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: 06-18 (100), 06-19 (100), 06-20 (100), 06-21 (100), 06-22 (100) — by astronomy; check the weather when the night is within four days.

2031-06-18astronomy score per night — click a bar for that night2031-07-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-06-20 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:25	4.42	1%	109.1°
2031-06-21 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:20	4.42	4%	115.2°
2031-06-22 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:15	4.42	8%	120.4°
2031-06-23 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:15	4.43	14%	124.4°
2031-06-24 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:10	4.43	21%	126.9°
2031-06-25 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:05	4.44	30%	127.6°
2031-06-26 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 04:00	4.45	39%	126.2°
2031-06-27 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 03:55	4.46	49%	122.9°
2031-06-28 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	87.2° 03:55	4.48	60%	117.9°
2031-06-29 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 03:50	4.5	70%	111.3°
2031-06-30 Mon	100	—	unknown	23:10–03:45 (good, 4.58 h)	87.2° 03:45	4.51	80%	103.6°
2031-07-01 Tue	100	—	unknown	23:10–03:45 (good, 4.58 h)	87.2° 03:40	4.53	88%	95.0°
2031-07-02 Wed	79	—	unknown	23:10–03:45 (good, 4.58 h)	87.2° 03:40	4.56	95%	86.0°
2031-07-03 Thu	67	—	unknown	23:15–03:45 (good, 4.5 h)	87.2° 03:35	4.58	99%	77.0°
2031-07-04 Fri	55	—	unknown	00:20–03:45 (good, 3.42 h)	87.2° 03:30	4.6	100%	68.5°
2031-07-05 Sat	48	—	unknown	23:10–03:45 (marginal, 4.58 h)	87.2° 03:25	4.63	98%	61.2°
2031-07-06 Sun	49	—	unknown	00:35–00:40 (good, 0.08 h)	87.2° 03:20	4.66	93%	55.8°
2031-07-07 Mon	56	—	unknown	23:10–01:35 (good, 2.42 h)	87.2° 03:20	4.69	86%	52.9°
2031-07-08 Tue	90	—	unknown	23:05–03:25 (good, 4.33 h)	87.2° 03:15	4.72	77%	52.7°
2031-07-09 Wed	95	—	unknown	23:05–03:50 (good, 4.75 h)	87.2° 03:10	4.76	66%	55.1°
2031-07-10 Thu	99	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 03:05	4.79	56%	59.5°
2031-07-11 Fri	100	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 03:00	4.83	45%	65.3°
2031-07-12 Sat	100	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 03:00	4.87	36%	71.9°
2031-07-13 Sun	100	—	unknown	23:00–03:55 (good, 4.92 h)	87.2° 02:55	4.91	26%	79.0°
2031-07-14 Mon	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:50	4.95	18%	86.2°
2031-07-15 Tue	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:45	4.99	12%	93.5°
2031-07-16 Wed	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:45	5.03	6%	100.7°
2031-07-17 Thu	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:40	5.08	2%	107.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-18&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.