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: 08-12 (100), 08-13 (100), 08-14 (100), 08-15 (100), 08-16 (100) — by astronomy; check the weather when the night is within four days.

2040-08-12astronomy score per night — click a bar for that night2040-09-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-08-12 Sun	100	—	unknown	22:15–04:45 (good, 6.5 h)	71.1° 23:55	6.5	22%	103.9°
2040-08-13 Mon	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.56	31%	95.3°
2040-08-14 Tue	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.62	41%	86.3°
2040-08-15 Wed	100	—	unknown	22:10–04:50 (good, 6.67 h)	71.1° 23:45	6.68	52%	77.3°
2040-08-16 Thu	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:40	6.73	63%	68.4°
2040-08-17 Fri	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:35	6.79	73%	60.1°
2040-08-18 Sat	94	—	unknown	22:00–04:40 (good, 6.67 h)	71.1° 23:30	6.85	83%	53.1°
2040-08-19 Sun	84	—	unknown	00:45–02:40 (good, 1.92 h)	71.1° 23:30	6.91	91%	48.4°
2040-08-20 Mon	55	—	unknown	22:00–04:55 (marginal, 6.92 h)	71.1° 23:25	6.96	97%	46.8°
2040-08-21 Tue	53	—	unknown	21:55–04:40 (marginal, 6.75 h)	71.1° 23:20	7.02	100%	48.9°
2040-08-22 Wed	58	—	unknown	21:55–22:30 (good, 0.58 h)	71.1° 23:15	7.08	99%	54.2°
2040-08-23 Thu	69	—	unknown	21:50–00:00 (good, 2.17 h)	71.1° 23:15	7.14	96%	61.5°
2040-08-24 Fri	76	—	unknown	21:50–01:35 (good, 3.75 h)	71.1° 23:10	7.19	91%	70.1°
2040-08-25 Sat	100	—	unknown	21:50–02:35 (good, 4.75 h)	71.1° 23:05	7.25	84%	79.2°
2040-08-26 Sun	100	—	unknown	21:45–03:35 (good, 5.83 h)	71.1° 23:00	7.31	75%	88.3°
2040-08-27 Mon	100	—	unknown	21:45–03:45 (good, 6.0 h)	71.1° 22:55	7.36	65%	97.2°
2040-08-28 Tue	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:55	7.42	55%	105.5°
2040-08-29 Wed	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:50	7.48	46%	113.3°
2040-08-30 Thu	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:45	7.53	36%	120.2°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-08-12&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.