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: 06-02 (100), 06-03 (100), 06-04 (100), 06-05 (100), 06-06 (100) — by astronomy; check the weather when the night is within four days.

2040-05-30astronomy score per night — click a bar for that night2040-06-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-05-30 Wed	76	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:45	4.85	74%	47.1°
2040-05-31 Thu	89	—	unknown	23:40–03:45 (good, 4.08 h)	71.1° 04:45	4.81	63%	49.9°
2040-06-01 Fri	97	—	unknown	23:40–03:45 (good, 4.08 h)	71.1° 04:40	4.77	52%	55.2°
2040-06-02 Sat	100	—	unknown	23:35–03:45 (good, 4.17 h)	71.1° 04:35	4.74	41%	62.2°
2040-06-03 Sun	100	—	unknown	23:30–03:45 (good, 4.25 h)	71.1° 04:30	4.71	31%	70.2°
2040-06-04 Mon	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 04:25	4.67	21%	78.7°
2040-06-05 Tue	100	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:25	4.64	14%	87.3°
2040-06-06 Wed	100	—	unknown	23:20–03:40 (good, 4.33 h)	71.1° 04:20	4.62	8%	95.9°
2040-06-07 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 04:15	4.59	3%	104.2°
2040-06-08 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:10	4.57	1%	112.0°
2040-06-09 Sat	100	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:05	4.54	0%	119.0°
2040-06-10 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:05	4.52	1%	125.1°
2040-06-11 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:00	4.5	4%	129.7°
2040-06-12 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.49	9%	132.4°
2040-06-13 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.47	15%	133.0°
2040-06-14 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.46	22%	131.4°
2040-06-15 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:45	4.45	31%	127.7°
2040-06-16 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.44	40%	122.2°
2040-06-17 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	50%	115.4°
2040-06-18 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.43	61%	107.5°
2040-06-19 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.42	71%	98.8°
2040-06-20 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	80%	89.5°
2040-06-21 Thu	100	—	unknown	23:25–03:40 (good, 4.25 h)	71.1° 03:20	4.42	88%	79.9°
2040-06-22 Fri	67	—	unknown	00:15–03:40 (good, 3.42 h)	71.1° 03:15	4.43	95%	70.4°
2040-06-23 Sat	54	—	unknown	01:10–03:40 (good, 2.5 h)	71.1° 03:10	4.43	99%	61.5°
2040-06-24 Sun	46	—	unknown	23:15–04:30 (marginal, 5.25 h)	71.1° 03:10	4.44	100%	53.9°
2040-06-25 Mon	43	—	unknown	23:15–03:40 (marginal, 4.42 h)	71.1° 03:05	4.45	98%	48.8°
2040-06-26 Tue	49	—	unknown	23:15–03:40 (marginal, 4.42 h)	71.1° 03:00	4.46	93%	46.9°
2040-06-27 Wed	85	—	unknown	23:15–02:55 (good, 3.67 h)	71.1° 02:55	4.48	86%	48.6°
2040-06-28 Thu	95	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:55	4.49	76%	53.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-30&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.