C/2018 F1 (Grauer)
| Parameter |
Value |
| Designation |
C/2018 F1 (Grauer) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-12-14T01:55:08.552640Z |
| Orbit solution date (soln_date, UTC) |
2021-09-04T23:42:57Z |
| Obs used |
221 |
| NEO |
- |
| M1 |
12.700 |
| K1 |
6.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2018-03-17T08:17:23.424000Z |
| Discovery magnitude (MPC) |
19.10 T |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-03-06.0000000 |
| e |
0.99071069 |
| q (au) |
2.993048 |
| a (au) |
322.203595 |
| i (deg) |
46.070619 |
| Ω (om, deg) |
177.285875 |
| ω (w, deg) |
71.628120 |
| M (ma, deg) |
0.013960 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.042 + 4.054\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.042 |
| n |
4.054 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
1.000 |
| 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 |
| 2017-12-22 |
2018-07-16 |
+4.3609 |
-2.361 |
| 2019-03-22 |
2019-08-08 |
-24.0881 |
+12.948 |
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 |
01:10:34.70 |
-10:47:55.6 |
HIP 5625 |
26.24 |
| 2026-02-03 12:00 |
01:10:38.11 |
-10:47:18.0 |
HIP 5625 |
25.66 |
| 2026-02-04 00:00 |
01:10:41.56 |
-10:46:40.1 |
HIP 5625 |
25.11 |
| 2026-02-04 12:00 |
01:10:45.06 |
-10:46:02.2 |
HIP 5625 |
24.58 |
| 2026-02-05 00:00 |
01:10:48.60 |
-10:45:24.1 |
HIP 5625 |
24.08 |
| 2026-02-05 12:00 |
01:10:52.18 |
-10:44:45.9 |
HIP 5625 |
23.61 |
| 2026-02-06 00:00 |
01:10:55.81 |
-10:44:07.7 |
HIP 5625 |
23.17 |
| 2026-02-06 12:00 |
01:10:59.48 |
-10:43:29.3 |
HIP 5625 |
22.77 |
| 2026-02-07 00:00 |
01:11:03.19 |
-10:42:50.7 |
HIP 5625 |
22.41 |
| 2026-02-07 12:00 |
01:11:06.94 |
-10:42:12.1 |
HIP 5625 |
22.09 |
| 2026-02-08 00:00 |
01:11:10.74 |
-10:41:33.4 |
HIP 5625 |
21.82 |
| 2026-02-08 12:00 |
01:11:14.58 |
-10:40:54.6 |
HIP 5625 |
21.60 |
| 2026-02-09 00:00 |
01:11:18.45 |
-10:40:15.7 |
HIP 5625 |
21.43 |
| 2026-02-09 12:00 |
01:11:22.37 |
-10:39:36.7 |
HIP 5625 |
21.32 |
| 2026-02-10 00:00 |
01:11:26.34 |
-10:38:57.6 |
HIP 5625 |
21.27 |
| 2026-02-10 12:00 |
01:11:30.34 |
-10:38:18.4 |
HIP 5625 |
21.27 |
| 2026-02-11 00:00 |
01:11:34.38 |
-10:37:39.1 |
HIP 5625 |
21.34 |
| 2026-02-11 12:00 |
01:11:38.46 |
-10:36:59.8 |
HIP 5625 |
21.47 |
| 2026-02-12 00:00 |
01:11:42.59 |
-10:36:20.3 |
HIP 5625 |
21.67 |
| 2026-02-12 12:00 |
01:11:46.75 |
-10:35:40.8 |
HIP 5625 |
21.93 |
| 2026-02-13 00:00 |
01:11:50.95 |
-10:35:01.3 |
HIP 5625 |
22.25 |
| 2026-02-13 12:00 |
01:11:55.19 |
-10:34:21.6 |
HIP 5625 |
22.63 |
| 2026-02-14 00:00 |
01:11:59.47 |
-10:33:41.9 |
HIP 5625 |
23.07 |
| 2026-02-14 12:00 |
01:12:03.79 |
-10:33:02.1 |
HIP 5625 |
23.56 |
| 2026-02-15 00:00 |
01:12:08.15 |
-10:32:22.3 |
HIP 5625 |
24.11 |
| 2026-02-15 12:00 |
01:12:12.54 |
-10:31:42.4 |
HIP 5625 |
24.72 |
| 2026-02-16 00:00 |
01:12:16.97 |
-10:31:02.5 |
HIP 5625 |
25.37 |
| 2026-02-16 12:00 |
01:12:21.44 |
-10:30:22.5 |
HIP 5625 |
26.07 |
| 2026-02-17 00:00 |
01:12:25.95 |
-10:29:42.5 |
HIP 5625 |
26.82 |
| 2026-02-17 12:00 |
01:12:30.49 |
-10:29:02.4 |
HIP 5625 |
27.61 |
| 2026-02-18 00:00 |
01:12:35.07 |
-10:28:22.3 |
HIP 5625 |
28.44 |
| 2026-02-18 12:00 |
01:12:39.69 |
-10:27:42.2 |
HIP 5625 |
29.30 |
| 2026-02-19 00:00 |
01:12:44.34 |
-10:27:02.0 |
HIP 5625 |
30.20 |
| 2026-02-19 12:00 |
01:12:49.02 |
-10:26:21.8 |
HIP 5625 |
31.14 |
| 2026-02-20 00:00 |
01:12:53.74 |
-10:25:41.6 |
HIP 5625 |
32.10 |
| 2026-02-20 12:00 |
01:12:58.50 |
-10:25:01.3 |
HIP 5625 |
33.09 |
| 2026-02-21 00:00 |
01:13:03.29 |
-10:24:21.0 |
HIP 5625 |
34.12 |
| 2026-02-21 12:00 |
01:13:08.11 |
-10:23:40.7 |
HIP 5814 |
33.91 |
| 2026-02-22 00:00 |
01:13:12.97 |
-10:23:00.4 |
HIP 5814 |
32.62 |
| 2026-02-22 12:00 |
01:13:17.86 |
-10:22:20.1 |
HIP 5814 |
31.33 |
| 2026-02-23 00:00 |
01:13:22.79 |
-10:21:39.8 |
HIP 5814 |
30.05 |
| 2026-02-23 12:00 |
01:13:27.74 |
-10:20:59.5 |
HIP 5814 |
28.77 |
| 2026-02-24 00:00 |
01:13:32.73 |
-10:20:19.2 |
HIP 5814 |
27.49 |