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: 06-09 (100), 06-10 (100), 06-11 (100), 06-12 (100), 06-13 (100) — by astronomy; check the weather when the night is within four days.

2045-05-27astronomy score per night — click a bar for that night2045-06-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-05-27 Sat	75	—	unknown	00:20–03:50 (good, 3.5 h)	71.1° 05:00	4.98	91%	97.3°
2045-05-28 Sun	66	—	unknown	00:35–03:50 (good, 3.25 h)	71.1° 04:55	4.93	96%	87.8°
2045-05-29 Mon	56	—	unknown	01:15–03:50 (good, 2.58 h)	71.1° 04:50	4.89	99%	78.4°
2045-05-30 Tue	49	—	unknown	01:50–03:45 (good, 1.92 h)	71.1° 04:50	4.86	100%	69.5°
2045-05-31 Wed	44	—	unknown	02:25–03:45 (good, 1.33 h)	71.1° 04:45	4.82	98%	61.4°
2045-06-01 Thu	41	—	unknown	23:15–03:45 (marginal, 4.5 h)	71.1° 04:40	4.78	95%	54.2°
2045-06-02 Fri	48	—	unknown	23:35–23:45 (good, 0.17 h)	71.1° 04:35	4.75	90%	48.6°
2045-06-03 Sat	65	—	unknown	01:40–03:15 (good, 1.58 h)	71.1° 04:30	4.71	84%	44.8°
2045-06-04 Sun	74	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:30	4.68	76%	43.4°
2045-06-05 Mon	83	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:25	4.65	68%	44.6°
2045-06-06 Tue	92	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:20	4.62	59%	48.2°
2045-06-07 Wed	95	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:15	4.6	49%	53.6°
2045-06-08 Thu	98	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:10	4.57	40%	60.6°
2045-06-09 Fri	100	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:10	4.55	30%	68.7°
2045-06-10 Sat	100	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:05	4.53	21%	77.6°
2045-06-11 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:00	4.51	13%	87.1°
2045-06-12 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.49	7%	97.0°
2045-06-13 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.47	2%	107.0°
2045-06-14 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.46	0%	116.7°
2045-06-15 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:45	4.45	1%	125.4°
2045-06-16 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.44	5%	132.3°
2045-06-17 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	11%	136.1°
2045-06-18 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	20%	136.2°
2045-06-19 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.42	30%	132.5°
2045-06-20 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	41%	126.1°
2045-06-21 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:20	4.42	52%	118.0°
2045-06-22 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	63%	109.0°
2045-06-23 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	73%	99.6°
2045-06-24 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.44	82%	90.1°
2045-06-25 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.45	89%	80.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-05-27&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.