| Parameter |
Value |
| Designation |
C/2007 D2 (Spacewatch) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2006-11-24T08:05:07.175040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:05Z |
| Obs used |
72 |
| NEO |
- |
| M1 |
18.600 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2007-02-25.0000000 |
| e |
0.97763484 |
| q (au) |
1.245656 |
| a (au) |
55.696245 |
| i (deg) |
178.618011 |
| Ω (om, deg) |
297.125793 |
| ω (w, deg) |
65.126637 |
| M (ma, deg) |
0.219721 |
Magnitude
Scatter + Global Linear
$$
M_a = (18.407 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
18.407 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.715 |
| k |
0.989 |
| 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 |
04:26:33.99 |
+20:41:02.5 |
HIP 20785 |
20.00 |
| 2026-03-26 12:00 |
04:26:35.35 |
+20:41:06.3 |
HIP 20785 |
19.82 |
| 2026-03-27 00:00 |
04:26:36.74 |
+20:41:10.1 |
HIP 20785 |
19.64 |
| 2026-03-27 12:00 |
04:26:38.15 |
+20:41:14.0 |
HIP 20785 |
19.47 |
| 2026-03-28 00:00 |
04:26:39.59 |
+20:41:17.9 |
HIP 20785 |
19.29 |
| 2026-03-28 12:00 |
04:26:41.05 |
+20:41:21.9 |
HIP 20785 |
19.11 |
| 2026-03-29 00:00 |
04:26:42.54 |
+20:41:26.0 |
HIP 20785 |
18.94 |
| 2026-03-29 12:00 |
04:26:44.05 |
+20:41:30.1 |
HIP 20785 |
18.77 |
| 2026-03-30 00:00 |
04:26:45.58 |
+20:41:34.2 |
HIP 20785 |
18.60 |
| 2026-03-30 12:00 |
04:26:47.14 |
+20:41:38.4 |
HIP 20785 |
18.44 |
| 2026-03-31 00:00 |
04:26:48.73 |
+20:41:42.6 |
HIP 20785 |
18.28 |
| 2026-03-31 12:00 |
04:26:50.34 |
+20:41:46.9 |
HIP 20785 |
18.12 |
| 2026-04-01 00:00 |
04:26:51.97 |
+20:41:51.3 |
HIP 20785 |
17.97 |
| 2026-04-01 12:00 |
04:26:53.63 |
+20:41:55.7 |
HIP 20785 |
17.82 |
| 2026-04-02 00:00 |
04:26:55.31 |
+20:42:00.1 |
HIP 20785 |
17.69 |
| 2026-04-02 12:00 |
04:26:57.01 |
+20:42:04.6 |
HIP 20785 |
17.55 |
| 2026-04-03 00:00 |
04:26:58.74 |
+20:42:09.1 |
HIP 20785 |
17.43 |
| 2026-04-03 12:00 |
04:27:00.49 |
+20:42:13.7 |
HIP 20785 |
17.31 |
| 2026-04-04 00:00 |
04:27:02.26 |
+20:42:18.3 |
HIP 20785 |
17.20 |
| 2026-04-04 12:00 |
04:27:04.06 |
+20:42:23.0 |
HIP 20785 |
17.10 |
| 2026-04-05 00:00 |
04:27:05.88 |
+20:42:27.7 |
HIP 20785 |
17.00 |
| 2026-04-05 12:00 |
04:27:07.72 |
+20:42:32.4 |
HIP 20785 |
16.92 |
| 2026-04-06 00:00 |
04:27:09.58 |
+20:42:37.2 |
HIP 20785 |
16.85 |
| 2026-04-06 12:00 |
04:27:11.47 |
+20:42:42.1 |
HIP 20785 |
16.79 |
| 2026-04-07 00:00 |
04:27:13.38 |
+20:42:47.0 |
HIP 20785 |
16.74 |
| 2026-04-07 12:00 |
04:27:15.31 |
+20:42:51.9 |
HIP 20785 |
16.70 |
| 2026-04-08 00:00 |
04:27:17.26 |
+20:42:56.9 |
HIP 20785 |
16.67 |
| 2026-04-08 12:00 |
04:27:19.23 |
+20:43:01.9 |
HIP 20785 |
16.66 |
| 2026-04-09 00:00 |
04:27:21.23 |
+20:43:07.0 |
HIP 20785 |
16.66 |
| 2026-04-09 12:00 |
04:27:23.25 |
+20:43:12.0 |
HIP 20785 |
16.68 |
| 2026-04-10 00:00 |
04:27:25.28 |
+20:43:17.2 |
HIP 20785 |
16.71 |
| 2026-04-10 12:00 |
04:27:27.34 |
+20:43:22.4 |
HIP 20785 |
16.75 |
| 2026-04-11 00:00 |
04:27:29.42 |
+20:43:27.6 |
HIP 20785 |
16.81 |
| 2026-04-11 12:00 |
04:27:31.52 |
+20:43:32.8 |
HIP 20897 |
16.77 |
| 2026-04-12 00:00 |
04:27:33.64 |
+20:43:38.1 |
HIP 20897 |
16.30 |
| 2026-04-12 12:00 |
04:27:35.79 |
+20:43:43.5 |
HIP 20897 |
15.83 |
| 2026-04-13 00:00 |
04:27:37.95 |
+20:43:48.8 |
HIP 20897 |
15.35 |
| 2026-04-13 12:00 |
04:27:40.13 |
+20:43:54.3 |
HIP 20897 |
14.87 |
| 2026-04-14 00:00 |
04:27:42.33 |
+20:43:59.7 |
HIP 20897 |
14.39 |
| 2026-04-14 12:00 |
04:27:44.55 |
+20:44:05.2 |
HIP 20897 |
13.91 |
| 2026-04-15 00:00 |
04:27:46.79 |
+20:44:10.7 |
HIP 20897 |
13.42 |
| 2026-04-15 12:00 |
04:27:49.05 |
+20:44:16.3 |
HIP 20897 |
12.94 |
| 2026-04-16 00:00 |
04:27:51.33 |
+20:44:21.8 |
HIP 20897 |
12.46 |