| Parameter |
Value |
| Designation |
C/2015 D1 (SOHO) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-02-19T17:57:35.902080Z |
| Orbit solution date (soln_date, UTC) |
2021-04-16T12:05:35Z |
| Obs used |
417 |
| NEO |
Yes |
| M1 |
10.000 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-02-20.0000000 |
| e |
0.99432307 |
| q (au) |
0.028322 |
| a (au) |
4.989017 |
| i (deg) |
69.615618 |
| Ω (om, deg) |
95.881026 |
| ω (w, deg) |
234.955413 |
| M (ma, deg) |
0.022259 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.386 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.386 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| 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 |
| 2015-02-18 |
2015-02-19 |
+1.3163 |
+2.493 |
| 2015-02-19 |
2015-02-20 |
+4.2155 |
+6.540 |
| 2015-02-20 |
2015-03-17 |
-1.1628 |
-1.516 |
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 |
09:03:59.68 |
+63:55:06.3 |
HIP 44625 |
13.47 |
| 2026-06-01 12:00 |
09:04:02.82 |
+63:54:31.6 |
HIP 44625 |
13.57 |
| 2026-06-02 00:00 |
09:04:06.01 |
+63:53:57.0 |
HIP 44625 |
13.69 |
| 2026-06-02 12:00 |
09:04:09.25 |
+63:53:22.4 |
HIP 44625 |
13.84 |
| 2026-06-03 00:00 |
09:04:12.54 |
+63:52:47.9 |
HIP 44625 |
14.01 |
| 2026-06-03 12:00 |
09:04:15.88 |
+63:52:13.5 |
HIP 44625 |
14.22 |
| 2026-06-04 00:00 |
09:04:19.26 |
+63:51:39.2 |
HIP 44625 |
14.44 |
| 2026-06-04 12:00 |
09:04:22.68 |
+63:51:05.0 |
HIP 44625 |
14.69 |
| 2026-06-05 00:00 |
09:04:26.16 |
+63:50:30.8 |
HIP 44625 |
14.97 |
| 2026-06-05 12:00 |
09:04:29.68 |
+63:49:56.8 |
HIP 44625 |
15.26 |
| 2026-06-06 00:00 |
09:04:33.24 |
+63:49:22.8 |
HIP 44625 |
15.58 |
| 2026-06-06 12:00 |
09:04:36.85 |
+63:48:48.9 |
HIP 44625 |
15.92 |
| 2026-06-07 00:00 |
09:04:40.51 |
+63:48:15.2 |
HIP 44625 |
16.27 |
| 2026-06-07 12:00 |
09:04:44.21 |
+63:47:41.5 |
HIP 44625 |
16.64 |
| 2026-06-08 00:00 |
09:04:47.95 |
+63:47:07.9 |
HIP 44625 |
17.03 |
| 2026-06-08 12:00 |
09:04:51.74 |
+63:46:34.4 |
HIP 44625 |
17.44 |
| 2026-06-09 00:00 |
09:04:55.57 |
+63:46:01.0 |
HIP 44625 |
17.86 |
| 2026-06-09 12:00 |
09:04:59.45 |
+63:45:27.7 |
HIP 44625 |
18.30 |
| 2026-06-10 00:00 |
09:05:03.37 |
+63:44:54.6 |
HIP 44625 |
18.74 |
| 2026-06-10 12:00 |
09:05:07.33 |
+63:44:21.5 |
HIP 44625 |
19.20 |
| 2026-06-11 00:00 |
09:05:11.34 |
+63:43:48.5 |
HIP 44625 |
19.68 |
| 2026-06-11 12:00 |
09:05:15.39 |
+63:43:15.7 |
HIP 44625 |
20.16 |
| 2026-06-12 00:00 |
09:05:19.48 |
+63:42:42.9 |
HIP 44625 |
20.65 |
| 2026-06-12 12:00 |
09:05:23.61 |
+63:42:10.3 |
HIP 44625 |
21.16 |
| 2026-06-13 00:00 |
09:05:27.79 |
+63:41:37.8 |
HIP 44625 |
21.67 |
| 2026-06-13 12:00 |
09:05:32.00 |
+63:41:05.4 |
HIP 44625 |
22.19 |
| 2026-06-14 00:00 |
09:05:36.26 |
+63:40:33.2 |
HIP 44625 |
22.72 |
| 2026-06-14 12:00 |
09:05:40.56 |
+63:40:01.1 |
HIP 44625 |
23.26 |
| 2026-06-15 00:00 |
09:05:44.89 |
+63:39:29.0 |
HIP 44625 |
23.81 |
| 2026-06-15 12:00 |
09:05:49.27 |
+63:38:57.2 |
HIP 44625 |
24.36 |
| 2026-06-16 00:00 |
09:05:53.68 |
+63:38:25.4 |
HIP 44625 |
24.92 |
| 2026-06-16 12:00 |
09:05:58.14 |
+63:37:53.8 |
HIP 44625 |
25.48 |
| 2026-06-17 00:00 |
09:06:02.63 |
+63:37:22.3 |
HIP 44625 |
26.05 |
| 2026-06-17 12:00 |
09:06:07.17 |
+63:36:51.0 |
HIP 44625 |
26.63 |
| 2026-06-18 00:00 |
09:06:11.74 |
+63:36:19.8 |
HIP 44625 |
27.21 |
| 2026-06-18 12:00 |
09:06:16.34 |
+63:35:48.7 |
HIP 44970 |
27.05 |
| 2026-06-19 00:00 |
09:06:20.99 |
+63:35:17.8 |
HIP 44970 |
26.34 |
| 2026-06-19 12:00 |
09:06:25.67 |
+63:34:47.0 |
HIP 44970 |
25.63 |
| 2026-06-20 00:00 |
09:06:30.39 |
+63:34:16.4 |
HIP 44970 |
24.91 |
| 2026-06-20 12:00 |
09:06:35.14 |
+63:33:45.9 |
HIP 44970 |
24.20 |
| 2026-06-21 00:00 |
09:06:39.93 |
+63:33:15.6 |
HIP 44970 |
23.48 |
| 2026-06-21 12:00 |
09:06:44.76 |
+63:32:45.4 |
HIP 44970 |
22.76 |
| 2026-06-22 00:00 |
09:06:49.62 |
+63:32:15.4 |
HIP 44970 |
22.04 |