| Parameter |
Value |
| Designation |
C/1991 F2 (Helin-Lawrence) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1992-01-20T00:37:43.368960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:41Z |
| Obs used |
108 |
| NEO |
- |
| M1 |
9.100 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1991-12-22.0000000 |
| e |
1.00042110 |
| q (au) |
1.517723 |
| a (au) |
-3604.185791 |
| i (deg) |
95.456559 |
| Ω (om, deg) |
11.835020 |
| ω (w, deg) |
271.158650 |
| M (ma, deg) |
-0.000132 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.280 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.280 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.848 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
20:31:34.12 |
+60:21:55.1 |
HIP 101307 |
5.08 |
| 2026-07-29 12:00 |
20:31:30.07 |
+60:21:53.6 |
HIP 101307 |
5.48 |
| 2026-07-30 00:00 |
20:31:26.02 |
+60:21:51.9 |
HIP 101307 |
5.89 |
| 2026-07-30 12:00 |
20:31:21.96 |
+60:21:49.9 |
HIP 101307 |
6.32 |
| 2026-07-31 00:00 |
20:31:17.91 |
+60:21:47.7 |
HIP 101307 |
6.76 |
| 2026-07-31 12:00 |
20:31:13.86 |
+60:21:45.2 |
HIP 101307 |
7.21 |
| 2026-08-01 00:00 |
20:31:09.81 |
+60:21:42.4 |
HIP 101307 |
7.67 |
| 2026-08-01 12:00 |
20:31:05.76 |
+60:21:39.4 |
HIP 101307 |
8.14 |
| 2026-08-02 00:00 |
20:31:01.72 |
+60:21:36.1 |
HIP 101307 |
8.61 |
| 2026-08-02 12:00 |
20:30:57.68 |
+60:21:32.6 |
HIP 101307 |
9.08 |
| 2026-08-03 00:00 |
20:30:53.63 |
+60:21:28.8 |
HIP 101307 |
9.57 |
| 2026-08-03 12:00 |
20:30:49.60 |
+60:21:24.8 |
HIP 101307 |
10.05 |
| 2026-08-04 00:00 |
20:30:45.56 |
+60:21:20.5 |
HIP 101307 |
10.54 |
| 2026-08-04 12:00 |
20:30:41.53 |
+60:21:16.0 |
HIP 101065 |
10.98 |
| 2026-08-05 00:00 |
20:30:37.51 |
+60:21:11.2 |
HIP 101065 |
10.55 |
| 2026-08-05 12:00 |
20:30:33.48 |
+60:21:06.1 |
HIP 101065 |
10.13 |
| 2026-08-06 00:00 |
20:30:29.47 |
+60:21:00.8 |
HIP 101065 |
9.72 |
| 2026-08-06 12:00 |
20:30:25.45 |
+60:20:55.3 |
HIP 101065 |
9.32 |
| 2026-08-07 00:00 |
20:30:21.44 |
+60:20:49.4 |
HIP 101065 |
8.93 |
| 2026-08-07 12:00 |
20:30:17.44 |
+60:20:43.4 |
HIP 101065 |
8.56 |
| 2026-08-08 00:00 |
20:30:13.44 |
+60:20:37.0 |
HIP 101065 |
8.21 |
| 2026-08-08 12:00 |
20:30:09.45 |
+60:20:30.4 |
HIP 101065 |
7.87 |
| 2026-08-09 00:00 |
20:30:05.47 |
+60:20:23.6 |
HIP 101065 |
7.56 |
| 2026-08-09 12:00 |
20:30:01.49 |
+60:20:16.5 |
HIP 101065 |
7.28 |
| 2026-08-10 00:00 |
20:29:57.52 |
+60:20:09.2 |
HIP 101065 |
7.02 |
| 2026-08-10 12:00 |
20:29:53.56 |
+60:20:01.6 |
HIP 101065 |
6.80 |
| 2026-08-11 00:00 |
20:29:49.60 |
+60:19:53.7 |
HIP 101065 |
6.60 |
| 2026-08-11 12:00 |
20:29:45.65 |
+60:19:45.6 |
HIP 101065 |
6.45 |
| 2026-08-12 00:00 |
20:29:41.71 |
+60:19:37.3 |
HIP 101065 |
6.34 |
| 2026-08-12 12:00 |
20:29:37.78 |
+60:19:28.7 |
HIP 101065 |
6.27 |
| 2026-08-13 00:00 |
20:29:33.86 |
+60:19:19.8 |
HIP 101065 |
6.25 |
| 2026-08-13 12:00 |
20:29:29.94 |
+60:19:10.7 |
HIP 101065 |
6.27 |
| 2026-08-14 00:00 |
20:29:26.04 |
+60:19:01.4 |
HIP 101065 |
6.34 |
| 2026-08-14 12:00 |
20:29:22.15 |
+60:18:51.8 |
HIP 101065 |
6.45 |
| 2026-08-15 00:00 |
20:29:18.26 |
+60:18:41.9 |
HIP 101065 |
6.60 |
| 2026-08-15 12:00 |
20:29:14.39 |
+60:18:31.8 |
HIP 101065 |
6.79 |
| 2026-08-16 00:00 |
20:29:10.53 |
+60:18:21.5 |
HIP 101065 |
7.02 |
| 2026-08-16 12:00 |
20:29:06.68 |
+60:18:10.9 |
HIP 101065 |
7.28 |
| 2026-08-17 00:00 |
20:29:02.84 |
+60:18:00.1 |
HIP 101065 |
7.56 |
| 2026-08-17 12:00 |
20:28:59.01 |
+60:17:49.0 |
HIP 101065 |
7.88 |
| 2026-08-18 00:00 |
20:28:55.20 |
+60:17:37.7 |
HIP 101065 |
8.21 |
| 2026-08-18 12:00 |
20:28:51.39 |
+60:17:26.2 |
HIP 101065 |
8.57 |
| 2026-08-19 00:00 |
20:28:47.60 |
+60:17:14.4 |
HIP 101065 |
8.94 |