C/2025 R2 (SWAN)

Metadata

Parameter Value
Designation C/2025 R2 (SWAN)
Type C
Perihelion (tp_cal, UTC) 2025-09-12T20:18:14.512320Z
Orbit solution date (soln_date, UTC) 2026-03-31T09:42:19Z
Obs used 2322
NEO -
M1 13.900
K1 10.000
PC -
Discovery observation (MPC, UTC) 2025-09-11T23:33:15.552000Z
Discovery magnitude (MPC) 7.50 V
Discovery observatory (MPC) 247 · Roving Observer
Osculating Elements
Parameter Value
Epoch (epoch_cal, TDB) 2025-11-11.0000000
e 0.99419736
q (au) 0.504084
a (au) 86.871582
i (deg) 4.472978
Ω (om, deg) 335.325999
ω (w, deg) 308.358672
M (ma, deg) 0.072006

Magnitude

C/2025 R2 (SWAN) · Magnitude (Full range)

Scatter + Global Linear

$$ M_a = (12.726 + 4.952\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$

Model Parameters

Parameter Value
H0 12.726
n 4.952
gf 1.000
gb -1.000
k 0.932
δ90 9.994
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
2025-09-12 2026-03-09 -1.7108 -0.928

log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)

Finding Chart

C/2025 R2 (SWAN) · Next 30 Days

Ephemeris

Date/Time (UTC) RA (J2000) Dec (J2000) Nearest HIP Dist from HIP (arcmin)
2026-03-26 00:00 02:49:25.03 +20:06:38.0 HIP 13094 16.41
2026-03-26 12:00 02:50:01.81 +20:09:05.7 HIP 13229 21.18
2026-03-27 00:00 02:50:38.57 +20:11:33.0 HIP 13229 18.94
2026-03-27 12:00 02:51:15.30 +20:14:00.0 HIP 13229 20.73
2026-03-28 00:00 02:51:52.00 +20:16:26.4 HIP 13418 15.68
2026-03-28 12:00 02:52:28.68 +20:18:52.4 HIP 13418 12.15
2026-03-29 00:00 02:53:05.32 +20:21:18.0 HIP 13418 14.46
2026-03-29 12:00 02:53:41.94 +20:23:43.2 HIP 13532 13.20
2026-03-30 00:00 02:54:18.52 +20:26:08.0 HIP 13532 7.82
2026-03-30 12:00 02:54:55.08 +20:28:32.3 HIP 13571 6.28
2026-03-31 00:00 02:55:31.61 +20:30:56.2 HIP 13571 13.00
2026-03-31 12:00 02:56:08.11 +20:33:19.6 HIP 13571 21.36
2026-04-01 00:00 02:56:44.58 +20:35:42.7 HIP 13834 19.34
2026-04-01 12:00 02:57:21.02 +20:38:05.2 HIP 13834 10.51
2026-04-02 00:00 02:57:57.44 +20:40:27.4 HIP 13834 1.82
2026-04-02 12:00 02:58:33.82 +20:42:49.1 HIP 13834 7.24
2026-04-03 00:00 02:59:10.17 +20:45:10.4 HIP 13834 16.04
2026-04-03 12:00 02:59:46.49 +20:47:31.2 HIP 13834 24.84
2026-04-04 00:00 03:00:22.78 +20:49:51.6 HIP 13834 33.63
2026-04-04 12:00 03:00:59.05 +20:52:11.6 HIP 13914 37.58
2026-04-05 00:00 03:01:35.28 +20:54:31.1 HIP 14203 40.82
2026-04-05 12:00 03:02:11.48 +20:56:50.2 HIP 14203 39.10
2026-04-06 00:00 03:02:47.65 +20:59:08.8 HIP 14292 35.64
2026-04-06 12:00 03:03:23.79 +21:01:27.1 HIP 14292 29.47
2026-04-07 00:00 03:03:59.90 +21:03:44.8 HIP 14378 23.17
2026-04-07 12:00 03:04:35.98 +21:06:02.1 HIP 14378 17.37
2026-04-08 00:00 03:05:12.03 +21:08:19.0 HIP 14378 14.80
2026-04-08 12:00 03:05:48.04 +21:10:35.5 HIP 14378 16.96
2026-04-09 00:00 03:06:24.03 +21:12:51.5 HIP 14481 22.15
2026-04-09 12:00 03:06:59.98 +21:15:07.0 HIP 14481 23.46
2026-04-10 00:00 03:07:35.91 +21:17:22.2 HIP 14481 27.58
2026-04-10 12:00 03:08:11.80 +21:19:36.8 HIP 14727 28.78
2026-04-11 00:00 03:08:47.66 +21:21:51.1 HIP 14727 20.98
2026-04-11 12:00 03:09:23.48 +21:24:04.8 HIP 14727 14.20
2026-04-12 00:00 03:09:59.28 +21:26:18.2 HIP 14727 10.60
2026-04-12 12:00 03:10:35.04 +21:28:31.1 HIP 14727 13.10
2026-04-13 00:00 03:11:10.77 +21:30:43.5 HIP 14727 19.47
2026-04-13 12:00 03:11:46.46 +21:32:55.5 HIP 14993 21.34
2026-04-14 00:00 03:12:22.12 +21:35:07.0 HIP 14993 12.77
2026-04-14 12:00 03:12:57.75 +21:37:18.1 HIP 14993 4.21
2026-04-15 00:00 03:13:33.35 +21:39:28.8 HIP 14993 4.36
2026-04-15 12:00 03:14:08.91 +21:41:39.0 HIP 14993 12.90
2026-04-16 00:00 03:14:44.43 +21:43:48.7 HIP 14993 21.43