501P/Rankin
Metadata
| Parameter | Value |
|---|---|
| Designation | 501P/Rankin |
| Type | P |
| Perihelion (tp_cal, UTC) | 2020-12-10T08:39:13.299840Z |
| Orbit solution date (soln_date, UTC) | 2025-07-31T16:54:57Z |
| Obs used | 98 |
| NEO | Yes |
| M1 | 21.900 |
| K1 | 4.500 |
| PC | - |
| Discovery observation (MPC, UTC) | 2024-06-15T10:13:37.545600Z |
| Discovery magnitude (MPC) | 20.90 G |
| Discovery observatory (MPC) | G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2022-05-24.0000000 |
| e | 0.69572032 |
| q (au) | 0.680308 |
| a (au) | 2.235797 |
| i (deg) | 10.104448 |
| Ω (om, deg) | 140.492867 |
| ω (w, deg) | 52.799047 |
| M (ma, deg) | 156.147750 |
Magnitude
Scatter + Global Linear
$$ M_a = (20.000 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 20.000 |
| n | 6.000 |
| gf | 1.000 |
| gb | -0.852 |
| k | 0.990 |
| 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 |
|---|---|---|---|
| 2024-03-22 | 2024-07-29 | -14.2235 | +1.816 |
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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 03:29:36.11 | +06:07:32.2 | HIP 16358 | 17.63 |
| 2026-09-20 12:00 | 03:29:29.05 | +06:04:55.5 | HIP 16178 | 17.07 |
| 2026-09-21 00:00 | 03:29:21.62 | +06:02:17.2 | HIP 16178 | 14.56 |
| 2026-09-21 12:00 | 03:29:13.83 | +05:59:37.5 | HIP 16178 | 12.29 |
| 2026-09-22 00:00 | 03:29:05.67 | +05:56:56.3 | HIP 16178 | 10.49 |
| 2026-09-22 12:00 | 03:28:57.13 | +05:54:13.7 | HIP 16178 | 9.51 |
| 2026-09-23 00:00 | 03:28:48.23 | +05:51:29.6 | HIP 16178 | 9.68 |
| 2026-09-23 12:00 | 03:28:38.96 | +05:48:44.1 | HIP 16178 | 11.03 |
| 2026-09-24 00:00 | 03:28:29.32 | +05:45:57.1 | HIP 16178 | 13.26 |
| 2026-09-24 12:00 | 03:28:19.30 | +05:43:08.7 | HIP 16108 | 14.88 |
| 2026-09-25 00:00 | 03:28:08.91 | +05:40:18.9 | HIP 16108 | 15.05 |
| 2026-09-25 12:00 | 03:27:58.14 | +05:37:27.7 | HIP 16108 | 16.14 |
| 2026-09-26 00:00 | 03:27:46.99 | +05:34:35.1 | HIP 16108 | 18.04 |
| 2026-09-26 12:00 | 03:27:35.47 | +05:31:41.1 | HIP 16108 | 20.57 |
| 2026-09-27 00:00 | 03:27:23.57 | +05:28:45.7 | HIP 16003 | 19.88 |
| 2026-09-27 12:00 | 03:27:11.28 | +05:25:49.0 | HIP 16003 | 17.70 |
| 2026-09-28 00:00 | 03:26:58.62 | +05:22:50.9 | HIP 16003 | 16.29 |
| 2026-09-28 12:00 | 03:26:45.58 | +05:19:51.4 | HIP 16003 | 15.92 |
| 2026-09-29 00:00 | 03:26:32.15 | +05:16:50.7 | HIP 16003 | 16.73 |
| 2026-09-29 12:00 | 03:26:18.34 | +05:13:48.6 | HIP 16003 | 18.63 |
| 2026-09-30 00:00 | 03:26:04.15 | +05:10:45.2 | HIP 16003 | 21.38 |
| 2026-09-30 12:00 | 03:25:49.57 | +05:07:40.5 | HIP 15938 | 17.72 |
| 2026-10-01 00:00 | 03:25:34.61 | +05:04:34.6 | HIP 15938 | 13.26 |
| 2026-10-01 12:00 | 03:25:19.26 | +05:01:27.4 | HIP 15938 | 9.16 |
| 2026-10-02 00:00 | 03:25:03.53 | +04:58:19.0 | HIP 15938 | 6.39 |
| 2026-10-02 12:00 | 03:24:47.41 | +04:55:09.3 | HIP 15938 | 7.03 |
| 2026-10-03 00:00 | 03:24:30.90 | +04:51:58.4 | HIP 15938 | 10.59 |
| 2026-10-03 12:00 | 03:24:14.01 | +04:48:46.4 | HIP 15807 | 9.66 |
| 2026-10-04 00:00 | 03:23:56.73 | +04:45:33.2 | HIP 15807 | 8.60 |
| 2026-10-04 12:00 | 03:23:39.06 | +04:42:18.8 | HIP 15807 | 10.61 |
| 2026-10-05 00:00 | 03:23:21.00 | +04:39:03.3 | HIP 15807 | 14.58 |
| 2026-10-05 12:00 | 03:23:02.56 | +04:35:46.8 | HIP 15807 | 19.40 |
| 2026-10-06 00:00 | 03:22:43.74 | +04:32:29.1 | HIP 15687 | 22.07 |
| 2026-10-06 12:00 | 03:22:24.53 | +04:29:10.4 | HIP 15687 | 17.24 |
| 2026-10-07 00:00 | 03:22:04.93 | +04:25:50.7 | HIP 15687 | 13.21 |
| 2026-10-07 12:00 | 03:21:44.95 | +04:22:30.0 | HIP 15687 | 11.07 |
| 2026-10-08 00:00 | 03:21:24.59 | +04:19:08.3 | HIP 15687 | 12.00 |
| 2026-10-08 12:00 | 03:21:03.85 | +04:15:45.6 | HIP 15687 | 15.58 |
| 2026-10-09 00:00 | 03:20:42.73 | +04:12:22.0 | HIP 15687 | 20.53 |
| 2026-10-09 12:00 | 03:20:21.23 | +04:08:57.6 | HIP 15628 | 21.93 |
| 2026-10-10 00:00 | 03:19:59.36 | +04:05:32.3 | HIP 15427 | 18.61 |
| 2026-10-10 12:00 | 03:19:37.11 | +04:02:06.1 | HIP 15427 | 15.69 |
| 2026-10-11 00:00 | 03:19:14.48 | +03:58:39.2 | HIP 15427 | 15.17 |