| Parameter |
Value |
| Designation |
C/1997 BA6 (Spacewatch) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1999-11-27T13:51:09.898560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:50Z |
| Obs used |
520 |
| NEO |
- |
| M1 |
4.300 |
| K1 |
10.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-05-01.0000000 |
| e |
0.99888457 |
| q (au) |
3.436463 |
| a (au) |
3080.849437 |
| i (deg) |
72.717049 |
| Ω (om, deg) |
317.660522 |
| ω (w, deg) |
285.939608 |
| M (ma, deg) |
0.000896 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.715 + 5.249\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.715 |
| n |
5.249 |
| gf |
1.000 |
| gb |
-0.692 |
| k |
0.800 |
| 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 |
| 1997-01-11 |
1998-11-25 |
+4.3922 |
-3.507 |
| 1998-11-25 |
1999-11-21 |
-2.6888 |
+1.565 |
| 1999-11-30 |
2002-09-12 |
-3.6083 |
+2.137 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
21:23:35.38 |
+58:11:13.3 |
HIP 105758 |
12.83 |
| 2026-03-26 12:00 |
21:23:38.55 |
+58:11:43.9 |
HIP 105758 |
12.47 |
| 2026-03-27 00:00 |
21:23:41.68 |
+58:12:14.7 |
HIP 105758 |
12.14 |
| 2026-03-27 12:00 |
21:23:44.80 |
+58:12:45.8 |
HIP 105758 |
11.85 |
| 2026-03-28 00:00 |
21:23:47.88 |
+58:13:16.9 |
HIP 105758 |
11.59 |
| 2026-03-28 12:00 |
21:23:50.93 |
+58:13:48.3 |
HIP 105758 |
11.37 |
| 2026-03-29 00:00 |
21:23:53.96 |
+58:14:19.8 |
HIP 105758 |
11.18 |
| 2026-03-29 12:00 |
21:23:56.96 |
+58:14:51.6 |
HIP 105758 |
11.04 |
| 2026-03-30 00:00 |
21:23:59.93 |
+58:15:23.4 |
HIP 105758 |
10.94 |
| 2026-03-30 12:00 |
21:24:02.87 |
+58:15:55.5 |
HIP 105758 |
10.89 |
| 2026-03-31 00:00 |
21:24:05.78 |
+58:16:27.7 |
HIP 105758 |
10.87 |
| 2026-03-31 12:00 |
21:24:08.66 |
+58:17:00.1 |
HIP 105758 |
10.91 |
| 2026-04-01 00:00 |
21:24:11.51 |
+58:17:32.7 |
HIP 105794 |
10.65 |
| 2026-04-01 12:00 |
21:24:14.33 |
+58:18:05.4 |
HIP 105794 |
10.31 |
| 2026-04-02 00:00 |
21:24:17.13 |
+58:18:38.3 |
HIP 105794 |
10.00 |
| 2026-04-02 12:00 |
21:24:19.89 |
+58:19:11.3 |
HIP 105794 |
9.73 |
| 2026-04-03 00:00 |
21:24:22.62 |
+58:19:44.5 |
HIP 105794 |
9.50 |
| 2026-04-03 12:00 |
21:24:25.32 |
+58:20:17.8 |
HIP 105794 |
9.32 |
| 2026-04-04 00:00 |
21:24:28.00 |
+58:20:51.3 |
HIP 105794 |
9.19 |
| 2026-04-04 12:00 |
21:24:30.64 |
+58:21:24.9 |
HIP 105794 |
9.10 |
| 2026-04-05 00:00 |
21:24:33.25 |
+58:21:58.7 |
HIP 105794 |
9.08 |
| 2026-04-05 12:00 |
21:24:35.82 |
+58:22:32.7 |
HIP 105794 |
9.10 |
| 2026-04-06 00:00 |
21:24:38.37 |
+58:23:06.7 |
HIP 105794 |
9.17 |
| 2026-04-06 12:00 |
21:24:40.89 |
+58:23:40.9 |
HIP 105794 |
9.30 |
| 2026-04-07 00:00 |
21:24:43.37 |
+58:24:15.3 |
HIP 105794 |
9.47 |
| 2026-04-07 12:00 |
21:24:45.82 |
+58:24:49.8 |
HIP 105794 |
9.70 |
| 2026-04-08 00:00 |
21:24:48.24 |
+58:25:24.4 |
HIP 105794 |
9.96 |
| 2026-04-08 12:00 |
21:24:50.63 |
+58:25:59.2 |
HIP 105794 |
10.26 |
| 2026-04-09 00:00 |
21:24:52.98 |
+58:26:34.1 |
HIP 105794 |
10.61 |
| 2026-04-09 12:00 |
21:24:55.31 |
+58:27:09.1 |
HIP 105794 |
10.98 |
| 2026-04-10 00:00 |
21:24:57.59 |
+58:27:44.2 |
HIP 105794 |
11.38 |
| 2026-04-10 12:00 |
21:24:59.85 |
+58:28:19.5 |
HIP 105794 |
11.81 |
| 2026-04-11 00:00 |
21:25:02.07 |
+58:28:54.9 |
HIP 105794 |
12.26 |
| 2026-04-11 12:00 |
21:25:04.26 |
+58:29:30.4 |
HIP 105794 |
12.74 |
| 2026-04-12 00:00 |
21:25:06.42 |
+58:30:06.0 |
HIP 105794 |
13.23 |
| 2026-04-12 12:00 |
21:25:08.54 |
+58:30:41.8 |
HIP 105794 |
13.74 |
| 2026-04-13 00:00 |
21:25:10.63 |
+58:31:17.6 |
HIP 105794 |
14.27 |
| 2026-04-13 12:00 |
21:25:12.68 |
+58:31:53.6 |
HIP 105794 |
14.80 |
| 2026-04-14 00:00 |
21:25:14.70 |
+58:32:29.7 |
HIP 105794 |
15.35 |
| 2026-04-14 12:00 |
21:25:16.69 |
+58:33:05.8 |
HIP 105794 |
15.91 |
| 2026-04-15 00:00 |
21:25:18.64 |
+58:33:42.1 |
HIP 105794 |
16.48 |
| 2026-04-15 12:00 |
21:25:20.56 |
+58:34:18.5 |
HIP 105794 |
17.06 |
| 2026-04-16 00:00 |
21:25:22.44 |
+58:34:55.0 |
HIP 105794 |
17.65 |