65P/Gunn
Metadata
| Parameter | Value |
|---|---|
| Designation | 65P/Gunn |
| Type | P |
| Perihelion (tp_cal, UTC) | 2017-10-17T19:29:29.777280Z |
| Orbit solution date (soln_date, UTC) | 2026-05-29T11:30:15Z |
| Obs used | 3127 |
| NEO | - |
| M1 | 11.600 |
| K1 | 6.500 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2020-08-11.0000000 |
| e | 0.24982542 |
| q (au) | 2.913942 |
| a (au) | 3.884352 |
| i (deg) | 9.182775 |
| Ω (om, deg) | 62.020590 |
| ω (w, deg) | 213.808540 |
| M (ma, deg) | 132.372774 |
Magnitude
Scatter + Global Linear
$$ M_a = (11.124 + 2.682\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 11.124 |
| n | 2.682 |
| gf | 0.810 |
| gb | -0.500 |
| k | 0.971 |
| 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 |
|---|---|---|---|
| 2021-12-05 | 2024-04-01 | -8.3958 | +4.219 |
| 2024-04-01 | 2026-05-24 | +5.5254 | -3.091 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Finding Chart
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-06-01 00:00 | 00:20:27.91 | -06:52:05.1 | HIP 1573 | 24.86 |
| 2026-06-01 12:00 | 00:20:55.82 | -06:49:51.8 | HIP 1778 | 27.03 |
| 2026-06-02 00:00 | 00:21:23.59 | -06:47:39.7 | HIP 1778 | 19.86 |
| 2026-06-02 12:00 | 00:21:51.22 | -06:45:28.8 | HIP 1778 | 12.82 |
| 2026-06-03 00:00 | 00:22:18.70 | -06:43:19.0 | HIP 1778 | 6.19 |
| 2026-06-03 12:00 | 00:22:46.03 | -06:41:10.5 | HIP 1778 | 3.81 |
| 2026-06-04 00:00 | 00:23:13.22 | -06:39:03.2 | HIP 1778 | 9.56 |
| 2026-06-04 12:00 | 00:23:40.26 | -06:36:57.1 | HIP 1812 | 13.56 |
| 2026-06-05 00:00 | 00:24:07.14 | -06:34:52.2 | HIP 1812 | 18.11 |
| 2026-06-05 12:00 | 00:24:33.88 | -06:32:48.5 | HIP 1812 | 23.85 |
| 2026-06-06 00:00 | 00:25:00.47 | -06:30:46.1 | HIP 1812 | 30.07 |
| 2026-06-06 12:00 | 00:25:26.90 | -06:28:44.9 | HIP 2044 | 25.73 |
| 2026-06-07 00:00 | 00:25:53.18 | -06:26:45.0 | HIP 2044 | 22.70 |
| 2026-06-07 12:00 | 00:26:19.31 | -06:24:46.3 | HIP 2044 | 21.49 |
| 2026-06-08 00:00 | 00:26:45.28 | -06:22:48.9 | HIP 2201 | 17.19 |
| 2026-06-08 12:00 | 00:27:11.09 | -06:20:52.8 | HIP 2201 | 12.60 |
| 2026-06-09 00:00 | 00:27:36.75 | -06:18:58.0 | HIP 2201 | 10.57 |
| 2026-06-09 12:00 | 00:28:02.25 | -06:17:04.4 | HIP 2201 | 12.35 |
| 2026-06-10 00:00 | 00:28:27.58 | -06:15:12.1 | HIP 2201 | 16.72 |
| 2026-06-10 12:00 | 00:28:52.76 | -06:13:21.2 | HIP 2302 | 18.90 |
| 2026-06-11 00:00 | 00:29:17.77 | -06:11:31.5 | HIP 2292 | 16.93 |
| 2026-06-11 12:00 | 00:29:42.62 | -06:09:43.2 | HIP 2292 | 16.49 |
| 2026-06-12 00:00 | 00:30:07.31 | -06:07:56.2 | HIP 2292 | 18.43 |
| 2026-06-12 12:00 | 00:30:31.83 | -06:06:10.5 | HIP 2350 | 21.86 |
| 2026-06-13 00:00 | 00:30:56.18 | -06:04:26.1 | HIP 2350 | 23.29 |
| 2026-06-13 12:00 | 00:31:20.36 | -06:02:43.1 | HIP 2566 | 20.96 |
| 2026-06-14 00:00 | 00:31:44.37 | -06:01:01.5 | HIP 2566 | 16.99 |
| 2026-06-14 12:00 | 00:32:08.21 | -05:59:21.2 | HIP 2566 | 14.68 |
| 2026-06-15 00:00 | 00:32:31.88 | -05:57:42.3 | HIP 2566 | 14.74 |
| 2026-06-15 12:00 | 00:32:55.38 | -05:56:04.7 | HIP 2566 | 17.10 |
| 2026-06-16 00:00 | 00:33:18.70 | -05:54:28.6 | HIP 2699 | 17.30 |
| 2026-06-16 12:00 | 00:33:41.84 | -05:52:53.8 | HIP 2699 | 11.85 |
| 2026-06-17 00:00 | 00:34:04.81 | -05:51:20.4 | HIP 2699 | 7.30 |
| 2026-06-17 12:00 | 00:34:27.60 | -05:49:48.3 | HIP 2699 | 6.02 |
| 2026-06-18 00:00 | 00:34:50.21 | -05:48:17.7 | HIP 2699 | 9.35 |
| 2026-06-18 12:00 | 00:35:12.64 | -05:46:48.5 | HIP 2699 | 14.34 |
| 2026-06-19 00:00 | 00:35:34.89 | -05:45:20.7 | HIP 2843 | 12.97 |
| 2026-06-19 12:00 | 00:35:56.96 | -05:43:54.2 | HIP 2843 | 9.75 |
| 2026-06-20 00:00 | 00:36:18.85 | -05:42:29.2 | HIP 2843 | 9.29 |
| 2026-06-20 12:00 | 00:36:40.55 | -05:41:05.6 | HIP 2843 | 11.85 |
| 2026-06-21 00:00 | 00:37:02.06 | -05:39:43.5 | HIP 2843 | 15.99 |
| 2026-06-21 12:00 | 00:37:23.39 | -05:38:22.7 | HIP 2843 | 20.74 |
| 2026-06-22 00:00 | 00:37:44.53 | -05:37:03.4 | HIP 2980 | 23.03 |