2I = C/2019 Q4 (Borisov)
| Parameter |
Value |
| Designation |
C/2019 Q4 (Borisov) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-12-08T13:16:05.885760Z |
| Orbit solution date (soln_date, UTC) |
2024-06-24T15:49:04Z |
| Obs used |
964 |
| NEO |
- |
| M1 |
13.800 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2019-08-30T01:03:19.872000Z |
| Discovery magnitude (MPC) |
17.80 R |
| Discovery observatory (MPC) |
L51 · MARGO, Nauchnyi |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-01-05.0000000 |
| e |
3.35647578 |
| q (au) |
2.006521 |
| a (au) |
-0.851492 |
| i (deg) |
44.052642 |
| Ω (om, deg) |
308.147729 |
| ω (w, deg) |
209.123686 |
| M (ma, deg) |
34.429470 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.856 + 2.255\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.856 |
| n |
2.255 |
| gf |
1.000 |
| gb |
-0.707 |
| k |
0.800 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2018-12-13 |
2019-12-08 |
+1.5350 |
-0.658 |
| 2019-12-08 |
2020-03-05 |
+1.5946 |
-0.700 |
| 2020-03-05 |
2020-09-30 |
+12.2454 |
-6.134 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
18:08:27.49 |
-53:33:09.0 |
HIP 88640 |
25.13 |
| 2026-02-03 12:00 |
18:08:31.04 |
-53:33:20.8 |
HIP 88640 |
25.54 |
| 2026-02-04 00:00 |
18:08:34.56 |
-53:33:32.9 |
HIP 88640 |
25.96 |
| 2026-02-04 12:00 |
18:08:38.05 |
-53:33:45.0 |
HIP 88640 |
26.38 |
| 2026-02-05 00:00 |
18:08:41.51 |
-53:33:57.2 |
HIP 88640 |
26.80 |
| 2026-02-05 12:00 |
18:08:44.95 |
-53:34:09.6 |
HIP 88640 |
27.21 |
| 2026-02-06 00:00 |
18:08:48.36 |
-53:34:22.1 |
HIP 88640 |
27.63 |
| 2026-02-06 12:00 |
18:08:51.75 |
-53:34:34.7 |
HIP 88640 |
28.05 |
| 2026-02-07 00:00 |
18:08:55.10 |
-53:34:47.4 |
HIP 88640 |
28.47 |
| 2026-02-07 12:00 |
18:08:58.43 |
-53:35:00.3 |
HIP 88640 |
28.89 |
| 2026-02-08 00:00 |
18:09:01.73 |
-53:35:13.2 |
HIP 88640 |
29.30 |
| 2026-02-08 12:00 |
18:09:05.00 |
-53:35:26.3 |
HIP 88640 |
29.72 |
| 2026-02-09 00:00 |
18:09:08.24 |
-53:35:39.5 |
HIP 88640 |
30.13 |
| 2026-02-09 12:00 |
18:09:11.46 |
-53:35:52.8 |
HIP 88640 |
30.55 |
| 2026-02-10 00:00 |
18:09:14.64 |
-53:36:06.2 |
HIP 88640 |
30.96 |
| 2026-02-10 12:00 |
18:09:17.80 |
-53:36:19.8 |
HIP 88640 |
31.37 |
| 2026-02-11 00:00 |
18:09:20.92 |
-53:36:33.4 |
HIP 88640 |
31.78 |
| 2026-02-11 12:00 |
18:09:24.02 |
-53:36:47.2 |
HIP 88640 |
32.19 |
| 2026-02-12 00:00 |
18:09:27.08 |
-53:37:01.0 |
HIP 88640 |
32.59 |
| 2026-02-12 12:00 |
18:09:30.12 |
-53:37:15.0 |
HIP 88640 |
32.99 |
| 2026-02-13 00:00 |
18:09:33.12 |
-53:37:29.1 |
HIP 88640 |
33.40 |
| 2026-02-13 12:00 |
18:09:36.09 |
-53:37:43.3 |
HIP 88640 |
33.80 |
| 2026-02-14 00:00 |
18:09:39.04 |
-53:37:57.6 |
HIP 88640 |
34.19 |
| 2026-02-14 12:00 |
18:09:41.95 |
-53:38:12.0 |
HIP 88640 |
34.59 |
| 2026-02-15 00:00 |
18:09:44.83 |
-53:38:26.5 |
HIP 88640 |
34.98 |
| 2026-02-15 12:00 |
18:09:47.67 |
-53:38:41.1 |
HIP 88640 |
35.37 |
| 2026-02-16 00:00 |
18:09:50.49 |
-53:38:55.8 |
HIP 88949 |
35.71 |
| 2026-02-16 12:00 |
18:09:53.27 |
-53:39:10.6 |
HIP 88949 |
36.00 |
| 2026-02-17 00:00 |
18:09:56.03 |
-53:39:25.5 |
HIP 88949 |
36.30 |
| 2026-02-17 12:00 |
18:09:58.75 |
-53:39:40.5 |
HIP 88949 |
36.60 |
| 2026-02-18 00:00 |
18:10:01.43 |
-53:39:55.6 |
HIP 88949 |
36.91 |
| 2026-02-18 12:00 |
18:10:04.09 |
-53:40:10.8 |
HIP 89125 |
36.80 |
| 2026-02-19 00:00 |
18:10:06.71 |
-53:40:26.1 |
HIP 89125 |
36.44 |
| 2026-02-19 12:00 |
18:10:09.30 |
-53:40:41.5 |
HIP 89125 |
36.08 |
| 2026-02-20 00:00 |
18:10:11.85 |
-53:40:57.0 |
HIP 89125 |
35.72 |
| 2026-02-20 12:00 |
18:10:14.37 |
-53:41:12.6 |
HIP 89125 |
35.36 |
| 2026-02-21 00:00 |
18:10:16.86 |
-53:41:28.2 |
HIP 89125 |
35.01 |
| 2026-02-21 12:00 |
18:10:19.31 |
-53:41:44.0 |
HIP 89125 |
34.66 |
| 2026-02-22 00:00 |
18:10:21.73 |
-53:41:59.8 |
HIP 89125 |
34.31 |
| 2026-02-22 12:00 |
18:10:24.12 |
-53:42:15.7 |
HIP 89125 |
33.96 |
| 2026-02-23 00:00 |
18:10:26.47 |
-53:42:31.7 |
HIP 89125 |
33.62 |
| 2026-02-23 12:00 |
18:10:28.79 |
-53:42:47.8 |
HIP 89125 |
33.28 |
| 2026-02-24 00:00 |
18:10:31.07 |
-53:43:04.0 |
HIP 89125 |
32.94 |