| Parameter |
Value |
| Designation |
19P/Borrelly |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2022-02-01T18:20:14.879040Z |
| Orbit solution date (soln_date, UTC) |
2024-12-30T09:03:27Z |
| Obs used |
2452 |
| NEO |
- |
| M1 |
9.800 |
| K1 |
14.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-03-06.0000000 |
| e |
0.63791428 |
| q (au) |
1.306030 |
| a (au) |
3.606965 |
| i (deg) |
29.318662 |
| Ω (om, deg) |
74.300843 |
| ω (w, deg) |
351.861606 |
| M (ma, deg) |
312.122920 |
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) |
| 2026-05-12 00:00 |
17:34:40.02 |
-26:15:48.2 |
HIP 86020 |
28.61 |
| 2026-05-12 12:00 |
17:34:23.65 |
-26:16:35.9 |
HIP 86020 |
28.24 |
| 2026-05-13 00:00 |
17:34:07.12 |
-26:17:23.4 |
HIP 86020 |
28.38 |
| 2026-05-13 12:00 |
17:33:50.42 |
-26:18:10.6 |
HIP 85783 |
28.32 |
| 2026-05-14 00:00 |
17:33:33.56 |
-26:18:57.6 |
HIP 85783 |
24.63 |
| 2026-05-14 12:00 |
17:33:16.53 |
-26:19:44.3 |
HIP 85783 |
20.96 |
| 2026-05-15 00:00 |
17:32:59.35 |
-26:20:30.8 |
HIP 85783 |
17.35 |
| 2026-05-15 12:00 |
17:32:42.01 |
-26:21:17.1 |
HIP 85783 |
13.89 |
| 2026-05-16 00:00 |
17:32:24.51 |
-26:22:03.1 |
HIP 85783 |
10.74 |
| 2026-05-16 12:00 |
17:32:06.86 |
-26:22:48.9 |
HIP 85783 |
8.33 |
| 2026-05-17 00:00 |
17:31:49.06 |
-26:23:34.4 |
HIP 85783 |
7.47 |
| 2026-05-17 12:00 |
17:31:31.11 |
-26:24:19.6 |
HIP 85783 |
8.67 |
| 2026-05-18 00:00 |
17:31:13.01 |
-26:25:04.5 |
HIP 85783 |
11.34 |
| 2026-05-18 12:00 |
17:30:54.77 |
-26:25:49.2 |
HIP 85783 |
14.71 |
| 2026-05-19 00:00 |
17:30:36.38 |
-26:26:33.6 |
HIP 85783 |
18.43 |
| 2026-05-19 12:00 |
17:30:17.86 |
-26:27:17.6 |
HIP 85783 |
22.34 |
| 2026-05-20 00:00 |
17:29:59.19 |
-26:28:01.4 |
HIP 85538 |
22.09 |
| 2026-05-20 12:00 |
17:29:40.40 |
-26:28:44.9 |
HIP 85538 |
18.79 |
| 2026-05-21 00:00 |
17:29:21.47 |
-26:29:28.1 |
HIP 85538 |
15.95 |
| 2026-05-21 12:00 |
17:29:02.41 |
-26:30:11.0 |
HIP 85538 |
13.87 |
| 2026-05-22 00:00 |
17:28:43.22 |
-26:30:53.6 |
HIP 85538 |
12.97 |
| 2026-05-22 12:00 |
17:28:23.91 |
-26:31:35.8 |
HIP 85538 |
13.50 |
| 2026-05-23 00:00 |
17:28:04.47 |
-26:32:17.7 |
HIP 85538 |
15.33 |
| 2026-05-23 12:00 |
17:27:44.92 |
-26:32:59.3 |
HIP 85387 |
17.83 |
| 2026-05-24 00:00 |
17:27:25.24 |
-26:33:40.6 |
HIP 85387 |
15.78 |
| 2026-05-24 12:00 |
17:27:05.46 |
-26:34:21.5 |
HIP 85387 |
14.82 |
| 2026-05-25 00:00 |
17:26:45.55 |
-26:35:02.1 |
HIP 85387 |
15.17 |
| 2026-05-25 12:00 |
17:26:25.54 |
-26:35:42.3 |
HIP 85387 |
16.78 |
| 2026-05-26 00:00 |
17:26:05.43 |
-26:36:22.2 |
HIP 85387 |
19.34 |
| 2026-05-26 12:00 |
17:25:45.20 |
-26:37:01.8 |
HIP 85292 |
22.46 |
| 2026-05-27 00:00 |
17:25:24.88 |
-26:37:40.9 |
HIP 85189 |
21.02 |
| 2026-05-27 12:00 |
17:25:04.45 |
-26:38:19.7 |
HIP 85189 |
18.39 |
| 2026-05-28 00:00 |
17:24:43.93 |
-26:38:58.2 |
HIP 85189 |
16.64 |
| 2026-05-28 12:00 |
17:24:23.31 |
-26:39:36.3 |
HIP 85189 |
16.09 |
| 2026-05-29 00:00 |
17:24:02.60 |
-26:40:14.0 |
HIP 85189 |
16.86 |
| 2026-05-29 12:00 |
17:23:41.81 |
-26:40:51.3 |
HIP 85189 |
18.81 |
| 2026-05-30 00:00 |
17:23:20.92 |
-26:41:28.2 |
HIP 85189 |
21.64 |
| 2026-05-30 12:00 |
17:22:59.95 |
-26:42:04.8 |
HIP 84931 |
24.20 |
| 2026-05-31 00:00 |
17:22:38.91 |
-26:42:41.0 |
HIP 84931 |
20.61 |
| 2026-05-31 12:00 |
17:22:17.78 |
-26:43:16.8 |
HIP 84931 |
17.56 |
| 2026-06-01 00:00 |
17:21:56.57 |
-26:43:52.2 |
HIP 84931 |
15.40 |
| 2026-06-01 12:00 |
17:21:35.30 |
-26:44:27.2 |
HIP 84931 |
14.53 |
| 2026-06-02 00:00 |
17:21:13.95 |
-26:45:01.8 |
HIP 84931 |
15.20 |