Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for 3C 273: 02-01 (93), 02-02 (93), 02-03 (93), 02-04 (93), 02-05 (93) — by astronomy; check the weather when the night is within four days.

2041-02-01astronomy score per night — click a bar for that night2041-03-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-02-01 Fri	93	—	unknown	00:15–06:00 (good, 5.75 h)	50.1° 04:00	10.75	1%	137.8°
2041-02-02 Sat	93	—	unknown	00:10–06:00 (good, 5.83 h)	50.1° 04:00	10.71	5%	153.0°
2041-02-03 Sun	93	—	unknown	00:05–05:55 (good, 5.83 h)	50.1° 03:55	10.68	11%	167.9°
2041-02-04 Mon	93	—	unknown	00:05–05:55 (good, 5.83 h)	50.1° 03:50	10.64	19%	177.2°
2041-02-05 Tue	93	—	unknown	00:00–05:55 (good, 5.92 h)	50.1° 03:45	10.61	29%	163.4°
2041-02-06 Wed	93	—	unknown	00:00–05:55 (good, 5.92 h)	50.1° 03:40	10.57	39%	149.8°
2041-02-07 Thu	93	—	unknown	23:55–05:55 (good, 6.0 h)	50.1° 03:40	10.54	50%	136.7°
2041-02-08 Fri	93	—	unknown	23:55–05:50 (good, 5.92 h)	50.1° 03:35	10.5	60%	123.9°
2041-02-09 Sat	93	—	unknown	23:55–05:50 (good, 5.92 h)	50.1° 03:30	10.46	69%	111.5°
2041-02-10 Sun	92	—	unknown	00:00–05:50 (good, 5.83 h)	50.1° 03:25	10.43	78%	99.3°
2041-02-11 Mon	88	—	unknown	00:45–05:50 (good, 5.08 h)	50.1° 03:20	10.39	85%	87.2°
2041-02-12 Tue	66	—	unknown	02:30–05:50 (good, 3.33 h)	50.1° 03:20	10.35	91%	75.3°
2041-02-13 Wed	50	—	unknown	23:30–05:45 (marginal, 6.25 h)	50.1° 03:15	10.31	96%	63.5°
2041-02-14 Thu	36	—	unknown	23:50–05:45 (marginal, 5.92 h)	50.1° 03:10	10.27	99%	51.7°
2041-02-15 Fri	24	—	unknown	02:10–05:45 (marginal, 3.58 h)	50.1° 03:05	10.23	100%	39.8°
2041-02-16 Sat	17	—	unknown	04:00–05:45 (marginal, 1.75 h)	50.1° 03:05	10.19	99%	28.0°
2041-02-17 Sun	18	—	unknown	03:45–05:40 (marginal, 1.92 h)	50.1° 03:00	10.15	97%	16.0°
2041-02-18 Mon	21	—	unknown	23:20–05:40 (marginal, 6.33 h)	50.1° 02:55	10.11	93%	4.2°
2041-02-19 Tue	30	—	unknown	22:55–05:40 (marginal, 6.75 h)	50.1° 02:50	10.07	87%	8.3°
2041-02-20 Wed	42	—	unknown	22:40–05:40 (marginal, 7.0 h)	50.1° 02:45	10.03	80%	20.6°
2041-02-21 Thu	81	—	unknown	22:55–23:35 (good, 0.67 h)	50.1° 02:45	9.98	71%	33.1°
2041-02-22 Fri	88	—	unknown	22:50–04:55 (good, 6.08 h)	50.1° 02:40	9.94	61%	45.9°
2041-02-23 Sat	92	—	unknown	22:50–05:35 (good, 6.75 h)	50.1° 02:35	9.9	51%	59.1°
2041-02-24 Sun	93	—	unknown	22:45–05:30 (good, 6.75 h)	50.1° 02:30	9.85	40%	72.6°
2041-02-25 Mon	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.1° 02:25	9.81	29%	86.5°
2041-02-26 Tue	93	—	unknown	22:35–05:30 (good, 6.92 h)	50.1° 02:25	9.77	20%	100.9°
2041-02-27 Wed	93	—	unknown	22:35–05:25 (good, 6.83 h)	50.1° 02:20	9.72	11%	115.6°
2041-02-28 Thu	93	—	unknown	22:30–05:25 (good, 6.92 h)	50.1° 02:15	9.68	5%	130.7°
2041-03-01 Fri	93	—	unknown	22:25–05:25 (good, 7.0 h)	50.1° 02:10	9.63	1%	145.8°
2041-03-02 Sat	93	—	unknown	22:20–05:25 (good, 7.08 h)	50.1° 02:10	9.58	0%	161.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-02-01&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.