| Parameter |
Value |
| Designation |
C/2008 N1 (Holmes) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2009-09-25T21:06:06.120000Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:21Z |
| Obs used |
1522 |
| NEO |
- |
| M1 |
12.800 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-06-22.0000000 |
| e |
0.99713966 |
| q (au) |
2.783511 |
| a (au) |
973.139852 |
| i (deg) |
115.521017 |
| Ω (om, deg) |
357.472211 |
| ω (w, deg) |
100.813452 |
| M (ma, deg) |
359.996887 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.312 + 2.390\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.312 |
| n |
2.390 |
| gf |
1.000 |
| gb |
-0.883 |
| k |
0.999 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2008-07-01 |
2009-05-02 |
+2.0960 |
-1.501 |
| 2009-05-02 |
2009-09-25 |
+0.0188 |
-0.150 |
| 2009-09-26 |
2010-02-20 |
+7.1027 |
-3.886 |
| 2010-02-20 |
2010-06-30 |
+5.8832 |
-3.022 |
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 |
07:41:19.57 |
-35:51:26.1 |
HIP 37317 |
22.37 |
| 2026-06-01 12:00 |
07:41:22.31 |
-35:51:01.3 |
HIP 37317 |
22.69 |
| 2026-06-02 00:00 |
07:41:25.07 |
-35:50:36.8 |
HIP 37317 |
23.04 |
| 2026-06-02 12:00 |
07:41:27.85 |
-35:50:12.6 |
HIP 37317 |
23.40 |
| 2026-06-03 00:00 |
07:41:30.65 |
-35:49:48.7 |
HIP 37317 |
23.79 |
| 2026-06-03 12:00 |
07:41:33.47 |
-35:49:25.1 |
HIP 37623 |
24.13 |
| 2026-06-04 00:00 |
07:41:36.32 |
-35:49:01.7 |
HIP 37623 |
23.88 |
| 2026-06-04 12:00 |
07:41:39.19 |
-35:48:38.7 |
HIP 37623 |
23.65 |
| 2026-06-05 00:00 |
07:41:42.08 |
-35:48:16.1 |
HIP 37623 |
23.42 |
| 2026-06-05 12:00 |
07:41:44.98 |
-35:47:53.7 |
HIP 37623 |
23.21 |
| 2026-06-06 00:00 |
07:41:47.91 |
-35:47:31.6 |
HIP 37623 |
23.01 |
| 2026-06-06 12:00 |
07:41:50.86 |
-35:47:09.8 |
HIP 37623 |
22.82 |
| 2026-06-07 00:00 |
07:41:53.84 |
-35:46:48.4 |
HIP 37623 |
22.65 |
| 2026-06-07 12:00 |
07:41:56.83 |
-35:46:27.2 |
HIP 37658 |
22.47 |
| 2026-06-08 00:00 |
07:41:59.84 |
-35:46:06.4 |
HIP 37658 |
21.77 |
| 2026-06-08 12:00 |
07:42:02.87 |
-35:45:45.9 |
HIP 37658 |
21.08 |
| 2026-06-09 00:00 |
07:42:05.91 |
-35:45:25.6 |
HIP 37658 |
20.38 |
| 2026-06-09 12:00 |
07:42:08.98 |
-35:45:05.8 |
HIP 37658 |
19.68 |
| 2026-06-10 00:00 |
07:42:12.07 |
-35:44:46.2 |
HIP 37658 |
18.97 |
| 2026-06-10 12:00 |
07:42:15.18 |
-35:44:27.0 |
HIP 37658 |
18.27 |
| 2026-06-11 00:00 |
07:42:18.30 |
-35:44:08.0 |
HIP 37658 |
17.56 |
| 2026-06-11 12:00 |
07:42:21.44 |
-35:43:49.4 |
HIP 37658 |
16.86 |
| 2026-06-12 00:00 |
07:42:24.60 |
-35:43:31.2 |
HIP 37658 |
16.15 |
| 2026-06-12 12:00 |
07:42:27.78 |
-35:43:13.2 |
HIP 37658 |
15.44 |
| 2026-06-13 00:00 |
07:42:30.98 |
-35:42:55.6 |
HIP 37658 |
14.73 |
| 2026-06-13 12:00 |
07:42:34.19 |
-35:42:38.3 |
HIP 37658 |
14.02 |
| 2026-06-14 00:00 |
07:42:37.42 |
-35:42:21.3 |
HIP 37658 |
13.31 |
| 2026-06-14 12:00 |
07:42:40.67 |
-35:42:04.7 |
HIP 37658 |
12.59 |
| 2026-06-15 00:00 |
07:42:43.93 |
-35:41:48.4 |
HIP 37658 |
11.88 |
| 2026-06-15 12:00 |
07:42:47.21 |
-35:41:32.4 |
HIP 37658 |
11.16 |
| 2026-06-16 00:00 |
07:42:50.51 |
-35:41:16.8 |
HIP 37658 |
10.44 |
| 2026-06-16 12:00 |
07:42:53.82 |
-35:41:01.5 |
HIP 37658 |
9.72 |
| 2026-06-17 00:00 |
07:42:57.15 |
-35:40:46.6 |
HIP 37658 |
9.00 |
| 2026-06-17 12:00 |
07:43:00.49 |
-35:40:31.9 |
HIP 37658 |
8.28 |
| 2026-06-18 00:00 |
07:43:03.84 |
-35:40:17.7 |
HIP 37658 |
7.56 |
| 2026-06-18 12:00 |
07:43:07.22 |
-35:40:03.7 |
HIP 37658 |
6.84 |
| 2026-06-19 00:00 |
07:43:10.60 |
-35:39:50.1 |
HIP 37658 |
6.11 |
| 2026-06-19 12:00 |
07:43:14.00 |
-35:39:36.8 |
HIP 37658 |
5.39 |
| 2026-06-20 00:00 |
07:43:17.41 |
-35:39:23.9 |
HIP 37658 |
4.66 |
| 2026-06-20 12:00 |
07:43:20.84 |
-35:39:11.3 |
HIP 37658 |
3.94 |
| 2026-06-21 00:00 |
07:43:24.28 |
-35:38:59.1 |
HIP 37658 |
3.21 |
| 2026-06-21 12:00 |
07:43:27.73 |
-35:38:47.2 |
HIP 37658 |
2.49 |
| 2026-06-22 00:00 |
07:43:31.20 |
-35:38:35.6 |
HIP 37658 |
1.77 |