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.

2035-09-01astronomy score per night — click a bar for that night2035-09-30

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-09-01 Sat	—	unknown	—	50.2° 15:10	7.6	0%	28.9°
2035-09-02 Sun	—	unknown	—	50.2° 15:05	7.66	1%	14.9°
2035-09-03 Mon	—	unknown	—	50.2° 15:00	7.71	4%	2.3°
2035-09-04 Tue	—	unknown	—	50.2° 15:00	7.77	10%	12.5°
2035-09-05 Wed	—	unknown	—	50.2° 14:55	7.82	17%	25.4°
2035-09-06 Thu	—	unknown	—	50.2° 14:50	7.88	25%	38.0°
2035-09-07 Fri	—	unknown	—	50.2° 14:45	7.93	34%	50.3°
2035-09-08 Sat	—	unknown	—	50.2° 14:40	7.99	43%	62.4°
2035-09-09 Sun	—	unknown	—	50.2° 14:40	8.04	53%	74.3°
2035-09-10 Mon	—	unknown	—	50.2° 14:35	8.1	62%	86.1°
2035-09-11 Tue	—	unknown	—	50.2° 14:30	8.15	71%	98.0°
2035-09-12 Wed	—	unknown	—	50.2° 14:25	8.2	80%	109.9°
2035-09-13 Thu	—	unknown	—	50.2° 14:25	8.26	87%	122.0°
2035-09-14 Fri	—	unknown	—	50.2° 14:20	8.31	93%	134.3°
2035-09-15 Sat	—	unknown	—	50.2° 14:15	8.36	97%	146.8°
2035-09-16 Sun	—	unknown	—	50.2° 14:10	8.42	100%	159.6°
2035-09-17 Mon	—	unknown	—	50.2° 14:05	8.47	100%	172.5°
2035-09-18 Tue	—	unknown	—	50.2° 14:05	8.52	98%	173.5°
2035-09-19 Wed	—	unknown	—	50.2° 14:00	8.57	94%	160.2°
2035-09-20 Thu	—	unknown	—	50.2° 13:55	8.62	87%	146.5°
2035-09-21 Fri	—	unknown	—	50.2° 13:50	8.67	79%	132.6°
2035-09-22 Sat	—	unknown	—	50.2° 13:45	8.73	69%	118.6°
2035-09-23 Sun	—	unknown	—	50.2° 13:45	8.78	58%	104.5°
2035-09-24 Mon	—	unknown	—	50.2° 13:40	8.83	46%	90.4°
2035-09-25 Tue	—	unknown	—	50.2° 13:35	8.88	35%	76.2°
2035-09-26 Wed	—	unknown	—	50.2° 13:30	8.93	25%	62.1°
2035-09-27 Thu	—	unknown	—	50.2° 13:30	8.98	16%	47.9°
2035-09-28 Fri	—	unknown	—	50.2° 13:25	9.02	8%	33.9°
2035-09-29 Sat	—	unknown	—	50.2° 13:20	9.07	3%	20.1°
2035-09-30 Sun	—	unknown	—	50.2° 13:15	9.12	0%	6.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-09-01&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.