| Parameter |
Value |
| Designation |
C/2025 R1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-11-23T07:59:05.271360Z |
| Orbit solution date (soln_date, UTC) |
2026-05-08T13:42:12Z |
| Obs used |
351 |
| NEO |
- |
| M1 |
14.400 |
| K1 |
8.250 |
| 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) |
2025-10-10.0000000 |
| e |
0.98809507 |
| q (au) |
1.975215 |
| a (au) |
165.915713 |
| i (deg) |
110.027209 |
| Ω (om, deg) |
60.396276 |
| ω (w, deg) |
77.548954 |
| M (ma, deg) |
359.979555 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.946 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.946 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.934 |
| 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) |
| 2026-05-12 00:00 |
18:01:49.79 |
+23:27:49.6 |
HIP 88208 |
23.85 |
| 2026-05-12 12:00 |
18:00:35.04 |
+23:25:11.5 |
HIP 88106 |
14.54 |
| 2026-05-13 00:00 |
17:59:19.91 |
+23:22:27.1 |
HIP 88106 |
10.09 |
| 2026-05-13 12:00 |
17:58:04.41 |
+23:19:36.4 |
HIP 88106 |
24.64 |
| 2026-05-14 00:00 |
17:56:48.56 |
+23:16:39.2 |
HIP 87682 |
31.57 |
| 2026-05-14 12:00 |
17:55:32.37 |
+23:13:35.6 |
HIP 87682 |
13.95 |
| 2026-05-15 00:00 |
17:54:15.84 |
+23:10:25.4 |
HIP 87682 |
5.05 |
| 2026-05-15 12:00 |
17:52:59.01 |
+23:07:08.8 |
HIP 87595 |
8.64 |
| 2026-05-16 00:00 |
17:51:41.87 |
+23:03:45.5 |
HIP 87321 |
19.57 |
| 2026-05-16 12:00 |
17:50:24.45 |
+23:00:15.6 |
HIP 87321 |
15.23 |
| 2026-05-17 00:00 |
17:49:06.76 |
+22:56:39.1 |
HIP 87193 |
4.53 |
| 2026-05-17 12:00 |
17:47:48.80 |
+22:52:55.9 |
HIP 87059 |
8.28 |
| 2026-05-18 00:00 |
17:46:30.61 |
+22:49:05.9 |
HIP 87059 |
12.78 |
| 2026-05-18 12:00 |
17:45:12.19 |
+22:45:09.3 |
HIP 86756 |
23.14 |
| 2026-05-19 00:00 |
17:43:53.55 |
+22:41:05.9 |
HIP 86756 |
5.55 |
| 2026-05-19 12:00 |
17:42:34.72 |
+22:36:55.7 |
HIP 86726 |
14.61 |
| 2026-05-20 00:00 |
17:41:15.71 |
+22:32:38.8 |
HIP 86726 |
31.93 |
| 2026-05-20 12:00 |
17:39:56.54 |
+22:28:15.1 |
HIP 86361 |
15.94 |
| 2026-05-21 00:00 |
17:38:37.22 |
+22:23:44.6 |
HIP 86361 |
3.53 |
| 2026-05-21 12:00 |
17:37:17.76 |
+22:19:07.3 |
HIP 86245 |
2.95 |
| 2026-05-22 00:00 |
17:35:58.19 |
+22:14:23.3 |
HIP 86165 |
13.57 |
| 2026-05-22 12:00 |
17:34:38.51 |
+22:09:32.6 |
HIP 85873 |
29.57 |
| 2026-05-23 00:00 |
17:33:18.75 |
+22:04:35.1 |
HIP 85873 |
13.08 |
| 2026-05-23 12:00 |
17:31:58.93 |
+21:59:30.9 |
HIP 85873 |
14.13 |
| 2026-05-24 00:00 |
17:30:39.05 |
+21:54:20.1 |
HIP 85655 |
9.12 |
| 2026-05-24 12:00 |
17:29:19.13 |
+21:49:02.6 |
HIP 85567 |
18.98 |
| 2026-05-25 00:00 |
17:27:59.20 |
+21:43:38.4 |
HIP 85402 |
12.20 |
| 2026-05-25 12:00 |
17:26:39.26 |
+21:38:07.7 |
HIP 85402 |
8.13 |
| 2026-05-26 00:00 |
17:25:19.33 |
+21:32:30.4 |
HIP 85110 |
23.51 |
| 2026-05-26 12:00 |
17:23:59.43 |
+21:26:46.6 |
HIP 85110 |
8.66 |
| 2026-05-27 00:00 |
17:22:39.58 |
+21:20:56.4 |
HIP 84972 |
14.70 |
| 2026-05-27 12:00 |
17:21:19.79 |
+21:14:59.8 |
HIP 84972 |
11.20 |
| 2026-05-28 00:00 |
17:20:00.07 |
+21:08:56.8 |
HIP 84669 |
24.55 |
| 2026-05-28 12:00 |
17:18:40.44 |
+21:02:47.5 |
HIP 84669 |
21.09 |
| 2026-05-29 00:00 |
17:17:20.92 |
+20:56:31.9 |
HIP 84604 |
29.44 |
| 2026-05-29 12:00 |
17:16:01.52 |
+20:50:10.2 |
HIP 84458 |
26.14 |
| 2026-05-30 00:00 |
17:14:42.26 |
+20:43:42.3 |
HIP 84458 |
26.67 |
| 2026-05-30 12:00 |
17:13:23.15 |
+20:37:08.5 |
HIP 84187 |
15.95 |
| 2026-05-31 00:00 |
17:12:04.21 |
+20:30:28.6 |
HIP 84187 |
18.82 |
| 2026-05-31 12:00 |
17:10:45.46 |
+20:23:42.9 |
HIP 84006 |
11.01 |
| 2026-06-01 00:00 |
17:09:26.90 |
+20:16:51.3 |
HIP 84006 |
12.53 |
| 2026-06-01 12:00 |
17:08:08.56 |
+20:09:54.0 |
HIP 83868 |
12.07 |
| 2026-06-02 00:00 |
17:06:50.44 |
+20:02:51.0 |
HIP 83698 |
12.71 |