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: 09-04 (100), 09-13 (100), 09-14 (100), 09-15 (100), 09-16 (100) — by astronomy; check the weather when the night is within four days.

2041-09-04astronomy score per night — click a bar for that night2041-10-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-09-04 Wed	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:25	7.8	63%	59.2°
2041-09-05 Thu	93	—	unknown	21:25–03:30 (good, 6.08 h)	71.1° 22:20	7.85	73%	52.9°
2041-09-06 Fri	83	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.91	83%	48.6°
2041-09-07 Sat	53	—	unknown	21:25–03:45 (marginal, 6.33 h)	71.1° 22:15	7.96	91%	47.3°
2041-09-08 Sun	49	—	unknown	21:20–03:30 (marginal, 6.17 h)	71.1° 22:10	8.02	96%	49.5°
2041-09-09 Mon	50	—	unknown	21:20–21:25 (good, 0.08 h)	71.1° 22:05	8.07	100%	54.9°
2041-09-10 Tue	57	—	unknown	21:15–22:35 (good, 1.33 h)	71.1° 22:05	8.13	100%	62.6°
2041-09-11 Wed	69	—	unknown	21:15–00:10 (good, 2.92 h)	71.1° 22:00	8.18	96%	71.7°
2041-09-12 Thu	79	—	unknown	21:15–01:10 (good, 3.92 h)	71.1° 21:55	8.23	91%	81.4°
2041-09-13 Fri	100	—	unknown	21:10–02:15 (good, 5.08 h)	71.1° 21:50	8.29	83%	91.1°
2041-09-14 Sat	100	—	unknown	21:10–02:35 (good, 5.42 h)	71.1° 21:45	8.34	74%	100.5°
2041-09-15 Sun	100	—	unknown	21:05–02:40 (good, 5.58 h)	71.1° 21:45	8.39	63%	109.2°
2041-09-16 Mon	100	—	unknown	21:05–02:40 (good, 5.58 h)	71.1° 21:40	8.44	53%	117.0°
2041-09-17 Tue	100	—	unknown	21:05–02:35 (good, 5.5 h)	71.1° 21:35	8.5	43%	123.6°
2041-09-18 Wed	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.55	33%	128.6°
2041-09-19 Thu	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:25	8.6	25%	131.7°
2041-09-20 Fri	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:25	8.65	17%	132.6°
2041-09-21 Sat	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.7	10%	131.3°
2041-09-22 Sun	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.75	5%	128.0°
2041-09-23 Mon	100	—	unknown	20:50–02:20 (good, 5.5 h)	71.1° 21:10	8.8	2%	123.0°
2041-09-24 Tue	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.85	0%	116.7°
2041-09-25 Wed	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.9	0%	109.6°
2041-09-26 Thu	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.95	2%	101.8°
2041-09-27 Fri	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.0	6%	93.7°
2041-09-28 Sat	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:50	9.05	12%	85.4°
2041-09-29 Sun	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.1	19%	77.0°
2041-09-30 Mon	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.15	27%	68.9°
2041-10-01 Tue	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:40	9.2	37%	61.4°
2041-10-02 Wed	96	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:35	9.24	48%	54.8°
2041-10-03 Thu	87	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:30	9.29	59%	49.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-09-04&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.