 116373 |
33.34 |
| 2026-08-10 12:00 |
23:31:13.25 |
-55:25:15.2 |
HIP 115890 |
33.08 |
| 2026-08-11 00:00 |
23:31:07.44 |
-55:26:00.0 |
HIP 115890 |
31.98 |
| 2026-08-11 12:00 |
23:31:01.59 |
-55:26:44.3 |
HIP 115890 |
30.89 |
| 2026-08-12 00:00 |
23:30:55.71 |
-55:27:28.4 |
HIP 115890 |
29.80 |
| 2026-08-12 12:00 |
23:30:49.80 |
-55:28:12.2 |
HIP 115890 |
28.71 |
| 2026-08-13 00:00 |
23:30:43.85 |
-55:28:55.7 |
HIP 115890 |
27.62 |
| 2026-08-13 12:00 |
23:30:37.87 |
-55:29:38.9 |
HIP 115890 |
26.54 |
| 2026-08-14 00:00 |
23:30:31.86 |
-55:30:21.8 |
HIP 115890 |
25.46 |
| 2026-08-14 12:00 |
23:30:25.81 |
-55:31:04.3 |
HIP 115890 |
24.39 |
| 2026-08-15 00:00 |
23:30:19.73 |
-55:31:46.6 |
HIP 115890 |
23.32 |
| 2026-08-15 12:00 |
23:30:13.62 |
-55:32:28.5 |
HIP 115890 |
22.26 |
| 2026-08-16 00:00 |
23:30:07.48 |
-55:33:10.1 |
HIP 115890 |
21.21 |
| 2026-08-16 12:00 |
23:30:01.31 |
-55:33:51.3 |
HIP 115890 |
20.16 |
| 2026-08-17 00:00 |
23:29:55.11 |
-55:34:32.2 |
HIP 115890 |
19.12 |
| 2026-08-17 12:00 |
23:29:48.88 |
-55:35:12.8 |
HIP 115890 |
18.10 |
| 2026-08-18 00:00 |
23:29:42.63 |
-55:35:53.1 |
HIP 115890 |
17.09 |
| 2026-08-18 12:00 |
23:29:36.34 |
-55:36:33.0 |
HIP 115890 |
16.10 |
| 2026-08-19 00:00 |
23:29:30.03 |
-55:37:12.6 |
HIP 115890 |
15.12 |