| Parameter |
Value |
| Designation |
C/1971 E1 (Toba) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1971-04-17T05:58:54.240960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:19Z |
| Obs used |
137 |
| NEO |
- |
| M1 |
4.900 |
| K1 |
24.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1971-05-08.0000000 |
| e |
1.00097756 |
| q (au) |
1.233346 |
| a (au) |
-1261.660970 |
| i (deg) |
109.684237 |
| Ω (om, deg) |
104.077477 |
| ω (w, deg) |
152.361820 |
| M (ma, deg) |
0.000456 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.808 + 5.913\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.808 |
| n |
5.913 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.984 |
| 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 |
| 1971-04-18 |
1971-06-28 |
+16.5114 |
-2.215 |
| 1971-06-28 |
1971-09-09 |
-10.7727 |
+3.319 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
07:37:40.02 |
-17:51:31.4 |
HIP 37132 |
26.34 |
| 2026-06-01 12:00 |
07:37:41.11 |
-17:51:23.8 |
HIP 37132 |
26.20 |
| 2026-06-02 00:00 |
07:37:42.21 |
-17:51:16.2 |
HIP 37132 |
26.06 |
| 2026-06-02 12:00 |
07:37:43.32 |
-17:51:08.7 |
HIP 37132 |
25.92 |
| 2026-06-03 00:00 |
07:37:44.43 |
-17:51:01.4 |
HIP 37132 |
25.79 |
| 2026-06-03 12:00 |
07:37:45.56 |
-17:50:54.1 |
HIP 37132 |
25.67 |
| 2026-06-04 00:00 |
07:37:46.69 |
-17:50:46.9 |
HIP 37132 |
25.54 |
| 2026-06-04 12:00 |
07:37:47.83 |
-17:50:39.9 |
HIP 37132 |
25.42 |
| 2026-06-05 00:00 |
07:37:48.97 |
-17:50:33.0 |
HIP 37132 |
25.31 |
| 2026-06-05 12:00 |
07:37:50.13 |
-17:50:26.1 |
HIP 37132 |
25.20 |
| 2026-06-06 00:00 |
07:37:51.29 |
-17:50:19.4 |
HIP 37132 |
25.10 |
| 2026-06-06 12:00 |
07:37:52.46 |
-17:50:12.8 |
HIP 37132 |
25.00 |
| 2026-06-07 00:00 |
07:37:53.64 |
-17:50:06.2 |
HIP 37313 |
24.90 |
| 2026-06-07 12:00 |
07:37:54.82 |
-17:49:59.8 |
HIP 37313 |
24.62 |
| 2026-06-08 00:00 |
07:37:56.01 |
-17:49:53.5 |
HIP 37313 |
24.35 |
| 2026-06-08 12:00 |
07:37:57.21 |
-17:49:47.3 |
HIP 37313 |
24.08 |
| 2026-06-09 00:00 |
07:37:58.42 |
-17:49:41.2 |
HIP 37313 |
23.81 |
| 2026-06-09 12:00 |
07:37:59.63 |
-17:49:35.2 |
HIP 37313 |
23.53 |
| 2026-06-10 00:00 |
07:38:00.85 |
-17:49:29.4 |
HIP 37313 |
23.25 |
| 2026-06-10 12:00 |
07:38:02.08 |
-17:49:23.6 |
HIP 37313 |
22.97 |
| 2026-06-11 00:00 |
07:38:03.31 |
-17:49:17.9 |
HIP 37313 |
22.70 |
| 2026-06-11 12:00 |
07:38:04.56 |
-17:49:12.4 |
HIP 37313 |
22.42 |
| 2026-06-12 00:00 |
07:38:05.80 |
-17:49:07.0 |
HIP 37313 |
22.13 |
| 2026-06-12 12:00 |
07:38:07.06 |
-17:49:01.6 |
HIP 37313 |
21.85 |
| 2026-06-13 00:00 |
07:38:08.32 |
-17:48:56.4 |
HIP 37313 |
21.57 |
| 2026-06-13 12:00 |
07:38:09.58 |
-17:48:51.3 |
HIP 37313 |
21.29 |
| 2026-06-14 00:00 |
07:38:10.86 |
-17:48:46.3 |
HIP 37313 |
21.00 |
| 2026-06-14 12:00 |
07:38:12.14 |
-17:48:41.5 |
HIP 37313 |
20.71 |
| 2026-06-15 00:00 |
07:38:13.42 |
-17:48:36.7 |
HIP 37313 |
20.43 |
| 2026-06-15 12:00 |
07:38:14.71 |
-17:48:32.0 |
HIP 37313 |
20.14 |
| 2026-06-16 00:00 |
07:38:16.01 |
-17:48:27.5 |
HIP 37313 |
19.85 |
| 2026-06-16 12:00 |
07:38:17.32 |
-17:48:23.1 |
HIP 37313 |
19.56 |
| 2026-06-17 00:00 |
07:38:18.62 |
-17:48:18.8 |
HIP 37313 |
19.27 |
| 2026-06-17 12:00 |
07:38:19.94 |
-17:48:14.6 |
HIP 37313 |
18.98 |
| 2026-06-18 00:00 |
07:38:21.26 |
-17:48:10.5 |
HIP 37313 |
18.69 |
| 2026-06-18 12:00 |
07:38:22.58 |
-17:48:06.5 |
HIP 37313 |
18.40 |
| 2026-06-19 00:00 |
07:38:23.91 |
-17:48:02.7 |
HIP 37313 |
18.10 |
| 2026-06-19 12:00 |
07:38:25.25 |
-17:47:58.9 |
HIP 37313 |
17.81 |
| 2026-06-20 00:00 |
07:38:26.59 |
-17:47:55.3 |
HIP 37313 |
17.51 |
| 2026-06-20 12:00 |
07:38:27.94 |
-17:47:51.8 |
HIP 37313 |
17.22 |
| 2026-06-21 00:00 |
07:38:29.29 |
-17:47:48.4 |
HIP 37313 |
16.92 |
| 2026-06-21 12:00 |
07:38:30.64 |
-17:47:45.1 |
HIP 37313 |
16.63 |
| 2026-06-22 00:00 |
07:38:32.00 |
-17:47:42.0 |
HIP 37313 |
16.33 |