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: 08-23 (100), 08-24 (100), 08-25 (100), 08-26 (100), 09-05 (100) — by astronomy; check the weather when the night is within four days.

2031-08-23astronomy score per night — click a bar for that night2031-09-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-08-23 Sat	100	—	unknown	21:55–04:20 (good, 6.42 h)	71.1° 23:15	7.09	30%	91.8°
2031-08-24 Sun	100	—	unknown	21:50–04:20 (good, 6.5 h)	71.1° 23:10	7.15	41%	81.1°
2031-08-25 Mon	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:10	7.2	52%	70.4°
2031-08-26 Tue	100	—	unknown	21:50–04:10 (good, 6.33 h)	71.1° 23:05	7.26	63%	60.0°
2031-08-27 Wed	93	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.32	74%	50.4°
2031-08-28 Thu	84	—	unknown	00:30–02:25 (good, 1.92 h)	71.1° 22:55	7.37	83%	42.6°
2031-08-29 Fri	44	—	unknown	21:40–04:25 (marginal, 6.75 h)	71.1° 22:50	7.43	91%	37.9°
2031-08-30 Sat	35	—	unknown	21:40–04:00 (marginal, 6.33 h)	71.1° 22:50	7.49	97%	37.9°
2031-08-31 Sun	35	—	unknown	21:40–03:45 (marginal, 6.08 h)	71.1° 22:45	7.54	100%	42.6°
2031-09-01 Mon	43	—	unknown	21:35–03:40 (marginal, 6.08 h)	71.1° 22:40	7.6	99%	50.5°
2031-09-02 Tue	56	—	unknown	21:35–22:35 (good, 1.0 h)	71.1° 22:35	7.66	97%	60.2°
2031-09-03 Wed	74	—	unknown	21:30–00:45 (good, 3.25 h)	71.1° 22:30	7.71	92%	70.6°
2031-09-04 Thu	81	—	unknown	21:30–02:00 (good, 4.5 h)	71.1° 22:30	7.77	84%	81.2°
2031-09-05 Fri	100	—	unknown	21:30–03:05 (good, 5.58 h)	71.1° 22:25	7.82	76%	91.6°
2031-09-06 Sat	100	—	unknown	21:25–03:10 (good, 5.75 h)	71.1° 22:20	7.88	67%	101.7°
2031-09-07 Sun	100	—	unknown	21:25–03:15 (good, 5.83 h)	71.1° 22:15	7.93	57%	111.3°
2031-09-08 Mon	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:15	7.99	48%	120.3°
2031-09-09 Tue	100	—	unknown	21:20–03:10 (good, 5.83 h)	71.1° 22:10	8.04	38%	128.4°
2031-09-10 Wed	100	—	unknown	21:20–03:10 (good, 5.83 h)	71.1° 22:05	8.09	29%	135.3°
2031-09-11 Thu	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.15	21%	140.3°
2031-09-12 Fri	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 21:55	8.2	14%	142.7°
2031-09-13 Sat	100	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:55	8.26	8%	141.9°
2031-09-14 Sun	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.31	4%	138.1°
2031-09-15 Mon	100	—	unknown	21:10–02:50 (good, 5.67 h)	71.1° 21:45	8.36	1%	131.7°
2031-09-16 Tue	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.41	0%	123.7°
2031-09-17 Wed	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:35	8.47	2%	114.5°
2031-09-18 Thu	100	—	unknown	21:00–02:40 (good, 5.67 h)	71.1° 21:35	8.52	5%	104.5°
2031-09-19 Fri	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.57	10%	94.1°
2031-09-20 Sat	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:25	8.62	18%	83.4°
2031-09-21 Sun	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:20	8.67	27%	72.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-08-23&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.