| 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) |
| 2026-05-12 00:00 |
07:37:03.99 |
-17:57:56.6 |
HIP 36913 |
24.45 |
| 2026-05-12 12:00 |
07:37:04.69 |
-17:57:45.2 |
HIP 36913 |
24.60 |
| 2026-05-13 00:00 |
07:37:05.40 |
-17:57:34.0 |
HIP 36913 |
24.76 |
| 2026-05-13 12:00 |
07:37:06.12 |
-17:57:22.8 |
HIP 36913 |
24.91 |
| 2026-05-14 00:00 |
07:37:06.86 |
-17:57:11.7 |
HIP 36913 |
25.08 |
| 2026-05-14 12:00 |
07:37:07.60 |
-17:57:00.6 |
HIP 36913 |
25.24 |
| 2026-05-15 00:00 |
07:37:08.36 |
-17:56:49.7 |
HIP 36913 |
25.41 |
| 2026-05-15 12:00 |
07:37:09.12 |
-17:56:38.8 |
HIP 36913 |
25.59 |
| 2026-05-16 00:00 |
07:37:09.90 |
-17:56:28.1 |
HIP 36913 |
25.77 |
| 2026-05-16 12:00 |
07:37:10.69 |
-17:56:17.4 |
HIP 36913 |
25.95 |
| 2026-05-17 00:00 |
07:37:11.49 |
-17:56:06.8 |
HIP 36913 |
26.13 |
| 2026-05-17 12:00 |
07:37:12.30 |
-17:55:56.3 |
HIP 36913 |
26.33 |
| 2026-05-18 00:00 |
07:37:13.12 |
-17:55:45.8 |
HIP 36913 |
26.52 |
| 2026-05-18 12:00 |
07:37:13.95 |
-17:55:35.5 |
HIP 36913 |
26.72 |
| 2026-05-19 00:00 |
07:37:14.79 |
-17:55:25.2 |
HIP 36913 |
26.92 |
| 2026-05-19 12:00 |
07:37:15.64 |
-17:55:15.1 |
HIP 36913 |
27.12 |
| 2026-05-20 00:00 |
07:37:16.50 |
-17:55:05.0 |
HIP 36913 |
27.33 |
| 2026-05-20 12:00 |
07:37:17.37 |
-17:54:55.0 |
HIP 36913 |
27.54 |
| 2026-05-21 00:00 |
07:37:18.25 |
-17:54:45.1 |
HIP 36913 |
27.76 |
| 2026-05-21 12:00 |
07:37:19.14 |
-17:54:35.3 |
HIP 36913 |
27.97 |
| 2026-05-22 00:00 |
07:37:20.04 |
-17:54:25.6 |
HIP 36913 |
28.19 |
| 2026-05-22 12:00 |
07:37:20.95 |
-17:54:16.0 |
HIP 36913 |
28.42 |
| 2026-05-23 00:00 |
07:37:21.87 |
-17:54:06.4 |
HIP 36913 |
28.65 |
| 2026-05-23 12:00 |
07:37:22.80 |
-17:53:57.0 |
HIP 36913 |
28.88 |
| 2026-05-24 00:00 |
07:37:23.74 |
-17:53:47.7 |
HIP 36913 |
29.11 |
| 2026-05-24 12:00 |
07:37:24.69 |
-17:53:38.4 |
HIP 37132 |
28.92 |
| 2026-05-25 00:00 |
07:37:25.65 |
-17:53:29.3 |
HIP 37132 |
28.73 |
| 2026-05-25 12:00 |
07:37:26.62 |
-17:53:20.2 |
HIP 37132 |
28.54 |
| 2026-05-26 00:00 |
07:37:27.60 |
-17:53:11.3 |
HIP 37132 |
28.35 |
| 2026-05-26 12:00 |
07:37:28.58 |
-17:53:02.4 |
HIP 37132 |
28.17 |
| 2026-05-27 00:00 |
07:37:29.58 |
-17:52:53.6 |
HIP 37132 |
27.98 |
| 2026-05-27 12:00 |
07:37:30.58 |
-17:52:45.0 |
HIP 37132 |
27.81 |
| 2026-05-28 00:00 |
07:37:31.60 |
-17:52:36.4 |
HIP 37132 |
27.63 |
| 2026-05-28 12:00 |
07:37:32.62 |
-17:52:27.9 |
HIP 37132 |
27.46 |
| 2026-05-29 00:00 |
07:37:33.65 |
-17:52:19.6 |
HIP 37132 |
27.29 |
| 2026-05-29 12:00 |
07:37:34.69 |
-17:52:11.3 |
HIP 37132 |
27.12 |
| 2026-05-30 00:00 |
07:37:35.74 |
-17:52:03.1 |
HIP 37132 |
26.96 |
| 2026-05-30 12:00 |
07:37:36.80 |
-17:51:55.0 |
HIP 37132 |
26.80 |
| 2026-05-31 00:00 |
07:37:37.86 |
-17:51:47.1 |
HIP 37132 |
26.64 |
| 2026-05-31 12:00 |
07:37:38.94 |
-17:51:39.2 |
HIP 37132 |
26.49 |
| 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 |