| 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) |
| 2026-06-01 00:00 |
09:03:55.18 |
+12:58:48.6 |
HIP 44581 |
26.67 |
| 2026-06-01 12:00 |
09:03:56.85 |
+12:58:43.0 |
HIP 44581 |
26.52 |
| 2026-06-02 00:00 |
09:03:58.54 |
+12:58:37.2 |
HIP 44581 |
26.37 |
| 2026-06-02 12:00 |
09:04:00.26 |
+12:58:31.2 |
HIP 44581 |
26.22 |
| 2026-06-03 00:00 |
09:04:02.01 |
+12:58:25.2 |
HIP 44581 |
26.08 |
| 2026-06-03 12:00 |
09:04:03.80 |
+12:58:18.9 |
HIP 44581 |
25.95 |
| 2026-06-04 00:00 |
09:04:05.61 |
+12:58:12.6 |
HIP 44581 |
25.82 |
| 2026-06-04 12:00 |
09:04:07.44 |
+12:58:06.1 |
HIP 44581 |
25.69 |
| 2026-06-05 00:00 |
09:04:09.31 |
+12:57:59.4 |
HIP 44581 |
25.58 |
| 2026-06-05 12:00 |
09:04:11.21 |
+12:57:52.6 |
HIP 44581 |
25.47 |
| 2026-06-06 00:00 |
09:04:13.13 |
+12:57:45.7 |
HIP 44581 |
25.36 |
| 2026-06-06 12:00 |
09:04:15.08 |
+12:57:38.6 |
HIP 44581 |
25.27 |
| 2026-06-07 00:00 |
09:04:17.07 |
+12:57:31.3 |
HIP 44581 |
25.18 |
| 2026-06-07 12:00 |
09:04:19.07 |
+12:57:24.0 |
HIP 44581 |
25.11 |
| 2026-06-08 00:00 |
09:04:21.11 |
+12:57:16.5 |
HIP 44581 |
25.04 |
| 2026-06-08 12:00 |
09:04:23.17 |
+12:57:08.8 |
HIP 44581 |
24.99 |
| 2026-06-09 00:00 |
09:04:25.26 |
+12:57:01.0 |
HIP 44581 |
24.94 |
| 2026-06-09 12:00 |
09:04:27.38 |
+12:56:53.1 |
HIP 44581 |
24.91 |
| 2026-06-10 00:00 |
09:04:29.53 |
+12:56:45.0 |
HIP 44581 |
24.88 |
| 2026-06-10 12:00 |
09:04:31.70 |
+12:56:36.8 |
HIP 44581 |
24.87 |
| 2026-06-11 00:00 |
09:04:33.90 |
+12:56:28.5 |
HIP 44581 |
24.87 |
| 2026-06-11 12:00 |
09:04:36.12 |
+12:56:20.0 |
HIP 44581 |
24.89 |
| 2026-06-12 00:00 |
09:04:38.38 |
+12:56:11.3 |
HIP 44581 |
24.92 |
| 2026-06-12 12:00 |
09:04:40.65 |
+12:56:02.6 |
HIP 44581 |
24.96 |
| 2026-06-13 00:00 |
09:04:42.96 |
+12:55:53.7 |
HIP 44581 |
25.02 |
| 2026-06-13 12:00 |
09:04:45.29 |
+12:55:44.6 |
HIP 44581 |
25.09 |
| 2026-06-14 00:00 |
09:04:47.64 |
+12:55:35.5 |
HIP 44581 |
25.18 |
| 2026-06-14 12:00 |
09:04:50.02 |
+12:55:26.2 |
HIP 44581 |
25.28 |
| 2026-06-15 00:00 |
09:04:52.43 |
+12:55:16.7 |
HIP 44581 |
25.40 |
| 2026-06-15 12:00 |
09:04:54.86 |
+12:55:07.1 |
HIP 44581 |
25.53 |
| 2026-06-16 00:00 |
09:04:57.31 |
+12:54:57.4 |
HIP 44581 |
25.68 |
| 2026-06-16 12:00 |
09:04:59.79 |
+12:54:47.6 |
HIP 44581 |
25.85 |
| 2026-06-17 00:00 |
09:05:02.30 |
+12:54:37.6 |
HIP 44581 |
26.03 |
| 2026-06-17 12:00 |
09:05:04.83 |
+12:54:27.5 |
HIP 44581 |
26.23 |
| 2026-06-18 00:00 |
09:05:07.38 |
+12:54:17.3 |
HIP 44581 |
26.45 |
| 2026-06-18 12:00 |
09:05:09.96 |
+12:54:06.9 |
HIP 44581 |
26.68 |
| 2026-06-19 00:00 |
09:05:12.55 |
+12:53:56.4 |
HIP 44581 |
26.93 |
| 2026-06-19 12:00 |
09:05:15.18 |
+12:53:45.8 |
HIP 44581 |
27.20 |
| 2026-06-20 00:00 |
09:05:17.82 |
+12:53:35.1 |
HIP 44581 |
27.48 |
| 2026-06-20 12:00 |
09:05:20.49 |
+12:53:24.2 |
HIP 44581 |
27.78 |
| 2026-06-21 00:00 |
09:05:23.18 |
+12:53:13.2 |
HIP 44581 |
28.09 |
| 2026-06-21 12:00 |
09:05:25.89 |
+12:53:02.1 |
HIP 44581 |
28.42 |
| 2026-06-22 00:00 |
09:05:28.63 |
+12:52:50.8 |
HIP 44581 |
28.77 |