| Parameter |
Value |
| Designation |
C/2004 Q2 (Machholz) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2005-01-24T21:52:04.915200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:43Z |
| Obs used |
3612 |
| NEO |
- |
| M1 |
11.200 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2005-03-30.0000000 |
| e |
0.99950132 |
| q (au) |
1.205042 |
| a (au) |
2416.445814 |
| i (deg) |
38.588949 |
| Ω (om, deg) |
93.622895 |
| ω (w, deg) |
19.504703 |
| M (ma, deg) |
0.000532 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.612 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.612 |
| n |
6.000 |
| gf |
0.800 |
| gb |
-0.921 |
| k |
0.988 |
| 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 |
| 2004-08-28 |
2005-01-24 |
-4.3509 |
+1.375 |
| 2005-01-24 |
2006-09-09 |
-1.9949 |
+0.688 |
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 |
18:18:26.21 |
-23:34:04.4 |
HIP 89741 |
30.66 |
| 2026-06-01 12:00 |
18:18:23.46 |
-23:34:06.6 |
HIP 89741 |
30.83 |
| 2026-06-02 00:00 |
18:18:20.70 |
-23:34:08.9 |
HIP 89741 |
31.00 |
| 2026-06-02 12:00 |
18:18:17.93 |
-23:34:11.2 |
HIP 89566 |
31.01 |
| 2026-06-03 00:00 |
18:18:15.15 |
-23:34:13.5 |
HIP 89566 |
30.50 |
| 2026-06-03 12:00 |
18:18:12.35 |
-23:34:15.8 |
HIP 89566 |
30.00 |
| 2026-06-04 00:00 |
18:18:09.55 |
-23:34:18.0 |
HIP 89566 |
29.49 |
| 2026-06-04 12:00 |
18:18:06.74 |
-23:34:20.3 |
HIP 89566 |
29.00 |
| 2026-06-05 00:00 |
18:18:03.91 |
-23:34:22.6 |
HIP 89566 |
28.50 |
| 2026-06-05 12:00 |
18:18:01.08 |
-23:34:24.9 |
HIP 89566 |
28.01 |
| 2026-06-06 00:00 |
18:17:58.24 |
-23:34:27.2 |
HIP 89566 |
27.53 |
| 2026-06-06 12:00 |
18:17:55.39 |
-23:34:29.4 |
HIP 89566 |
27.05 |
| 2026-06-07 00:00 |
18:17:52.53 |
-23:34:31.7 |
HIP 89566 |
26.57 |
| 2026-06-07 12:00 |
18:17:49.66 |
-23:34:34.0 |
HIP 89566 |
26.11 |
| 2026-06-08 00:00 |
18:17:46.79 |
-23:34:36.3 |
HIP 89566 |
25.65 |
| 2026-06-08 12:00 |
18:17:43.90 |
-23:34:38.5 |
HIP 89566 |
25.20 |
| 2026-06-09 00:00 |
18:17:41.01 |
-23:34:40.8 |
HIP 89566 |
24.75 |
| 2026-06-09 12:00 |
18:17:38.11 |
-23:34:43.1 |
HIP 89566 |
24.32 |
| 2026-06-10 00:00 |
18:17:35.21 |
-23:34:45.4 |
HIP 89566 |
23.89 |
| 2026-06-10 12:00 |
18:17:32.29 |
-23:34:47.6 |
HIP 89503 |
23.24 |
| 2026-06-11 00:00 |
18:17:29.37 |
-23:34:49.9 |
HIP 89503 |
22.57 |
| 2026-06-11 12:00 |
18:17:26.44 |
-23:34:52.2 |
HIP 89503 |
21.90 |
| 2026-06-12 00:00 |
18:17:23.51 |
-23:34:54.4 |
HIP 89503 |
21.23 |
| 2026-06-12 12:00 |
18:17:20.57 |
-23:34:56.7 |
HIP 89503 |
20.56 |
| 2026-06-13 00:00 |
18:17:17.62 |
-23:34:58.9 |
HIP 89503 |
19.89 |
| 2026-06-13 12:00 |
18:17:14.67 |
-23:35:01.2 |
HIP 89503 |
19.22 |
| 2026-06-14 00:00 |
18:17:11.71 |
-23:35:03.4 |
HIP 89503 |
18.55 |
| 2026-06-14 12:00 |
18:17:08.75 |
-23:35:05.7 |
HIP 89503 |
17.87 |
| 2026-06-15 00:00 |
18:17:05.78 |
-23:35:07.9 |
HIP 89503 |
17.20 |
| 2026-06-15 12:00 |
18:17:02.81 |
-23:35:10.2 |
HIP 89503 |
16.52 |
| 2026-06-16 00:00 |
18:16:59.83 |
-23:35:12.4 |
HIP 89503 |
15.84 |
| 2026-06-16 12:00 |
18:16:56.85 |
-23:35:14.7 |
HIP 89503 |
15.17 |
| 2026-06-17 00:00 |
18:16:53.87 |
-23:35:16.9 |
HIP 89503 |
14.49 |
| 2026-06-17 12:00 |
18:16:50.88 |
-23:35:19.2 |
HIP 89503 |
13.82 |
| 2026-06-18 00:00 |
18:16:47.89 |
-23:35:21.4 |
HIP 89503 |
13.14 |
| 2026-06-18 12:00 |
18:16:44.89 |
-23:35:23.6 |
HIP 89503 |
12.46 |
| 2026-06-19 00:00 |
18:16:41.89 |
-23:35:25.8 |
HIP 89503 |
11.79 |
| 2026-06-19 12:00 |
18:16:38.89 |
-23:35:28.1 |
HIP 89503 |
11.11 |
| 2026-06-20 00:00 |
18:16:35.89 |
-23:35:30.3 |
HIP 89503 |
10.44 |
| 2026-06-20 12:00 |
18:16:32.88 |
-23:35:32.5 |
HIP 89503 |
9.77 |
| 2026-06-21 00:00 |
18:16:29.87 |
-23:35:34.7 |
HIP 89503 |
9.10 |
| 2026-06-21 12:00 |
18:16:26.86 |
-23:35:36.9 |
HIP 89503 |
8.44 |
| 2026-06-22 00:00 |
18:16:23.85 |
-23:35:39.1 |
HIP 89503 |
7.77 |