| 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) |
| 2026-05-12 00:00 |
20:39:14.43 |
+59:39:39.9 |
HIP 101973 |
5.68 |
| 2026-05-12 12:00 |
20:39:13.44 |
+59:40:08.7 |
HIP 101973 |
5.60 |
| 2026-05-13 00:00 |
20:39:12.41 |
+59:40:37.4 |
HIP 101973 |
5.57 |
| 2026-05-13 12:00 |
20:39:11.35 |
+59:41:06.1 |
HIP 101973 |
5.59 |
| 2026-05-14 00:00 |
20:39:10.26 |
+59:41:34.6 |
HIP 101973 |
5.65 |
| 2026-05-14 12:00 |
20:39:09.14 |
+59:42:03.1 |
HIP 101973 |
5.76 |
| 2026-05-15 00:00 |
20:39:07.99 |
+59:42:31.5 |
HIP 101973 |
5.92 |
| 2026-05-15 12:00 |
20:39:06.80 |
+59:42:59.9 |
HIP 101973 |
6.11 |
| 2026-05-16 00:00 |
20:39:05.58 |
+59:43:28.1 |
HIP 101973 |
6.34 |
| 2026-05-16 12:00 |
20:39:04.33 |
+59:43:56.2 |
HIP 101973 |
6.60 |
| 2026-05-17 00:00 |
20:39:03.05 |
+59:44:24.3 |
HIP 101973 |
6.90 |
| 2026-05-17 12:00 |
20:39:01.73 |
+59:44:52.2 |
HIP 101973 |
7.21 |
| 2026-05-18 00:00 |
20:39:00.38 |
+59:45:20.1 |
HIP 101973 |
7.55 |
| 2026-05-18 12:00 |
20:38:59.00 |
+59:45:47.9 |
HIP 101973 |
7.91 |
| 2026-05-19 00:00 |
20:38:57.59 |
+59:46:15.6 |
HIP 101973 |
8.28 |
| 2026-05-19 12:00 |
20:38:56.15 |
+59:46:43.1 |
HIP 101973 |
8.67 |
| 2026-05-20 00:00 |
20:38:54.68 |
+59:47:10.6 |
HIP 101973 |
9.08 |
| 2026-05-20 12:00 |
20:38:53.17 |
+59:47:37.9 |
HIP 101973 |
9.49 |
| 2026-05-21 00:00 |
20:38:51.64 |
+59:48:05.2 |
HIP 101973 |
9.91 |
| 2026-05-21 12:00 |
20:38:50.07 |
+59:48:32.3 |
HIP 101973 |
10.34 |
| 2026-05-22 00:00 |
20:38:48.47 |
+59:48:59.4 |
HIP 101973 |
10.78 |
| 2026-05-22 12:00 |
20:38:46.84 |
+59:49:26.3 |
HIP 101973 |
11.22 |
| 2026-05-23 00:00 |
20:38:45.18 |
+59:49:53.1 |
HIP 101973 |
11.67 |
| 2026-05-23 12:00 |
20:38:43.49 |
+59:50:19.8 |
HIP 101973 |
12.13 |
| 2026-05-24 00:00 |
20:38:41.76 |
+59:50:46.4 |
HIP 101973 |
12.59 |
| 2026-05-24 12:00 |
20:38:40.01 |
+59:51:12.8 |
HIP 101973 |
13.05 |
| 2026-05-25 00:00 |
20:38:38.23 |
+59:51:39.1 |
HIP 101973 |
13.51 |
| 2026-05-25 12:00 |
20:38:36.42 |
+59:52:05.3 |
HIP 101973 |
13.98 |
| 2026-05-26 00:00 |
20:38:34.57 |
+59:52:31.4 |
HIP 101973 |
14.45 |
| 2026-05-26 12:00 |
20:38:32.70 |
+59:52:57.3 |
HIP 101973 |
14.93 |
| 2026-05-27 00:00 |
20:38:30.80 |
+59:53:23.2 |
HIP 101973 |
15.40 |
| 2026-05-27 12:00 |
20:38:28.86 |
+59:53:48.8 |
HIP 101973 |
15.88 |
| 2026-05-28 00:00 |
20:38:26.90 |
+59:54:14.4 |
HIP 101973 |
16.36 |
| 2026-05-28 12:00 |
20:38:24.91 |
+59:54:39.8 |
HIP 101973 |
16.84 |
| 2026-05-29 00:00 |
20:38:22.89 |
+59:55:05.1 |
HIP 101973 |
17.32 |
| 2026-05-29 12:00 |
20:38:20.84 |
+59:55:30.2 |
HIP 101973 |
17.81 |
| 2026-05-30 00:00 |
20:38:18.76 |
+59:55:55.2 |
HIP 101973 |
18.29 |
| 2026-05-30 12:00 |
20:38:16.65 |
+59:56:20.1 |
HIP 101973 |
18.78 |
| 2026-05-31 00:00 |
20:38:14.51 |
+59:56:44.8 |
HIP 101973 |
19.26 |
| 2026-05-31 12:00 |
20:38:12.35 |
+59:57:09.4 |
HIP 101973 |
19.75 |
| 2026-06-01 00:00 |
20:38:10.15 |
+59:57:33.8 |
HIP 101973 |
20.24 |
| 2026-06-01 12:00 |
20:38:07.93 |
+59:57:58.1 |
HIP 101973 |
20.73 |
| 2026-06-02 00:00 |
20:38:05.68 |
+59:58:22.3 |
HIP 101973 |
21.22 |