C/1997 BA6 (Spacewatch)
| 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) |
| 2026-02-03 00:00 |
21:16:34.31 |
+57:40:30.3 |
HIP 105004 |
16.16 |
| 2026-02-03 12:00 |
21:16:38.89 |
+57:40:33.8 |
HIP 105004 |
16.39 |
| 2026-02-04 00:00 |
21:16:43.48 |
+57:40:37.7 |
HIP 105004 |
16.65 |
| 2026-02-04 12:00 |
21:16:48.06 |
+57:40:41.9 |
HIP 105004 |
16.93 |
| 2026-02-05 00:00 |
21:16:52.64 |
+57:40:46.5 |
HIP 105004 |
17.24 |
| 2026-02-05 12:00 |
21:16:57.23 |
+57:40:51.3 |
HIP 105004 |
17.56 |
| 2026-02-06 00:00 |
21:17:01.81 |
+57:40:56.4 |
HIP 105004 |
17.91 |
| 2026-02-06 12:00 |
21:17:06.40 |
+57:41:01.9 |
HIP 105004 |
18.27 |
| 2026-02-07 00:00 |
21:17:10.98 |
+57:41:07.6 |
HIP 105004 |
18.65 |
| 2026-02-07 12:00 |
21:17:15.56 |
+57:41:13.7 |
HIP 105004 |
19.05 |
| 2026-02-08 00:00 |
21:17:20.14 |
+57:41:20.1 |
HIP 105004 |
19.47 |
| 2026-02-08 12:00 |
21:17:24.72 |
+57:41:26.8 |
HIP 105004 |
19.90 |
| 2026-02-09 00:00 |
21:17:29.30 |
+57:41:33.8 |
HIP 105004 |
20.34 |
| 2026-02-09 12:00 |
21:17:33.88 |
+57:41:41.1 |
HIP 105004 |
20.80 |
| 2026-02-10 00:00 |
21:17:38.45 |
+57:41:48.7 |
HIP 105004 |
21.27 |
| 2026-02-10 12:00 |
21:17:43.02 |
+57:41:56.6 |
HIP 105142 |
21.70 |
| 2026-02-11 00:00 |
21:17:47.59 |
+57:42:04.8 |
HIP 105142 |
21.79 |
| 2026-02-11 12:00 |
21:17:52.15 |
+57:42:13.4 |
HIP 105142 |
21.91 |
| 2026-02-12 00:00 |
21:17:56.71 |
+57:42:22.2 |
HIP 105142 |
22.05 |
| 2026-02-12 12:00 |
21:18:01.27 |
+57:42:31.4 |
HIP 105142 |
22.21 |
| 2026-02-13 00:00 |
21:18:05.82 |
+57:42:40.8 |
HIP 105142 |
22.39 |
| 2026-02-13 12:00 |
21:18:10.37 |
+57:42:50.6 |
HIP 105142 |
22.60 |
| 2026-02-14 00:00 |
21:18:14.91 |
+57:43:00.7 |
HIP 105142 |
22.82 |
| 2026-02-14 12:00 |
21:18:19.44 |
+57:43:11.0 |
HIP 105142 |
23.06 |
| 2026-02-15 00:00 |
21:18:23.97 |
+57:43:21.7 |
HIP 105142 |
23.33 |
| 2026-02-15 12:00 |
21:18:28.50 |
+57:43:32.7 |
HIP 105142 |
23.61 |
| 2026-02-16 00:00 |
21:18:33.02 |
+57:43:44.0 |
HIP 105142 |
23.91 |
| 2026-02-16 12:00 |
21:18:37.53 |
+57:43:55.6 |
HIP 105142 |
24.23 |
| 2026-02-17 00:00 |
21:18:42.03 |
+57:44:07.4 |
HIP 105142 |
24.56 |
| 2026-02-17 12:00 |
21:18:46.53 |
+57:44:19.6 |
HIP 105142 |
24.92 |
| 2026-02-18 00:00 |
21:18:51.02 |
+57:44:32.1 |
HIP 105142 |
25.28 |
| 2026-02-18 12:00 |
21:18:55.50 |
+57:44:44.9 |
HIP 105142 |
25.67 |
| 2026-02-19 00:00 |
21:18:59.98 |
+57:44:57.9 |
HIP 105142 |
26.06 |
| 2026-02-19 12:00 |
21:19:04.44 |
+57:45:11.3 |
HIP 105142 |
26.47 |
| 2026-02-20 00:00 |
21:19:08.90 |
+57:45:25.0 |
HIP 105142 |
26.90 |
| 2026-02-20 12:00 |
21:19:13.34 |
+57:45:38.9 |
HIP 105142 |
27.33 |
| 2026-02-21 00:00 |
21:19:17.78 |
+57:45:53.2 |
HIP 105522 |
27.20 |
| 2026-02-21 12:00 |
21:19:22.21 |
+57:46:07.7 |
HIP 105522 |
26.78 |
| 2026-02-22 00:00 |
21:19:26.62 |
+57:46:22.6 |
HIP 105522 |
26.37 |
| 2026-02-22 12:00 |
21:19:31.03 |
+57:46:37.7 |
HIP 105522 |
25.97 |
| 2026-02-23 00:00 |
21:19:35.42 |
+57:46:53.1 |
HIP 105522 |
25.59 |
| 2026-02-23 12:00 |
21:19:39.81 |
+57:47:08.8 |
HIP 105522 |
25.22 |
| 2026-02-24 00:00 |
21:19:44.18 |
+57:47:24.8 |
HIP 105522 |
24.87 |