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.

2036-04-21astronomy score per night — click a bar for that night2036-05-20

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-04-21 Mon	—	unknown	—	42.9° 16:55	6.91	20%	101.6°
2036-04-22 Tue	—	unknown	—	42.9° 16:55	6.85	13%	90.3°
2036-04-23 Wed	—	unknown	—	42.9° 16:50	6.8	7%	78.8°
2036-04-24 Thu	—	unknown	—	42.9° 16:45	6.74	3%	67.0°
2036-04-25 Fri	—	unknown	—	42.9° 16:40	6.68	0%	55.3°
2036-04-26 Sat	—	unknown	—	42.9° 16:40	6.62	0%	43.9°
2036-04-27 Sun	—	unknown	—	42.9° 16:35	6.56	3%	33.5°
2036-04-28 Mon	—	unknown	—	42.9° 16:30	6.5	8%	26.1°
2036-04-29 Tue	—	unknown	—	42.9° 16:25	6.45	15%	24.7°
2036-04-30 Wed	—	unknown	—	42.9° 16:20	6.39	25%	30.3°
2036-05-01 Thu	—	unknown	—	42.9° 16:20	6.33	35%	40.1°
2036-05-02 Fri	—	unknown	—	42.9° 16:15	6.27	46%	51.7°
2036-05-03 Sat	—	unknown	—	42.9° 16:10	6.21	58%	64.0°
2036-05-04 Sun	—	unknown	—	42.9° 16:05	6.16	69%	76.6°
2036-05-05 Mon	—	unknown	—	42.9° 16:00	6.1	78%	89.3°
2036-05-06 Tue	—	unknown	—	42.9° 16:00	6.04	87%	101.8°
2036-05-07 Wed	—	unknown	—	42.9° 15:55	5.99	93%	114.1°
2036-05-08 Thu	—	unknown	—	42.9° 15:50	5.93	98%	125.8°
2036-05-09 Fri	—	unknown	—	42.9° 15:45	5.87	100%	136.8°
2036-05-10 Sat	—	unknown	—	42.9° 15:45	5.82	99%	146.4°
2036-05-11 Sun	—	unknown	—	42.9° 15:40	5.76	97%	153.3°
2036-05-12 Mon	—	unknown	—	42.9° 15:35	5.71	93%	155.6°
2036-05-13 Tue	—	unknown	—	42.9° 15:30	5.65	87%	152.3°
2036-05-14 Wed	—	unknown	—	42.9° 15:25	5.6	80%	145.3°
2036-05-15 Thu	—	unknown	—	42.9° 15:25	5.55	72%	136.3°
2036-05-16 Fri	—	unknown	—	42.9° 15:20	5.49	63%	126.4°
2036-05-17 Sat	—	unknown	—	42.9° 15:15	5.44	54%	116.0°
2036-05-18 Sun	—	unknown	—	42.9° 15:10	5.39	45%	105.3°
2036-05-19 Mon	—	unknown	—	42.9° 15:05	5.34	35%	94.3°
2036-05-20 Tue	—	unknown	—	42.9° 15:05	5.29	26%	83.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-04-21&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.