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), 06-11 (100) — by astronomy; check the weather when the night is within four days.

2042-05-19astronomy score per night — click a bar for that night2042-06-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-19 Mon	94	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:30	5.36	0%	107.1°
2042-05-20 Tue	96	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:30	5.31	3%	115.9°
2042-05-21 Wed	98	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:25	5.26	8%	123.3°
2042-05-22 Thu	99	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.22	15%	128.8°
2042-05-23 Fri	99	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.17	23%	132.0°
2042-05-24 Sat	100	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:10	5.12	32%	132.7°
2042-05-25 Sun	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.08	42%	130.9°
2042-05-26 Mon	100	—	unknown	00:10–03:50 (good, 3.67 h)	71.1° 05:05	5.03	52%	127.0°
2042-05-27 Tue	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:00	4.99	61%	121.6°
2042-05-28 Wed	99	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 04:55	4.95	70%	115.1°
2042-05-29 Thu	96	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 04:55	4.91	78%	107.8°
2042-05-30 Fri	80	—	unknown	00:10–03:45 (good, 3.58 h)	71.1° 04:50	4.87	86%	100.0°
2042-05-31 Sat	72	—	unknown	00:10–03:45 (good, 3.58 h)	71.1° 04:45	4.83	92%	91.9°
2042-06-01 Sun	64	—	unknown	00:45–03:45 (good, 3.0 h)	71.1° 04:40	4.79	96%	83.6°
2042-06-02 Mon	56	—	unknown	01:20–03:45 (good, 2.42 h)	71.1° 04:35	4.76	99%	75.4°
2042-06-03 Tue	50	—	unknown	01:50–03:45 (good, 1.92 h)	71.1° 04:35	4.72	100%	67.4°
2042-06-04 Wed	46	—	unknown	02:20–03:45 (good, 1.42 h)	71.1° 04:30	4.69	99%	60.0°
2042-06-05 Thu	44	—	unknown	02:30–03:00 (good, 0.5 h)	71.1° 04:25	4.66	95%	53.8°
2042-06-06 Fri	63	—	unknown	01:45–03:20 (good, 1.58 h)	71.1° 04:20	4.63	90%	49.3°
2042-06-07 Sat	75	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:15	4.6	82%	47.2°
2042-06-08 Sun	87	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:15	4.58	73%	48.1°
2042-06-09 Mon	95	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:10	4.55	62%	51.8°
2042-06-10 Tue	98	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:05	4.53	51%	57.9°
2042-06-11 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:00	4.51	40%	65.7°
2042-06-12 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:00	4.49	29%	74.6°
2042-06-13 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.48	19%	84.2°
2042-06-14 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.46	11%	94.0°
2042-06-15 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:45	4.45	5%	103.6°
2042-06-16 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.44	1%	112.6°
2042-06-17 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.43	0%	120.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-19&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.