| Parameter |
Value |
| Designation |
C/1999 T1 (McNaught-Hartley) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2000-12-13T11:19:42.432960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:02Z |
| Obs used |
661 |
| NEO |
- |
| M1 |
8.300 |
| K1 |
7.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-11-18.0000000 |
| e |
0.99985577 |
| q (au) |
1.171699 |
| a (au) |
8123.927279 |
| i (deg) |
79.975213 |
| Ω (om, deg) |
182.483007 |
| ω (w, deg) |
344.758001 |
| M (ma, deg) |
359.999966 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.381 + 4.354\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.381 |
| n |
4.354 |
| gf |
0.998 |
| gb |
-0.917 |
| k |
0.998 |
| δ90 |
9.996 |
| 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 |
| 1999-10-07 |
2000-01-03 |
+19.0088 |
-13.854 |
| 2000-01-03 |
2000-12-12 |
-2.2204 |
+0.385 |
| 2000-12-15 |
2001-11-05 |
+1.3645 |
-0.126 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
22:54:05.47 |
+28:30:58.1 |
HIP 113063 |
7.54 |
| 2026-06-01 12:00 |
22:54:05.61 |
+28:31:18.8 |
HIP 113063 |
7.26 |
| 2026-06-02 00:00 |
22:54:05.73 |
+28:31:39.4 |
HIP 113063 |
6.98 |
| 2026-06-02 12:00 |
22:54:05.84 |
+28:32:00.0 |
HIP 113063 |
6.70 |
| 2026-06-03 00:00 |
22:54:05.92 |
+28:32:20.4 |
HIP 113063 |
6.43 |
| 2026-06-03 12:00 |
22:54:05.97 |
+28:32:40.8 |
HIP 113063 |
6.17 |
| 2026-06-04 00:00 |
22:54:06.01 |
+28:33:01.1 |
HIP 113063 |
5.91 |
| 2026-06-04 12:00 |
22:54:06.03 |
+28:33:21.3 |
HIP 113063 |
5.66 |
| 2026-06-05 00:00 |
22:54:06.02 |
+28:33:41.3 |
HIP 113063 |
5.41 |
| 2026-06-05 12:00 |
22:54:05.99 |
+28:34:01.3 |
HIP 113063 |
5.18 |
| 2026-06-06 00:00 |
22:54:05.94 |
+28:34:21.2 |
HIP 113063 |
4.95 |
| 2026-06-06 12:00 |
22:54:05.87 |
+28:34:41.0 |
HIP 113063 |
4.73 |
| 2026-06-07 00:00 |
22:54:05.77 |
+28:35:00.7 |
HIP 113063 |
4.52 |
| 2026-06-07 12:00 |
22:54:05.66 |
+28:35:20.3 |
HIP 113063 |
4.32 |
| 2026-06-08 00:00 |
22:54:05.52 |
+28:35:39.8 |
HIP 113063 |
4.14 |
| 2026-06-08 12:00 |
22:54:05.36 |
+28:35:59.1 |
HIP 113063 |
3.97 |
| 2026-06-09 00:00 |
22:54:05.18 |
+28:36:18.4 |
HIP 113063 |
3.81 |
| 2026-06-09 12:00 |
22:54:04.98 |
+28:36:37.6 |
HIP 113063 |
3.68 |
| 2026-06-10 00:00 |
22:54:04.75 |
+28:36:56.6 |
HIP 113063 |
3.56 |
| 2026-06-10 12:00 |
22:54:04.51 |
+28:37:15.6 |
HIP 113063 |
3.47 |
| 2026-06-11 00:00 |
22:54:04.24 |
+28:37:34.4 |
HIP 113063 |
3.39 |
| 2026-06-11 12:00 |
22:54:03.95 |
+28:37:53.1 |
HIP 113063 |
3.35 |
| 2026-06-12 00:00 |
22:54:03.64 |
+28:38:11.7 |
HIP 113063 |
3.32 |
| 2026-06-12 12:00 |
22:54:03.30 |
+28:38:30.2 |
HIP 113063 |
3.33 |
| 2026-06-13 00:00 |
22:54:02.95 |
+28:38:48.5 |
HIP 113063 |
3.35 |
| 2026-06-13 12:00 |
22:54:02.57 |
+28:39:06.8 |
HIP 113063 |
3.40 |
| 2026-06-14 00:00 |
22:54:02.17 |
+28:39:24.9 |
HIP 113063 |
3.48 |
| 2026-06-14 12:00 |
22:54:01.75 |
+28:39:42.9 |
HIP 113063 |
3.57 |
| 2026-06-15 00:00 |
22:54:01.31 |
+28:40:00.7 |
HIP 113063 |
3.69 |
| 2026-06-15 12:00 |
22:54:00.85 |
+28:40:18.5 |
HIP 113063 |
3.82 |
| 2026-06-16 00:00 |
22:54:00.36 |
+28:40:36.1 |
HIP 113063 |
3.97 |
| 2026-06-16 12:00 |
22:53:59.86 |
+28:40:53.6 |
HIP 113063 |
4.13 |
| 2026-06-17 00:00 |
22:53:59.33 |
+28:41:10.9 |
HIP 113063 |
4.30 |
| 2026-06-17 12:00 |
22:53:58.78 |
+28:41:28.1 |
HIP 113063 |
4.48 |
| 2026-06-18 00:00 |
22:53:58.21 |
+28:41:45.2 |
HIP 113063 |
4.68 |
| 2026-06-18 12:00 |
22:53:57.61 |
+28:42:02.1 |
HIP 113063 |
4.88 |
| 2026-06-19 00:00 |
22:53:57.00 |
+28:42:18.9 |
HIP 113063 |
5.09 |
| 2026-06-19 12:00 |
22:53:56.36 |
+28:42:35.6 |
HIP 113063 |
5.30 |
| 2026-06-20 00:00 |
22:53:55.71 |
+28:42:52.1 |
HIP 113063 |
5.52 |
| 2026-06-20 12:00 |
22:53:55.03 |
+28:43:08.5 |
HIP 113063 |
5.75 |
| 2026-06-21 00:00 |
22:53:54.33 |
+28:43:24.8 |
HIP 113063 |
5.98 |
| 2026-06-21 12:00 |
22:53:53.61 |
+28:43:40.9 |
HIP 113063 |
6.21 |
| 2026-06-22 00:00 |
22:53:52.87 |
+28:43:56.8 |
HIP 113063 |
6.45 |