| Parameter |
Value |
| Designation |
C/1997 G2 (Montani) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1998-04-16T07:14:20.978880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:50Z |
| Obs used |
187 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
13.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1997-07-26.0000000 |
| e |
0.99416325 |
| q (au) |
3.084963 |
| a (au) |
528.541310 |
| i (deg) |
69.835498 |
| Ω (om, deg) |
55.802519 |
| ω (w, deg) |
239.843035 |
| M (ma, deg) |
359.978562 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.554 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.554 |
| n |
6.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
04:01:31.21 |
+50:31:27.7 |
HIP 18808 |
7.45 |
| 2026-07-29 12:00 |
04:01:32.85 |
+50:31:48.1 |
HIP 18808 |
7.04 |
| 2026-07-30 00:00 |
04:01:34.47 |
+50:32:08.6 |
HIP 18808 |
6.63 |
| 2026-07-30 12:00 |
04:01:36.07 |
+50:32:29.0 |
HIP 18808 |
6.22 |
| 2026-07-31 00:00 |
04:01:37.63 |
+50:32:49.5 |
HIP 18808 |
5.81 |
| 2026-07-31 12:00 |
04:01:39.17 |
+50:33:10.0 |
HIP 18808 |
5.41 |
| 2026-08-01 00:00 |
04:01:40.68 |
+50:33:30.6 |
HIP 18808 |
5.01 |
| 2026-08-01 12:00 |
04:01:42.16 |
+50:33:51.1 |
HIP 18808 |
4.61 |
| 2026-08-02 00:00 |
04:01:43.62 |
+50:34:11.7 |
HIP 18808 |
4.22 |
| 2026-08-02 12:00 |
04:01:45.04 |
+50:34:32.3 |
HIP 18808 |
3.84 |
| 2026-08-03 00:00 |
04:01:46.44 |
+50:34:52.9 |
HIP 18808 |
3.46 |
| 2026-08-03 12:00 |
04:01:47.81 |
+50:35:13.5 |
HIP 18808 |
3.09 |
| 2026-08-04 00:00 |
04:01:49.15 |
+50:35:34.1 |
HIP 18808 |
2.73 |
| 2026-08-04 12:00 |
04:01:50.47 |
+50:35:54.8 |
HIP 18808 |
2.38 |
| 2026-08-05 00:00 |
04:01:51.75 |
+50:36:15.4 |
HIP 18808 |
2.06 |
| 2026-08-05 12:00 |
04:01:53.01 |
+50:36:36.1 |
HIP 18808 |
1.76 |
| 2026-08-06 00:00 |
04:01:54.24 |
+50:36:56.7 |
HIP 18808 |
1.51 |
| 2026-08-06 12:00 |
04:01:55.44 |
+50:37:17.4 |
HIP 18808 |
1.33 |
| 2026-08-07 00:00 |
04:01:56.61 |
+50:37:38.1 |
HIP 18808 |
1.25 |
| 2026-08-07 12:00 |
04:01:57.75 |
+50:37:58.7 |
HIP 18808 |
1.28 |
| 2026-08-08 00:00 |
04:01:58.87 |
+50:38:19.4 |
HIP 18808 |
1.41 |
| 2026-08-08 12:00 |
04:01:59.95 |
+50:38:40.1 |
HIP 18808 |
1.63 |
| 2026-08-09 00:00 |
04:02:01.00 |
+50:39:00.8 |
HIP 18808 |
1.89 |
| 2026-08-09 12:00 |
04:02:02.03 |
+50:39:21.4 |
HIP 18808 |
2.19 |
| 2026-08-10 00:00 |
04:02:03.02 |
+50:39:42.1 |
HIP 18808 |
2.50 |
| 2026-08-10 12:00 |
04:02:03.99 |
+50:40:02.8 |
HIP 18808 |
2.83 |
| 2026-08-11 00:00 |
04:02:04.92 |
+50:40:23.4 |
HIP 18808 |
3.16 |
| 2026-08-11 12:00 |
04:02:05.83 |
+50:40:44.1 |
HIP 18808 |
3.50 |
| 2026-08-12 00:00 |
04:02:06.70 |
+50:41:04.7 |
HIP 18808 |
3.85 |
| 2026-08-12 12:00 |
04:02:07.54 |
+50:41:25.4 |
HIP 18808 |
4.19 |
| 2026-08-13 00:00 |
04:02:08.36 |
+50:41:46.0 |
HIP 18808 |
4.53 |
| 2026-08-13 12:00 |
04:02:09.14 |
+50:42:06.6 |
HIP 18808 |
4.88 |
| 2026-08-14 00:00 |
04:02:09.89 |
+50:42:27.2 |
HIP 18808 |
5.22 |
| 2026-08-14 12:00 |
04:02:10.62 |
+50:42:47.8 |
HIP 18794 |
5.47 |
| 2026-08-15 00:00 |
04:02:11.31 |
+50:43:08.4 |
HIP 18794 |
5.53 |
| 2026-08-15 12:00 |
04:02:11.97 |
+50:43:28.9 |
HIP 18794 |
5.61 |
| 2026-08-16 00:00 |
04:02:12.60 |
+50:43:49.4 |
HIP 18794 |
5.71 |
| 2026-08-16 12:00 |
04:02:13.20 |
+50:44:09.9 |
HIP 18794 |
5.82 |
| 2026-08-17 00:00 |
04:02:13.77 |
+50:44:30.4 |
HIP 18794 |
5.95 |
| 2026-08-17 12:00 |
04:02:14.30 |
+50:44:50.9 |
HIP 18794 |
6.09 |
| 2026-08-18 00:00 |
04:02:14.81 |
+50:45:11.3 |
HIP 18794 |
6.24 |
| 2026-08-18 12:00 |
04:02:15.29 |
+50:45:31.7 |
HIP 18794 |
6.40 |
| 2026-08-19 00:00 |
04:02:15.73 |
+50:45:52.1 |
HIP 18794 |
6.57 |