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: 09-23 (100), 09-24 (100), 09-25 (100), 09-26 (100), 09-27 (100) — by astronomy; check the weather when the night is within four days.

2040-09-21astronomy score per night — click a bar for that night2040-10-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-09-21 Fri	70	—	unknown	20:55–23:10 (good, 2.25 h)	87.2° 22:15	8.71	98%	67.3°
2040-09-22 Sat	75	—	unknown	20:55–00:40 (good, 3.75 h)	87.2° 22:10	8.77	94%	71.7°
2040-09-23 Sun	100	—	unknown	20:50–01:45 (good, 4.92 h)	87.2° 22:10	8.82	88%	76.9°
2040-09-24 Mon	100	—	unknown	20:50–02:45 (good, 5.92 h)	87.2° 22:05	8.87	80%	82.6°
2040-09-25 Tue	100	—	unknown	20:50–03:40 (good, 6.83 h)	87.2° 22:00	8.92	71%	88.3°
2040-09-26 Wed	100	—	unknown	20:45–03:50 (good, 7.08 h)	87.2° 21:55	8.97	62%	94.0°
2040-09-27 Thu	100	—	unknown	20:45–03:55 (good, 7.17 h)	87.2° 21:55	9.01	53%	99.5°
2040-09-28 Fri	100	—	unknown	20:40–04:00 (good, 7.33 h)	87.2° 21:50	9.06	43%	104.5°
2040-09-29 Sat	100	—	unknown	20:40–04:00 (good, 7.33 h)	87.2° 21:45	9.11	34%	108.9°
2040-09-30 Sun	100	—	unknown	20:40–03:55 (good, 7.25 h)	87.2° 21:40	9.16	25%	112.6°
2040-10-01 Mon	100	—	unknown	20:35–03:55 (good, 7.33 h)	87.2° 21:35	9.21	18%	115.4°
2040-10-02 Tue	100	—	unknown	20:35–03:55 (good, 7.33 h)	87.2° 21:35	9.26	11%	117.1°
2040-10-03 Wed	100	—	unknown	20:35–03:50 (good, 7.25 h)	87.2° 21:30	9.3	6%	117.5°
2040-10-04 Thu	100	—	unknown	20:30–03:45 (good, 7.25 h)	87.2° 21:25	9.35	2%	116.5°
2040-10-05 Fri	100	—	unknown	20:30–03:40 (good, 7.17 h)	87.2° 21:20	9.4	0%	114.1°
2040-10-06 Sat	100	—	unknown	20:30–03:35 (good, 7.08 h)	87.2° 21:15	9.44	1%	110.5°
2040-10-07 Sun	100	—	unknown	20:25–03:35 (good, 7.17 h)	87.2° 21:15	9.49	3%	105.8°
2040-10-08 Mon	100	—	unknown	20:25–03:30 (good, 7.08 h)	87.2° 21:10	9.54	8%	100.3°
2040-10-09 Tue	100	—	unknown	20:25–03:25 (good, 7.0 h)	87.2° 21:05	9.58	15%	94.2°
2040-10-10 Wed	100	—	unknown	20:20–03:20 (good, 7.0 h)	87.2° 21:00	9.63	24%	87.8°
2040-10-11 Thu	100	—	unknown	20:20–03:20 (good, 7.0 h)	87.2° 21:00	9.67	34%	81.5°
2040-10-12 Fri	100	—	unknown	20:20–03:15 (good, 6.92 h)	87.2° 20:55	9.72	45%	75.6°
2040-10-13 Sat	96	—	unknown	20:15–03:10 (good, 6.92 h)	87.2° 20:50	9.76	56%	70.3°
2040-10-14 Sun	87	—	unknown	20:15–03:05 (good, 6.83 h)	87.2° 20:45	9.8	68%	66.2°
2040-10-15 Mon	69	—	unknown	20:15–02:35 (good, 6.33 h)	87.2° 20:40	9.85	78%	63.5°
2040-10-16 Tue	65	—	unknown	20:10–23:55 (good, 3.75 h)	87.2° 20:40	9.89	87%	62.5°
2040-10-17 Wed	63	—	unknown	20:10–21:00 (good, 0.83 h)	87.2° 20:35	9.93	93%	63.3°
2040-10-18 Thu	62	—	unknown	20:10–21:00 (good, 0.83 h)	87.2° 20:30	9.98	98%	65.9°
2040-10-19 Fri	65	—	unknown	20:10–21:40 (good, 1.5 h)	87.2° 20:25	10.02	100%	69.8°
2040-10-20 Sat	71	—	unknown	20:05–22:50 (good, 2.75 h)	87.2° 20:20	10.06	99%	74.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-09-21&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.