| Parameter |
Value |
| Designation |
C/2015 X7 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2016-07-30T05:59:33.682560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:20Z |
| Obs used |
620 |
| NEO |
- |
| M1 |
11.600 |
| K1 |
6.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-09-22.0000000 |
| e |
1.00189036 |
| q (au) |
3.684550 |
| a (au) |
-1949.127032 |
| i (deg) |
57.578925 |
| Ω (om, deg) |
139.884070 |
| ω (w, deg) |
348.488537 |
| M (ma, deg) |
0.000616 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.078 + 2.092\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.078 |
| n |
2.092 |
| gf |
1.000 |
| gb |
-0.502 |
| 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 |
| 2015-01-28 |
2016-05-01 |
-0.2726 |
-0.309 |
| 2016-11-02 |
2017-06-16 |
-0.5340 |
+0.555 |
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 |
18:28:56.63 |
+24:52:32.0 |
HIP 90483 |
19.29 |
| 2026-06-01 12:00 |
18:28:51.98 |
+24:52:49.9 |
HIP 90483 |
18.59 |
| 2026-06-02 00:00 |
18:28:47.31 |
+24:53:07.3 |
HIP 90483 |
17.93 |
| 2026-06-02 12:00 |
18:28:42.61 |
+24:53:24.2 |
HIP 90483 |
17.30 |
| 2026-06-03 00:00 |
18:28:37.89 |
+24:53:40.7 |
HIP 90483 |
16.71 |
| 2026-06-03 12:00 |
18:28:33.15 |
+24:53:56.6 |
HIP 90483 |
16.17 |
| 2026-06-04 00:00 |
18:28:28.39 |
+24:54:12.2 |
HIP 90483 |
15.68 |
| 2026-06-04 12:00 |
18:28:23.62 |
+24:54:27.2 |
HIP 90483 |
15.24 |
| 2026-06-05 00:00 |
18:28:18.82 |
+24:54:41.8 |
HIP 90483 |
14.87 |
| 2026-06-05 12:00 |
18:28:14.00 |
+24:54:55.8 |
HIP 90483 |
14.56 |
| 2026-06-06 00:00 |
18:28:09.16 |
+24:55:09.4 |
HIP 90483 |
14.32 |
| 2026-06-06 12:00 |
18:28:04.31 |
+24:55:22.6 |
HIP 90483 |
14.16 |
| 2026-06-07 00:00 |
18:27:59.43 |
+24:55:35.2 |
HIP 90483 |
14.08 |
| 2026-06-07 12:00 |
18:27:54.54 |
+24:55:47.4 |
HIP 90483 |
14.08 |
| 2026-06-08 00:00 |
18:27:49.63 |
+24:55:59.0 |
HIP 90483 |
14.17 |
| 2026-06-08 12:00 |
18:27:44.71 |
+24:56:10.2 |
HIP 90483 |
14.33 |
| 2026-06-09 00:00 |
18:27:39.76 |
+24:56:20.9 |
HIP 90483 |
14.57 |
| 2026-06-09 12:00 |
18:27:34.80 |
+24:56:31.1 |
HIP 90483 |
14.89 |
| 2026-06-10 00:00 |
18:27:29.83 |
+24:56:40.8 |
HIP 90483 |
15.28 |
| 2026-06-10 12:00 |
18:27:24.84 |
+24:56:50.0 |
HIP 90483 |
15.73 |
| 2026-06-11 00:00 |
18:27:19.84 |
+24:56:58.8 |
HIP 90483 |
16.25 |
| 2026-06-11 12:00 |
18:27:14.82 |
+24:57:07.0 |
HIP 90483 |
16.82 |
| 2026-06-12 00:00 |
18:27:09.79 |
+24:57:14.7 |
HIP 90483 |
17.45 |
| 2026-06-12 12:00 |
18:27:04.74 |
+24:57:21.9 |
HIP 90483 |
18.11 |
| 2026-06-13 00:00 |
18:26:59.68 |
+24:57:28.7 |
HIP 90483 |
18.82 |
| 2026-06-13 12:00 |
18:26:54.61 |
+24:57:34.9 |
HIP 90483 |
19.57 |
| 2026-06-14 00:00 |
18:26:49.53 |
+24:57:40.6 |
HIP 90483 |
20.35 |
| 2026-06-14 12:00 |
18:26:44.43 |
+24:57:45.8 |
HIP 90483 |
21.16 |
| 2026-06-15 00:00 |
18:26:39.33 |
+24:57:50.5 |
HIP 90483 |
22.00 |
| 2026-06-15 12:00 |
18:26:34.21 |
+24:57:54.7 |
HIP 90483 |
22.86 |
| 2026-06-16 00:00 |
18:26:29.09 |
+24:57:58.4 |
HIP 90483 |
23.75 |
| 2026-06-16 12:00 |
18:26:23.95 |
+24:58:01.6 |
HIP 90483 |
24.65 |
| 2026-06-17 00:00 |
18:26:18.81 |
+24:58:04.3 |
HIP 90483 |
25.57 |
| 2026-06-17 12:00 |
18:26:13.65 |
+24:58:06.4 |
HIP 90265 |
25.35 |
| 2026-06-18 00:00 |
18:26:08.49 |
+24:58:08.1 |
HIP 90265 |
24.67 |
| 2026-06-18 12:00 |
18:26:03.33 |
+24:58:09.2 |
HIP 90265 |
24.02 |
| 2026-06-19 00:00 |
18:25:58.15 |
+24:58:09.9 |
HIP 90265 |
23.40 |
| 2026-06-19 12:00 |
18:25:52.97 |
+24:58:10.0 |
HIP 90265 |
22.81 |
| 2026-06-20 00:00 |
18:25:47.78 |
+24:58:09.6 |
HIP 90265 |
22.27 |
| 2026-06-20 12:00 |
18:25:42.59 |
+24:58:08.7 |
HIP 90265 |
21.76 |
| 2026-06-21 00:00 |
18:25:37.39 |
+24:58:07.3 |
HIP 90265 |
21.30 |
| 2026-06-21 12:00 |
18:25:32.18 |
+24:58:05.4 |
HIP 90265 |
20.89 |
| 2026-06-22 00:00 |
18:25:26.98 |
+24:58:03.0 |
HIP 90265 |
20.53 |