| Parameter |
Value |
| Designation |
273P/Pons-Gambart |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2012-12-19T16:06:04.144320Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:28:12Z |
| Obs used |
1140 |
| NEO |
Yes |
| M1 |
11.300 |
| K1 |
8.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-03-18.0000000 |
| e |
0.97532437 |
| q (au) |
0.810159 |
| a (au) |
32.832346 |
| i (deg) |
136.396031 |
| Ω (om, deg) |
320.431172 |
| ω (w, deg) |
20.191912 |
| M (ma, deg) |
0.462759 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.697 + 5.779\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.697 |
| n |
5.779 |
| gf |
0.989 |
| gb |
-0.949 |
| 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 |
| 2012-12-22 |
2013-01-27 |
-8.2343 |
-1.482 |
| 2013-01-27 |
2013-02-11 |
+1.7962 |
-1.599 |
| 2013-02-11 |
2013-03-04 |
+15.9200 |
-2.714 |
| 2013-03-04 |
2013-04-29 |
+2.7105 |
-0.831 |
| 2013-04-29 |
2014-04-04 |
-2.5481 |
+0.557 |
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 |
09:15:48.39 |
+12:00:33.5 |
HIP 45538 |
30.28 |
| 2026-09-20 12:00 |
09:15:51.19 |
+12:00:15.8 |
HIP 45538 |
30.18 |
| 2026-09-21 00:00 |
09:15:53.98 |
+11:59:58.2 |
HIP 45538 |
30.10 |
| 2026-09-21 12:00 |
09:15:56.74 |
+11:59:40.7 |
HIP 45538 |
30.04 |
| 2026-09-22 00:00 |
09:15:59.48 |
+11:59:23.2 |
HIP 45538 |
30.00 |
| 2026-09-22 12:00 |
09:16:02.19 |
+11:59:05.8 |
HIP 45538 |
29.97 |
| 2026-09-23 00:00 |
09:16:04.88 |
+11:58:48.5 |
HIP 45538 |
29.97 |
| 2026-09-23 12:00 |
09:16:07.55 |
+11:58:31.3 |
HIP 45538 |
29.99 |
| 2026-09-24 00:00 |
09:16:10.20 |
+11:58:14.1 |
HIP 45538 |
30.02 |
| 2026-09-24 12:00 |
09:16:12.83 |
+11:57:57.0 |
HIP 45538 |
30.07 |
| 2026-09-25 00:00 |
09:16:15.43 |
+11:57:40.0 |
HIP 45538 |
30.13 |
| 2026-09-25 12:00 |
09:16:18.01 |
+11:57:23.1 |
HIP 45538 |
30.22 |
| 2026-09-26 00:00 |
09:16:20.56 |
+11:57:06.3 |
HIP 45538 |
30.31 |
| 2026-09-26 12:00 |
09:16:23.09 |
+11:56:49.5 |
HIP 45538 |
30.43 |
| 2026-09-27 00:00 |
09:16:25.60 |
+11:56:32.8 |
HIP 45538 |
30.55 |
| 2026-09-27 12:00 |
09:16:28.08 |
+11:56:16.2 |
HIP 45538 |
30.70 |
| 2026-09-28 00:00 |
09:16:30.54 |
+11:55:59.7 |
HIP 45538 |
30.85 |
| 2026-09-28 12:00 |
09:16:32.97 |
+11:55:43.3 |
HIP 45538 |
31.02 |
| 2026-09-29 00:00 |
09:16:35.38 |
+11:55:26.9 |
HIP 45538 |
31.20 |
| 2026-09-29 12:00 |
09:16:37.76 |
+11:55:10.7 |
HIP 45614 |
30.90 |
| 2026-09-30 00:00 |
09:16:40.12 |
+11:54:54.5 |
HIP 45614 |
30.35 |
| 2026-09-30 12:00 |
09:16:42.46 |
+11:54:38.4 |
HIP 45614 |
29.80 |
| 2026-10-01 00:00 |
09:16:44.76 |
+11:54:22.5 |
HIP 45614 |
29.27 |
| 2026-10-01 12:00 |
09:16:47.04 |
+11:54:06.6 |
HIP 45614 |
28.74 |
| 2026-10-02 00:00 |
09:16:49.30 |
+11:53:50.8 |
HIP 45614 |
28.22 |
| 2026-10-02 12:00 |
09:16:51.53 |
+11:53:35.1 |
HIP 45614 |
27.70 |
| 2026-10-03 00:00 |
09:16:53.73 |
+11:53:19.5 |
HIP 45614 |
27.20 |
| 2026-10-03 12:00 |
09:16:55.91 |
+11:53:04.0 |
HIP 45614 |
26.71 |
| 2026-10-04 00:00 |
09:16:58.06 |
+11:52:48.5 |
HIP 45614 |
26.22 |
| 2026-10-04 12:00 |
09:17:00.18 |
+11:52:33.2 |
HIP 45614 |
25.74 |
| 2026-10-05 00:00 |
09:17:02.28 |
+11:52:18.0 |
HIP 45614 |
25.27 |
| 2026-10-05 12:00 |
09:17:04.35 |
+11:52:02.9 |
HIP 45614 |
24.81 |
| 2026-10-06 00:00 |
09:17:06.39 |
+11:51:47.9 |
HIP 45614 |
24.36 |
| 2026-10-06 12:00 |
09:17:08.40 |
+11:51:33.0 |
HIP 45614 |
23.92 |
| 2026-10-07 00:00 |
09:17:10.39 |
+11:51:18.2 |
HIP 45614 |
23.49 |
| 2026-10-07 12:00 |
09:17:12.34 |
+11:51:03.5 |
HIP 45614 |
23.06 |
| 2026-10-08 00:00 |
09:17:14.27 |
+11:50:49.0 |
HIP 45614 |
22.65 |
| 2026-10-08 12:00 |
09:17:16.17 |
+11:50:34.5 |
HIP 45614 |
22.24 |
| 2026-10-09 00:00 |
09:17:18.04 |
+11:50:20.1 |
HIP 45614 |
21.85 |
| 2026-10-09 12:00 |
09:17:19.88 |
+11:50:05.9 |
HIP 45614 |
21.46 |
| 2026-10-10 00:00 |
09:17:21.70 |
+11:49:51.8 |
HIP 45614 |
21.08 |
| 2026-10-10 12:00 |
09:17:23.48 |
+11:49:37.7 |
HIP 45614 |
20.72 |
| 2026-10-11 00:00 |
09:17:25.23 |
+11:49:23.8 |
HIP 45614 |
20.36 |