| Parameter |
Value |
| Designation |
C/1991 Y1 (Zanotta-Brewington) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1992-01-31T23:47:40.372800Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:41Z |
| Obs used |
266 |
| NEO |
- |
| M1 |
10.200 |
| K1 |
14.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1992-01-10.0000000 |
| e |
1.00005670 |
| q (au) |
0.643969 |
| a (au) |
-11357.972781 |
| i (deg) |
50.028225 |
| Ω (om, deg) |
254.908258 |
| ω (w, deg) |
197.872524 |
| M (ma, deg) |
-0.000018 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.204 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.204 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
1.000 |
| 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 |
| 1991-12-23 |
1992-01-31 |
+0.0509 |
+0.039 |
| 1992-02-01 |
1992-05-02 |
+12.8239 |
+2.103 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
17:16:10.37 |
-18:29:31.5 |
HIP 84467 |
10.57 |
| 2026-03-26 12:00 |
17:16:09.85 |
-18:29:28.1 |
HIP 84467 |
10.62 |
| 2026-03-27 00:00 |
17:16:09.32 |
-18:29:24.7 |
HIP 84467 |
10.67 |
| 2026-03-27 12:00 |
17:16:08.78 |
-18:29:21.3 |
HIP 84467 |
10.72 |
| 2026-03-28 00:00 |
17:16:08.21 |
-18:29:17.9 |
HIP 84467 |
10.78 |
| 2026-03-28 12:00 |
17:16:07.62 |
-18:29:14.5 |
HIP 84467 |
10.83 |
| 2026-03-29 00:00 |
17:16:07.02 |
-18:29:11.0 |
HIP 84467 |
10.89 |
| 2026-03-29 12:00 |
17:16:06.40 |
-18:29:07.6 |
HIP 84467 |
10.95 |
| 2026-03-30 00:00 |
17:16:05.76 |
-18:29:04.1 |
HIP 84467 |
11.01 |
| 2026-03-30 12:00 |
17:16:05.11 |
-18:29:00.6 |
HIP 84467 |
11.08 |
| 2026-03-31 00:00 |
17:16:04.44 |
-18:28:57.1 |
HIP 84467 |
11.15 |
| 2026-03-31 12:00 |
17:16:03.75 |
-18:28:53.6 |
HIP 84467 |
11.22 |
| 2026-04-01 00:00 |
17:16:03.04 |
-18:28:50.1 |
HIP 84467 |
11.29 |
| 2026-04-01 12:00 |
17:16:02.32 |
-18:28:46.6 |
HIP 84467 |
11.37 |
| 2026-04-02 00:00 |
17:16:01.57 |
-18:28:43.0 |
HIP 84467 |
11.44 |
| 2026-04-02 12:00 |
17:16:00.81 |
-18:28:39.5 |
HIP 84467 |
11.53 |
| 2026-04-03 00:00 |
17:16:00.04 |
-18:28:35.9 |
HIP 84467 |
11.61 |
| 2026-04-03 12:00 |
17:15:59.24 |
-18:28:32.3 |
HIP 84467 |
11.70 |
| 2026-04-04 00:00 |
17:15:58.43 |
-18:28:28.7 |
HIP 84467 |
11.79 |
| 2026-04-04 12:00 |
17:15:57.61 |
-18:28:25.1 |
HIP 84467 |
11.89 |
| 2026-04-05 00:00 |
17:15:56.76 |
-18:28:21.5 |
HIP 84467 |
11.99 |
| 2026-04-05 12:00 |
17:15:55.90 |
-18:28:17.9 |
HIP 84467 |
12.09 |
| 2026-04-06 00:00 |
17:15:55.02 |
-18:28:14.3 |
HIP 84467 |
12.20 |
| 2026-04-06 12:00 |
17:15:54.13 |
-18:28:10.6 |
HIP 84467 |
12.31 |
| 2026-04-07 00:00 |
17:15:53.21 |
-18:28:07.0 |
HIP 84467 |
12.43 |
| 2026-04-07 12:00 |
17:15:52.29 |
-18:28:03.3 |
HIP 84467 |
12.55 |
| 2026-04-08 00:00 |
17:15:51.34 |
-18:27:59.7 |
HIP 84467 |
12.67 |
| 2026-04-08 12:00 |
17:15:50.38 |
-18:27:56.0 |
HIP 84467 |
12.80 |
| 2026-04-09 00:00 |
17:15:49.40 |
-18:27:52.3 |
HIP 84467 |
12.94 |
| 2026-04-09 12:00 |
17:15:48.41 |
-18:27:48.6 |
HIP 84390 |
12.81 |
| 2026-04-10 00:00 |
17:15:47.40 |
-18:27:44.9 |
HIP 84390 |
12.60 |
| 2026-04-10 12:00 |
17:15:46.37 |
-18:27:41.2 |
HIP 84390 |
12.40 |
| 2026-04-11 00:00 |
17:15:45.32 |
-18:27:37.5 |
HIP 84390 |
12.19 |
| 2026-04-11 12:00 |
17:15:44.27 |
-18:27:33.7 |
HIP 84390 |
11.98 |
| 2026-04-12 00:00 |
17:15:43.19 |
-18:27:30.0 |
HIP 84390 |
11.77 |
| 2026-04-12 12:00 |
17:15:42.10 |
-18:27:26.3 |
HIP 84390 |
11.56 |
| 2026-04-13 00:00 |
17:15:40.99 |
-18:27:22.5 |
HIP 84390 |
11.35 |
| 2026-04-13 12:00 |
17:15:39.87 |
-18:27:18.8 |
HIP 84390 |
11.14 |
| 2026-04-14 00:00 |
17:15:38.73 |
-18:27:15.0 |
HIP 84390 |
10.93 |
| 2026-04-14 12:00 |
17:15:37.58 |
-18:27:11.2 |
HIP 84390 |
10.72 |
| 2026-04-15 00:00 |
17:15:36.41 |
-18:27:07.5 |
HIP 84390 |
10.51 |
| 2026-04-15 12:00 |
17:15:35.22 |
-18:27:03.7 |
HIP 84390 |
10.31 |
| 2026-04-16 00:00 |
17:15:34.02 |
-18:26:59.9 |
HIP 84390 |
10.11 |