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.

2038-04-19astronomy score per night — click a bar for that night2038-05-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-04-19 Mon	—	unknown	—	79.2° 13:05	7.06	100%	155.8°
2038-04-20 Tue	—	unknown	—	79.2° 13:05	7.0	96%	150.2°
2038-04-21 Wed	—	unknown	—	79.2° 13:00	6.94	91%	140.0°
2038-04-22 Thu	—	unknown	—	79.2° 12:55	6.88	83%	128.1°
2038-04-23 Fri	—	unknown	—	79.2° 12:50	6.82	74%	115.9°
2038-04-24 Sat	—	unknown	—	79.2° 12:45	6.77	64%	103.7°
2038-04-25 Sun	—	unknown	—	79.2° 12:45	6.71	53%	91.8°
2038-04-26 Mon	—	unknown	—	79.2° 12:40	6.65	43%	80.3°
2038-04-27 Tue	—	unknown	—	79.2° 12:35	6.59	34%	69.1°
2038-04-28 Wed	—	unknown	—	79.2° 12:30	6.53	25%	58.3°
2038-04-29 Thu	—	unknown	—	79.2° 12:25	6.47	17%	48.0°
2038-04-30 Fri	—	unknown	—	79.2° 12:25	6.42	11%	38.5°
2038-05-01 Sat	—	unknown	—	79.2° 12:20	6.36	6%	30.4°
2038-05-02 Sun	—	unknown	—	79.2° 12:15	6.3	2%	25.1°
2038-05-03 Mon	—	unknown	—	79.2° 12:10	6.24	0%	24.5°
2038-05-04 Tue	—	unknown	—	79.2° 12:10	6.19	0%	28.8°
2038-05-05 Wed	—	unknown	—	79.2° 12:00	6.13	2%	36.5°
2038-05-06 Thu	—	unknown	—	79.2° 12:00	6.07	6%	46.0°
2038-05-07 Fri	—	unknown	—	79.2° 11:50	6.01	11%	56.5°
2038-05-08 Sat	—	unknown	—	79.2° 11:50	5.96	18%	67.6°
2038-05-09 Sun	—	unknown	—	79.2° 11:45	5.9	27%	79.1°
2038-05-10 Mon	—	unknown	—	79.2° 11:40	5.85	37%	90.9°
2038-05-11 Tue	—	unknown	—	79.2° 11:35	5.79	47%	103.0°
2038-05-12 Wed	—	unknown	—	79.2° 11:30	5.73	58%	115.3°
2038-05-13 Thu	—	unknown	—	79.2° 11:30	5.68	69%	127.6°
2038-05-14 Fri	—	unknown	—	79.2° 11:25	5.63	79%	139.5°
2038-05-15 Sat	—	unknown	—	79.2° 11:20	5.57	88%	149.7°
2038-05-16 Sun	—	unknown	—	79.2° 11:15	5.52	95%	155.6°
2038-05-17 Mon	—	unknown	—	79.2° 11:15	5.47	99%	153.6°
2038-05-18 Tue	—	unknown	—	79.2° 11:10	5.42	100%	145.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-04-19&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.