C/2025 J1 (Borisov)
| Parameter |
Value |
| Designation |
C/2025 J1 (Borisov) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-06-11T19:23:41.706240Z |
| Orbit solution date (soln_date, UTC) |
2026-01-13T08:12:19Z |
| Obs used |
479 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
13.500 |
| 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) |
2025-09-03.0000000 |
| e |
0.99691142 |
| q (au) |
3.580501 |
| a (au) |
1159.272419 |
| i (deg) |
95.444968 |
| Ω (om, deg) |
273.975803 |
| ω (w, deg) |
166.619256 |
| M (ma, deg) |
359.992963 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.166 + 5.710\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.166 |
| n |
5.710 |
| gf |
1.000 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
05:06:34.72 |
+70:01:06.8 |
HIP 23545 |
14.62 |
| 2026-02-03 12:00 |
05:05:44.15 |
+69:48:57.2 |
HIP 23545 |
18.33 |
| 2026-02-04 00:00 |
05:04:55.38 |
+69:36:46.1 |
HIP 23869 |
15.84 |
| 2026-02-04 12:00 |
05:04:08.36 |
+69:24:33.9 |
HIP 23425 |
18.47 |
| 2026-02-05 00:00 |
05:03:23.05 |
+69:12:20.4 |
HIP 23425 |
7.41 |
| 2026-02-05 12:00 |
05:02:39.40 |
+69:00:06.0 |
HIP 23425 |
10.00 |
| 2026-02-06 00:00 |
05:01:57.37 |
+68:47:50.7 |
HIP 23220 |
18.13 |
| 2026-02-06 12:00 |
05:01:16.92 |
+68:35:34.6 |
HIP 23220 |
8.23 |
| 2026-02-07 00:00 |
05:00:38.02 |
+68:23:17.9 |
HIP 23220 |
11.64 |
| 2026-02-07 12:00 |
05:00:00.62 |
+68:11:00.6 |
HIP 23220 |
23.03 |
| 2026-02-08 00:00 |
04:59:24.69 |
+67:58:42.9 |
HIP 23066 |
15.21 |
| 2026-02-08 12:00 |
04:58:50.19 |
+67:46:25.0 |
HIP 23066 |
5.93 |
| 2026-02-09 00:00 |
04:58:17.08 |
+67:34:06.9 |
HIP 23124 |
9.02 |
| 2026-02-09 12:00 |
04:57:45.34 |
+67:21:48.6 |
HIP 23124 |
5.73 |
| 2026-02-10 00:00 |
04:57:14.92 |
+67:09:30.4 |
HIP 23124 |
17.44 |
| 2026-02-10 12:00 |
04:56:45.80 |
+66:57:12.3 |
HIP 23124 |
29.89 |
| 2026-02-11 00:00 |
04:56:17.95 |
+66:44:54.5 |
HIP 22783 |
27.80 |
| 2026-02-11 12:00 |
04:55:51.32 |
+66:32:36.9 |
HIP 22783 |
16.20 |
| 2026-02-12 00:00 |
04:55:25.91 |
+66:20:19.8 |
HIP 22783 |
8.32 |
| 2026-02-12 12:00 |
04:55:01.67 |
+66:08:03.1 |
HIP 22733 |
12.40 |
| 2026-02-13 00:00 |
04:54:38.57 |
+65:55:47.1 |
HIP 22733 |
8.72 |
| 2026-02-13 12:00 |
04:54:16.60 |
+65:43:31.7 |
HIP 22733 |
17.63 |
| 2026-02-14 00:00 |
04:53:55.72 |
+65:31:17.1 |
HIP 23047 |
26.78 |
| 2026-02-14 12:00 |
04:53:35.91 |
+65:19:03.3 |
HIP 22468 |
22.06 |
| 2026-02-15 00:00 |
04:53:17.14 |
+65:06:50.5 |
HIP 22468 |
21.99 |
| 2026-02-15 12:00 |
04:52:59.40 |
+64:54:38.6 |
HIP 22468 |
28.08 |
| 2026-02-16 00:00 |
04:52:42.64 |
+64:42:27.9 |
HIP 22961 |
30.17 |
| 2026-02-16 12:00 |
04:52:26.86 |
+64:30:18.3 |
HIP 22961 |
26.50 |
| 2026-02-17 00:00 |
04:52:12.02 |
+64:18:09.9 |
HIP 22961 |
28.13 |
| 2026-02-17 12:00 |
04:51:58.12 |
+64:06:02.8 |
HIP 22476 |
30.90 |
| 2026-02-18 00:00 |
04:51:45.12 |
+63:53:57.0 |
HIP 22476 |
19.49 |
| 2026-02-18 12:00 |
04:51:33.00 |
+63:41:52.7 |
HIP 22476 |
10.18 |
| 2026-02-19 00:00 |
04:51:21.75 |
+63:29:49.9 |
HIP 22626 |
4.87 |
| 2026-02-19 12:00 |
04:51:11.34 |
+63:17:48.6 |
HIP 22498 |
5.67 |
| 2026-02-20 00:00 |
04:51:01.76 |
+63:05:48.9 |
HIP 22498 |
14.79 |
| 2026-02-20 12:00 |
04:50:52.99 |
+62:53:51.0 |
HIP 22648 |
15.64 |
| 2026-02-21 00:00 |
04:50:45.00 |
+62:41:54.7 |
HIP 22648 |
10.96 |
| 2026-02-21 12:00 |
04:50:37.78 |
+62:30:00.2 |
HIP 22648 |
16.72 |
| 2026-02-22 00:00 |
04:50:31.32 |
+62:18:07.6 |
HIP 22648 |
26.85 |
| 2026-02-22 12:00 |
04:50:25.59 |
+62:06:16.8 |
HIP 22553 |
35.13 |
| 2026-02-23 00:00 |
04:50:20.57 |
+61:54:28.0 |
HIP 22553 |
23.70 |
| 2026-02-23 12:00 |
04:50:16.26 |
+61:42:41.2 |
HIP 22553 |
12.99 |
| 2026-02-24 00:00 |
04:50:12.64 |
+61:30:56.4 |
HIP 22553 |
7.26 |