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.

2027-08-17astronomy score per night — click a bar for that night2027-09-15

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-17 Tue	—	unknown	—	50.2° 16:10	6.74	100%	145.1°
2027-08-18 Wed	—	unknown	—	50.2° 16:05	6.8	98%	156.4°
2027-08-19 Thu	—	unknown	—	50.2° 16:00	6.86	94%	166.7°
2027-08-20 Fri	—	unknown	—	50.2° 15:55	6.92	88%	170.6°
2027-08-21 Sat	—	unknown	—	50.2° 15:55	6.97	81%	162.6°
2027-08-22 Sun	—	unknown	—	50.2° 15:50	7.03	72%	151.0°
2027-08-23 Mon	—	unknown	—	50.2° 15:45	7.09	62%	138.6°
2027-08-24 Tue	—	unknown	—	50.2° 15:40	7.15	52%	125.6°
2027-08-25 Wed	—	unknown	—	50.2° 15:35	7.2	41%	112.3°
2027-08-26 Thu	—	unknown	—	50.2° 15:35	7.26	30%	98.5°
2027-08-27 Fri	—	unknown	—	50.2° 15:30	7.32	20%	84.3°
2027-08-28 Sat	—	unknown	—	50.2° 15:25	7.37	11%	69.8°
2027-08-29 Sun	—	unknown	—	50.2° 15:20	7.43	5%	55.0°
2027-08-30 Mon	—	unknown	—	50.2° 15:20	7.49	1%	40.3°
2027-08-31 Tue	—	unknown	—	50.2° 15:15	7.54	0%	25.9°
2027-09-01 Wed	—	unknown	—	50.2° 15:10	7.6	2%	13.1°
2027-09-02 Thu	—	unknown	—	50.2° 15:05	7.65	7%	10.3°
2027-09-03 Fri	—	unknown	—	50.2° 15:00	7.71	14%	21.1°
2027-09-04 Sat	—	unknown	—	50.2° 15:00	7.76	22%	33.9°
2027-09-05 Sun	—	unknown	—	50.2° 14:55	7.82	32%	46.7°
2027-09-06 Mon	—	unknown	—	50.2° 14:50	7.87	42%	59.2°
2027-09-07 Tue	—	unknown	—	50.2° 14:45	7.93	52%	71.5°
2027-09-08 Wed	—	unknown	—	50.2° 14:40	7.98	61%	83.5°
2027-09-09 Thu	—	unknown	—	50.2° 14:40	8.04	70%	95.3°
2027-09-10 Fri	—	unknown	—	50.2° 14:35	8.09	79%	107.0°
2027-09-11 Sat	—	unknown	—	50.2° 14:30	8.15	86%	118.7°
2027-09-12 Sun	—	unknown	—	50.2° 14:25	8.2	92%	130.3°
2027-09-13 Mon	—	unknown	—	50.2° 14:25	8.25	96%	141.9°
2027-09-14 Tue	—	unknown	—	50.2° 14:20	8.31	99%	153.4°
2027-09-15 Wed	—	unknown	—	50.2° 14:15	8.36	100%	164.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-17&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.