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.

2030-05-02astronomy score per night — click a bar for that night2030-05-31

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-05-02 Thu	76	—	unknown	01:35–04:30 (good, 2.92 h)	71.1° 06:40	6.3	0%	93.7°
2030-05-03 Fri	78	—	unknown	01:35–04:30 (good, 2.92 h)	71.1° 06:35	6.25	2%	103.0°
2030-05-04 Sat	78	—	unknown	01:30–04:25 (good, 2.92 h)	71.1° 06:30	6.19	5%	112.0°
2030-05-05 Sun	79	—	unknown	01:25–04:25 (good, 3.0 h)	71.1° 06:25	6.13	10%	120.6°
2030-05-06 Mon	80	—	unknown	01:20–04:20 (good, 3.0 h)	71.1° 06:25	6.07	16%	128.5°
2030-05-07 Tue	82	—	unknown	01:20–04:20 (good, 3.0 h)	71.1° 06:20	6.02	24%	135.2°
2030-05-08 Wed	83	—	unknown	01:15–04:20 (good, 3.08 h)	71.1° 06:15	5.96	32%	140.0°
2030-05-09 Thu	83	—	unknown	01:15–04:15 (good, 3.0 h)	71.1° 06:10	5.9	42%	142.0°
2030-05-10 Fri	84	—	unknown	01:10–04:15 (good, 3.08 h)	71.1° 06:05	5.85	52%	140.6°
2030-05-11 Sat	84	—	unknown	01:10–04:15 (good, 3.08 h)	71.1° 06:05	5.79	63%	135.8°
2030-05-12 Sun	84	—	unknown	01:05–04:10 (good, 3.08 h)	71.1° 06:00	5.74	73%	128.3°
2030-05-13 Mon	84	—	unknown	01:05–04:10 (good, 3.08 h)	71.1° 05:55	5.68	82%	118.8°
2030-05-14 Tue	70	—	unknown	01:05–04:10 (good, 3.08 h)	71.1° 05:50	5.63	90%	108.1°
2030-05-15 Wed	59	—	unknown	01:10–04:05 (good, 2.92 h)	71.1° 05:50	5.58	96%	96.5°
2030-05-16 Thu	50	—	unknown	01:50–04:05 (good, 2.25 h)	71.1° 05:45	5.52	100%	84.6°
2030-05-17 Fri	42	—	unknown	02:45–04:05 (good, 1.33 h)	71.1° 05:40	5.47	100%	72.7°
2030-05-18 Sat	35	—	unknown	03:35–04:00 (good, 0.42 h)	71.1° 05:35	5.42	97%	61.4°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-05-02&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.