C/1971 E1 (Toba)
| 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 |
1971-07-09 |
+12.6274 |
-1.673 |
| 1971-07-09 |
1971-09-09 |
-8.7165 |
+2.624 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
07:38:40.12 |
-18:40:39.6 |
HIP 37261 |
6.39 |
| 2026-02-03 12:00 |
07:38:38.64 |
-18:40:31.3 |
HIP 37261 |
6.74 |
| 2026-02-04 00:00 |
07:38:37.17 |
-18:40:22.9 |
HIP 37261 |
7.10 |
| 2026-02-04 12:00 |
07:38:35.71 |
-18:40:14.4 |
HIP 37261 |
7.45 |
| 2026-02-05 00:00 |
07:38:34.25 |
-18:40:05.8 |
HIP 37261 |
7.81 |
| 2026-02-05 12:00 |
07:38:32.80 |
-18:39:57.0 |
HIP 37261 |
8.16 |
| 2026-02-06 00:00 |
07:38:31.35 |
-18:39:48.2 |
HIP 37261 |
8.52 |
| 2026-02-06 12:00 |
07:38:29.91 |
-18:39:39.2 |
HIP 37261 |
8.87 |
| 2026-02-07 00:00 |
07:38:28.47 |
-18:39:30.2 |
HIP 37261 |
9.23 |
| 2026-02-07 12:00 |
07:38:27.04 |
-18:39:21.0 |
HIP 37261 |
9.59 |
| 2026-02-08 00:00 |
07:38:25.61 |
-18:39:11.8 |
HIP 37261 |
9.94 |
| 2026-02-08 12:00 |
07:38:24.20 |
-18:39:02.4 |
HIP 37261 |
10.30 |
| 2026-02-09 00:00 |
07:38:22.78 |
-18:38:53.0 |
HIP 37261 |
10.65 |
| 2026-02-09 12:00 |
07:38:21.38 |
-18:38:43.4 |
HIP 37261 |
11.01 |
| 2026-02-10 00:00 |
07:38:19.98 |
-18:38:33.7 |
HIP 37261 |
11.37 |
| 2026-02-10 12:00 |
07:38:18.59 |
-18:38:24.0 |
HIP 37261 |
11.72 |
| 2026-02-11 00:00 |
07:38:17.20 |
-18:38:14.1 |
HIP 37261 |
12.08 |
| 2026-02-11 12:00 |
07:38:15.82 |
-18:38:04.1 |
HIP 37261 |
12.43 |
| 2026-02-12 00:00 |
07:38:14.45 |
-18:37:54.1 |
HIP 37261 |
12.78 |
| 2026-02-12 12:00 |
07:38:13.08 |
-18:37:43.9 |
HIP 37261 |
13.14 |
| 2026-02-13 00:00 |
07:38:11.72 |
-18:37:33.6 |
HIP 37261 |
13.49 |
| 2026-02-13 12:00 |
07:38:10.37 |
-18:37:23.3 |
HIP 37261 |
13.84 |
| 2026-02-14 00:00 |
07:38:09.03 |
-18:37:12.8 |
HIP 37261 |
14.19 |
| 2026-02-14 12:00 |
07:38:07.69 |
-18:37:02.3 |
HIP 37097 |
13.92 |
| 2026-02-15 00:00 |
07:38:06.36 |
-18:36:51.6 |
HIP 37097 |
13.56 |
| 2026-02-15 12:00 |
07:38:05.04 |
-18:36:40.9 |
HIP 37097 |
13.21 |
| 2026-02-16 00:00 |
07:38:03.73 |
-18:36:30.1 |
HIP 37097 |
12.86 |
| 2026-02-16 12:00 |
07:38:02.42 |
-18:36:19.2 |
HIP 37097 |
12.51 |
| 2026-02-17 00:00 |
07:38:01.13 |
-18:36:08.2 |
HIP 37097 |
12.15 |
| 2026-02-17 12:00 |
07:37:59.84 |
-18:35:57.1 |
HIP 37097 |
11.80 |
| 2026-02-18 00:00 |
07:37:58.56 |
-18:35:45.9 |
HIP 37097 |
11.46 |
| 2026-02-18 12:00 |
07:37:57.28 |
-18:35:34.6 |
HIP 37097 |
11.11 |
| 2026-02-19 00:00 |
07:37:56.02 |
-18:35:23.3 |
HIP 37097 |
10.76 |
| 2026-02-19 12:00 |
07:37:54.76 |
-18:35:11.8 |
HIP 37097 |
10.41 |
| 2026-02-20 00:00 |
07:37:53.51 |
-18:35:00.3 |
HIP 37097 |
10.07 |
| 2026-02-20 12:00 |
07:37:52.28 |
-18:34:48.7 |
HIP 37097 |
9.72 |
| 2026-02-21 00:00 |
07:37:51.05 |
-18:34:37.0 |
HIP 37097 |
9.38 |
| 2026-02-21 12:00 |
07:37:49.83 |
-18:34:25.2 |
HIP 37097 |
9.04 |
| 2026-02-22 00:00 |
07:37:48.61 |
-18:34:13.4 |
HIP 37097 |
8.69 |
| 2026-02-22 12:00 |
07:37:47.41 |
-18:34:01.5 |
HIP 37097 |
8.35 |
| 2026-02-23 00:00 |
07:37:46.22 |
-18:33:49.5 |
HIP 37097 |
8.01 |
| 2026-02-23 12:00 |
07:37:45.03 |
-18:33:37.4 |
HIP 37097 |
7.68 |
| 2026-02-24 00:00 |
07:37:43.86 |
-18:33:25.2 |
HIP 37097 |
7.34 |