| 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 · University of Arizona 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) |
| 2026-09-20 00:00 |
01:32:34.78 |
-11:10:48.4 |
HIP 7310 |
25.04 |
| 2026-09-20 12:00 |
01:32:30.11 |
-11:11:37.1 |
HIP 7310 |
25.72 |
| 2026-09-21 00:00 |
01:32:25.41 |
-11:12:25.7 |
HIP 7080 |
25.59 |
| 2026-09-21 12:00 |
01:32:20.69 |
-11:13:14.2 |
HIP 7080 |
25.42 |
| 2026-09-22 00:00 |
01:32:15.94 |
-11:14:02.6 |
HIP 7080 |
25.32 |
| 2026-09-22 12:00 |
01:32:11.17 |
-11:14:50.8 |
HIP 7080 |
25.30 |
| 2026-09-23 00:00 |
01:32:06.38 |
-11:15:38.8 |
HIP 7080 |
25.36 |
| 2026-09-23 12:00 |
01:32:01.56 |
-11:16:26.7 |
HIP 7080 |
25.48 |
| 2026-09-24 00:00 |
01:31:56.72 |
-11:17:14.4 |
HIP 7080 |
25.69 |
| 2026-09-24 12:00 |
01:31:51.86 |
-11:18:02.0 |
HIP 7080 |
25.96 |
| 2026-09-25 00:00 |
01:31:46.98 |
-11:18:49.4 |
HIP 7080 |
26.31 |
| 2026-09-25 12:00 |
01:31:42.08 |
-11:19:36.7 |
HIP 7080 |
26.72 |
| 2026-09-26 00:00 |
01:31:37.16 |
-11:20:23.8 |
HIP 7080 |
27.20 |
| 2026-09-26 12:00 |
01:31:32.22 |
-11:21:10.7 |
HIP 7080 |
27.75 |
| 2026-09-27 00:00 |
01:31:27.26 |
-11:21:57.4 |
HIP 7080 |
28.35 |
| 2026-09-27 12:00 |
01:31:22.29 |
-11:22:43.9 |
HIP 7080 |
29.01 |
| 2026-09-28 00:00 |
01:31:17.29 |
-11:23:30.3 |
HIP 7080 |
29.72 |
| 2026-09-28 12:00 |
01:31:12.28 |
-11:24:16.5 |
HIP 7080 |
30.48 |
| 2026-09-29 00:00 |
01:31:07.24 |
-11:25:02.4 |
HIP 6926 |
30.46 |
| 2026-09-29 12:00 |
01:31:02.20 |
-11:25:48.2 |
HIP 6926 |
29.03 |
| 2026-09-30 00:00 |
01:30:57.13 |
-11:26:33.8 |
HIP 6926 |
27.59 |
| 2026-09-30 12:00 |
01:30:52.05 |
-11:27:19.2 |
HIP 6926 |
26.15 |
| 2026-10-01 00:00 |
01:30:46.95 |
-11:28:04.4 |
HIP 6926 |
24.71 |
| 2026-10-01 12:00 |
01:30:41.84 |
-11:28:49.4 |
HIP 6926 |
23.27 |
| 2026-10-02 00:00 |
01:30:36.71 |
-11:29:34.1 |
HIP 6926 |
21.84 |
| 2026-10-02 12:00 |
01:30:31.57 |
-11:30:18.7 |
HIP 6926 |
20.40 |
| 2026-10-03 00:00 |
01:30:26.42 |
-11:31:03.0 |
HIP 6926 |
18.97 |
| 2026-10-03 12:00 |
01:30:21.25 |
-11:31:47.1 |
HIP 6926 |
17.54 |
| 2026-10-04 00:00 |
01:30:16.07 |
-11:32:30.9 |
HIP 6926 |
16.11 |
| 2026-10-04 12:00 |
01:30:10.87 |
-11:33:14.6 |
HIP 6926 |
14.69 |
| 2026-10-05 00:00 |
01:30:05.67 |
-11:33:58.0 |
HIP 6926 |
13.28 |
| 2026-10-05 12:00 |
01:30:00.45 |
-11:34:41.1 |
HIP 6926 |
11.87 |
| 2026-10-06 00:00 |
01:29:55.22 |
-11:35:24.1 |
HIP 6926 |
10.49 |
| 2026-10-06 12:00 |
01:29:49.98 |
-11:36:06.7 |
HIP 6926 |
9.12 |
| 2026-10-07 00:00 |
01:29:44.74 |
-11:36:49.2 |
HIP 6926 |
7.79 |
| 2026-10-07 12:00 |
01:29:39.48 |
-11:37:31.3 |
HIP 6926 |
6.52 |
| 2026-10-08 00:00 |
01:29:34.21 |
-11:38:13.3 |
HIP 6926 |
5.35 |
| 2026-10-08 12:00 |
01:29:28.94 |
-11:38:54.9 |
HIP 6926 |
4.35 |
| 2026-10-09 00:00 |
01:29:23.65 |
-11:39:36.3 |
HIP 6926 |
3.68 |
| 2026-10-09 12:00 |
01:29:18.37 |
-11:40:17.4 |
HIP 6926 |
3.53 |
| 2026-10-10 00:00 |
01:29:13.07 |
-11:40:58.3 |
HIP 6926 |
3.95 |
| 2026-10-10 12:00 |
01:29:07.77 |
-11:41:38.8 |
HIP 6926 |
4.79 |
| 2026-10-11 00:00 |
01:29:02.46 |
-11:42:19.1 |
HIP 6926 |
5.88 |