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: 06-20 (100), 06-21 (100), 06-22 (100), 06-23 (100), 06-24 (100) — by astronomy; check the weather when the night is within four days.

2041-06-20astronomy score per night — click a bar for that night2041-07-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-06-20 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	52%	63.6°
2041-06-21 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:20	4.42	41%	72.0°
2041-06-22 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	30%	81.0°
2041-06-23 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	21%	90.2°
2041-06-24 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.44	13%	99.2°
2041-06-25 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.45	7%	107.8°
2041-06-26 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:00	4.46	2%	115.7°
2041-06-27 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:00	4.47	0%	122.5°
2041-06-28 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:55	4.49	0%	127.9°
2041-06-29 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:50	4.5	2%	131.4°
2041-06-30 Sun	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:45	4.52	6%	132.8°
2041-07-01 Mon	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:40	4.55	11%	131.8°
2041-07-02 Tue	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:40	4.57	18%	128.7°
2041-07-03 Wed	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:35	4.59	26%	123.9°
2041-07-04 Thu	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:30	4.62	34%	117.8°
2041-07-05 Fri	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:25	4.65	44%	110.8°
2041-07-06 Sat	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:20	4.68	53%	103.0°
2041-07-07 Sun	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:20	4.71	63%	94.7°
2041-07-08 Mon	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:15	4.74	73%	86.1°
2041-07-09 Tue	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:10	4.78	82%	77.3°
2041-07-10 Wed	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:05	4.81	89%	68.6°
2041-07-11 Thu	99	—	unknown	23:40–03:55 (good, 4.25 h)	71.1° 02:05	4.85	95%	60.5°
2041-07-12 Fri	57	—	unknown	02:20–03:55 (good, 1.58 h)	71.1° 02:00	4.89	99%	53.6°
2041-07-13 Sat	47	—	unknown	23:00–03:55 (marginal, 4.92 h)	71.1° 01:55	4.93	100%	48.8°
2041-07-14 Sun	49	—	unknown	23:00–04:00 (marginal, 5.0 h)	71.1° 01:50	4.97	98%	47.2°
2041-07-15 Mon	57	—	unknown	23:00–00:45 (good, 1.75 h)	71.1° 01:45	5.01	93%	49.1°
2041-07-16 Tue	96	—	unknown	23:00–02:35 (good, 3.58 h)	71.1° 01:45	5.06	86%	54.1°
2041-07-17 Wed	99	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:40	5.1	77%	61.2°
2041-07-18 Thu	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:35	5.15	66%	69.7°
2041-07-19 Fri	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:30	5.19	55%	78.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-06-20&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.