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: 08-31 (100), 09-01 (100), 09-02 (100), 09-03 (100), 09-04 (100) — by astronomy; check the weather when the night is within four days.

2040-08-31astronomy score per night — click a bar for that night2040-09-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-08-31 Fri	100	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:40	7.59	27%	126.0°
2040-09-01 Sat	100	—	unknown	21:35–03:40 (good, 6.08 h)	71.1° 22:35	7.65	19%	130.3°
2040-09-02 Sun	100	—	unknown	21:30–03:40 (good, 6.17 h)	71.1° 22:35	7.7	12%	132.7°
2040-09-03 Mon	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:30	7.76	7%	132.9°
2040-09-04 Tue	100	—	unknown	21:30–03:30 (good, 6.0 h)	71.1° 22:25	7.81	3%	130.9°
2040-09-05 Wed	100	—	unknown	21:25–03:30 (good, 6.08 h)	71.1° 22:20	7.87	1%	126.8°
2040-09-06 Thu	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.92	0%	121.0°
2040-09-07 Fri	100	—	unknown	21:20–03:20 (good, 6.0 h)	71.1° 22:15	7.98	2%	113.9°
2040-09-08 Sat	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.03	5%	106.0°
2040-09-09 Sun	100	—	unknown	21:20–03:10 (good, 5.83 h)	71.1° 22:05	8.08	11%	97.5°
2040-09-10 Mon	100	—	unknown	21:15–03:10 (good, 5.92 h)	71.1° 22:00	8.14	18%	88.6°
2040-09-11 Tue	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.19	27%	79.6°
2040-09-12 Wed	100	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:55	8.25	37%	70.8°
2040-09-13 Thu	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.3	48%	62.5°
2040-09-14 Fri	96	—	unknown	21:10–02:50 (good, 5.67 h)	71.1° 21:45	8.35	60%	55.3°
2040-09-15 Sat	89	—	unknown	21:05–02:50 (good, 5.75 h)	71.1° 21:40	8.4	70%	49.9°
2040-09-16 Sun	72	—	unknown	21:05–01:10 (good, 4.08 h)	71.1° 21:40	8.46	80%	47.1°
2040-09-17 Mon	50	—	unknown	21:05–03:00 (marginal, 5.92 h)	71.1° 21:35	8.51	89%	47.8°
2040-09-18 Tue	47	—	unknown	21:00–02:50 (marginal, 5.83 h)	71.1° 21:30	8.56	95%	51.7°
2040-09-19 Wed	49	—	unknown	21:00–21:20 (good, 0.33 h)	71.1° 21:25	8.61	99%	58.2°
2040-09-20 Thu	56	—	unknown	20:55–22:30 (good, 1.58 h)	71.1° 21:25	8.66	100%	66.2°
2040-09-21 Fri	67	—	unknown	20:55–23:45 (good, 2.83 h)	71.1° 21:20	8.71	98%	75.2°
2040-09-22 Sat	79	—	unknown	20:55–00:40 (good, 3.75 h)	71.1° 21:15	8.77	94%	84.4°
2040-09-23 Sun	100	—	unknown	20:50–01:35 (good, 4.75 h)	71.1° 21:10	8.82	88%	93.6°
2040-09-24 Mon	100	—	unknown	20:50–01:55 (good, 5.08 h)	71.1° 21:05	8.87	80%	102.4°
2040-09-25 Tue	100	—	unknown	20:50–01:55 (good, 5.08 h)	71.1° 21:05	8.92	71%	110.5°
2040-09-26 Wed	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 21:00	8.97	62%	117.8°
2040-09-27 Thu	100	—	unknown	20:45–01:55 (good, 5.17 h)	71.1° 20:55	9.01	53%	124.1°
2040-09-28 Fri	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.06	43%	128.9°
2040-09-29 Sat	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.11	34%	132.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-08-31&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.