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.

2037-04-16astronomy score per night — click a bar for that night2037-05-15

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-04-16 Thu	—	unknown	—	72.5° 15:30	7.22	2%	20.2°
2037-04-17 Fri	—	unknown	—	72.5° 15:25	7.16	5%	10.3°
2037-04-18 Sat	—	unknown	—	72.5° 15:20	7.1	11%	11.1°
2037-04-19 Sun	—	unknown	—	72.5° 15:20	7.04	18%	21.7°
2037-04-20 Mon	—	unknown	—	72.5° 15:15	6.98	27%	34.2°
2037-04-21 Tue	—	unknown	—	72.5° 15:10	6.93	37%	47.3°
2037-04-22 Wed	—	unknown	—	72.5° 15:05	6.87	48%	60.8°
2037-04-23 Thu	—	unknown	—	72.5° 15:00	6.81	59%	74.7°
2037-04-24 Fri	—	unknown	—	72.5° 15:00	6.75	70%	88.8°
2037-04-25 Sat	—	unknown	—	72.5° 14:55	6.69	80%	103.1°
2037-04-26 Sun	—	unknown	—	72.5° 14:50	6.64	89%	117.6°
2037-04-27 Mon	—	unknown	—	72.5° 14:45	6.58	95%	132.0°
2037-04-28 Tue	—	unknown	—	72.5° 14:40	6.52	99%	146.3°
2037-04-29 Wed	—	unknown	—	72.5° 14:40	6.46	100%	159.9°
2037-04-30 Thu	—	unknown	—	72.5° 14:35	6.4	98%	170.6°
2037-05-01 Fri	—	unknown	—	72.5° 14:30	6.34	94%	166.9°
2037-05-02 Sat	—	unknown	—	72.5° 14:25	6.29	88%	155.1°
2037-05-03 Sun	—	unknown	—	72.5° 14:25	6.23	80%	142.6°
2037-05-04 Mon	—	unknown	—	72.5° 14:20	6.17	72%	130.3°
2037-05-05 Tue	—	unknown	—	72.5° 14:15	6.11	62%	118.1°
2037-05-06 Wed	—	unknown	—	72.5° 14:10	6.06	53%	106.1°
2037-05-07 Thu	—	unknown	—	72.5° 14:05	6.0	43%	94.3°
2037-05-08 Fri	—	unknown	—	72.5° 14:05	5.94	34%	82.6°
2037-05-09 Sat	—	unknown	—	72.5° 14:00	5.89	25%	70.9°
2037-05-10 Sun	—	unknown	—	72.5° 13:55	5.83	18%	59.2°
2037-05-11 Mon	—	unknown	—	72.5° 13:50	5.78	11%	47.4°
2037-05-12 Tue	—	unknown	—	72.5° 13:45	5.72	6%	35.5°
2037-05-13 Wed	—	unknown	—	72.5° 13:45	5.67	2%	23.6°
2037-05-14 Thu	—	unknown	—	72.5° 13:40	5.61	0%	12.7°
2037-05-15 Fri	—	unknown	—	72.5° 13:35	5.56	1%	9.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-04-16&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.