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: 08-26 (4), 08-25 (3), 08-23 (2), 08-24 (2), 08-19 (1) — by astronomy; check the weather when the night is within four days.

2026-07-28astronomy score per night — click a bar for that night2026-08-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-07-28 Tue	0	0	0	—	42.9° 10:30	5.63	100%	133.8°
2026-07-29 Wed	0	0	0	—	42.9° 10:25	5.68	100%	125.3°
2026-07-30 Thu	0	0	0	—	42.9° 10:20	5.74	98%	115.8°
2026-07-31 Fri	0	0	0	—	42.9° 10:20	5.79	95%	105.7°
2026-08-01 Sat	0	0	0	—	42.9° 10:15	5.85	89%	95.1°
2026-08-02 Sun	0	0	0	—	42.9° 10:10	5.9	82%	84.3°
2026-08-03 Mon	0	0	0	—	42.9° 10:05	5.96	73%	73.4°
2026-08-04 Tue	0	0	0	—	42.9° 10:00	6.01	63%	62.6°
2026-08-05 Wed	0	0	0	—	42.9° 10:00	6.07	52%	52.3°
2026-08-06 Thu	0	0	0	—	42.9° 09:55	6.13	40%	43.1°
2026-08-07 Fri	0	0	0	—	42.9° 09:50	6.18	30%	36.2°
2026-08-08 Sat	0	0	0	—	42.9° 09:45	6.24	19%	33.5°
2026-08-09 Sun	0	0	0	—	42.9° 09:45	6.3	11%	36.2°
2026-08-10 Mon	0	0	0	—	42.9° 09:40	6.35	5%	43.4°
2026-08-11 Tue	0	100	0	—	42.9° 09:35	6.41	1%	53.2°
2026-08-12 Wed	0	100	0	—	42.9° 09:30	6.47	0%	64.3°
2026-08-13 Thu	0	0	0	—	42.9° 09:25	6.53	2%	75.8°
2026-08-14 Fri	0	82	0	—	42.9° 09:25	6.58	6%	87.4°
2026-08-15 Sat	0	100	0	—	42.9° 09:20	6.64	12%	98.6°
2026-08-16 Sun	0	100	0	—	42.9° 09:15	6.7	20%	109.4°
2026-08-17 Mon	0	100	0	—	42.9° 09:10	6.76	29%	119.5°
2026-08-18 Tue	0	22	0	—	42.9° 09:05	6.81	39%	128.7°
2026-08-19 Wed	1	100	1	—	42.9° 09:05	6.87	48%	136.6°
2026-08-20 Thu	1	100	1	—	42.9° 09:00	6.93	58%	142.7°
2026-08-21 Fri	1	100	1	—	42.9° 08:55	6.99	67%	146.1°
2026-08-22 Sat	1	100	1	—	42.9° 08:50	7.04	76%	146.0°
2026-08-23 Sun	2	53	1	—	42.9° 08:50	7.1	83%	142.4°
2026-08-24 Mon	2	100	2	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.16	90%	136.1°
2026-08-25 Tue	3	94	3	05:30–05:40 (marginal, 0.17 h)	42.9° 08:40	7.22	95%	128.0°
2026-08-26 Wed	4	98	4	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.27	98%	118.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-07-28&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.