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.

2029-04-17astronomy score per night — click a bar for that night2029-05-16

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-04-17 Tue	—	unknown	—	42.9° 17:15	7.16	14%	32.4°
2029-04-18 Wed	—	unknown	—	42.9° 17:10	7.1	22%	29.8°
2029-04-19 Thu	—	unknown	—	42.9° 17:05	7.05	31%	31.8°
2029-04-20 Fri	—	unknown	—	42.9° 17:00	6.99	40%	37.8°
2029-04-21 Sat	—	unknown	—	42.9° 17:00	6.93	51%	46.6°
2029-04-22 Sun	—	unknown	—	42.9° 16:55	6.87	62%	57.1°
2029-04-23 Mon	—	unknown	—	42.9° 16:50	6.81	73%	68.7°
2029-04-24 Tue	—	unknown	—	42.9° 16:45	6.75	82%	81.1°
2029-04-25 Wed	—	unknown	—	42.9° 16:40	6.7	90%	93.9°
2029-04-26 Thu	—	unknown	—	42.9° 16:40	6.64	96%	106.9°
2029-04-27 Fri	—	unknown	—	42.9° 16:35	6.58	99%	119.7°
2029-04-28 Sat	—	unknown	—	42.9° 16:30	6.52	100%	131.7°
2029-04-29 Sun	—	unknown	—	42.9° 16:25	6.46	97%	141.9°
2029-04-30 Mon	—	unknown	—	42.9° 16:25	6.41	91%	148.7°
2029-05-01 Tue	—	unknown	—	42.9° 16:20	6.35	84%	150.1°
2029-05-02 Wed	—	unknown	—	42.9° 16:15	6.29	75%	146.0°
2029-05-03 Thu	—	unknown	—	42.9° 16:10	6.23	65%	138.4°
2029-05-04 Fri	—	unknown	—	42.9° 16:05	6.17	55%	129.1°
2029-05-05 Sat	—	unknown	—	42.9° 16:05	6.12	45%	119.1°
2029-05-06 Sun	—	unknown	—	42.9° 16:00	6.06	35%	108.9°
2029-05-07 Mon	—	unknown	—	42.9° 15:55	6.0	26%	98.6°
2029-05-08 Tue	—	unknown	—	42.9° 15:50	5.95	19%	88.3°
2029-05-09 Wed	—	unknown	—	42.9° 15:45	5.89	12%	78.0°
2029-05-10 Thu	—	unknown	—	42.9° 15:45	5.83	6%	67.9°
2029-05-11 Fri	—	unknown	—	42.9° 15:40	5.78	3%	58.1°
2029-05-12 Sat	—	unknown	—	42.9° 15:35	5.72	0%	48.7°
2029-05-13 Sun	—	unknown	—	42.9° 15:30	5.67	0%	40.2°
2029-05-14 Mon	—	unknown	—	42.9° 15:30	5.62	2%	33.5°
2029-05-15 Tue	—	unknown	—	42.9° 15:25	5.56	5%	29.9°
2029-05-16 Wed	—	unknown	—	42.9° 15:20	5.51	11%	30.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-04-17&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.