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 V1057 Cyg: 05-18 (100), 05-19 (100), 05-20 (100), 05-21 (100), 05-22 (100) — by astronomy; check the weather when the night is within four days.

2031-04-30astronomy score per night — click a bar for that night2031-05-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-30 Wed	78	—	unknown	01:35–04:35 (good, 3.0 h)	87.3° 07:45	6.43	61%	126.2°
2031-05-01 Thu	77	—	unknown	01:35–04:30 (good, 2.92 h)	87.3° 07:40	6.38	70%	127.7°
2031-05-02 Fri	77	—	unknown	01:35–04:30 (good, 2.92 h)	87.3° 07:35	6.32	79%	127.1°
2031-05-03 Sat	77	—	unknown	01:30–04:30 (good, 3.0 h)	87.3° 07:35	6.26	87%	124.2°
2031-05-04 Sun	69	—	unknown	01:30–04:25 (good, 2.92 h)	87.3° 07:30	6.2	94%	119.4°
2031-05-05 Mon	64	—	unknown	01:30–04:25 (good, 2.92 h)	87.3° 07:25	6.14	98%	112.8°
2031-05-06 Tue	59	—	unknown	01:30–04:25 (good, 2.92 h)	87.3° 07:20	6.09	100%	104.9°
2031-05-07 Wed	52	—	unknown	01:35–04:20 (good, 2.75 h)	87.3° 07:20	6.03	99%	96.3°
2031-05-08 Thu	48	—	unknown	01:45–04:20 (good, 2.58 h)	87.3° 07:15	5.97	96%	87.3°
2031-05-09 Fri	45	—	unknown	01:50–04:15 (good, 2.42 h)	87.3° 07:10	5.92	89%	78.4°
2031-05-10 Sat	46	—	unknown	01:25–04:15 (good, 2.83 h)	87.3° 07:05	5.86	81%	70.0°
2031-05-11 Sun	51	—	unknown	01:15–04:15 (good, 3.0 h)	87.3° 07:00	5.81	71%	62.7°
2031-05-12 Mon	64	—	unknown	00:45–04:10 (good, 3.42 h)	87.3° 07:00	5.75	60%	57.0°
2031-05-13 Tue	73	—	unknown	00:40–04:10 (good, 3.5 h)	87.3° 06:55	5.7	48%	53.4°
2031-05-14 Wed	81	—	unknown	00:35–04:10 (good, 3.58 h)	87.3° 06:50	5.64	38%	52.2°
2031-05-15 Thu	88	—	unknown	00:30–04:05 (good, 3.58 h)	87.3° 06:45	5.59	27%	53.5°
2031-05-16 Fri	94	—	unknown	00:30–04:05 (good, 3.58 h)	87.3° 06:40	5.54	18%	56.9°
2031-05-17 Sat	99	—	unknown	00:25–04:05 (good, 3.67 h)	87.3° 06:40	5.48	11%	61.9°
2031-05-18 Sun	100	—	unknown	00:20–04:05 (good, 3.75 h)	87.3° 06:35	5.43	6%	68.1°
2031-05-19 Mon	100	—	unknown	00:15–04:00 (good, 3.75 h)	87.3° 06:30	5.38	2%	75.1°
2031-05-20 Tue	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.3° 06:25	5.33	0%	82.4°
2031-05-21 Wed	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.3° 06:25	5.28	0%	89.8°
2031-05-22 Thu	100	—	unknown	00:05–03:55 (good, 3.83 h)	87.3° 06:20	5.23	2%	97.1°
2031-05-23 Fri	100	—	unknown	00:00–03:55 (good, 3.92 h)	87.3° 06:15	5.18	6%	104.2°
2031-05-24 Sat	100	—	unknown	23:55–03:55 (good, 4.0 h)	87.3° 06:10	5.14	12%	110.8°
2031-05-25 Sun	100	—	unknown	23:50–03:55 (good, 4.08 h)	87.3° 06:05	5.09	18%	116.7°
2031-05-26 Mon	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.3° 06:05	5.05	26%	121.7°
2031-05-27 Tue	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.3° 06:00	5.0	35%	125.4°
2031-05-28 Wed	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.3° 05:55	4.96	45%	127.5°
2031-05-29 Thu	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.3° 05:50	4.92	55%	127.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-30&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.