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: 02-24 (93), 02-25 (93), 02-26 (93), 02-27 (93), 02-28 (93) — by astronomy; check the weather when the night is within four days.

2041-02-19astronomy score per night — click a bar for that night2041-03-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2041-03-03 Sun	93	—	unknown	22:15–05:20 (good, 7.08 h)	50.1° 02:05	9.54	3%	175.8°
2041-03-04 Mon	93	—	unknown	22:15–05:20 (good, 7.08 h)	50.1° 02:00	9.49	8%	169.2°
2041-03-05 Tue	93	—	unknown	22:10–05:20 (good, 7.17 h)	50.1° 01:55	9.45	15%	155.1°
2041-03-06 Wed	93	—	unknown	22:05–05:15 (good, 7.17 h)	50.1° 01:50	9.4	23%	141.3°
2041-03-07 Thu	93	—	unknown	22:05–05:15 (good, 7.17 h)	50.1° 01:50	9.35	33%	128.0°
2041-03-08 Fri	93	—	unknown	22:05–05:15 (good, 7.17 h)	50.1° 01:45	9.3	43%	115.2°
2041-03-09 Sat	93	—	unknown	22:05–05:10 (good, 7.08 h)	50.1° 01:40	9.25	53%	102.7°
2041-03-10 Sun	89	—	unknown	22:10–05:10 (good, 7.0 h)	50.1° 01:35	9.21	62%	90.5°
2041-03-11 Mon	85	—	unknown	23:00–05:10 (good, 6.17 h)	50.1° 01:30	9.16	71%	78.5°
2041-03-12 Tue	80	—	unknown	00:55–05:05 (good, 4.17 h)	50.1° 01:30	9.11	80%	66.6°
2041-03-13 Wed	55	—	unknown	21:40–05:05 (marginal, 7.42 h)	50.1° 01:25	9.06	86%	54.8°
2041-03-14 Thu	38	—	unknown	22:05–05:00 (marginal, 6.92 h)	50.1° 01:20	9.01	92%	43.0°
2041-03-15 Fri	25	—	unknown	01:25–05:00 (marginal, 3.58 h)	50.1° 01:15	8.96	96%	31.2°
2041-03-16 Sat	21	—	unknown	02:30–05:00 (marginal, 2.5 h)	50.1° 01:15	8.91	99%	19.2°
2041-03-17 Sun	20	—	unknown	02:55–04:50 (marginal, 1.92 h)	50.1° 01:10	8.86	100%	7.2°
2041-03-18 Mon	22	—	unknown	21:25–01:15 (marginal, 3.83 h)	50.1° 01:05	8.81	99%	5.4°
2041-03-19 Tue	31	—	unknown	21:05–04:40 (marginal, 7.58 h)	50.1° 01:00	8.75	96%	17.6°
2041-03-20 Wed	62	—	unknown	21:10–21:25 (good, 0.25 h)	50.1° 00:55	8.7	91%	30.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-02-19&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.