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 Great Orion Nebula: 08-19 (1), 08-20 (1), 08-21 (1), 08-22 (1), 08-23 (1) — by astronomy; check the weather when the night is within four days.

2034-07-25astronomy score per night — click a bar for that night2034-08-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-07-25 Tue	0	—	unknown	—	42.9° 10:40	5.48	74%	148.8°
2034-07-26 Wed	0	—	unknown	—	42.9° 10:40	5.53	82%	154.8°
2034-07-27 Thu	0	—	unknown	—	42.9° 10:35	5.58	89%	156.3°
2034-07-28 Fri	0	—	unknown	—	42.9° 10:30	5.63	94%	152.1°
2034-07-29 Sat	0	—	unknown	—	42.9° 10:25	5.69	98%	144.0°
2034-07-30 Sun	0	—	unknown	—	42.9° 10:20	5.74	100%	133.9°
2034-07-31 Mon	0	—	unknown	—	42.9° 10:20	5.8	99%	122.6°
2034-08-01 Tue	0	—	unknown	—	42.9° 10:15	5.85	97%	110.6°
2034-08-02 Wed	0	—	unknown	—	42.9° 10:10	5.91	92%	98.2°
2034-08-03 Thu	0	—	unknown	—	42.9° 10:05	5.96	85%	85.6°
2034-08-04 Fri	0	—	unknown	—	42.9° 10:00	6.02	76%	72.8°
2034-08-05 Sat	0	—	unknown	—	42.9° 10:00	6.07	65%	60.2°
2034-08-06 Sun	0	—	unknown	—	42.9° 09:55	6.13	54%	47.9°
2034-08-07 Mon	0	—	unknown	—	42.9° 09:50	6.19	42%	36.6°
2034-08-08 Tue	0	—	unknown	—	42.9° 09:45	6.24	31%	27.5°
2034-08-09 Wed	0	—	unknown	—	42.9° 09:45	6.3	21%	23.5°
2034-08-10 Thu	0	—	unknown	—	42.9° 09:40	6.36	13%	27.0°
2034-08-11 Fri	0	—	unknown	—	42.9° 09:35	6.42	6%	35.7°
2034-08-12 Sat	0	—	unknown	—	42.9° 09:30	6.47	2%	46.7°
2034-08-13 Sun	0	—	unknown	—	42.9° 09:25	6.53	0%	58.5°
2034-08-14 Mon	0	—	unknown	—	42.9° 09:25	6.59	1%	70.5°
2034-08-15 Tue	0	—	unknown	—	42.9° 09:20	6.65	4%	82.4°
2034-08-16 Wed	0	—	unknown	—	42.9° 09:15	6.7	8%	94.1°
2034-08-17 Thu	0	—	unknown	—	42.9° 09:10	6.76	15%	105.5°
2034-08-18 Fri	0	—	unknown	—	42.9° 09:05	6.82	22%	116.6°
2034-08-19 Sat	1	—	unknown	—	42.9° 09:05	6.88	31%	127.2°
2034-08-20 Sun	1	—	unknown	—	42.9° 09:00	6.93	40%	137.2°
2034-08-21 Mon	1	—	unknown	—	42.9° 08:55	6.99	49%	146.2°
2034-08-22 Tue	1	—	unknown	—	42.9° 08:50	7.05	58%	153.3°
2034-08-23 Wed	1	—	unknown	—	42.9° 08:50	7.11	68%	156.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-07-25&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.