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.

2043-05-15astronomy score per night — click a bar for that night2043-06-13

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-05-15 Fri	—	unknown	—	42.9° 15:25	5.58	50%	68.0°
2043-05-16 Sat	—	unknown	—	42.9° 15:20	5.53	61%	78.4°
2043-05-17 Sun	—	unknown	—	42.9° 15:20	5.48	70%	88.7°
2043-05-18 Mon	—	unknown	—	42.9° 15:15	5.43	79%	98.8°
2043-05-19 Tue	—	unknown	—	42.9° 15:10	5.38	86%	108.6°
2043-05-20 Wed	—	unknown	—	42.9° 15:05	5.33	92%	118.1°
2043-05-21 Thu	—	unknown	—	42.9° 15:00	5.28	96%	127.0°
2043-05-22 Fri	—	unknown	—	42.9° 15:00	5.23	99%	135.0°
2043-05-23 Sat	—	unknown	—	42.9° 14:55	5.18	100%	141.5°
2043-05-24 Sun	—	unknown	—	42.9° 14:50	5.13	99%	145.5°
2043-05-25 Mon	—	unknown	—	42.9° 14:45	5.09	96%	146.2°
2043-05-26 Tue	—	unknown	—	42.9° 14:45	5.04	92%	143.2°
2043-05-27 Wed	—	unknown	—	42.9° 14:40	5.0	86%	137.2°
2043-05-28 Thu	—	unknown	—	42.9° 14:35	4.96	78%	129.2°
2043-05-29 Fri	—	unknown	—	42.9° 14:30	4.92	69%	119.9°
2043-05-30 Sat	—	unknown	—	42.9° 14:25	4.88	59%	109.6°
2043-05-31 Sun	—	unknown	—	42.9° 14:25	4.84	49%	98.7°
2043-06-01 Mon	—	unknown	—	42.9° 14:20	4.8	38%	87.3°
2043-06-02 Tue	—	unknown	—	42.9° 14:15	4.76	27%	75.7°
2043-06-03 Wed	—	unknown	—	42.9° 14:10	4.73	17%	64.0°
2043-06-04 Thu	—	unknown	—	42.9° 14:05	4.7	9%	52.8°
2043-06-05 Fri	—	unknown	—	42.9° 14:05	4.67	4%	42.9°
2043-06-06 Sat	—	unknown	—	42.9° 14:00	4.64	1%	35.8°
2043-06-07 Sun	—	unknown	—	42.9° 13:55	4.61	0%	33.6°
2043-06-08 Mon	—	unknown	—	42.9° 13:50	4.58	4%	37.0°
2043-06-09 Tue	—	unknown	—	42.9° 13:50	4.56	9%	44.5°
2043-06-10 Wed	—	unknown	—	42.9° 13:45	4.54	16%	54.0°
2043-06-11 Thu	—	unknown	—	42.9° 13:40	4.52	25%	64.4°
2043-06-12 Fri	—	unknown	—	42.9° 13:35	4.5	35%	75.0°
2043-06-13 Sat	—	unknown	—	42.9° 13:30	4.48	45%	85.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-05-15&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.