| Parameter |
Value |
| Designation |
C/2025 B2 (Borisov) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-09-11T19:31:22.848960Z |
| Orbit solution date (soln_date, UTC) |
2026-10-01T14:42:11Z |
| Obs used |
566 |
| NEO |
- |
| M1 |
6.500 |
| K1 |
8.250 |
| 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) |
2026-01-24.0000000 |
| e |
1.00194138 |
| q (au) |
8.238902 |
| a (au) |
-4243.835831 |
| i (deg) |
91.744917 |
| Ω (om, deg) |
84.867212 |
| ω (w, deg) |
78.862046 |
| M (ma, deg) |
-0.000823 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.801 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.801 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-25 00:00 |
16:47:45.23 |
+75:52:30.4 |
HIP 82496 |
16.90 |
| 2026-09-25 12:00 |
16:48:10.88 |
+75:47:28.2 |
HIP 82496 |
13.30 |
| 2026-09-26 00:00 |
16:48:36.72 |
+75:42:26.3 |
HIP 82496 |
11.11 |
| 2026-09-26 12:00 |
16:49:02.72 |
+75:37:24.7 |
HIP 82496 |
11.18 |
| 2026-09-27 00:00 |
16:49:28.90 |
+75:32:23.5 |
HIP 82345 |
9.64 |
| 2026-09-27 12:00 |
16:49:55.24 |
+75:27:22.7 |
HIP 82345 |
4.86 |
| 2026-09-28 00:00 |
16:50:21.75 |
+75:22:22.2 |
HIP 82345 |
3.18 |
| 2026-09-28 12:00 |
16:50:48.42 |
+75:17:22.1 |
HIP 82345 |
7.25 |
| 2026-09-29 00:00 |
16:51:15.25 |
+75:12:22.4 |
HIP 82345 |
12.28 |
| 2026-09-29 12:00 |
16:51:42.24 |
+75:07:23.1 |
HIP 82580 |
16.84 |
| 2026-09-30 00:00 |
16:52:09.37 |
+75:02:24.2 |
HIP 82580 |
21.37 |
| 2026-09-30 12:00 |
16:52:36.66 |
+74:57:25.7 |
HIP 82746 |
23.93 |
| 2026-10-01 00:00 |
16:53:04.10 |
+74:52:27.6 |
HIP 82746 |
18.65 |
| 2026-10-01 12:00 |
16:53:31.68 |
+74:47:29.9 |
HIP 82746 |
13.38 |
| 2026-10-02 00:00 |
16:53:59.40 |
+74:42:32.7 |
HIP 82746 |
8.10 |
| 2026-10-02 12:00 |
16:54:27.27 |
+74:37:35.9 |
HIP 82746 |
2.82 |
| 2026-10-03 00:00 |
16:54:55.27 |
+74:32:39.6 |
HIP 82746 |
2.46 |
| 2026-10-03 12:00 |
16:55:23.41 |
+74:27:43.7 |
HIP 82773 |
1.89 |
| 2026-10-04 00:00 |
16:55:51.68 |
+74:22:48.3 |
HIP 82886 |
6.12 |
| 2026-10-04 12:00 |
16:56:20.08 |
+74:17:53.4 |
HIP 82886 |
0.92 |
| 2026-10-05 00:00 |
16:56:48.62 |
+74:12:59.0 |
HIP 82886 |
4.47 |
| 2026-10-05 12:00 |
16:57:17.28 |
+74:08:05.1 |
HIP 82886 |
9.74 |
| 2026-10-06 00:00 |
16:57:46.06 |
+74:03:11.7 |
HIP 82886 |
15.01 |
| 2026-10-06 12:00 |
16:58:14.97 |
+73:58:18.8 |
HIP 82886 |
20.28 |
| 2026-10-07 00:00 |
16:58:43.99 |
+73:53:26.5 |
HIP 82886 |
25.55 |
| 2026-10-07 12:00 |
16:59:13.14 |
+73:48:34.7 |
HIP 83678 |
30.36 |
| 2026-10-08 00:00 |
16:59:42.40 |
+73:43:43.4 |
HIP 83291 |
25.88 |
| 2026-10-08 12:00 |
17:00:11.77 |
+73:38:52.7 |
HIP 83291 |
20.67 |
| 2026-10-09 00:00 |
17:00:41.26 |
+73:34:02.6 |
HIP 83291 |
15.52 |
| 2026-10-09 12:00 |
17:01:10.85 |
+73:29:13.1 |
HIP 83291 |
10.48 |
| 2026-10-10 00:00 |
17:01:40.56 |
+73:24:24.2 |
HIP 83291 |
5.88 |
| 2026-10-10 12:00 |
17:02:10.36 |
+73:19:35.9 |
HIP 83291 |
3.85 |
| 2026-10-11 00:00 |
17:02:40.27 |
+73:14:48.2 |
HIP 83291 |
7.11 |
| 2026-10-11 12:00 |
17:03:10.28 |
+73:10:01.1 |
HIP 83219 |
11.86 |
| 2026-10-12 00:00 |
17:03:40.39 |
+73:05:14.6 |
HIP 83219 |
15.36 |
| 2026-10-12 12:00 |
17:04:10.60 |
+73:00:28.8 |
HIP 83219 |
19.66 |
| 2026-10-13 00:00 |
17:04:40.90 |
+72:55:43.7 |
HIP 83914 |
23.18 |
| 2026-10-13 12:00 |
17:05:11.29 |
+72:50:59.2 |
HIP 83914 |
24.70 |
| 2026-10-14 00:00 |
17:05:41.77 |
+72:46:15.4 |
HIP 83914 |
27.14 |
| 2026-10-14 12:00 |
17:06:12.34 |
+72:41:32.3 |
HIP 83884 |
22.57 |
| 2026-10-15 00:00 |
17:06:42.99 |
+72:36:49.8 |
HIP 83884 |
17.35 |
| 2026-10-15 12:00 |
17:07:13.73 |
+72:32:08.1 |
HIP 83884 |
12.15 |
| 2026-10-16 00:00 |
17:07:44.55 |
+72:27:27.1 |
HIP 83884 |
6.99 |