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: 06-06 (100), 06-07 (100), 06-08 (100), 06-09 (100), 06-10 (100) — by astronomy; check the weather when the night is within four days.

2037-05-22astronomy score per night — click a bar for that night2037-06-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-05-22 Fri	96	—	unknown	00:25–03:55 (good, 3.5 h)	71.1° 05:20	5.21	56%	126.8°
2037-05-23 Sat	95	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:15	5.16	68%	118.4°
2037-05-24 Sun	90	—	unknown	00:25–03:55 (good, 3.5 h)	71.1° 05:10	5.11	78%	108.9°
2037-05-25 Mon	71	—	unknown	00:30–03:50 (good, 3.33 h)	71.1° 05:05	5.07	87%	98.6°
2037-05-26 Tue	61	—	unknown	01:00–03:50 (good, 2.83 h)	71.1° 05:05	5.02	93%	88.2°
2037-05-27 Wed	51	—	unknown	01:50–03:50 (good, 2.0 h)	71.1° 05:00	4.98	98%	77.9°
2037-05-28 Thu	43	—	unknown	02:40–03:50 (good, 1.17 h)	71.1° 04:55	4.94	100%	68.1°
2037-05-29 Fri	37	—	unknown	23:35–03:50 (marginal, 4.25 h)	71.1° 04:50	4.9	99%	59.3°
2037-05-30 Sat	34	—	unknown	23:30–03:45 (marginal, 4.25 h)	71.1° 04:50	4.86	96%	51.8°
2037-05-31 Sun	36	—	unknown	23:20–03:45 (marginal, 4.42 h)	71.1° 04:45	4.82	92%	46.2°
2037-06-01 Mon	54	—	unknown	23:40–00:00 (good, 0.33 h)	71.1° 04:40	4.78	85%	43.2°
2037-06-02 Tue	70	—	unknown	23:35–03:45 (good, 4.17 h)	71.1° 04:35	4.75	77%	43.0°
2037-06-03 Wed	83	—	unknown	23:30–03:45 (good, 4.25 h)	71.1° 04:30	4.72	69%	45.6°
2037-06-04 Thu	94	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:30	4.68	60%	50.3°
2037-06-05 Fri	97	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:25	4.65	50%	56.6°
2037-06-06 Sat	100	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:20	4.62	41%	64.0°
2037-06-07 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:15	4.6	32%	72.1°
2037-06-08 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:10	4.57	23%	80.7°
2037-06-09 Tue	100	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:10	4.55	15%	89.7°
2037-06-10 Wed	100	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:05	4.53	9%	98.9°
2037-06-11 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:00	4.51	4%	108.1°
2037-06-12 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.49	1%	117.0°
2037-06-13 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.47	0%	125.2°
2037-06-14 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.46	2%	131.9°
2037-06-15 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:45	4.45	6%	136.2°
2037-06-16 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.44	13%	137.0°
2037-06-17 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	21%	134.2°
2037-06-18 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	32%	128.3°
2037-06-19 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.42	43%	120.3°
2037-06-20 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	54%	111.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-22&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.