C/2017 K2 (PANSTARRS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2017 K2 (PANSTARRS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2022-12-19T17:27:24.742080Z |
| Orbit solution date (soln_date, UTC) | 2026-07-28T14:12:17Z |
| Obs used | 3121 |
| NEO | - |
| M1 | 8.500 |
| K1 | 4.500 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2021-09-09.0000000 |
| e | 1.00061578 |
| q (au) | 1.797284 |
| a (au) | -2918.712175 |
| i (deg) | 87.554842 |
| Ω (om, deg) | 88.241136 |
| ω (w, deg) | 236.192325 |
| M (ma, deg) | -0.002917 |
Magnitude
Scatter + Global Linear
$$ M_a = (8.414 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 8.414 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.822 |
| k | 0.988 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 2013-05-12 | 2022-05-07 | +0.2827 | -0.719 |
| 2022-05-07 | 2022-12-13 | +8.2159 | -3.820 |
| 2022-12-20 | 2024-01-29 | +5.9897 | -3.787 |
| 2024-01-29 | 2026-03-22 | +3.2192 | -2.277 |
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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 06:06:54.97 | +32:47:10.0 | HIP 28974 | 8.59 |
| 2026-07-29 12:00 | 06:07:04.00 | +32:47:45.2 | HIP 28974 | 9.48 |
| 2026-07-30 00:00 | 06:07:12.98 | +32:48:20.6 | HIP 28974 | 10.67 |
| 2026-07-30 12:00 | 06:07:21.92 | +32:48:56.0 | HIP 28974 | 12.07 |
| 2026-07-31 00:00 | 06:07:30.80 | +32:49:31.6 | HIP 28974 | 13.60 |
| 2026-07-31 12:00 | 06:07:39.64 | +32:50:07.4 | HIP 28994 | 15.09 |
| 2026-08-01 00:00 | 06:07:48.42 | +32:50:43.2 | HIP 28994 | 15.56 |
| 2026-08-01 12:00 | 06:07:57.15 | +32:51:19.2 | HIP 28994 | 16.25 |
| 2026-08-02 00:00 | 06:08:05.83 | +32:51:55.4 | HIP 28994 | 17.11 |
| 2026-08-02 12:00 | 06:08:14.46 | +32:52:31.7 | HIP 28994 | 18.13 |
| 2026-08-03 00:00 | 06:08:23.04 | +32:53:08.1 | HIP 28994 | 19.27 |
| 2026-08-03 12:00 | 06:08:31.56 | +32:53:44.7 | HIP 29230 | 19.86 |
| 2026-08-04 00:00 | 06:08:40.03 | +32:54:21.4 | HIP 29230 | 18.08 |
| 2026-08-04 12:00 | 06:08:48.45 | +32:54:58.2 | HIP 29230 | 16.34 |
| 2026-08-05 00:00 | 06:08:56.81 | +32:55:35.2 | HIP 29230 | 14.64 |
| 2026-08-05 12:00 | 06:09:05.11 | +32:56:12.3 | HIP 29230 | 12.99 |
| 2026-08-06 00:00 | 06:09:13.36 | +32:56:49.6 | HIP 29230 | 11.40 |
| 2026-08-06 12:00 | 06:09:21.55 | +32:57:27.0 | HIP 29230 | 9.90 |
| 2026-08-07 00:00 | 06:09:29.68 | +32:58:04.5 | HIP 29230 | 8.54 |
| 2026-08-07 12:00 | 06:09:37.76 | +32:58:42.2 | HIP 29230 | 7.38 |
| 2026-08-08 00:00 | 06:09:45.78 | +32:59:20.0 | HIP 29230 | 6.51 |
| 2026-08-08 12:00 | 06:09:53.74 | +32:59:58.0 | HIP 29230 | 6.06 |
| 2026-08-09 00:00 | 06:10:01.64 | +33:00:36.1 | HIP 29230 | 6.11 |
| 2026-08-09 12:00 | 06:10:09.48 | +33:01:14.3 | HIP 29230 | 6.63 |
| 2026-08-10 00:00 | 06:10:17.25 | +33:01:52.7 | HIP 29309 | 6.43 |
| 2026-08-10 12:00 | 06:10:24.97 | +33:02:31.3 | HIP 29309 | 5.23 |
| 2026-08-11 00:00 | 06:10:32.63 | +33:03:10.0 | HIP 29309 | 4.43 |
| 2026-08-11 12:00 | 06:10:40.22 | +33:03:48.8 | HIP 29309 | 4.23 |
| 2026-08-12 00:00 | 06:10:47.75 | +33:04:27.8 | HIP 29309 | 4.70 |
| 2026-08-12 12:00 | 06:10:55.21 | +33:05:06.9 | HIP 29309 | 5.66 |
| 2026-08-13 00:00 | 06:11:02.61 | +33:05:46.2 | HIP 29309 | 6.91 |
| 2026-08-13 12:00 | 06:11:09.95 | +33:06:25.6 | HIP 29309 | 8.31 |
| 2026-08-14 00:00 | 06:11:17.22 | +33:07:05.1 | HIP 29309 | 9.78 |
| 2026-08-14 12:00 | 06:11:24.42 | +33:07:44.8 | HIP 29309 | 11.30 |
| 2026-08-15 00:00 | 06:11:31.56 | +33:08:24.7 | HIP 29309 | 12.84 |
| 2026-08-15 12:00 | 06:11:38.63 | +33:09:04.7 | HIP 29309 | 14.39 |
| 2026-08-16 00:00 | 06:11:45.63 | +33:09:44.8 | HIP 29309 | 15.95 |
| 2026-08-16 12:00 | 06:11:52.56 | +33:10:25.1 | HIP 29478 | 15.61 |
| 2026-08-17 00:00 | 06:11:59.43 | +33:11:05.5 | HIP 29478 | 15.29 |
| 2026-08-17 12:00 | 06:12:06.22 | +33:11:46.1 | HIP 29478 | 15.15 |
| 2026-08-18 00:00 | 06:12:12.95 | +33:12:26.9 | HIP 29534 | 14.20 |
| 2026-08-18 12:00 | 06:12:19.61 | +33:13:07.7 | HIP 29534 | 13.00 |
| 2026-08-19 00:00 | 06:12:26.19 | +33:13:48.7 | HIP 29534 | 11.90 |