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.

2027-07-27astronomy score per night — click a bar for that night2027-08-25

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-27 Tue	—	unknown	—	50.2° 17:30	5.56	37%	134.9°
2027-07-28 Wed	—	unknown	—	50.2° 17:25	5.62	27%	121.5°
2027-07-29 Thu	—	unknown	—	50.2° 17:25	5.67	17%	107.5°
2027-07-30 Fri	—	unknown	—	50.2° 17:20	5.72	9%	93.1°
2027-07-31 Sat	—	unknown	—	50.2° 17:15	5.78	3%	78.3°
2027-08-01 Sun	—	unknown	—	50.2° 17:10	5.83	0%	63.4°
2027-08-02 Mon	—	unknown	—	50.2° 17:10	5.89	0%	48.4°
2027-08-03 Tue	—	unknown	—	50.2° 17:05	5.94	4%	33.7°
2027-08-04 Wed	—	unknown	—	50.2° 17:00	6.0	9%	19.9°
2027-08-05 Thu	—	unknown	—	50.2° 16:55	6.06	17%	9.6°
2027-08-06 Fri	—	unknown	—	50.2° 16:50	6.11	26%	14.0°
2027-08-07 Sat	—	unknown	—	50.2° 16:50	6.17	37%	25.9°
2027-08-08 Sun	—	unknown	—	50.2° 16:45	6.23	47%	38.4°
2027-08-09 Mon	—	unknown	—	50.2° 16:40	6.28	57%	50.8°
2027-08-10 Tue	—	unknown	—	50.2° 16:35	6.34	67%	63.0°
2027-08-11 Wed	—	unknown	—	50.2° 16:30	6.4	76%	75.0°
2027-08-12 Thu	—	unknown	—	50.2° 16:30	6.46	84%	86.8°
2027-08-13 Fri	—	unknown	—	50.2° 16:25	6.51	90%	98.6°
2027-08-14 Sat	—	unknown	—	50.2° 16:20	6.57	95%	110.3°
2027-08-15 Sun	—	unknown	—	50.2° 16:15	6.63	98%	121.9°
2027-08-16 Mon	—	unknown	—	50.2° 16:15	6.69	100%	133.6°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-27&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.