| Parameter |
Value |
| Designation |
C/1984 W2 (Hartley) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1985-09-28T09:29:19.821120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:31Z |
| Obs used |
53 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1986-02-18.0000000 |
| e |
0.99947295 |
| q (au) |
4.000285 |
| a (au) |
7589.981412 |
| i (deg) |
89.326939 |
| Ω (om, deg) |
250.204076 |
| ω (w, deg) |
255.271872 |
| M (ma, deg) |
0.000213 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.937 + 4.665\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.937 |
| n |
4.665 |
| gf |
1.000 |
| gb |
-0.502 |
| k |
1.000 |
| δ90 |
10.000 |
| 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 |
16:59:44.95 |
+24:03:32.6 |
HIP 83158 |
8.81 |
| 2026-07-29 12:00 |
16:59:43.66 |
+24:03:19.5 |
HIP 83158 |
9.00 |
| 2026-07-30 00:00 |
16:59:42.39 |
+24:03:06.3 |
HIP 83158 |
9.19 |
| 2026-07-30 12:00 |
16:59:41.13 |
+24:02:52.9 |
HIP 83158 |
9.40 |
| 2026-07-31 00:00 |
16:59:39.89 |
+24:02:39.5 |
HIP 83158 |
9.63 |
| 2026-07-31 12:00 |
16:59:38.66 |
+24:02:25.9 |
HIP 83158 |
9.86 |
| 2026-08-01 00:00 |
16:59:37.45 |
+24:02:12.2 |
HIP 83158 |
10.10 |
| 2026-08-01 12:00 |
16:59:36.24 |
+24:01:58.4 |
HIP 83158 |
10.35 |
| 2026-08-02 00:00 |
16:59:35.05 |
+24:01:44.4 |
HIP 83158 |
10.60 |
| 2026-08-02 12:00 |
16:59:33.88 |
+24:01:30.4 |
HIP 83158 |
10.87 |
| 2026-08-03 00:00 |
16:59:32.72 |
+24:01:16.2 |
HIP 83158 |
11.14 |
| 2026-08-03 12:00 |
16:59:31.57 |
+24:01:01.9 |
HIP 83158 |
11.42 |
| 2026-08-04 00:00 |
16:59:30.44 |
+24:00:47.5 |
HIP 83158 |
11.70 |
| 2026-08-04 12:00 |
16:59:29.32 |
+24:00:33.0 |
HIP 83158 |
11.99 |
| 2026-08-05 00:00 |
16:59:28.22 |
+24:00:18.4 |
HIP 83158 |
12.28 |
| 2026-08-05 12:00 |
16:59:27.13 |
+24:00:03.7 |
HIP 83158 |
12.57 |
| 2026-08-06 00:00 |
16:59:26.06 |
+23:59:48.9 |
HIP 83158 |
12.87 |
| 2026-08-06 12:00 |
16:59:25.00 |
+23:59:34.0 |
HIP 83158 |
13.17 |
| 2026-08-07 00:00 |
16:59:23.95 |
+23:59:18.9 |
HIP 83158 |
13.48 |
| 2026-08-07 12:00 |
16:59:22.92 |
+23:59:03.8 |
HIP 83158 |
13.79 |
| 2026-08-08 00:00 |
16:59:21.91 |
+23:58:48.6 |
HIP 83095 |
13.46 |
| 2026-08-08 12:00 |
16:59:20.91 |
+23:58:33.2 |
HIP 83095 |
13.12 |
| 2026-08-09 00:00 |
16:59:19.92 |
+23:58:17.8 |
HIP 83095 |
12.78 |
| 2026-08-09 12:00 |
16:59:18.95 |
+23:58:02.3 |
HIP 83095 |
12.44 |
| 2026-08-10 00:00 |
16:59:18.00 |
+23:57:46.6 |
HIP 83095 |
12.10 |
| 2026-08-10 12:00 |
16:59:17.06 |
+23:57:30.9 |
HIP 83095 |
11.76 |
| 2026-08-11 00:00 |
16:59:16.14 |
+23:57:15.1 |
HIP 83095 |
11.42 |
| 2026-08-11 12:00 |
16:59:15.23 |
+23:56:59.1 |
HIP 83095 |
11.09 |
| 2026-08-12 00:00 |
16:59:14.34 |
+23:56:43.1 |
HIP 83095 |
10.75 |
| 2026-08-12 12:00 |
16:59:13.46 |
+23:56:27.0 |
HIP 83095 |
10.42 |
| 2026-08-13 00:00 |
16:59:12.60 |
+23:56:10.8 |
HIP 83095 |
10.08 |
| 2026-08-13 12:00 |
16:59:11.75 |
+23:55:54.6 |
HIP 83095 |
9.75 |
| 2026-08-14 00:00 |
16:59:10.92 |
+23:55:38.2 |
HIP 83095 |
9.42 |
| 2026-08-14 12:00 |
16:59:10.11 |
+23:55:21.7 |
HIP 83095 |
9.09 |
| 2026-08-15 00:00 |
16:59:09.31 |
+23:55:05.2 |
HIP 83095 |
8.76 |
| 2026-08-15 12:00 |
16:59:08.53 |
+23:54:48.6 |
HIP 83095 |
8.43 |
| 2026-08-16 00:00 |
16:59:07.77 |
+23:54:31.9 |
HIP 83095 |
8.10 |
| 2026-08-16 12:00 |
16:59:07.02 |
+23:54:15.1 |
HIP 83095 |
7.77 |
| 2026-08-17 00:00 |
16:59:06.28 |
+23:53:58.2 |
HIP 83095 |
7.45 |
| 2026-08-17 12:00 |
16:59:05.57 |
+23:53:41.3 |
HIP 83095 |
7.12 |
| 2026-08-18 00:00 |
16:59:04.87 |
+23:53:24.3 |
HIP 83095 |
6.80 |
| 2026-08-18 12:00 |
16:59:04.18 |
+23:53:07.2 |
HIP 83095 |
6.48 |
| 2026-08-19 00:00 |
16:59:03.51 |
+23:52:50.1 |
HIP 83095 |
6.16 |