| Parameter |
Value |
| Designation |
C/2025 R1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-11-23T08:02:53.695680Z |
| Orbit solution date (soln_date, UTC) |
2026-07-06T12:12:28Z |
| Obs used |
386 |
| NEO |
- |
| M1 |
14.200 |
| K1 |
9.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2025-09-03T13:15:15.955200Z |
| Discovery magnitude (MPC) |
19.35 c |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-11-01.0000000 |
| e |
0.98807918 |
| q (au) |
1.975205 |
| a (au) |
165.693617 |
| i (deg) |
110.027262 |
| Ω (om, deg) |
60.396310 |
| ω (w, deg) |
77.550236 |
| M (ma, deg) |
359.989679 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.843 + 5.035\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.843 |
| n |
5.035 |
| gf |
1.000 |
| gb |
-0.597 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
15:33:36.42 |
+03:14:39.3 |
HIP 76159 |
6.58 |
| 2026-07-29 12:00 |
15:33:18.33 |
+03:06:40.5 |
HIP 76159 |
12.70 |
| 2026-07-30 00:00 |
15:33:00.66 |
+02:58:43.8 |
HIP 76172 |
14.26 |
| 2026-07-30 12:00 |
15:32:43.41 |
+02:50:49.3 |
HIP 76172 |
12.56 |
| 2026-07-31 00:00 |
15:32:26.59 |
+02:42:56.8 |
HIP 76172 |
16.46 |
| 2026-07-31 12:00 |
15:32:10.18 |
+02:35:06.5 |
HIP 76172 |
23.20 |
| 2026-08-01 00:00 |
15:31:54.19 |
+02:27:18.4 |
HIP 76194 |
28.85 |
| 2026-08-01 12:00 |
15:31:38.60 |
+02:19:32.3 |
HIP 76014 |
27.68 |
| 2026-08-02 00:00 |
15:31:23.42 |
+02:11:48.4 |
HIP 76014 |
20.04 |
| 2026-08-02 12:00 |
15:31:08.64 |
+02:04:06.6 |
HIP 76014 |
13.61 |
| 2026-08-03 00:00 |
15:30:54.25 |
+01:56:26.9 |
HIP 76014 |
10.63 |
| 2026-08-03 12:00 |
15:30:40.26 |
+01:48:49.3 |
HIP 75982 |
9.50 |
| 2026-08-04 00:00 |
15:30:26.66 |
+01:41:13.8 |
HIP 75982 |
8.83 |
| 2026-08-04 12:00 |
15:30:13.45 |
+01:33:40.4 |
HIP 75982 |
14.19 |
| 2026-08-05 00:00 |
15:30:00.62 |
+01:26:09.1 |
HIP 75859 |
15.78 |
| 2026-08-05 12:00 |
15:29:48.17 |
+01:18:39.9 |
HIP 75859 |
7.80 |
| 2026-08-06 00:00 |
15:29:36.09 |
+01:11:12.8 |
HIP 75859 |
1.94 |
| 2026-08-06 12:00 |
15:29:24.39 |
+01:03:47.7 |
HIP 75859 |
8.63 |
| 2026-08-07 00:00 |
15:29:13.05 |
+00:56:24.7 |
HIP 75859 |
16.43 |
| 2026-08-07 12:00 |
15:29:02.08 |
+00:49:03.7 |
HIP 75756 |
14.58 |
| 2026-08-08 00:00 |
15:28:51.47 |
+00:41:44.8 |
HIP 75756 |
7.05 |
| 2026-08-08 12:00 |
15:28:41.22 |
+00:34:27.9 |
HIP 75756 |
2.84 |
| 2026-08-09 00:00 |
15:28:31.33 |
+00:27:13.1 |
HIP 75756 |
9.21 |
| 2026-08-09 12:00 |
15:28:21.78 |
+00:20:00.3 |
HIP 75756 |
16.66 |
| 2026-08-10 00:00 |
15:28:12.59 |
+00:12:49.5 |
HIP 75705 |
19.54 |
| 2026-08-10 12:00 |
15:28:03.74 |
+00:05:40.7 |
HIP 75705 |
12.18 |
| 2026-08-11 00:00 |
15:27:55.23 |
-00:01:26.1 |
HIP 75705 |
5.18 |
| 2026-08-11 12:00 |
15:27:47.07 |
-00:08:30.9 |
HIP 75705 |
3.85 |
| 2026-08-12 00:00 |
15:27:39.23 |
-00:15:33.7 |
HIP 75705 |
10.49 |
| 2026-08-12 12:00 |
15:27:31.73 |
-00:22:34.6 |
HIP 75688 |
14.71 |
| 2026-08-13 00:00 |
15:27:24.56 |
-00:29:33.4 |
HIP 75688 |
9.02 |
| 2026-08-13 12:00 |
15:27:17.71 |
-00:36:30.3 |
HIP 75688 |
7.00 |
| 2026-08-14 00:00 |
15:27:11.18 |
-00:43:25.2 |
HIP 75688 |
10.83 |
| 2026-08-14 12:00 |
15:27:04.98 |
-00:50:18.2 |
HIP 75688 |
16.85 |
| 2026-08-15 00:00 |
15:26:59.09 |
-00:57:09.3 |
HIP 75559 |
14.34 |
| 2026-08-15 12:00 |
15:26:53.51 |
-01:03:58.4 |
HIP 75559 |
11.43 |
| 2026-08-16 00:00 |
15:26:48.23 |
-01:10:45.6 |
HIP 75586 |
6.05 |
| 2026-08-16 12:00 |
15:26:43.27 |
-01:17:30.9 |
HIP 75586 |
3.71 |
| 2026-08-17 00:00 |
15:26:38.61 |
-01:24:14.2 |
HIP 75586 |
9.21 |
| 2026-08-17 12:00 |
15:26:34.24 |
-01:30:55.7 |
HIP 75586 |
15.75 |
| 2026-08-18 00:00 |
15:26:30.17 |
-01:37:35.3 |
HIP 75648 |
17.14 |
| 2026-08-18 12:00 |
15:26:26.39 |
-01:44:13.0 |
HIP 75648 |
14.12 |
| 2026-08-19 00:00 |
15:26:22.91 |
-01:50:48.8 |
HIP 75648 |
13.88 |