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 V1057 Cyg: 05-20 (100), 05-21 (100), 05-22 (100), 05-23 (100), 06-06 (100) — by astronomy; check the weather when the night is within four days.

2037-05-20astronomy score per night — click a bar for that night2037-06-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-05-20 Wed	100	—	unknown	00:15–04:00 (good, 3.75 h)	87.3° 06:25	5.3	34%	117.4°
2037-05-21 Thu	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.3° 06:20	5.25	45%	119.4°
2037-05-22 Fri	100	—	unknown	00:10–03:55 (good, 3.75 h)	87.3° 06:15	5.21	56%	119.4°
2037-05-23 Sat	100	—	unknown	00:10–03:55 (good, 3.75 h)	87.3° 06:15	5.16	68%	117.4°
2037-05-24 Sun	98	—	unknown	00:10–03:55 (good, 3.75 h)	87.3° 06:10	5.11	78%	113.7°
2037-05-25 Mon	83	—	unknown	00:10–03:50 (good, 3.67 h)	87.3° 06:05	5.07	87%	108.6°
2037-05-26 Tue	75	—	unknown	00:15–03:50 (good, 3.58 h)	87.3° 06:00	5.02	93%	102.5°
2037-05-27 Wed	68	—	unknown	00:20–03:50 (good, 3.5 h)	87.3° 05:55	4.98	98%	95.8°
2037-05-28 Thu	61	—	unknown	00:50–03:50 (good, 3.0 h)	87.3° 05:55	4.94	100%	89.0°
2037-05-29 Fri	56	—	unknown	01:10–03:50 (good, 2.67 h)	87.3° 05:50	4.9	99%	82.4°
2037-05-30 Sat	53	—	unknown	01:10–03:45 (good, 2.58 h)	87.3° 05:45	4.86	96%	76.2°
2037-05-31 Sun	54	—	unknown	00:35–03:45 (good, 3.17 h)	87.3° 05:40	4.82	92%	70.8°
2037-06-01 Mon	70	—	unknown	23:25–03:45 (good, 4.33 h)	87.3° 05:40	4.78	85%	66.3°
2037-06-02 Tue	80	—	unknown	23:20–03:45 (good, 4.42 h)	87.3° 05:35	4.75	77%	63.0°
2037-06-03 Wed	89	—	unknown	23:15–03:45 (good, 4.5 h)	87.3° 05:30	4.72	69%	61.1°
2037-06-04 Thu	93	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 05:25	4.68	60%	60.5°
2037-06-05 Fri	97	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:20	4.65	50%	61.3°
2037-06-06 Sat	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:20	4.62	41%	63.4°
2037-06-07 Sun	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:15	4.6	32%	66.7°
2037-06-08 Mon	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:10	4.57	23%	71.1°
2037-06-09 Tue	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:05	4.55	15%	76.2°
2037-06-10 Wed	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:00	4.53	9%	82.1°
2037-06-11 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 05:00	4.51	4%	88.3°
2037-06-12 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:55	4.49	1%	94.8°
2037-06-13 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:50	4.47	0%	101.2°
2037-06-14 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:45	4.46	2%	107.3°
2037-06-15 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:45	4.45	6%	112.5°
2037-06-16 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:40	4.44	13%	116.5°
2037-06-17 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:35	4.43	21%	118.9°
2037-06-18 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:30	4.43	32%	119.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-20&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.