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.

2028-04-27astronomy score per night — click a bar for that night2028-05-26

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-04-27 Thu	—	unknown	—	42.9° 16:35	6.57	10%	32.8°
2028-04-28 Fri	—	unknown	—	42.9° 16:30	6.51	18%	31.5°
2028-04-29 Sat	—	unknown	—	42.9° 16:25	6.45	27%	35.1°
2028-04-30 Sun	—	unknown	—	42.9° 16:20	6.39	37%	42.6°
2028-05-01 Mon	—	unknown	—	42.9° 16:20	6.33	48%	52.4°
2028-05-02 Tue	—	unknown	—	42.9° 16:15	6.28	59%	63.5°
2028-05-03 Wed	—	unknown	—	42.9° 16:10	6.22	70%	75.4°
2028-05-04 Thu	—	unknown	—	42.9° 16:05	6.16	80%	87.6°
2028-05-05 Fri	—	unknown	—	42.9° 16:00	6.1	89%	100.0°
2028-05-06 Sat	—	unknown	—	42.9° 16:00	6.05	95%	112.1°
2028-05-07 Sun	—	unknown	—	42.9° 15:55	5.99	99%	123.7°
2028-05-08 Mon	—	unknown	—	42.9° 15:50	5.93	100%	134.2°
2028-05-09 Tue	—	unknown	—	42.9° 15:45	5.88	98%	142.7°
2028-05-10 Wed	—	unknown	—	42.9° 15:40	5.82	95%	147.8°
2028-05-11 Thu	—	unknown	—	42.9° 15:40	5.77	89%	148.4°
2028-05-12 Fri	—	unknown	—	42.9° 15:35	5.71	82%	144.4°
2028-05-13 Sat	—	unknown	—	42.9° 15:30	5.66	73%	137.5°
2028-05-14 Sun	—	unknown	—	42.9° 15:25	5.6	64%	129.0°
2028-05-15 Mon	—	unknown	—	42.9° 15:25	5.55	55%	119.7°
2028-05-16 Tue	—	unknown	—	42.9° 15:20	5.5	46%	110.0°
2028-05-17 Wed	—	unknown	—	42.9° 15:15	5.45	36%	100.0°
2028-05-18 Thu	—	unknown	—	42.9° 15:10	5.39	27%	89.9°
2028-05-19 Fri	—	unknown	—	42.9° 15:05	5.34	19%	79.6°
2028-05-20 Sat	—	unknown	—	42.9° 15:05	5.29	12%	69.4°
2028-05-21 Sun	—	unknown	—	42.9° 15:00	5.24	6%	59.2°
2028-05-22 Mon	—	unknown	—	42.9° 14:55	5.2	2%	49.4°
2028-05-23 Tue	—	unknown	—	42.9° 14:50	5.15	0%	40.6°
2028-05-24 Wed	—	unknown	—	42.9° 14:45	5.1	0%	34.0°
2028-05-25 Thu	—	unknown	—	42.9° 14:45	5.06	3%	31.2°
2028-05-26 Fri	—	unknown	—	42.9° 14:40	5.01	8%	33.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-27&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.