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 Vega: 05-21 (100), 05-22 (100), 05-23 (100), 05-24 (100), 05-25 (100) — by astronomy; check the weather when the night is within four days.

2028-05-21astronomy score per night — click a bar for that night2028-06-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-05-21 Sun	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 04:00	5.24	6%	93.5°
2028-05-22 Mon	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.2	2%	99.3°
2028-05-23 Tue	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:50	5.15	0%	104.8°
2028-05-24 Wed	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:45	5.1	0%	109.8°
2028-05-25 Thu	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.06	3%	113.9°
2028-05-26 Fri	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.01	8%	116.7°
2028-05-27 Sat	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:35	4.97	15%	117.9°
2028-05-28 Sun	100	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:30	4.93	24%	117.3°
2028-05-29 Mon	100	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:25	4.89	34%	114.9°
2028-05-30 Tue	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:25	4.85	46%	111.0°
2028-05-31 Wed	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.81	57%	105.9°
2028-06-01 Thu	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:15	4.78	68%	99.9°
2028-06-02 Fri	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:10	4.74	78%	93.5°
2028-06-03 Sat	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:05	4.71	87%	86.9°
2028-06-04 Sun	79	—	unknown	23:00–03:40 (good, 4.67 h)	87.1° 03:05	4.68	93%	80.6°
2028-06-05 Mon	71	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 03:00	4.65	98%	74.8°
2028-06-06 Tue	63	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:55	4.62	100%	69.7°
2028-06-07 Wed	58	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:50	4.59	99%	65.8°
2028-06-08 Thu	60	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.57	97%	63.2°
2028-06-09 Fri	88	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.54	92%	62.1°
2028-06-10 Sat	97	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:40	4.52	86%	62.4°
2028-06-11 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:35	4.5	79%	64.0°
2028-06-12 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:30	4.49	71%	66.8°
2028-06-13 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:30	4.47	62%	70.6°
2028-06-14 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.46	52%	75.0°
2028-06-15 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:20	4.45	43%	80.1°
2028-06-16 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:15	4.44	34%	85.6°
2028-06-17 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:10	4.43	25%	91.3°
2028-06-18 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:10	4.43	16%	97.1°
2028-06-19 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:05	4.42	10%	102.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-05-21&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.