C/2025 B2 (Borisov)
| Parameter |
Value |
| Designation |
C/2025 B2 (Borisov) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-09-11T10:04:21.924480Z |
| Orbit solution date (soln_date, UTC) |
2026-01-13T08:12:18Z |
| Obs used |
226 |
| NEO |
- |
| M1 |
6.800 |
| 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) |
2025-05-07.0000000 |
| e |
1.00094620 |
| q (au) |
8.239789 |
| a (au) |
-8708.276718 |
| i (deg) |
91.744230 |
| Ω (om, deg) |
84.865883 |
| ω (w, deg) |
78.832403 |
| M (ma, deg) |
-0.000597 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.042 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.042 |
| n |
6.000 |
| gf |
0.977 |
| gb |
-1.000 |
| 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) |
| 2026-02-03 00:00 |
22:16:00.45 |
+80:26:31.7 |
HIP 109575 |
25.39 |
| 2026-02-03 12:00 |
22:16:39.20 |
+80:24:40.0 |
HIP 109575 |
24.50 |
| 2026-02-04 00:00 |
22:17:17.90 |
+80:22:49.9 |
HIP 109575 |
23.86 |
| 2026-02-04 12:00 |
22:17:56.54 |
+80:21:01.4 |
HIP 109575 |
23.49 |
| 2026-02-05 00:00 |
22:18:35.13 |
+80:19:14.5 |
HIP 109575 |
23.39 |
| 2026-02-05 12:00 |
22:19:13.67 |
+80:17:29.3 |
HIP 109575 |
23.56 |
| 2026-02-06 00:00 |
22:19:52.16 |
+80:15:45.7 |
HIP 109575 |
23.99 |
| 2026-02-06 12:00 |
22:20:30.60 |
+80:14:03.7 |
HIP 109575 |
24.66 |
| 2026-02-07 00:00 |
22:21:08.99 |
+80:12:23.4 |
HIP 109575 |
25.55 |
| 2026-02-07 12:00 |
22:21:47.33 |
+80:10:44.7 |
HIP 110773 |
25.09 |
| 2026-02-08 00:00 |
22:22:25.61 |
+80:09:07.6 |
HIP 110773 |
22.88 |
| 2026-02-08 12:00 |
22:23:03.84 |
+80:07:32.2 |
HIP 110773 |
20.71 |
| 2026-02-09 00:00 |
22:23:42.03 |
+80:05:58.4 |
HIP 110773 |
18.60 |
| 2026-02-09 12:00 |
22:24:20.15 |
+80:04:26.3 |
HIP 110773 |
16.55 |
| 2026-02-10 00:00 |
22:24:58.23 |
+80:02:55.8 |
HIP 110773 |
14.60 |
| 2026-02-10 12:00 |
22:25:36.26 |
+80:01:27.0 |
HIP 110773 |
12.77 |
| 2026-02-11 00:00 |
22:26:14.23 |
+79:59:59.8 |
HIP 110773 |
11.11 |
| 2026-02-11 12:00 |
22:26:52.15 |
+79:58:34.2 |
HIP 110773 |
9.69 |
| 2026-02-12 00:00 |
22:27:30.02 |
+79:57:10.4 |
HIP 110773 |
8.64 |
| 2026-02-12 12:00 |
22:28:07.83 |
+79:55:48.1 |
HIP 110773 |
8.07 |
| 2026-02-13 00:00 |
22:28:45.59 |
+79:54:27.6 |
HIP 110773 |
8.07 |
| 2026-02-13 12:00 |
22:29:23.30 |
+79:53:08.7 |
HIP 110773 |
8.64 |
| 2026-02-14 00:00 |
22:30:00.95 |
+79:51:51.4 |
HIP 110773 |
9.66 |
| 2026-02-14 12:00 |
22:30:38.55 |
+79:50:35.8 |
HIP 110773 |
11.00 |
| 2026-02-15 00:00 |
22:31:16.09 |
+79:49:21.9 |
HIP 110773 |
12.55 |
| 2026-02-15 12:00 |
22:31:53.57 |
+79:48:09.6 |
HIP 110773 |
14.24 |
| 2026-02-16 00:00 |
22:32:31.00 |
+79:46:59.0 |
HIP 110773 |
16.00 |
| 2026-02-16 12:00 |
22:33:08.37 |
+79:45:50.1 |
HIP 110773 |
17.82 |
| 2026-02-17 00:00 |
22:33:45.68 |
+79:44:42.9 |
HIP 110773 |
19.68 |
| 2026-02-17 12:00 |
22:34:22.93 |
+79:43:37.3 |
HIP 110773 |
21.56 |
| 2026-02-18 00:00 |
22:35:00.12 |
+79:42:33.3 |
HIP 110773 |
23.45 |
| 2026-02-18 12:00 |
22:35:37.26 |
+79:41:31.1 |
HIP 110773 |
25.34 |
| 2026-02-19 00:00 |
22:36:14.33 |
+79:40:30.5 |
HIP 110773 |
27.24 |
| 2026-02-19 12:00 |
22:36:51.34 |
+79:39:31.5 |
HIP 110773 |
29.13 |
| 2026-02-20 00:00 |
22:37:28.29 |
+79:38:34.3 |
HIP 110773 |
31.02 |
| 2026-02-20 12:00 |
22:38:05.17 |
+79:37:38.7 |
HIP 110773 |
32.90 |
| 2026-02-21 00:00 |
22:38:42.00 |
+79:36:44.7 |
HIP 110773 |
34.77 |
| 2026-02-21 12:00 |
22:39:18.75 |
+79:35:52.4 |
HIP 110773 |
36.64 |
| 2026-02-22 00:00 |
22:39:55.44 |
+79:35:01.8 |
HIP 110773 |
38.49 |
| 2026-02-22 12:00 |
22:40:32.07 |
+79:34:12.9 |
HIP 110773 |
40.34 |
| 2026-02-23 00:00 |
22:41:08.63 |
+79:33:25.5 |
HIP 110773 |
42.17 |
| 2026-02-23 12:00 |
22:41:45.12 |
+79:32:39.9 |
HIP 113053 |
43.66 |
| 2026-02-24 00:00 |
22:42:21.55 |
+79:31:55.9 |
HIP 113053 |
41.91 |