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: 05-24 (100), 05-25 (100), 05-26 (100), 05-27 (100), 05-28 (100) — by astronomy; check the weather when the night is within four days.

2041-05-19astronomy score per night — click a bar for that night2041-06-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-05-19 Sun	50	—	unknown	01:45–04:00 (good, 2.25 h)	71.1° 05:30	5.35	82%	50.1°
2041-05-20 Mon	66	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:25	5.3	72%	47.6°
2041-05-21 Tue	77	—	unknown	00:20–04:00 (good, 3.67 h)	71.1° 05:25	5.25	62%	48.1°
2041-05-22 Wed	87	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.2	50%	51.8°
2041-05-23 Thu	95	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.16	39%	57.8°
2041-05-24 Fri	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.11	28%	65.5°
2041-05-25 Sat	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.07	18%	74.1°
2041-05-26 Sun	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:05	5.02	10%	83.3°
2041-05-27 Mon	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	4.98	5%	92.5°
2041-05-28 Tue	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.94	1%	101.6°
2041-05-29 Wed	100	—	unknown	23:50–03:50 (good, 4.0 h)	71.1° 04:50	4.9	0%	110.1°
2041-05-30 Thu	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:50	4.86	1%	117.8°
2041-05-31 Fri	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:45	4.82	4%	124.3°
2041-06-01 Sat	100	—	unknown	23:40–03:45 (good, 4.08 h)	71.1° 04:40	4.78	9%	129.1°
2041-06-02 Sun	100	—	unknown	23:35–03:45 (good, 4.17 h)	71.1° 04:35	4.75	16%	132.0°
2041-06-03 Mon	100	—	unknown	23:35–03:45 (good, 4.17 h)	71.1° 04:30	4.71	23%	132.6°
2041-06-04 Tue	100	—	unknown	23:30–03:40 (good, 4.17 h)	71.1° 04:30	4.68	32%	130.9°
2041-06-05 Wed	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:25	4.65	41%	127.2°
2041-06-06 Thu	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:20	4.62	50%	122.0°
2041-06-07 Fri	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:15	4.6	60%	115.5°
2041-06-08 Sat	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:10	4.57	69%	108.1°
2041-06-09 Sun	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:10	4.55	78%	100.0°
2041-06-10 Mon	100	—	unknown	23:30–03:40 (good, 4.17 h)	71.1° 04:05	4.53	86%	91.4°
2041-06-11 Tue	73	—	unknown	00:00–03:40 (good, 3.67 h)	71.1° 04:00	4.51	92%	82.6°
2041-06-12 Wed	62	—	unknown	00:45–03:40 (good, 2.92 h)	71.1° 03:55	4.49	97%	73.7°
2041-06-13 Thu	53	—	unknown	01:25–03:40 (good, 2.25 h)	71.1° 03:55	4.47	100%	65.2°
2041-06-14 Fri	47	—	unknown	02:45–03:40 (good, 0.92 h)	71.1° 03:50	4.46	100%	57.5°
2041-06-15 Sat	45	—	unknown	23:10–03:40 (marginal, 4.5 h)	71.1° 03:45	4.45	97%	51.4°
2041-06-16 Sun	69	—	unknown	23:10–23:35 (good, 0.42 h)	71.1° 03:40	4.44	92%	47.9°
2041-06-17 Mon	82	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	84%	47.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-05-19&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.