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: 05-27 (100), 05-28 (100), 05-29 (100), 05-30 (100), 05-31 (100) — by astronomy; check the weather when the night is within four days.

2030-05-19astronomy score per night — click a bar for that night2030-06-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-05-19 Sun	33	—	unknown	00:10–04:00 (marginal, 3.83 h)	71.1° 05:30	5.37	91%	51.4°
2030-05-20 Mon	34	—	unknown	00:00–04:00 (marginal, 4.0 h)	71.1° 05:30	5.32	83%	43.4°
2030-05-21 Tue	51	—	unknown	02:25–04:00 (good, 1.58 h)	71.1° 05:25	5.27	74%	38.8°
2030-05-22 Wed	64	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.22	64%	38.2°
2030-05-23 Thu	74	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.17	53%	41.4°
2030-05-24 Fri	84	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.13	43%	47.5°
2030-05-25 Sat	93	—	unknown	00:05–03:55 (good, 3.83 h)	71.1° 05:10	5.08	33%	55.1°
2030-05-26 Sun	99	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.04	24%	63.7°
2030-05-27 Mon	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	4.99	16%	72.8°
2030-05-28 Tue	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.95	10%	82.1°
2030-05-29 Wed	100	—	unknown	23:50–03:50 (good, 4.0 h)	71.1° 04:55	4.91	5%	91.4°
2030-05-30 Thu	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:50	4.87	2%	100.7°
2030-05-31 Fri	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:45	4.83	0%	109.8°
2030-06-01 Sat	100	—	unknown	23:40–03:45 (good, 4.08 h)	71.1° 04:40	4.79	0%	118.6°
2030-06-02 Sun	100	—	unknown	23:35–03:45 (good, 4.17 h)	71.1° 04:35	4.76	2%	126.7°
2030-06-03 Mon	100	—	unknown	23:30–03:45 (good, 4.25 h)	71.1° 04:35	4.73	6%	133.8°
2030-06-04 Tue	100	—	unknown	23:30–03:45 (good, 4.25 h)	71.1° 04:30	4.69	12%	139.1°
2030-06-05 Wed	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:25	4.66	19%	141.9°
2030-06-06 Thu	100	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:20	4.63	28%	141.4°
2030-06-07 Fri	100	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:15	4.61	37%	137.5°
2030-06-08 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:15	4.58	48%	130.8°
2030-06-09 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:10	4.56	58%	122.2°
2030-06-10 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:05	4.53	69%	112.2°
2030-06-11 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:00	4.51	79%	101.2°
2030-06-12 Wed	100	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:00	4.5	88%	89.7°
2030-06-13 Thu	69	—	unknown	00:15–03:40 (good, 3.42 h)	71.1° 03:55	4.48	95%	77.9°
2030-06-14 Fri	54	—	unknown	01:25–03:40 (good, 2.25 h)	71.1° 03:50	4.46	99%	66.4°
2030-06-15 Sat	43	—	unknown	23:10–03:40 (marginal, 4.5 h)	71.1° 03:45	4.45	100%	55.6°
2030-06-16 Sun	35	—	unknown	23:10–03:40 (marginal, 4.5 h)	71.1° 03:40	4.44	98%	46.5°
2030-06-17 Mon	35	—	unknown	23:10–03:40 (marginal, 4.5 h)	71.1° 03:40	4.43	93%	40.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-05-19&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.