| Parameter |
Value |
| Designation |
19P/Borrelly |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2022-02-01T18:24:39.669120Z |
| Orbit solution date (soln_date, UTC) |
2026-09-04T10:21:01Z |
| Obs used |
2462 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
14.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-03-13.0000000 |
| e |
0.63790517 |
| q (au) |
1.306062 |
| a (au) |
3.606961 |
| i (deg) |
29.317423 |
| Ω (om, deg) |
74.298103 |
| ω (w, deg) |
351.863257 |
| M (ma, deg) |
313.129553 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.210 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.210 |
| n |
6.000 |
| gf |
0.800 |
| gb |
-0.962 |
| k |
0.999 |
| δ90 |
1.000 |
| 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 |
| 2021-02-02 |
2021-07-04 |
-78.0808 |
+33.211 |
| 2021-07-04 |
2022-02-01 |
+6.5636 |
-1.743 |
| 2022-02-01 |
2022-05-18 |
-2.2914 |
-0.440 |
| 2022-05-18 |
2024-05-02 |
+2.9727 |
-2.179 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
16:45:47.21 |
-27:45:09.0 |
HIP 82008 |
13.26 |
| 2026-09-20 12:00 |
16:45:57.92 |
-27:45:41.6 |
HIP 82008 |
14.52 |
| 2026-09-21 00:00 |
16:46:08.80 |
-27:46:14.4 |
HIP 82008 |
16.08 |
| 2026-09-21 12:00 |
16:46:19.86 |
-27:46:47.5 |
HIP 82008 |
17.88 |
| 2026-09-22 00:00 |
16:46:31.08 |
-27:47:20.9 |
HIP 82008 |
19.86 |
| 2026-09-22 12:00 |
16:46:42.48 |
-27:47:54.5 |
HIP 82008 |
22.00 |
| 2026-09-23 00:00 |
16:46:54.04 |
-27:48:28.4 |
HIP 82008 |
24.25 |
| 2026-09-23 12:00 |
16:47:05.77 |
-27:49:02.5 |
HIP 82008 |
26.60 |
| 2026-09-24 00:00 |
16:47:17.67 |
-27:49:36.8 |
HIP 82315 |
28.87 |
| 2026-09-24 12:00 |
16:47:29.74 |
-27:50:11.5 |
HIP 82315 |
26.99 |
| 2026-09-25 00:00 |
16:47:41.97 |
-27:50:46.3 |
HIP 82315 |
25.23 |
| 2026-09-25 12:00 |
16:47:54.36 |
-27:51:21.4 |
HIP 82315 |
23.65 |
| 2026-09-26 00:00 |
16:48:06.92 |
-27:51:56.8 |
HIP 82315 |
22.28 |
| 2026-09-26 12:00 |
16:48:19.64 |
-27:52:32.4 |
HIP 82315 |
21.20 |
| 2026-09-27 00:00 |
16:48:32.52 |
-27:53:08.2 |
HIP 82315 |
20.46 |
| 2026-09-27 12:00 |
16:48:45.56 |
-27:53:44.3 |
HIP 82315 |
20.12 |
| 2026-09-28 00:00 |
16:48:58.76 |
-27:54:20.5 |
HIP 82315 |
20.20 |
| 2026-09-28 12:00 |
16:49:12.12 |
-27:54:57.1 |
HIP 82330 |
20.66 |
| 2026-09-29 00:00 |
16:49:25.65 |
-27:55:33.8 |
HIP 82330 |
21.17 |
| 2026-09-29 12:00 |
16:49:39.32 |
-27:56:10.8 |
HIP 82458 |
19.22 |
| 2026-09-30 00:00 |
16:49:53.16 |
-27:56:48.0 |
HIP 82458 |
16.11 |
| 2026-09-30 12:00 |
16:50:07.15 |
-27:57:25.4 |
HIP 82458 |
12.97 |
| 2026-10-01 00:00 |
16:50:21.30 |
-27:58:03.1 |
HIP 82458 |
9.80 |
| 2026-10-01 12:00 |
16:50:35.60 |
-27:58:40.9 |
HIP 82458 |
6.61 |
| 2026-10-02 00:00 |
16:50:50.06 |
-27:59:19.0 |
HIP 82458 |
3.46 |
| 2026-10-02 12:00 |
16:51:04.67 |
-27:59:57.3 |
HIP 82458 |
1.18 |
| 2026-10-03 00:00 |
16:51:19.43 |
-28:00:35.8 |
HIP 82479 |
1.40 |
| 2026-10-03 12:00 |
16:51:34.35 |
-28:01:14.5 |
HIP 82479 |
2.09 |
| 2026-10-04 00:00 |
16:51:49.41 |
-28:01:53.5 |
HIP 82479 |
5.44 |
| 2026-10-04 12:00 |
16:52:04.63 |
-28:02:32.6 |
HIP 82479 |
8.86 |
| 2026-10-05 00:00 |
16:52:20.00 |
-28:03:11.9 |
HIP 82479 |
12.31 |
| 2026-10-05 12:00 |
16:52:35.51 |
-28:03:51.4 |
HIP 82479 |
15.79 |
| 2026-10-06 00:00 |
16:52:51.18 |
-28:04:31.1 |
HIP 82697 |
18.63 |
| 2026-10-06 12:00 |
16:53:06.99 |
-28:05:11.1 |
HIP 82697 |
15.08 |
| 2026-10-07 00:00 |
16:53:22.95 |
-28:05:51.2 |
HIP 82697 |
11.52 |
| 2026-10-07 12:00 |
16:53:39.05 |
-28:06:31.5 |
HIP 82697 |
7.93 |
| 2026-10-08 00:00 |
16:53:55.30 |
-28:07:11.9 |
HIP 82697 |
4.34 |
| 2026-10-08 12:00 |
16:54:11.69 |
-28:07:52.6 |
HIP 82697 |
1.22 |
| 2026-10-09 00:00 |
16:54:28.23 |
-28:08:33.4 |
HIP 82697 |
3.37 |
| 2026-10-09 12:00 |
16:54:44.91 |
-28:09:14.5 |
HIP 82697 |
7.01 |
| 2026-10-10 00:00 |
16:55:01.73 |
-28:09:55.7 |
HIP 82697 |
10.75 |
| 2026-10-10 12:00 |
16:55:18.69 |
-28:10:37.0 |
HIP 82878 |
13.49 |
| 2026-10-11 00:00 |
16:55:35.79 |
-28:11:18.6 |
HIP 82878 |
10.37 |