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 Vega: 05-10 (100), 05-11 (100), 05-12 (100), 05-13 (100), 05-14 (100) — by astronomy; check the weather when the night is within four days.

2040-05-10astronomy score per night — click a bar for that night2040-06-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-05-10 Thu	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.1° 04:40	5.82	0%	106.2°
2040-05-11 Fri	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.1° 04:40	5.76	1%	110.0°
2040-05-12 Sat	100	—	unknown	22:40–04:10 (good, 5.5 h)	87.1° 04:35	5.71	3%	112.8°
2040-05-13 Sun	100	—	unknown	22:35–04:10 (good, 5.58 h)	87.1° 04:30	5.65	7%	114.5°
2040-05-14 Mon	100	—	unknown	22:35–04:10 (good, 5.58 h)	87.1° 04:25	5.6	13%	115.0°
2040-05-15 Tue	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:20	5.55	20%	114.5°
2040-05-16 Wed	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:20	5.49	28%	112.8°
2040-05-17 Thu	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:15	5.44	37%	110.1°
2040-05-18 Fri	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:10	5.39	46%	106.6°
2040-05-19 Sat	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:05	5.34	56%	102.3°
2040-05-20 Sun	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:00	5.29	66%	97.4°
2040-05-21 Mon	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 04:00	5.24	75%	92.1°
2040-05-22 Tue	82	—	unknown	23:05–03:55 (good, 4.83 h)	87.1° 03:55	5.19	84%	86.5°
2040-05-23 Wed	77	—	unknown	23:45–03:55 (good, 4.17 h)	87.1° 03:50	5.15	91%	80.9°
2040-05-24 Thu	70	—	unknown	00:15–03:55 (good, 3.67 h)	87.1° 03:45	5.1	97%	75.6°
2040-05-25 Fri	62	—	unknown	00:35–03:50 (good, 3.25 h)	87.1° 03:45	5.05	100%	70.9°
2040-05-26 Sat	60	—	unknown	00:15–03:50 (good, 3.58 h)	87.1° 03:40	5.01	100%	67.4°
2040-05-27 Sun	63	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:35	4.97	97%	65.3°
2040-05-28 Mon	90	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:30	4.93	91%	65.1°
2040-05-29 Tue	98	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:25	4.89	84%	66.6°
2040-05-30 Wed	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:25	4.85	74%	69.6°
2040-05-31 Thu	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.81	63%	73.9°
2040-06-01 Fri	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:15	4.77	52%	78.9°
2040-06-02 Sat	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:10	4.74	41%	84.3°
2040-06-03 Sun	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:05	4.71	31%	89.9°
2040-06-04 Mon	100	—	unknown	23:00–03:40 (good, 4.67 h)	87.1° 03:05	4.67	21%	95.4°
2040-06-05 Tue	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 03:00	4.64	14%	100.5°
2040-06-06 Wed	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:55	4.62	8%	105.2°
2040-06-07 Thu	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:50	4.59	3%	109.1°
2040-06-08 Fri	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.57	1%	112.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-10&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.