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.

Best nights for Seven Sisters: 04-10 (2), 04-11 (1), 04-12 (1), 04-13 (1), 04-14 (1) — by astronomy; check the weather when the night is within four days.

2042-04-10astronomy score per night — click a bar for that night2042-05-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-04-10 Thu	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	72.5° 15:55	7.57	75%	159.2°
2042-04-11 Fri	1	—	unknown	—	72.5° 15:50	7.52	66%	146.4°
2042-04-12 Sat	1	—	unknown	—	72.5° 15:45	7.46	56%	133.4°
2042-04-13 Sun	1	—	unknown	—	72.5° 15:45	7.4	45%	120.0°
2042-04-14 Mon	1	—	unknown	—	72.5° 15:40	7.34	34%	106.2°
2042-04-15 Tue	0	—	unknown	—	72.5° 15:35	7.29	24%	92.0°
2042-04-16 Wed	0	—	unknown	—	72.5° 15:30	7.23	14%	77.5°
2042-04-17 Thu	0	—	unknown	—	72.5° 15:25	7.17	7%	62.6°
2042-04-18 Fri	0	—	unknown	—	72.5° 15:25	7.11	2%	47.5°
2042-04-19 Sat	0	—	unknown	—	72.5° 15:20	7.05	0%	32.3°
2042-04-20 Sun	0	—	unknown	—	72.5° 15:15	7.0	1%	17.3°
2042-04-21 Mon	0	—	unknown	—	72.5° 15:10	6.94	5%	2.8°
2042-04-22 Tue	0	—	unknown	—	72.5° 15:05	6.88	11%	11.9°
2042-04-23 Wed	0	—	unknown	—	72.5° 15:05	6.82	19%	25.8°
2042-04-24 Thu	0	—	unknown	—	72.5° 15:00	6.76	28%	39.3°
2042-04-25 Fri	0	—	unknown	—	72.5° 14:55	6.71	38%	52.3°
2042-04-26 Sat	0	—	unknown	—	72.5° 14:50	6.65	48%	64.9°
2042-04-27 Sun	0	—	unknown	—	72.5° 14:50	6.59	58%	77.2°
2042-04-28 Mon	0	—	unknown	—	72.5° 14:45	6.53	68%	89.3°
2042-04-29 Tue	0	—	unknown	—	72.5° 14:40	6.47	76%	101.2°
2042-04-30 Wed	0	—	unknown	—	72.5° 14:35	6.41	84%	113.0°
2042-05-01 Thu	0	—	unknown	—	72.5° 14:30	6.36	90%	124.8°
2042-05-02 Fri	0	—	unknown	—	72.5° 14:30	6.3	95%	136.7°
2042-05-03 Sat	0	—	unknown	—	72.5° 14:25	6.24	98%	148.6°
2042-05-04 Sun	0	—	unknown	—	72.5° 14:20	6.18	100%	160.7°
2042-05-05 Mon	0	—	unknown	—	72.5° 14:15	6.13	100%	172.8°
2042-05-06 Tue	0	—	unknown	—	72.5° 14:10	6.07	97%	174.6°
2042-05-07 Wed	0	—	unknown	—	72.5° 14:10	6.01	93%	162.2°
2042-05-08 Thu	0	—	unknown	—	72.5° 14:05	5.96	87%	149.4°
2042-05-09 Fri	0	—	unknown	—	72.5° 14:00	5.9	79%	136.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-04-10&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.