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: 04-01 (100), 04-02 (100), 04-03 (100), 04-16 (100), 04-17 (100) — by astronomy; check the weather when the night is within four days.

2039-04-01astronomy score per night — click a bar for that night2039-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-01 Fri	100	—	unknown	01:30–05:30 (good, 4.0 h)	87.1° 07:20	8.09	50%	116.7°
2039-04-02 Sat	100	—	unknown	01:30–05:30 (good, 4.0 h)	87.1° 07:15	8.04	60%	115.4°
2039-04-03 Sun	100	—	unknown	01:30–05:25 (good, 3.92 h)	87.1° 07:10	7.98	70%	112.8°
2039-04-04 Mon	98	—	unknown	01:30–05:25 (good, 3.92 h)	87.1° 07:05	7.93	79%	108.9°
2039-04-05 Tue	80	—	unknown	01:30–05:20 (good, 3.83 h)	87.1° 07:00	7.87	87%	104.0°
2039-04-06 Wed	72	—	unknown	01:40–05:20 (good, 3.67 h)	87.1° 07:00	7.81	93%	98.3°
2039-04-07 Thu	64	—	unknown	02:20–05:20 (good, 3.0 h)	87.1° 06:55	7.76	98%	92.0°
2039-04-08 Fri	55	—	unknown	02:55–05:15 (good, 2.33 h)	87.1° 06:50	7.7	100%	85.4°
2039-04-09 Sat	51	—	unknown	03:20–05:15 (good, 1.92 h)	87.1° 06:45	7.64	99%	79.0°
2039-04-10 Sun	49	—	unknown	03:20–05:10 (good, 1.83 h)	87.1° 06:40	7.59	95%	73.1°
2039-04-11 Mon	51	—	unknown	02:45–05:10 (good, 2.42 h)	87.1° 06:40	7.53	89%	68.3°
2039-04-12 Tue	58	—	unknown	01:10–05:10 (good, 4.0 h)	87.1° 06:35	7.47	80%	65.0°
2039-04-13 Wed	78	—	unknown	00:35–05:05 (good, 4.5 h)	87.1° 06:30	7.42	70%	63.3°
2039-04-14 Thu	91	—	unknown	00:30–05:05 (good, 4.58 h)	87.1° 06:25	7.36	59%	63.5°
2039-04-15 Fri	98	—	unknown	00:30–05:00 (good, 4.5 h)	87.1° 06:25	7.3	48%	65.3°
2039-04-16 Sat	100	—	unknown	00:25–05:00 (good, 4.58 h)	87.1° 06:20	7.24	37%	68.5°
2039-04-17 Sun	100	—	unknown	00:20–05:00 (good, 4.67 h)	87.1° 06:15	7.19	27%	72.7°
2039-04-18 Mon	100	—	unknown	00:15–04:55 (good, 4.67 h)	87.1° 06:10	7.13	19%	77.7°
2039-04-19 Tue	100	—	unknown	00:15–04:55 (good, 4.67 h)	87.1° 06:05	7.07	12%	83.0°
2039-04-20 Wed	100	—	unknown	00:10–04:55 (good, 4.75 h)	87.1° 06:05	7.01	6%	88.6°
2039-04-21 Thu	100	—	unknown	00:05–04:50 (good, 4.75 h)	87.1° 06:00	6.95	2%	94.1°
2039-04-22 Fri	100	—	unknown	00:00–04:50 (good, 4.83 h)	87.1° 05:55	6.9	0%	99.4°
2039-04-23 Sat	100	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:50	6.84	0%	104.3°
2039-04-24 Sun	100	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:45	6.78	2%	108.7°
2039-04-25 Mon	100	—	unknown	23:50–04:45 (good, 4.92 h)	87.1° 05:45	6.72	6%	112.2°
2039-04-26 Tue	100	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:40	6.66	11%	114.8°
2039-04-27 Wed	100	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:35	6.6	17%	116.3°
2039-04-28 Thu	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:30	6.55	25%	116.6°
2039-04-29 Fri	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:30	6.49	34%	115.7°
2039-04-30 Sat	100	—	unknown	23:35–04:35 (good, 5.0 h)	87.1° 05:25	6.43	43%	113.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-01&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.