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: 09-02 (100), 09-03 (100), 09-04 (100), 09-05 (100), 09-06 (100) — by astronomy; check the weather when the night is within four days.

2040-09-02astronomy score per night — click a bar for that night2040-10-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-09-02 Sun	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.3° 23:30	7.7	12%	110.4°
2040-09-03 Mon	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.2° 23:25	7.76	7%	113.9°
2040-09-04 Tue	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.3° 23:25	7.81	3%	116.3°
2040-09-05 Wed	100	—	unknown	21:25–05:20 (good, 7.92 h)	87.3° 23:20	7.87	1%	117.5°
2040-09-06 Thu	100	—	unknown	21:25–05:20 (good, 7.92 h)	87.3° 23:15	7.92	0%	117.5°
2040-09-07 Fri	100	—	unknown	21:20–05:20 (good, 8.0 h)	87.3° 23:10	7.98	2%	116.0°
2040-09-08 Sat	100	—	unknown	21:20–05:20 (good, 8.0 h)	87.2° 23:05	8.03	5%	113.2°
2040-09-09 Sun	100	—	unknown	21:20–05:25 (good, 8.08 h)	87.3° 23:05	8.08	11%	109.3°
2040-09-10 Mon	100	—	unknown	21:15–05:20 (good, 8.08 h)	87.3° 23:00	8.14	18%	104.4°
2040-09-11 Tue	100	—	unknown	21:15–05:15 (good, 8.0 h)	87.3° 22:55	8.19	27%	98.7°
2040-09-12 Wed	100	—	unknown	21:10–05:10 (good, 8.0 h)	87.3° 22:50	8.25	37%	92.5°
2040-09-13 Thu	100	—	unknown	21:10–05:10 (good, 8.0 h)	87.2° 22:50	8.3	48%	86.2°
2040-09-14 Fri	100	—	unknown	21:10–05:05 (good, 7.92 h)	87.3° 22:45	8.35	60%	79.9°
2040-09-15 Sat	100	—	unknown	21:05–05:00 (good, 7.92 h)	87.3° 22:40	8.4	70%	74.0°
2040-09-16 Sun	93	—	unknown	21:05–04:55 (good, 7.83 h)	87.3° 22:35	8.46	80%	68.8°
2040-09-17 Mon	83	—	unknown	21:05–04:50 (good, 7.75 h)	87.3° 22:30	8.51	89%	65.0°
2040-09-18 Tue	64	—	unknown	21:00–22:30 (good, 1.5 h)	87.3° 22:30	8.56	95%	62.8°
2040-09-19 Wed	63	—	unknown	21:00–21:55 (good, 0.92 h)	87.3° 22:25	8.61	99%	62.5°
2040-09-20 Thu	66	—	unknown	20:55–22:15 (good, 1.33 h)	87.3° 22:20	8.66	100%	64.0°
2040-09-21 Fri	70	—	unknown	20:55–23:10 (good, 2.25 h)	87.3° 22:15	8.71	98%	67.3°
2040-09-22 Sat	75	—	unknown	20:55–00:40 (good, 3.75 h)	87.2° 22:10	8.77	94%	71.7°
2040-09-23 Sun	100	—	unknown	20:50–01:45 (good, 4.92 h)	87.3° 22:10	8.82	88%	76.9°
2040-09-24 Mon	100	—	unknown	20:50–02:45 (good, 5.92 h)	87.3° 22:05	8.87	80%	82.6°
2040-09-25 Tue	100	—	unknown	20:50–03:40 (good, 6.83 h)	87.3° 22:00	8.92	71%	88.4°
2040-09-26 Wed	100	—	unknown	20:45–03:50 (good, 7.08 h)	87.3° 21:55	8.97	62%	94.1°
2040-09-27 Thu	100	—	unknown	20:45–03:55 (good, 7.17 h)	87.2° 21:55	9.01	53%	99.5°
2040-09-28 Fri	100	—	unknown	20:40–04:00 (good, 7.33 h)	87.3° 21:50	9.06	43%	104.5°
2040-09-29 Sat	100	—	unknown	20:40–04:00 (good, 7.33 h)	87.3° 21:45	9.11	34%	109.0°
2040-09-30 Sun	100	—	unknown	20:40–03:55 (good, 7.25 h)	87.3° 21:40	9.16	25%	112.7°
2040-10-01 Mon	100	—	unknown	20:35–03:55 (good, 7.33 h)	87.3° 21:35	9.21	18%	115.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-09-02&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.