| Parameter |
Value |
| Designation |
C/2025 B2 (Borisov) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-09-11T13:05:35.995200Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T14:43:13Z |
| Obs used |
250 |
| NEO |
- |
| M1 |
6.700 |
| K1 |
8.750 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-01-20T18:38:49.344000Z |
| Discovery magnitude (MPC) |
20.30 G |
| Discovery observatory (MPC) |
L51 · MARGO, Nauchnyi |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-06-03.0000000 |
| e |
1.00110588 |
| q (au) |
8.239543 |
| a (au) |
-7450.695253 |
| i (deg) |
91.744063 |
| Ω (om, deg) |
84.865584 |
| ω (w, deg) |
78.841042 |
| M (ma, deg) |
-0.000713 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.120 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.120 |
| n |
6.000 |
| 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) |
| 2026-05-12 00:00 |
23:51:43.07 |
+82:35:59.0 |
HIP 117166 |
17.51 |
| 2026-05-12 12:00 |
23:51:50.07 |
+82:38:48.2 |
HIP 117166 |
15.79 |
| 2026-05-13 00:00 |
23:51:56.49 |
+82:41:38.2 |
HIP 117166 |
14.39 |
| 2026-05-13 12:00 |
23:52:02.31 |
+82:44:29.2 |
HIP 117166 |
13.42 |
| 2026-05-14 00:00 |
23:52:07.52 |
+82:47:21.2 |
HIP 117166 |
13.00 |
| 2026-05-14 12:00 |
23:52:12.10 |
+82:50:14.0 |
HIP 117436 |
10.82 |
| 2026-05-15 00:00 |
23:52:16.03 |
+82:53:07.7 |
HIP 117436 |
8.73 |
| 2026-05-15 12:00 |
23:52:19.30 |
+82:56:02.4 |
HIP 117436 |
7.20 |
| 2026-05-16 00:00 |
23:52:21.89 |
+82:58:57.9 |
HIP 117436 |
6.64 |
| 2026-05-16 12:00 |
23:52:23.78 |
+83:01:54.2 |
HIP 117436 |
7.30 |
| 2026-05-17 00:00 |
23:52:24.96 |
+83:04:51.5 |
HIP 117436 |
8.92 |
| 2026-05-17 12:00 |
23:52:25.39 |
+83:07:49.5 |
HIP 118027 |
8.08 |
| 2026-05-18 00:00 |
23:52:25.07 |
+83:10:48.4 |
HIP 118027 |
7.22 |
| 2026-05-18 12:00 |
23:52:23.98 |
+83:13:48.1 |
HIP 118027 |
7.57 |
| 2026-05-19 00:00 |
23:52:22.08 |
+83:16:48.7 |
HIP 118027 |
8.99 |
| 2026-05-19 12:00 |
23:52:19.37 |
+83:19:50.0 |
HIP 118027 |
11.09 |
| 2026-05-20 00:00 |
23:52:15.81 |
+83:22:52.0 |
HIP 118027 |
13.57 |
| 2026-05-20 12:00 |
23:52:11.38 |
+83:25:54.9 |
HIP 118027 |
16.26 |
| 2026-05-21 00:00 |
23:52:06.07 |
+83:28:58.5 |
HIP 118027 |
19.08 |
| 2026-05-21 12:00 |
23:51:59.84 |
+83:32:02.8 |
HIP 118027 |
21.99 |
| 2026-05-22 00:00 |
23:51:52.67 |
+83:35:07.9 |
HIP 118027 |
24.95 |
| 2026-05-22 12:00 |
23:51:44.53 |
+83:38:13.6 |
HIP 117233 |
26.51 |
| 2026-05-23 00:00 |
23:51:35.40 |
+83:41:20.1 |
HIP 117233 |
23.50 |
| 2026-05-23 12:00 |
23:51:25.25 |
+83:44:27.2 |
HIP 117233 |
20.50 |
| 2026-05-24 00:00 |
23:51:14.05 |
+83:47:34.9 |
HIP 117233 |
17.53 |
| 2026-05-24 12:00 |
23:51:01.76 |
+83:50:43.4 |
HIP 117233 |
14.61 |
| 2026-05-25 00:00 |
23:50:48.36 |
+83:53:52.4 |
HIP 117233 |
11.79 |
| 2026-05-25 12:00 |
23:50:33.82 |
+83:57:02.1 |
HIP 117233 |
9.18 |
| 2026-05-26 00:00 |
23:50:18.09 |
+84:00:12.3 |
HIP 117233 |
7.03 |
| 2026-05-26 12:00 |
23:50:01.15 |
+84:03:23.1 |
HIP 117233 |
5.89 |
| 2026-05-27 00:00 |
23:49:42.96 |
+84:06:34.5 |
HIP 117233 |
6.36 |
| 2026-05-27 12:00 |
23:49:23.47 |
+84:09:46.4 |
HIP 117233 |
8.17 |
| 2026-05-28 00:00 |
23:49:02.65 |
+84:12:58.9 |
HIP 117233 |
10.68 |
| 2026-05-28 12:00 |
23:48:40.46 |
+84:16:11.8 |
HIP 117233 |
13.51 |
| 2026-05-29 00:00 |
23:48:16.86 |
+84:19:25.2 |
HIP 117233 |
16.51 |
| 2026-05-29 12:00 |
23:47:51.79 |
+84:22:39.1 |
HIP 117233 |
19.60 |
| 2026-05-30 00:00 |
23:47:25.22 |
+84:25:53.4 |
HIP 117233 |
22.75 |
| 2026-05-30 12:00 |
23:46:57.09 |
+84:29:08.2 |
HIP 116818 |
21.62 |
| 2026-05-31 00:00 |
23:46:27.35 |
+84:32:23.3 |
HIP 116818 |
18.37 |
| 2026-05-31 12:00 |
23:45:55.96 |
+84:35:38.8 |
HIP 116818 |
15.13 |
| 2026-06-01 00:00 |
23:45:22.85 |
+84:38:54.6 |
HIP 116818 |
11.92 |
| 2026-06-01 12:00 |
23:44:47.97 |
+84:42:10.8 |
HIP 116818 |
8.81 |
| 2026-06-02 00:00 |
23:44:11.25 |
+84:45:27.3 |
HIP 116818 |
5.94 |