| 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) |
| 2026-05-12 00:00 |
17:14:13.28 |
-18:23:41.7 |
HIP 84270 |
12.04 |
| 2026-05-12 12:00 |
17:14:11.43 |
-18:23:37.9 |
HIP 84270 |
11.78 |
| 2026-05-13 00:00 |
17:14:09.58 |
-18:23:34.2 |
HIP 84270 |
11.53 |
| 2026-05-13 12:00 |
17:14:07.71 |
-18:23:30.5 |
HIP 84270 |
11.29 |
| 2026-05-14 00:00 |
17:14:05.84 |
-18:23:26.8 |
HIP 84270 |
11.06 |
| 2026-05-14 12:00 |
17:14:03.96 |
-18:23:23.1 |
HIP 84270 |
10.84 |
| 2026-05-15 00:00 |
17:14:02.07 |
-18:23:19.4 |
HIP 84270 |
10.64 |
| 2026-05-15 12:00 |
17:14:00.17 |
-18:23:15.7 |
HIP 84270 |
10.45 |
| 2026-05-16 00:00 |
17:13:58.26 |
-18:23:12.1 |
HIP 84270 |
10.27 |
| 2026-05-16 12:00 |
17:13:56.35 |
-18:23:08.4 |
HIP 84270 |
10.11 |
| 2026-05-17 00:00 |
17:13:54.43 |
-18:23:04.7 |
HIP 84270 |
9.97 |
| 2026-05-17 12:00 |
17:13:52.50 |
-18:23:01.1 |
HIP 84270 |
9.85 |
| 2026-05-18 00:00 |
17:13:50.57 |
-18:22:57.5 |
HIP 84270 |
9.75 |
| 2026-05-18 12:00 |
17:13:48.62 |
-18:22:53.8 |
HIP 84270 |
9.67 |
| 2026-05-19 00:00 |
17:13:46.67 |
-18:22:50.2 |
HIP 84270 |
9.61 |
| 2026-05-19 12:00 |
17:13:44.72 |
-18:22:46.6 |
HIP 84270 |
9.57 |
| 2026-05-20 00:00 |
17:13:42.75 |
-18:22:43.0 |
HIP 84270 |
9.55 |
| 2026-05-20 12:00 |
17:13:40.78 |
-18:22:39.5 |
HIP 84270 |
9.56 |
| 2026-05-21 00:00 |
17:13:38.81 |
-18:22:35.9 |
HIP 84270 |
9.59 |
| 2026-05-21 12:00 |
17:13:36.82 |
-18:22:32.3 |
HIP 84270 |
9.64 |
| 2026-05-22 00:00 |
17:13:34.83 |
-18:22:28.8 |
HIP 84270 |
9.72 |
| 2026-05-22 12:00 |
17:13:32.84 |
-18:22:25.3 |
HIP 84270 |
9.82 |
| 2026-05-23 00:00 |
17:13:30.84 |
-18:22:21.7 |
HIP 84270 |
9.94 |
| 2026-05-23 12:00 |
17:13:28.84 |
-18:22:18.2 |
HIP 84270 |
10.08 |
| 2026-05-24 00:00 |
17:13:26.82 |
-18:22:14.7 |
HIP 84270 |
10.24 |
| 2026-05-24 12:00 |
17:13:24.81 |
-18:22:11.2 |
HIP 84270 |
10.42 |
| 2026-05-25 00:00 |
17:13:22.79 |
-18:22:07.8 |
HIP 84270 |
10.62 |
| 2026-05-25 12:00 |
17:13:20.76 |
-18:22:04.3 |
HIP 84270 |
10.84 |
| 2026-05-26 00:00 |
17:13:18.73 |
-18:22:00.9 |
HIP 84270 |
11.08 |
| 2026-05-26 12:00 |
17:13:16.70 |
-18:21:57.4 |
HIP 84270 |
11.33 |
| 2026-05-27 00:00 |
17:13:14.66 |
-18:21:54.0 |
HIP 84270 |
11.59 |
| 2026-05-27 12:00 |
17:13:12.61 |
-18:21:50.6 |
HIP 84270 |
11.88 |
| 2026-05-28 00:00 |
17:13:10.57 |
-18:21:47.2 |
HIP 84270 |
12.17 |
| 2026-05-28 12:00 |
17:13:08.51 |
-18:21:43.9 |
HIP 84270 |
12.48 |
| 2026-05-29 00:00 |
17:13:06.46 |
-18:21:40.5 |
HIP 84270 |
12.80 |
| 2026-05-29 12:00 |
17:13:04.40 |
-18:21:37.2 |
HIP 84270 |
13.13 |
| 2026-05-30 00:00 |
17:13:02.34 |
-18:21:33.8 |
HIP 84270 |
13.47 |
| 2026-05-30 12:00 |
17:13:00.27 |
-18:21:30.5 |
HIP 84270 |
13.82 |
| 2026-05-31 00:00 |
17:12:58.20 |
-18:21:27.2 |
HIP 84270 |
14.17 |
| 2026-05-31 12:00 |
17:12:56.13 |
-18:21:23.9 |
HIP 84270 |
14.54 |
| 2026-06-01 00:00 |
17:12:54.05 |
-18:21:20.7 |
HIP 84270 |
14.91 |
| 2026-06-01 12:00 |
17:12:51.97 |
-18:21:17.4 |
HIP 84270 |
15.30 |
| 2026-06-02 00:00 |
17:12:49.89 |
-18:21:14.2 |
HIP 84270 |
15.68 |