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: 05-31 (100), 06-01 (100), 06-02 (100), 06-03 (100), 06-16 (100) — by astronomy; check the weather when the night is within four days.

2028-05-31astronomy score per night — click a bar for that night2028-06-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-05-31 Wed	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:45	4.81	57%	127.8°
2028-06-01 Thu	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:40	4.78	68%	119.0°
2028-06-02 Fri	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:35	4.74	78%	109.2°
2028-06-03 Sat	100	—	unknown	23:50–03:45 (good, 3.92 h)	71.1° 04:30	4.71	87%	98.8°
2028-06-04 Sun	74	—	unknown	00:00–03:40 (good, 3.67 h)	71.1° 04:25	4.68	93%	88.3°
2028-06-05 Mon	62	—	unknown	00:45–03:40 (good, 2.92 h)	71.1° 04:25	4.65	98%	77.9°
2028-06-06 Tue	52	—	unknown	01:35–03:40 (good, 2.08 h)	71.1° 04:20	4.62	100%	68.1°
2028-06-07 Wed	44	—	unknown	02:50–03:40 (good, 0.83 h)	71.1° 04:15	4.59	99%	59.0°
2028-06-08 Thu	39	—	unknown	23:05–03:40 (marginal, 4.58 h)	71.1° 04:10	4.57	97%	51.2°
2028-06-09 Fri	44	—	unknown	23:05–23:10 (good, 0.08 h)	71.1° 04:05	4.54	92%	45.1°
2028-06-10 Sat	63	—	unknown	23:05–23:40 (good, 0.58 h)	71.1° 04:05	4.52	86%	41.5°
2028-06-11 Sun	72	—	unknown	23:10–02:40 (good, 3.5 h)	71.1° 04:00	4.5	79%	40.7°
2028-06-12 Mon	82	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.49	71%	42.8°
2028-06-13 Tue	91	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.47	62%	47.3°
2028-06-14 Wed	95	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.46	52%	53.6°
2028-06-15 Thu	98	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:45	4.45	43%	61.1°
2028-06-16 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.44	34%	69.5°
2028-06-17 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	25%	78.5°
2028-06-18 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.43	16%	87.9°
2028-06-19 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.42	10%	97.7°
2028-06-20 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	4%	107.5°
2028-06-21 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:20	4.42	1%	117.2°
2028-06-22 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	0%	126.1°
2028-06-23 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.43	2%	133.6°
2028-06-24 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.44	6%	138.3°
2028-06-25 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.45	13%	139.3°
2028-06-26 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:00	4.46	22%	136.1°
2028-06-27 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 02:55	4.47	32%	129.7°
2028-06-28 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:55	4.49	43%	121.2°
2028-06-29 Thu	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:50	4.51	55%	111.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-05-31&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.