| Parameter |
Value |
| Designation |
C/2025 B2 (Borisov) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-09-11T14:21:54.469440Z |
| Orbit solution date (soln_date, UTC) |
2026-05-28T12:12:16Z |
| Obs used |
273 |
| NEO |
- |
| M1 |
6.600 |
| 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) |
2025-07-07.0000000 |
| e |
1.00120560 |
| q (au) |
8.239388 |
| a (au) |
-6834.249426 |
| i (deg) |
91.744014 |
| Ω (om, deg) |
84.865506 |
| ω (w, deg) |
78.845077 |
| M (ma, deg) |
-0.000753 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.264 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.264 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.998 |
| 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
23:43:32.64 |
+84:48:44.0 |
HIP 116818 |
3.97 |
| 2026-06-03 00:00 |
23:42:52.08 |
+84:52:00.9 |
HIP 116818 |
4.38 |
| 2026-06-03 12:00 |
23:42:09.48 |
+84:55:18.1 |
HIP 116818 |
6.76 |
| 2026-06-04 00:00 |
23:41:24.79 |
+84:58:35.4 |
HIP 116818 |
9.79 |
| 2026-06-04 12:00 |
23:40:37.93 |
+85:01:52.9 |
HIP 117350 |
9.48 |
| 2026-06-05 00:00 |
23:39:48.81 |
+85:05:10.5 |
HIP 117350 |
10.06 |
| 2026-06-05 12:00 |
23:38:57.37 |
+85:08:28.2 |
HIP 117350 |
11.72 |
| 2026-06-06 00:00 |
23:38:03.52 |
+85:11:45.9 |
HIP 117350 |
14.07 |
| 2026-06-06 12:00 |
23:37:07.17 |
+85:15:03.6 |
HIP 116945 |
14.49 |
| 2026-06-07 00:00 |
23:36:08.23 |
+85:18:21.2 |
HIP 116945 |
12.28 |
| 2026-06-07 12:00 |
23:35:06.60 |
+85:21:38.8 |
HIP 116945 |
10.79 |
| 2026-06-08 00:00 |
23:34:02.19 |
+85:24:56.2 |
HIP 116945 |
10.36 |
| 2026-06-08 12:00 |
23:32:54.89 |
+85:28:13.4 |
HIP 116945 |
11.13 |
| 2026-06-09 00:00 |
23:31:44.59 |
+85:31:30.4 |
HIP 116945 |
12.90 |
| 2026-06-09 12:00 |
23:30:31.19 |
+85:34:47.2 |
HIP 116945 |
15.33 |
| 2026-06-10 00:00 |
23:29:14.57 |
+85:38:03.5 |
HIP 116945 |
18.16 |
| 2026-06-10 12:00 |
23:27:54.59 |
+85:41:19.5 |
HIP 115753 |
19.18 |
| 2026-06-11 00:00 |
23:26:31.15 |
+85:44:35.1 |
HIP 115753 |
15.92 |
| 2026-06-11 12:00 |
23:25:04.10 |
+85:47:50.1 |
HIP 115753 |
12.84 |
| 2026-06-12 00:00 |
23:23:33.32 |
+85:51:04.5 |
HIP 115753 |
10.13 |
| 2026-06-12 12:00 |
23:21:58.64 |
+85:54:18.3 |
HIP 115753 |
8.21 |
| 2026-06-13 00:00 |
23:20:19.94 |
+85:57:31.3 |
HIP 115109 |
6.06 |
| 2026-06-13 12:00 |
23:18:37.06 |
+86:00:43.5 |
HIP 115109 |
2.69 |
| 2026-06-14 00:00 |
23:16:49.83 |
+86:03:54.9 |
HIP 115109 |
2.19 |
| 2026-06-14 12:00 |
23:14:58.09 |
+86:07:05.2 |
HIP 115109 |
5.45 |
| 2026-06-15 00:00 |
23:13:01.68 |
+86:10:14.5 |
HIP 115109 |
9.08 |
| 2026-06-15 12:00 |
23:11:00.42 |
+86:13:22.6 |
HIP 115109 |
12.77 |
| 2026-06-16 00:00 |
23:08:54.13 |
+86:16:29.5 |
HIP 115109 |
16.49 |
| 2026-06-16 12:00 |
23:06:42.62 |
+86:19:35.0 |
HIP 115550 |
17.61 |
| 2026-06-17 00:00 |
23:04:25.70 |
+86:22:39.0 |
HIP 115550 |
18.92 |
| 2026-06-17 12:00 |
23:02:03.19 |
+86:25:41.4 |
HIP 115550 |
20.87 |
| 2026-06-18 00:00 |
22:59:34.87 |
+86:28:42.1 |
HIP 115550 |
23.29 |
| 2026-06-18 12:00 |
22:57:00.55 |
+86:31:40.9 |
HIP 111103 |
24.08 |
| 2026-06-19 00:00 |
22:54:20.02 |
+86:34:37.7 |
HIP 111103 |
21.69 |
| 2026-06-19 12:00 |
22:51:33.07 |
+86:37:32.5 |
HIP 111103 |
19.72 |
| 2026-06-20 00:00 |
22:48:39.49 |
+86:40:24.9 |
HIP 111103 |
18.32 |
| 2026-06-20 12:00 |
22:45:39.07 |
+86:43:15.0 |
HIP 111103 |
17.63 |
| 2026-06-21 00:00 |
22:42:31.61 |
+86:46:02.4 |
HIP 111103 |
17.75 |
| 2026-06-21 12:00 |
22:39:16.88 |
+86:48:47.1 |
HIP 111103 |
18.66 |
| 2026-06-22 00:00 |
22:35:54.69 |
+86:51:28.9 |
HIP 111103 |
20.26 |