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: 09-02 (15), 09-03 (14), 09-01 (13), 09-04 (13), 08-31 (10) — by astronomy; check the weather when the night is within four days.

2036-08-06astronomy score per night — click a bar for that night2036-09-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-08-06 Wed	0	—	unknown	—	42.9° 09:55	6.16	100%	124.5°
2036-08-07 Thu	0	—	unknown	—	42.9° 09:50	6.22	99%	114.1°
2036-08-08 Fri	0	—	unknown	—	42.9° 09:45	6.27	97%	103.4°
2036-08-09 Sat	0	—	unknown	—	42.9° 09:40	6.33	93%	92.5°
2036-08-10 Sun	0	—	unknown	—	42.9° 09:35	6.39	87%	81.5°
2036-08-11 Mon	0	—	unknown	—	42.9° 09:35	6.45	80%	70.5°
2036-08-12 Tue	0	—	unknown	—	42.9° 09:30	6.5	71%	59.4°
2036-08-13 Wed	0	—	unknown	—	42.9° 09:25	6.56	62%	48.5°
2036-08-14 Thu	0	—	unknown	—	42.9° 09:20	6.62	51%	38.2°
2036-08-15 Fri	0	—	unknown	—	42.9° 09:15	6.68	41%	29.4°
2036-08-16 Sat	0	—	unknown	—	42.9° 09:15	6.73	30%	24.5°
2036-08-17 Sun	0	—	unknown	—	42.9° 09:10	6.79	20%	26.5°
2036-08-18 Mon	0	—	unknown	—	42.9° 09:05	6.85	11%	34.7°
2036-08-19 Tue	1	—	unknown	—	42.9° 09:00	6.91	5%	46.1°
2036-08-20 Wed	1	—	unknown	—	42.9° 09:00	6.96	1%	59.1°
2036-08-21 Thu	1	—	unknown	—	42.9° 08:55	7.02	0%	72.6°
2036-08-22 Fri	1	—	unknown	—	42.9° 08:50	7.08	2%	86.3°
2036-08-23 Sat	2	—	unknown	05:30–05:35 (marginal, 0.08 h)	42.9° 08:45	7.13	7%	99.8°
2036-08-24 Sun	3	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:40	7.19	14%	112.8°
2036-08-25 Mon	4	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.25	23%	125.1°
2036-08-26 Tue	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.31	33%	136.4°
2036-08-27 Wed	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.36	43%	146.1°
2036-08-28 Thu	7	—	unknown	05:10–05:45 (marginal, 0.58 h)	42.9° 08:25	7.42	53%	153.1°
2036-08-29 Fri	9	—	unknown	04:35–05:45 (marginal, 1.17 h)	42.9° 08:20	7.48	63%	155.6°
2036-08-30 Sat	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.53	72%	152.7°
2036-08-31 Sun	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.59	80%	145.8°
2036-09-01 Mon	13	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.64	87%	137.0°
2036-09-02 Tue	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.7	93%	127.2°
2036-09-03 Wed	14	—	unknown	05:00–05:15 (good, 0.25 h)	42.9° 08:00	7.75	97%	116.8°
2036-09-04 Thu	13	—	unknown	05:00–05:15 (good, 0.25 h)	42.9° 08:00	7.81	99%	106.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-08-06&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.