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 (1), 04-11 (1), 04-12 (1), 04-13 (1), 04-14 (1) — by astronomy; check the weather when the night is within four days.

2037-04-10astronomy score per night — click a bar for that night2037-05-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-04-10 Fri	1	—	unknown	21:00–21:05 (marginal, 0.08 h)	72.5° 15:55	7.56	19%	90.7°
2037-04-11 Sat	1	—	unknown	—	72.5° 15:50	7.5	12%	79.0°
2037-04-12 Sun	1	—	unknown	—	72.5° 15:45	7.45	7%	67.3°
2037-04-13 Mon	1	—	unknown	—	72.5° 15:40	7.39	3%	55.5°
2037-04-14 Tue	1	—	unknown	—	72.5° 15:40	7.33	1%	43.7°
2037-04-15 Wed	0	—	unknown	—	72.5° 15:35	7.27	0%	31.9°
2037-04-16 Thu	0	—	unknown	—	72.5° 15:30	7.22	2%	20.2°
2037-04-17 Fri	0	—	unknown	—	72.5° 15:25	7.16	5%	10.3°
2037-04-18 Sat	0	—	unknown	—	72.5° 15:20	7.1	11%	11.1°
2037-04-19 Sun	0	—	unknown	—	72.5° 15:20	7.04	18%	21.7°
2037-04-20 Mon	0	—	unknown	—	72.5° 15:15	6.98	27%	34.2°
2037-04-21 Tue	0	—	unknown	—	72.5° 15:10	6.93	37%	47.3°
2037-04-22 Wed	0	—	unknown	—	72.5° 15:05	6.87	48%	60.8°
2037-04-23 Thu	0	—	unknown	—	72.5° 15:00	6.81	59%	74.7°
2037-04-24 Fri	0	—	unknown	—	72.5° 15:00	6.75	70%	88.8°
2037-04-25 Sat	0	—	unknown	—	72.5° 14:55	6.69	80%	103.1°
2037-04-26 Sun	0	—	unknown	—	72.5° 14:50	6.64	89%	117.6°
2037-04-27 Mon	0	—	unknown	—	72.5° 14:45	6.58	95%	132.0°
2037-04-28 Tue	0	—	unknown	—	72.5° 14:40	6.52	99%	146.3°
2037-04-29 Wed	0	—	unknown	—	72.5° 14:40	6.46	100%	159.9°
2037-04-30 Thu	0	—	unknown	—	72.5° 14:35	6.4	98%	170.6°
2037-05-01 Fri	0	—	unknown	—	72.5° 14:30	6.34	94%	166.9°
2037-05-02 Sat	0	—	unknown	—	72.5° 14:25	6.29	88%	155.1°
2037-05-03 Sun	0	—	unknown	—	72.5° 14:25	6.23	80%	142.6°
2037-05-04 Mon	0	—	unknown	—	72.5° 14:20	6.17	72%	130.3°
2037-05-05 Tue	0	—	unknown	—	72.5° 14:15	6.11	62%	118.1°
2037-05-06 Wed	0	—	unknown	—	72.5° 14:10	6.06	53%	106.1°
2037-05-07 Thu	0	—	unknown	—	72.5° 14:05	6.0	43%	94.3°
2037-05-08 Fri	0	—	unknown	—	72.5° 14:05	5.94	34%	82.6°
2037-05-09 Sat	0	—	unknown	—	72.5° 14:00	5.89	25%	70.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-04-10&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.