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.

Best nights for HD 189733: 01-04 (4), 01-05 (3), 01-06 (2), 01-07 (2), 01-08 (1) — by astronomy; check the weather when the night is within four days.

2037-01-04astronomy score per night — click a bar for that night2037-02-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-01-04 Sun	4	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	89%	134.3°
2037-01-05 Mon	3	—	unknown	18:15–18:30 (marginal, 0.25 h)	71.1° 13:20	11.4	80%	127.7°
2037-01-06 Tue	2	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:20	11.38	70%	119.1°
2037-01-07 Wed	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.37	59%	109.5°
2037-01-08 Thu	1	—	unknown	—	71.1° 13:10	11.35	48%	99.5°
2037-01-09 Fri	1	—	unknown	—	71.1° 13:05	11.34	37%	89.5°
2037-01-10 Sat	1	—	unknown	—	71.1° 13:00	11.32	27%	79.7°
2037-01-11 Sun	1	—	unknown	—	71.1° 13:00	11.3	19%	70.3°
2037-01-12 Mon	0	—	unknown	—	71.1° 12:55	11.28	11%	61.6°
2037-01-13 Tue	0	—	unknown	—	71.1° 12:50	11.26	6%	54.0°
2037-01-14 Wed	0	—	unknown	—	71.1° 12:45	11.24	2%	47.8°
2037-01-15 Thu	0	—	unknown	—	71.1° 12:40	11.22	0%	43.6°
2037-01-16 Fri	0	—	unknown	—	71.1° 12:40	11.2	0%	42.0°
2037-01-17 Sat	0	—	unknown	—	71.1° 12:35	11.17	2%	43.2°
2037-01-18 Sun	0	—	unknown	—	71.1° 12:30	11.15	6%	46.8°
2037-01-19 Mon	0	—	unknown	—	71.1° 12:25	11.12	11%	52.4°
2037-01-20 Tue	0	—	unknown	—	71.1° 12:25	11.1	17%	59.3°
2037-01-21 Wed	0	—	unknown	—	71.1° 12:20	11.07	25%	67.1°
2037-01-22 Thu	0	—	unknown	—	71.1° 12:15	11.05	34%	75.6°
2037-01-23 Fri	0	—	unknown	—	71.1° 12:10	11.02	43%	84.5°
2037-01-24 Sat	0	—	unknown	—	71.1° 12:05	10.99	53%	93.7°
2037-01-25 Sun	0	—	unknown	—	71.1° 12:00	10.96	63%	103.1°
2037-01-26 Mon	0	—	unknown	—	71.1° 11:55	10.93	73%	112.5°
2037-01-27 Tue	1	—	unknown	—	71.1° 11:50	10.9	82%	121.4°
2037-01-28 Wed	1	—	unknown	—	71.1° 11:45	10.87	90%	129.4°
2037-01-29 Thu	1	—	unknown	—	71.1° 11:45	10.84	96%	135.4°
2037-01-30 Fri	1	—	unknown	—	71.1° 11:40	10.81	99%	137.9°
2037-01-31 Sat	1	—	unknown	—	71.1° 11:35	10.78	100%	136.2°
2037-02-01 Sun	1	—	unknown	—	71.1° 11:30	10.75	97%	130.7°
2037-02-02 Mon	1	—	unknown	—	71.1° 11:30	10.71	92%	122.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-01-04&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.