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 North America Nebula: 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.

2031-05-21astronomy score per night — click a bar for that night2031-06-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-21 Wed	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.2° 06:25	5.28	0%	89.8°
2031-05-22 Thu	100	—	unknown	00:05–03:55 (good, 3.83 h)	87.2° 06:20	5.23	2%	97.1°
2031-05-23 Fri	100	—	unknown	00:00–03:55 (good, 3.92 h)	87.2° 06:15	5.18	6%	104.2°
2031-05-24 Sat	100	—	unknown	23:55–03:55 (good, 4.0 h)	87.2° 06:10	5.14	12%	110.8°
2031-05-25 Sun	100	—	unknown	23:50–03:55 (good, 4.08 h)	87.2° 06:05	5.09	18%	116.7°
2031-05-26 Mon	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.2° 06:05	5.05	26%	121.6°
2031-05-27 Tue	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.2° 06:00	5.0	35%	125.3°
2031-05-28 Wed	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.2° 05:55	4.96	45%	127.4°
2031-05-29 Thu	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.2° 05:50	4.92	55%	127.5°
2031-05-30 Fri	100	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:45	4.88	65%	125.5°
2031-05-31 Sat	100	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:45	4.84	74%	121.5°
2031-06-01 Sun	100	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:40	4.8	83%	115.7°
2031-06-02 Mon	89	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:35	4.77	91%	108.4°
2031-06-03 Tue	80	—	unknown	23:45–03:45 (good, 4.0 h)	87.2° 05:30	4.73	96%	100.1°
2031-06-04 Wed	69	—	unknown	00:00–03:45 (good, 3.75 h)	87.2° 05:30	4.7	100%	91.1°
2031-06-05 Thu	59	—	unknown	00:40–03:40 (good, 3.0 h)	87.2° 05:25	4.67	100%	82.0°
2031-06-06 Fri	53	—	unknown	01:10–03:40 (good, 2.5 h)	87.2° 05:20	4.64	97%	73.2°
2031-06-07 Sat	51	—	unknown	01:05–03:40 (good, 2.58 h)	87.2° 05:15	4.61	91%	65.2°
2031-06-08 Sun	70	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:10	4.59	83%	58.7°
2031-06-09 Mon	80	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:10	4.56	74%	54.3°
2031-06-10 Tue	89	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:05	4.54	63%	52.4°
2031-06-11 Wed	93	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 05:00	4.52	52%	53.1°
2031-06-12 Thu	97	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:55	4.5	41%	56.0°
2031-06-13 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:50	4.48	31%	60.8°
2031-06-14 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:50	4.47	22%	66.7°
2031-06-15 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:45	4.46	14%	73.4°
2031-06-16 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:40	4.44	8%	80.5°
2031-06-17 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:35	4.44	4%	87.9°
2031-06-18 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:35	4.43	1%	95.2°
2031-06-19 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:30	4.43	0%	102.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-21&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.