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.

2027-03-21astronomy score per night — click a bar for that night2027-04-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-03-21 Sun	—	unknown	—	89.7° 13:10	8.68	100%	136.4°
2027-03-22 Mon	—	unknown	—	89.6° 13:05	8.63	100%	145.4°
2027-03-23 Tue	—	unknown	—	89.5° 13:00	8.58	97%	150.8°
2027-03-24 Wed	—	unknown	—	89.6° 13:00	8.53	92%	150.7°
2027-03-25 Thu	—	unknown	—	89.7° 12:55	8.47	86%	145.8°
2027-03-26 Fri	—	unknown	—	89.7° 12:50	8.42	78%	137.9°
2027-03-27 Sat	—	unknown	—	89.6° 12:45	8.37	70%	128.6°
2027-03-28 Sun	—	unknown	—	89.5° 13:45	8.31	60%	118.7°
2027-03-29 Mon	—	unknown	—	89.6° 13:40	8.26	51%	108.5°
2027-03-30 Tue	—	unknown	—	89.7° 13:35	8.2	42%	98.2°
2027-03-31 Wed	—	unknown	—	89.7° 13:30	8.15	32%	87.8°
2027-04-01 Thu	—	unknown	—	89.5° 13:25	8.1	24%	77.4°
2027-04-02 Fri	—	unknown	—	89.6° 13:25	8.04	16%	66.9°
2027-04-03 Sat	—	unknown	—	89.7° 13:20	7.99	10%	56.6°
2027-04-04 Sun	—	unknown	—	89.7° 13:15	7.93	5%	46.7°
2027-04-05 Mon	—	unknown	—	89.6° 13:10	7.87	1%	37.8°
2027-04-06 Tue	—	unknown	—	89.5° 13:05	7.82	0%	31.1°
2027-04-07 Wed	—	unknown	—	89.6° 13:05	7.76	1%	28.6°
2027-04-08 Thu	—	unknown	—	89.7° 13:00	7.71	5%	31.7°
2027-04-09 Fri	—	unknown	—	89.7° 12:55	7.65	10%	39.3°
2027-04-10 Sat	—	unknown	—	89.6° 12:50	7.59	18%	49.4°
2027-04-11 Sun	—	unknown	—	89.5° 12:50	7.54	28%	60.7°
2027-04-12 Mon	—	unknown	—	89.6° 12:45	7.48	38%	72.8°
2027-04-13 Tue	—	unknown	—	89.7° 12:40	7.42	50%	85.1°
2027-04-14 Wed	—	unknown	—	89.7° 12:35	7.36	61%	97.5°
2027-04-15 Thu	—	unknown	—	89.5° 12:30	7.31	72%	109.8°
2027-04-16 Fri	—	unknown	—	89.5° 12:30	7.25	81%	121.7°
2027-04-17 Sat	—	unknown	—	89.7° 12:25	7.19	89%	132.9°
2027-04-18 Sun	—	unknown	—	89.7° 12:20	7.13	95%	142.5°
2027-04-19 Mon	—	unknown	—	89.6° 12:15	7.08	99%	149.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-03-21&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.