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: 04-28 (100), 04-29 (100), 04-30 (100), 05-01 (100), 05-02 (100) — by astronomy; check the weather when the night is within four days.

2031-04-28astronomy score per night — click a bar for that night2031-05-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-28 Mon	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:30	6.55	42%	122.0°
2031-04-29 Tue	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:30	6.49	51%	120.2°
2031-04-30 Wed	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:25	6.43	61%	117.0°
2031-05-01 Thu	100	—	unknown	23:40–04:30 (good, 4.83 h)	87.1° 05:20	6.38	70%	112.5°
2031-05-02 Fri	100	—	unknown	23:40–04:30 (good, 4.83 h)	87.1° 05:15	6.32	79%	106.9°
2031-05-03 Sat	100	—	unknown	23:45–04:30 (good, 4.75 h)	87.1° 05:10	6.26	87%	100.5°
2031-05-04 Sun	82	—	unknown	23:55–04:25 (good, 4.5 h)	87.1° 05:10	6.2	94%	93.4°
2031-05-05 Mon	76	—	unknown	00:40–04:25 (good, 3.75 h)	87.1° 05:05	6.14	98%	85.9°
2031-05-06 Tue	67	—	unknown	01:15–04:25 (good, 3.17 h)	87.1° 05:00	6.09	100%	78.4°
2031-05-07 Wed	60	—	unknown	01:40–04:20 (good, 2.67 h)	87.1° 04:55	6.03	99%	71.4°
2031-05-08 Thu	57	—	unknown	01:35–04:20 (good, 2.75 h)	87.1° 04:50	5.97	96%	65.3°
2031-05-09 Fri	74	—	unknown	00:00–04:15 (good, 4.25 h)	87.1° 04:50	5.92	89%	60.7°
2031-05-10 Sat	86	—	unknown	22:50–04:15 (good, 5.42 h)	87.1° 04:45	5.86	81%	58.1°
2031-05-11 Sun	92	—	unknown	22:45–04:15 (good, 5.5 h)	87.1° 04:40	5.81	71%	57.8°
2031-05-12 Mon	97	—	unknown	22:40–04:10 (good, 5.5 h)	87.1° 04:35	5.75	60%	59.7°
2031-05-13 Tue	100	—	unknown	22:40–04:10 (good, 5.5 h)	87.1° 04:35	5.7	48%	63.5°
2031-05-14 Wed	100	—	unknown	22:35–04:10 (good, 5.58 h)	87.1° 04:30	5.64	38%	68.7°
2031-05-15 Thu	100	—	unknown	22:30–04:05 (good, 5.58 h)	87.1° 04:25	5.59	27%	74.8°
2031-05-16 Fri	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:20	5.54	18%	81.4°
2031-05-17 Sat	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:15	5.48	11%	88.3°
2031-05-18 Sun	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:15	5.43	6%	95.1°
2031-05-19 Mon	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:10	5.38	2%	101.6°
2031-05-20 Tue	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:05	5.33	0%	107.6°
2031-05-21 Wed	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:00	5.28	0%	112.8°
2031-05-22 Thu	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.23	2%	117.2°
2031-05-23 Fri	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.18	6%	120.3°
2031-05-24 Sat	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:50	5.14	12%	122.0°
2031-05-25 Sun	100	—	unknown	22:50–03:55 (good, 5.08 h)	87.1° 03:45	5.09	18%	122.2°
2031-05-26 Mon	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.05	26%	120.9°
2031-05-27 Tue	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.0	35%	118.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-28&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.