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.

2040-06-19astronomy score per night — click a bar for that night2040-07-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-06-19 Tue	—	unknown	—	42.9° 13:05	4.42	71%	118.4°
2040-06-20 Wed	—	unknown	—	42.9° 13:00	4.42	80%	129.2°
2040-06-21 Thu	—	unknown	—	42.9° 12:55	4.42	88%	139.1°
2040-06-22 Fri	—	unknown	—	42.9° 12:55	4.43	95%	146.8°
2040-06-23 Sat	—	unknown	—	42.9° 12:50	4.43	99%	149.7°
2040-06-24 Sun	—	unknown	—	42.9° 12:45	4.44	100%	146.2°
2040-06-25 Mon	—	unknown	—	42.9° 12:40	4.45	98%	137.8°
2040-06-26 Tue	—	unknown	—	42.9° 12:40	4.46	93%	126.8°
2040-06-27 Wed	—	unknown	—	42.9° 12:35	4.48	86%	114.8°
2040-06-28 Thu	—	unknown	—	42.9° 12:30	4.49	76%	102.5°
2040-06-29 Fri	—	unknown	—	42.9° 12:25	4.51	66%	90.4°
2040-06-30 Sat	—	unknown	—	42.9° 12:20	4.53	55%	78.6°
2040-07-01 Sun	—	unknown	—	42.9° 12:20	4.55	45%	67.3°
2040-07-02 Mon	—	unknown	—	42.9° 12:15	4.57	34%	56.8°
2040-07-03 Tue	—	unknown	—	42.9° 12:10	4.6	25%	47.1°
2040-07-04 Wed	—	unknown	—	42.9° 12:05	4.63	17%	38.9°
2040-07-05 Thu	—	unknown	—	42.9° 12:00	4.66	10%	32.9°
2040-07-06 Fri	—	unknown	—	42.9° 11:55	4.69	5%	30.3°
2040-07-07 Sat	—	unknown	—	42.9° 11:50	4.72	2%	31.9°
2040-07-08 Sun	—	unknown	—	42.9° 11:45	4.75	0%	37.0°
2040-07-09 Mon	—	unknown	—	42.9° 11:45	4.79	0%	44.4°
2040-07-10 Tue	—	unknown	—	42.9° 11:40	4.82	2%	53.1°
2040-07-11 Wed	—	unknown	—	42.9° 11:35	4.86	6%	62.6°
2040-07-12 Thu	—	unknown	—	42.9° 11:30	4.9	11%	72.6°
2040-07-13 Fri	—	unknown	—	42.9° 11:25	4.94	18%	82.9°
2040-07-14 Sat	—	unknown	—	42.9° 11:25	4.98	26%	93.5°
2040-07-15 Sun	—	unknown	—	42.9° 11:20	5.02	35%	104.2°
2040-07-16 Mon	—	unknown	—	42.9° 11:15	5.07	45%	114.9°
2040-07-17 Tue	—	unknown	—	42.9° 11:10	5.11	56%	125.5°
2040-07-18 Wed	—	unknown	—	42.9° 11:05	5.16	66%	135.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-06-19&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.