| Parameter |
Value |
| Designation |
C/1999 A1 (Tilbrook) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1999-01-29T15:46:41.666880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:57Z |
| Obs used |
68 |
| NEO |
- |
| M1 |
14.300 |
| K1 |
10.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1999-01-20.0000000 |
| e |
0.99589489 |
| q (au) |
0.730741 |
| a (au) |
178.007719 |
| i (deg) |
89.481788 |
| Ω (om, deg) |
259.123002 |
| ω (w, deg) |
232.669862 |
| M (ma, deg) |
359.995992 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.200 + 2.643\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.200 |
| n |
2.643 |
| gf |
0.800 |
| gb |
-1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
17:31:28.37 |
+16:30:37.6 |
HIP 85870 |
19.72 |
| 2026-03-26 12:00 |
17:31:27.89 |
+16:31:01.9 |
HIP 85799 |
19.46 |
| 2026-03-27 00:00 |
17:31:27.38 |
+16:31:26.1 |
HIP 85799 |
19.11 |
| 2026-03-27 12:00 |
17:31:26.86 |
+16:31:50.2 |
HIP 85799 |
18.78 |
| 2026-03-28 00:00 |
17:31:26.31 |
+16:32:14.4 |
HIP 85799 |
18.45 |
| 2026-03-28 12:00 |
17:31:25.74 |
+16:32:38.5 |
HIP 85799 |
18.13 |
| 2026-03-29 00:00 |
17:31:25.14 |
+16:33:02.5 |
HIP 85799 |
17.81 |
| 2026-03-29 12:00 |
17:31:24.53 |
+16:33:26.6 |
HIP 85799 |
17.50 |
| 2026-03-30 00:00 |
17:31:23.90 |
+16:33:50.6 |
HIP 85799 |
17.20 |
| 2026-03-30 12:00 |
17:31:23.24 |
+16:34:14.5 |
HIP 85799 |
16.91 |
| 2026-03-31 00:00 |
17:31:22.56 |
+16:34:38.5 |
HIP 85799 |
16.62 |
| 2026-03-31 12:00 |
17:31:21.86 |
+16:35:02.3 |
HIP 85799 |
16.35 |
| 2026-04-01 00:00 |
17:31:21.15 |
+16:35:26.2 |
HIP 85799 |
16.08 |
| 2026-04-01 12:00 |
17:31:20.40 |
+16:35:50.0 |
HIP 85799 |
15.83 |
| 2026-04-02 00:00 |
17:31:19.64 |
+16:36:13.7 |
HIP 85799 |
15.58 |
| 2026-04-02 12:00 |
17:31:18.86 |
+16:36:37.4 |
HIP 85799 |
15.35 |
| 2026-04-03 00:00 |
17:31:18.06 |
+16:37:01.0 |
HIP 85799 |
15.13 |
| 2026-04-03 12:00 |
17:31:17.24 |
+16:37:24.6 |
HIP 85799 |
14.93 |
| 2026-04-04 00:00 |
17:31:16.39 |
+16:37:48.2 |
HIP 85799 |
14.74 |
| 2026-04-04 12:00 |
17:31:15.53 |
+16:38:11.7 |
HIP 85799 |
14.56 |
| 2026-04-05 00:00 |
17:31:14.64 |
+16:38:35.1 |
HIP 85799 |
14.40 |
| 2026-04-05 12:00 |
17:31:13.73 |
+16:38:58.5 |
HIP 85799 |
14.25 |
| 2026-04-06 00:00 |
17:31:12.81 |
+16:39:21.8 |
HIP 85799 |
14.12 |
| 2026-04-06 12:00 |
17:31:11.86 |
+16:39:45.0 |
HIP 85799 |
14.01 |
| 2026-04-07 00:00 |
17:31:10.89 |
+16:40:08.2 |
HIP 85799 |
13.92 |
| 2026-04-07 12:00 |
17:31:09.90 |
+16:40:31.3 |
HIP 85799 |
13.85 |
| 2026-04-08 00:00 |
17:31:08.90 |
+16:40:54.4 |
HIP 85799 |
13.79 |
| 2026-04-08 12:00 |
17:31:07.87 |
+16:41:17.4 |
HIP 85799 |
13.75 |
| 2026-04-09 00:00 |
17:31:06.82 |
+16:41:40.3 |
HIP 85799 |
13.74 |
| 2026-04-09 12:00 |
17:31:05.75 |
+16:42:03.2 |
HIP 85799 |
13.74 |
| 2026-04-10 00:00 |
17:31:04.66 |
+16:42:26.0 |
HIP 85799 |
13.76 |
| 2026-04-10 12:00 |
17:31:03.55 |
+16:42:48.7 |
HIP 85799 |
13.81 |
| 2026-04-11 00:00 |
17:31:02.43 |
+16:43:11.3 |
HIP 85799 |
13.87 |
| 2026-04-11 12:00 |
17:31:01.28 |
+16:43:33.8 |
HIP 85799 |
13.95 |
| 2026-04-12 00:00 |
17:31:00.11 |
+16:43:56.3 |
HIP 85799 |
14.05 |
| 2026-04-12 12:00 |
17:30:58.92 |
+16:44:18.7 |
HIP 85799 |
14.18 |
| 2026-04-13 00:00 |
17:30:57.72 |
+16:44:41.0 |
HIP 85799 |
14.32 |
| 2026-04-13 12:00 |
17:30:56.49 |
+16:45:03.2 |
HIP 85799 |
14.48 |
| 2026-04-14 00:00 |
17:30:55.24 |
+16:45:25.4 |
HIP 85799 |
14.66 |
| 2026-04-14 12:00 |
17:30:53.98 |
+16:45:47.4 |
HIP 85799 |
14.85 |
| 2026-04-15 00:00 |
17:30:52.70 |
+16:46:09.4 |
HIP 85799 |
15.07 |
| 2026-04-15 12:00 |
17:30:51.39 |
+16:46:31.2 |
HIP 85799 |
15.30 |
| 2026-04-16 00:00 |
17:30:50.07 |
+16:46:53.0 |
HIP 85799 |
15.54 |