C/2004 Q2 (Machholz)
| 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 |
-4.3508 |
+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) |
| 2026-02-03 00:00 |
18:19:22.96 |
-23:29:18.8 |
HIP 89741 |
26.32 |
| 2026-02-03 12:00 |
18:19:25.46 |
-23:29:18.7 |
HIP 89741 |
26.48 |
| 2026-02-04 00:00 |
18:19:27.93 |
-23:29:18.6 |
HIP 89741 |
26.65 |
| 2026-02-04 12:00 |
18:19:30.39 |
-23:29:18.5 |
HIP 89741 |
26.83 |
| 2026-02-05 00:00 |
18:19:32.83 |
-23:29:18.5 |
HIP 89741 |
27.02 |
| 2026-02-05 12:00 |
18:19:35.25 |
-23:29:18.4 |
HIP 89741 |
27.22 |
| 2026-02-06 00:00 |
18:19:37.65 |
-23:29:18.3 |
HIP 89741 |
27.42 |
| 2026-02-06 12:00 |
18:19:40.04 |
-23:29:18.2 |
HIP 89741 |
27.64 |
| 2026-02-07 00:00 |
18:19:42.41 |
-23:29:18.2 |
HIP 89741 |
27.86 |
| 2026-02-07 12:00 |
18:19:44.76 |
-23:29:18.1 |
HIP 89741 |
28.09 |
| 2026-02-08 00:00 |
18:19:47.10 |
-23:29:18.1 |
HIP 89741 |
28.32 |
| 2026-02-08 12:00 |
18:19:49.41 |
-23:29:18.1 |
HIP 89741 |
28.57 |
| 2026-02-09 00:00 |
18:19:51.71 |
-23:29:18.0 |
HIP 89741 |
28.81 |
| 2026-02-09 12:00 |
18:19:53.99 |
-23:29:18.0 |
HIP 89741 |
29.07 |
| 2026-02-10 00:00 |
18:19:56.24 |
-23:29:18.0 |
HIP 89741 |
29.32 |
| 2026-02-10 12:00 |
18:19:58.48 |
-23:29:18.0 |
HIP 89741 |
29.59 |
| 2026-02-11 00:00 |
18:20:00.71 |
-23:29:18.0 |
HIP 89915 |
29.69 |
| 2026-02-11 12:00 |
18:20:02.91 |
-23:29:18.0 |
HIP 89915 |
29.49 |
| 2026-02-12 00:00 |
18:20:05.09 |
-23:29:18.0 |
HIP 89915 |
29.31 |
| 2026-02-12 12:00 |
18:20:07.25 |
-23:29:18.1 |
HIP 89915 |
29.13 |
| 2026-02-13 00:00 |
18:20:09.39 |
-23:29:18.1 |
HIP 89915 |
28.96 |
| 2026-02-13 12:00 |
18:20:11.52 |
-23:29:18.2 |
HIP 89915 |
28.80 |
| 2026-02-14 00:00 |
18:20:13.62 |
-23:29:18.2 |
HIP 89915 |
28.65 |
| 2026-02-14 12:00 |
18:20:15.70 |
-23:29:18.3 |
HIP 89915 |
28.51 |
| 2026-02-15 00:00 |
18:20:17.76 |
-23:29:18.3 |
HIP 89915 |
28.37 |
| 2026-02-15 12:00 |
18:20:19.80 |
-23:29:18.4 |
HIP 89915 |
28.24 |
| 2026-02-16 00:00 |
18:20:21.82 |
-23:29:18.5 |
HIP 89915 |
28.13 |
| 2026-02-16 12:00 |
18:20:23.82 |
-23:29:18.6 |
HIP 89915 |
28.02 |
| 2026-02-17 00:00 |
18:20:25.80 |
-23:29:18.7 |
HIP 89915 |
27.91 |
| 2026-02-17 12:00 |
18:20:27.75 |
-23:29:18.8 |
HIP 89915 |
27.82 |
| 2026-02-18 00:00 |
18:20:29.69 |
-23:29:19.0 |
HIP 89915 |
27.73 |
| 2026-02-18 12:00 |
18:20:31.60 |
-23:29:19.1 |
HIP 89915 |
27.65 |
| 2026-02-19 00:00 |
18:20:33.49 |
-23:29:19.2 |
HIP 89915 |
27.58 |
| 2026-02-19 12:00 |
18:20:35.36 |
-23:29:19.4 |
HIP 89915 |
27.52 |
| 2026-02-20 00:00 |
18:20:37.21 |
-23:29:19.6 |
HIP 89915 |
27.46 |
| 2026-02-20 12:00 |
18:20:39.03 |
-23:29:19.8 |
HIP 89915 |
27.41 |
| 2026-02-21 00:00 |
18:20:40.84 |
-23:29:19.9 |
HIP 89915 |
27.36 |
| 2026-02-21 12:00 |
18:20:42.62 |
-23:29:20.1 |
HIP 89915 |
27.33 |
| 2026-02-22 00:00 |
18:20:44.37 |
-23:29:20.4 |
HIP 89915 |
27.29 |
| 2026-02-22 12:00 |
18:20:46.11 |
-23:29:20.6 |
HIP 89915 |
27.27 |
| 2026-02-23 00:00 |
18:20:47.82 |
-23:29:20.8 |
HIP 89915 |
27.25 |
| 2026-02-23 12:00 |
18:20:49.51 |
-23:29:21.0 |
HIP 89915 |
27.23 |
| 2026-02-24 00:00 |
18:20:51.18 |
-23:29:21.3 |
HIP 89915 |
27.23 |