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: 08-17 (100), 08-18 (100), 08-19 (100), 08-20 (100), 08-21 (100) — by astronomy; check the weather when the night is within four days.

2039-08-17astronomy score per night — click a bar for that night2039-09-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-08-17 Wed	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:40	6.75	4%	134.0°
2039-08-18 Thu	100	—	unknown	22:05–04:40 (good, 6.58 h)	71.1° 23:35	6.81	1%	133.4°
2039-08-19 Fri	100	—	unknown	22:00–04:40 (good, 6.67 h)	71.1° 23:30	6.86	0%	130.1°
2039-08-20 Sat	100	—	unknown	22:00–04:35 (good, 6.58 h)	71.1° 23:25	6.92	1%	124.6°
2039-08-21 Sun	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:25	6.98	5%	117.5°
2039-08-22 Mon	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.04	11%	109.1°
2039-08-23 Tue	100	—	unknown	21:55–04:20 (good, 6.42 h)	71.1° 23:15	7.09	18%	99.9°
2039-08-24 Wed	100	—	unknown	21:50–04:20 (good, 6.5 h)	71.1° 23:10	7.15	28%	90.4°
2039-08-25 Thu	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:10	7.21	38%	80.7°
2039-08-26 Fri	100	—	unknown	21:50–04:10 (good, 6.33 h)	71.1° 23:05	7.26	50%	71.2°
2039-08-27 Sat	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.32	61%	62.4°
2039-08-28 Sun	96	—	unknown	21:45–04:00 (good, 6.25 h)	71.1° 22:55	7.38	72%	54.8°
2039-08-29 Mon	89	—	unknown	21:40–04:00 (good, 6.33 h)	71.1° 22:50	7.43	82%	49.1°
2039-08-30 Tue	76	—	unknown	03:30–03:55 (good, 0.42 h)	71.1° 22:50	7.49	90%	46.2°
2039-08-31 Wed	50	—	unknown	21:40–04:10 (marginal, 6.5 h)	71.1° 22:45	7.55	95%	46.5°
2039-09-01 Thu	50	—	unknown	21:35–03:55 (marginal, 6.33 h)	71.1° 22:40	7.6	99%	50.0°
2039-09-02 Fri	54	—	unknown	21:35–22:05 (good, 0.5 h)	71.1° 22:35	7.66	100%	55.9°
2039-09-03 Sat	64	—	unknown	21:30–23:25 (good, 1.92 h)	71.1° 22:30	7.71	98%	63.4°
2039-09-04 Sun	75	—	unknown	21:30–00:50 (good, 3.33 h)	71.1° 22:30	7.77	95%	71.6°
2039-09-05 Mon	100	—	unknown	21:30–01:45 (good, 4.25 h)	71.1° 22:25	7.82	89%	80.2°
2039-09-06 Tue	100	—	unknown	21:25–02:40 (good, 5.25 h)	71.1° 22:20	7.88	82%	88.8°
2039-09-07 Wed	100	—	unknown	21:25–03:00 (good, 5.58 h)	71.1° 22:15	7.93	74%	97.3°
2039-09-08 Thu	100	—	unknown	21:20–03:05 (good, 5.75 h)	71.1° 22:15	7.99	65%	105.5°
2039-09-09 Fri	100	—	unknown	21:20–03:05 (good, 5.75 h)	71.1° 22:10	8.04	56%	113.2°
2039-09-10 Sat	100	—	unknown	21:20–03:05 (good, 5.75 h)	71.1° 22:05	8.1	47%	120.2°
2039-09-11 Sun	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.15	37%	126.2°
2039-09-12 Mon	100	—	unknown	21:15–03:00 (good, 5.75 h)	71.1° 21:55	8.2	28%	130.8°
2039-09-13 Tue	100	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:55	8.26	20%	133.5°
2039-09-14 Wed	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.31	13%	133.8°
2039-09-15 Thu	100	—	unknown	21:10–02:50 (good, 5.67 h)	71.1° 21:45	8.36	7%	131.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-08-17&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.