C/2025 J1 (Borisov)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2025 J1 (Borisov) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2026-06-11T19:27:32.636160Z |
| Orbit solution date (soln_date, UTC) | 2026-05-22T14:12:19Z |
| Obs used | 891 |
| NEO | - |
| M1 | 8.400 |
| K1 | 10.500 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2025-05-02T23:26:46.752000Z |
| Discovery magnitude (MPC) | 19.30 G |
| Discovery observatory (MPC) | L51 · MARGO, Nauchnyi |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-11-22.0000000 |
| e | 0.99712999 |
| q (au) | 3.580304 |
| a (au) | 1247.490099 |
| i (deg) | 95.444637 |
| Ω (om, deg) | 273.976289 |
| ω (w, deg) | 166.624172 |
| M (ma, deg) | 359.995486 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.245 + 5.853\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.245 |
| n | 5.853 |
| gf | 1.000 |
| gb | -0.834 |
| k | 0.800 |
| 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 |
|---|---|---|---|
| 2025-04-29 | 2025-10-22 | +3.8556 | -2.619 |
| 2025-10-22 | 2026-05-05 | -12.7046 | +7.430 |
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 | 05:59:09.61 | +35:45:39.4 | HIP 28388 | 18.70 |
| 2026-06-01 12:00 | 05:59:37.89 | +35:40:17.8 | HIP 28388 | 22.49 |
| 2026-06-02 00:00 | 06:00:06.15 | +35:34:56.8 | HIP 28506 | 22.81 |
| 2026-06-02 12:00 | 06:00:34.40 | +35:29:36.4 | HIP 28506 | 15.39 |
| 2026-06-03 00:00 | 06:01:02.63 | +35:24:16.8 | HIP 28506 | 8.76 |
| 2026-06-03 12:00 | 06:01:30.84 | +35:18:57.7 | HIP 28506 | 6.30 |
| 2026-06-04 00:00 | 06:01:59.03 | +35:13:39.3 | HIP 28506 | 11.20 |
| 2026-06-04 12:00 | 06:02:27.21 | +35:08:21.5 | HIP 28506 | 18.27 |
| 2026-06-05 00:00 | 06:02:55.37 | +35:03:04.3 | HIP 28506 | 25.78 |
| 2026-06-05 12:00 | 06:03:23.51 | +34:57:47.7 | HIP 28729 | 18.89 |
| 2026-06-06 00:00 | 06:03:51.62 | +34:52:31.7 | HIP 28729 | 11.85 |
| 2026-06-06 12:00 | 06:04:19.72 | +34:47:16.2 | HIP 28729 | 6.81 |
| 2026-06-07 00:00 | 06:04:47.80 | +34:42:01.3 | HIP 28729 | 8.62 |
| 2026-06-07 12:00 | 06:05:15.86 | +34:36:47.0 | HIP 28729 | 14.96 |
| 2026-06-08 00:00 | 06:05:43.89 | +34:31:33.1 | HIP 28729 | 22.25 |
| 2026-06-08 12:00 | 06:06:11.90 | +34:26:19.9 | HIP 29008 | 26.29 |
| 2026-06-09 00:00 | 06:06:39.89 | +34:21:07.1 | HIP 29072 | 19.60 |
| 2026-06-09 12:00 | 06:07:07.85 | +34:15:54.8 | HIP 29072 | 11.92 |
| 2026-06-10 00:00 | 06:07:35.78 | +34:10:43.0 | HIP 29072 | 4.57 |
| 2026-06-10 12:00 | 06:08:03.70 | +34:05:31.7 | HIP 29072 | 4.49 |
| 2026-06-11 00:00 | 06:08:31.58 | +34:00:20.9 | HIP 29072 | 11.82 |
| 2026-06-11 12:00 | 06:08:59.44 | +33:55:10.5 | HIP 29242 | 17.55 |
| 2026-06-12 00:00 | 06:09:27.27 | +33:50:00.6 | HIP 29242 | 19.13 |
| 2026-06-12 12:00 | 06:09:55.07 | +33:44:51.2 | HIP 29242 | 23.31 |
| 2026-06-13 00:00 | 06:10:22.84 | +33:39:42.1 | HIP 29242 | 28.98 |
| 2026-06-13 12:00 | 06:10:50.58 | +33:34:33.5 | HIP 29230 | 31.67 |
| 2026-06-14 00:00 | 06:11:18.29 | +33:29:25.3 | HIP 29230 | 30.38 |
| 2026-06-14 12:00 | 06:11:45.96 | +33:24:17.5 | HIP 29534 | 24.42 |
| 2026-06-15 00:00 | 06:12:13.61 | +33:19:10.0 | HIP 29534 | 16.74 |
| 2026-06-15 12:00 | 06:12:41.22 | +33:14:03.0 | HIP 29534 | 9.14 |
| 2026-06-16 00:00 | 06:13:08.79 | +33:08:56.3 | HIP 29534 | 2.35 |
| 2026-06-16 12:00 | 06:13:36.33 | +33:03:50.0 | HIP 29534 | 6.80 |
| 2026-06-17 00:00 | 06:14:03.83 | +32:58:44.0 | HIP 29534 | 14.33 |
| 2026-06-17 12:00 | 06:14:31.29 | +32:53:38.4 | HIP 29534 | 21.97 |
| 2026-06-18 00:00 | 06:14:58.72 | +32:48:33.1 | HIP 29615 | 21.23 |
| 2026-06-18 12:00 | 06:15:26.11 | +32:43:28.2 | HIP 29615 | 19.52 |
| 2026-06-19 00:00 | 06:15:53.45 | +32:38:23.5 | HIP 29874 | 19.65 |
| 2026-06-19 12:00 | 06:16:20.76 | +32:33:19.1 | HIP 29874 | 16.29 |
| 2026-06-20 00:00 | 06:16:48.02 | +32:28:15.1 | HIP 29911 | 13.54 |
| 2026-06-20 12:00 | 06:17:15.24 | +32:23:11.3 | HIP 29878 | 8.03 |
| 2026-06-21 00:00 | 06:17:42.41 | +32:18:07.7 | HIP 29878 | 3.48 |
| 2026-06-21 12:00 | 06:18:09.55 | +32:13:04.5 | HIP 29878 | 8.77 |
| 2026-06-22 00:00 | 06:18:36.63 | +32:08:01.5 | HIP 29878 | 16.07 |