| 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) |
| 2026-03-26 00:00 |
20:38:23.84 |
+58:54:03.6 |
HIP 101770 |
8.97 |
| 2026-03-26 12:00 |
20:38:25.79 |
+58:54:30.0 |
HIP 101770 |
8.87 |
| 2026-03-27 00:00 |
20:38:27.72 |
+58:54:56.5 |
HIP 101770 |
8.79 |
| 2026-03-27 12:00 |
20:38:29.62 |
+58:55:23.1 |
HIP 101770 |
8.74 |
| 2026-03-28 00:00 |
20:38:31.49 |
+58:55:49.9 |
HIP 101770 |
8.71 |
| 2026-03-28 12:00 |
20:38:33.34 |
+58:56:16.8 |
HIP 101770 |
8.71 |
| 2026-03-29 00:00 |
20:38:35.15 |
+58:56:43.8 |
HIP 101770 |
8.73 |
| 2026-03-29 12:00 |
20:38:36.94 |
+58:57:10.8 |
HIP 101770 |
8.78 |
| 2026-03-30 00:00 |
20:38:38.70 |
+58:57:38.0 |
HIP 101770 |
8.85 |
| 2026-03-30 12:00 |
20:38:40.43 |
+58:58:05.3 |
HIP 101770 |
8.94 |
| 2026-03-31 00:00 |
20:38:42.14 |
+58:58:32.7 |
HIP 101770 |
9.06 |
| 2026-03-31 12:00 |
20:38:43.81 |
+58:59:00.3 |
HIP 101770 |
9.21 |
| 2026-04-01 00:00 |
20:38:45.46 |
+58:59:27.9 |
HIP 101770 |
9.37 |
| 2026-04-01 12:00 |
20:38:47.08 |
+58:59:55.6 |
HIP 101770 |
9.55 |
| 2026-04-02 00:00 |
20:38:48.67 |
+59:00:23.4 |
HIP 101770 |
9.76 |
| 2026-04-02 12:00 |
20:38:50.23 |
+59:00:51.3 |
HIP 101770 |
9.98 |
| 2026-04-03 00:00 |
20:38:51.76 |
+59:01:19.3 |
HIP 101770 |
10.21 |
| 2026-04-03 12:00 |
20:38:53.26 |
+59:01:47.3 |
HIP 101770 |
10.47 |
| 2026-04-04 00:00 |
20:38:54.73 |
+59:02:15.5 |
HIP 101770 |
10.73 |
| 2026-04-04 12:00 |
20:38:56.18 |
+59:02:43.8 |
HIP 101770 |
11.01 |
| 2026-04-05 00:00 |
20:38:57.59 |
+59:03:12.1 |
HIP 101770 |
11.31 |
| 2026-04-05 12:00 |
20:38:58.98 |
+59:03:40.5 |
HIP 101770 |
11.61 |
| 2026-04-06 00:00 |
20:39:00.33 |
+59:04:09.0 |
HIP 101770 |
11.93 |
| 2026-04-06 12:00 |
20:39:01.66 |
+59:04:37.6 |
HIP 101770 |
12.25 |
| 2026-04-07 00:00 |
20:39:02.95 |
+59:05:06.3 |
HIP 101770 |
12.59 |
| 2026-04-07 12:00 |
20:39:04.21 |
+59:05:35.0 |
HIP 101770 |
12.93 |
| 2026-04-08 00:00 |
20:39:05.45 |
+59:06:03.8 |
HIP 101770 |
13.28 |
| 2026-04-08 12:00 |
20:39:06.65 |
+59:06:32.7 |
HIP 101770 |
13.63 |
| 2026-04-09 00:00 |
20:39:07.83 |
+59:07:01.7 |
HIP 101770 |
13.99 |
| 2026-04-09 12:00 |
20:39:08.97 |
+59:07:30.7 |
HIP 101770 |
14.36 |
| 2026-04-10 00:00 |
20:39:10.08 |
+59:07:59.8 |
HIP 101770 |
14.74 |
| 2026-04-10 12:00 |
20:39:11.16 |
+59:08:28.9 |
HIP 101770 |
15.11 |
| 2026-04-11 00:00 |
20:39:12.21 |
+59:08:58.1 |
HIP 101770 |
15.50 |
| 2026-04-11 12:00 |
20:39:13.23 |
+59:09:27.4 |
HIP 101770 |
15.88 |
| 2026-04-12 00:00 |
20:39:14.22 |
+59:09:56.7 |
HIP 101770 |
16.27 |
| 2026-04-12 12:00 |
20:39:15.18 |
+59:10:26.1 |
HIP 101770 |
16.67 |
| 2026-04-13 00:00 |
20:39:16.11 |
+59:10:55.6 |
HIP 101770 |
17.07 |
| 2026-04-13 12:00 |
20:39:17.00 |
+59:11:25.0 |
HIP 101770 |
17.47 |
| 2026-04-14 00:00 |
20:39:17.86 |
+59:11:54.6 |
HIP 101770 |
17.87 |
| 2026-04-14 12:00 |
20:39:18.70 |
+59:12:24.2 |
HIP 101770 |
18.27 |
| 2026-04-15 00:00 |
20:39:19.50 |
+59:12:53.8 |
HIP 101770 |
18.68 |
| 2026-04-15 12:00 |
20:39:20.26 |
+59:13:23.5 |
HIP 101770 |
19.09 |
| 2026-04-16 00:00 |
20:39:21.00 |
+59:13:53.2 |
HIP 101770 |
19.50 |