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: 09-04 (17), 09-03 (15), 09-02 (14), 09-01 (12), 08-31 (10) — by astronomy; check the weather when the night is within four days.

2046-08-06astronomy score per night — click a bar for that night2046-09-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-08-06 Mon	0	—	unknown	—	42.9° 09:55	6.14	27%	107.9°
2046-08-07 Tue	0	—	unknown	—	42.9° 09:50	6.19	37%	119.6°
2046-08-08 Wed	0	—	unknown	—	42.9° 09:45	6.25	49%	130.2°
2046-08-09 Thu	0	—	unknown	—	42.9° 09:45	6.31	60%	139.2°
2046-08-10 Fri	0	—	unknown	—	42.9° 09:40	6.36	70%	145.6°
2046-08-11 Sat	0	—	unknown	—	42.9° 09:35	6.42	79%	147.9°
2046-08-12 Sun	0	—	unknown	—	42.9° 09:30	6.48	87%	145.7°
2046-08-13 Mon	0	—	unknown	—	42.9° 09:25	6.54	93%	139.9°
2046-08-14 Tue	0	—	unknown	—	42.9° 09:25	6.59	97%	131.9°
2046-08-15 Wed	0	—	unknown	—	42.9° 09:20	6.65	100%	122.7°
2046-08-16 Thu	0	—	unknown	—	42.9° 09:15	6.71	100%	113.0°
2046-08-17 Fri	0	—	unknown	—	42.9° 09:10	6.77	98%	103.1°
2046-08-18 Sat	0	—	unknown	—	42.9° 09:10	6.82	95%	93.0°
2046-08-19 Sun	0	—	unknown	—	42.9° 09:05	6.88	90%	83.0°
2046-08-20 Mon	0	—	unknown	—	42.9° 09:00	6.94	84%	73.1°
2046-08-21 Tue	0	—	unknown	—	42.9° 08:55	7.0	76%	63.3°
2046-08-22 Wed	0	—	unknown	—	42.9° 08:50	7.05	68%	54.0°
2046-08-23 Thu	1	—	unknown	—	42.9° 08:50	7.11	58%	45.4°
2046-08-24 Fri	1	—	unknown	—	42.9° 08:45	7.17	48%	38.0°
2046-08-25 Sat	2	—	unknown	04:55–05:05 (marginal, 0.17 h)	42.9° 08:40	7.23	38%	33.2°
2046-08-26 Sun	3	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.28	28%	32.3°
2046-08-27 Mon	4	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.34	19%	36.1°
2046-08-28 Tue	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.4	11%	43.7°
2046-08-29 Wed	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.45	5%	53.9°
2046-08-30 Thu	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.51	1%	65.5°
2046-08-31 Fri	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.56	0%	78.0°
2046-09-01 Sat	12	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.62	2%	90.8°
2046-09-02 Sun	14	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.68	7%	103.6°
2046-09-03 Mon	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.73	15%	115.9°
2046-09-04 Tue	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.79	24%	127.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-08-06&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.