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: 05-21 (100), 05-22 (100), 05-23 (100), 05-24 (100), 05-25 (100) — by astronomy; check the weather when the night is within four days.

2039-05-21astronomy score per night — click a bar for that night2039-06-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-05-21 Sat	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:00	5.28	1%	107.6°
2039-05-22 Sun	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.23	0%	111.3°
2039-05-23 Mon	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.18	1%	114.2°
2039-05-24 Tue	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:50	5.13	3%	116.0°
2039-05-25 Wed	100	—	unknown	22:50–03:55 (good, 5.08 h)	87.1° 03:45	5.09	7%	116.6°
2039-05-26 Thu	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.04	13%	116.0°
2039-05-27 Fri	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.0	20%	114.1°
2039-05-28 Sat	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:35	4.96	28%	111.1°
2039-05-29 Sun	100	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:30	4.92	38%	107.1°
2039-05-30 Mon	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:25	4.88	48%	102.2°
2039-05-31 Tue	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.84	59%	96.7°
2039-06-01 Wed	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.8	69%	90.6°
2039-06-02 Thu	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:15	4.77	79%	84.4°
2039-06-03 Fri	78	—	unknown	23:05–03:45 (good, 4.67 h)	87.1° 03:10	4.73	88%	78.2°
2039-06-04 Sat	68	—	unknown	23:45–03:45 (good, 4.0 h)	87.1° 03:05	4.7	95%	72.5°
2039-06-05 Sun	59	—	unknown	00:10–03:40 (good, 3.5 h)	87.1° 03:00	4.67	99%	67.9°
2039-06-06 Mon	55	—	unknown	23:55–03:40 (good, 3.75 h)	87.1° 03:00	4.64	100%	64.7°
2039-06-07 Tue	57	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:55	4.61	98%	63.4°
2039-06-08 Wed	89	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:50	4.58	93%	64.1°
2039-06-09 Thu	99	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.56	86%	66.6°
2039-06-10 Fri	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.54	77%	70.4°
2039-06-11 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:40	4.52	67%	75.2°
2039-06-12 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:35	4.5	57%	80.5°
2039-06-13 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:30	4.48	47%	86.0°
2039-06-14 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.47	37%	91.6°
2039-06-15 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.45	28%	97.0°
2039-06-16 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:20	4.44	19%	102.1°
2039-06-17 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:15	4.44	12%	106.6°
2039-06-18 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:10	4.43	7%	110.5°
2039-06-19 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:05	4.42	3%	113.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-05-21&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.