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: 09-10 (100), 09-11 (100), 09-12 (100), 09-13 (100), 09-14 (100) — by astronomy; check the weather when the night is within four days.

2028-09-10astronomy score per night — click a bar for that night2028-10-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-09-10 Sun	100	—	unknown	21:15–04:50 (good, 7.58 h)	87.2° 23:00	8.13	61%	84.9°
2028-09-11 Mon	100	—	unknown	21:15–04:55 (good, 7.67 h)	87.2° 22:55	8.19	51%	92.5°
2028-09-12 Tue	100	—	unknown	21:15–05:00 (good, 7.75 h)	87.2° 22:50	8.24	41%	100.2°
2028-09-13 Wed	100	—	unknown	21:10–05:00 (good, 7.83 h)	87.2° 22:50	8.29	30%	107.7°
2028-09-14 Thu	100	—	unknown	21:10–05:00 (good, 7.83 h)	87.2° 22:45	8.35	20%	114.8°
2028-09-15 Fri	100	—	unknown	21:05–05:00 (good, 7.92 h)	87.2° 22:40	8.4	12%	120.7°
2028-09-16 Sat	100	—	unknown	21:05–04:55 (good, 7.83 h)	87.2° 22:35	8.45	5%	124.9°
2028-09-17 Sun	100	—	unknown	21:05–04:50 (good, 7.75 h)	87.2° 22:30	8.5	1%	126.4°
2028-09-18 Mon	100	—	unknown	21:00–04:50 (good, 7.83 h)	87.2° 22:30	8.56	0%	125.0°
2028-09-19 Tue	100	—	unknown	21:00–04:45 (good, 7.75 h)	87.2° 22:25	8.61	2%	120.9°
2028-09-20 Wed	100	—	unknown	20:55–04:40 (good, 7.75 h)	87.3° 22:20	8.66	7%	114.8°
2028-09-21 Thu	100	—	unknown	20:55–04:35 (good, 7.67 h)	87.2° 22:15	8.71	14%	107.5°
2028-09-22 Fri	100	—	unknown	20:55–04:30 (good, 7.58 h)	87.2° 22:10	8.76	23%	99.5°
2028-09-23 Sat	100	—	unknown	20:50–04:30 (good, 7.67 h)	87.2° 22:10	8.81	33%	91.4°
2028-09-24 Sun	100	—	unknown	20:50–04:25 (good, 7.58 h)	87.2° 22:05	8.86	44%	83.6°
2028-09-25 Mon	100	—	unknown	20:50–04:20 (good, 7.5 h)	87.2° 22:00	8.91	54%	76.2°
2028-09-26 Tue	98	—	unknown	20:45–04:15 (good, 7.5 h)	87.2° 21:55	8.96	64%	69.4°
2028-09-27 Wed	90	—	unknown	20:45–04:15 (good, 7.5 h)	87.2° 21:55	9.01	73%	63.6°
2028-09-28 Thu	83	—	unknown	20:40–04:10 (good, 7.5 h)	87.2° 21:50	9.06	81%	58.9°
2028-09-29 Fri	59	—	unknown	20:40–04:40 (marginal, 8.0 h)	87.2° 21:45	9.11	88%	55.5°
2028-09-30 Sat	55	—	unknown	20:40–04:30 (marginal, 7.83 h)	87.2° 21:40	9.16	93%	53.8°
2028-10-01 Sun	52	—	unknown	20:35–04:15 (marginal, 7.67 h)	87.2° 21:35	9.2	97%	53.8°
2028-10-02 Mon	51	—	unknown	20:35–04:00 (marginal, 7.42 h)	87.2° 21:35	9.25	99%	55.6°
2028-10-03 Tue	55	—	unknown	20:35–03:50 (marginal, 7.25 h)	87.2° 21:30	9.3	100%	59.0°
2028-10-04 Wed	64	—	unknown	20:30–21:30 (good, 1.0 h)	87.3° 21:25	9.35	98%	63.8°
2028-10-05 Thu	71	—	unknown	20:30–23:00 (good, 2.5 h)	87.2° 21:20	9.39	95%	69.6°
2028-10-06 Fri	77	—	unknown	20:30–00:40 (good, 4.17 h)	87.2° 21:15	9.44	90%	76.1°
2028-10-07 Sat	100	—	unknown	20:25–01:45 (good, 5.33 h)	87.2° 21:15	9.49	84%	83.3°
2028-10-08 Sun	100	—	unknown	20:25–02:50 (good, 6.42 h)	87.2° 21:10	9.53	76%	90.7°
2028-10-09 Mon	100	—	unknown	20:25–03:05 (good, 6.67 h)	87.2° 21:05	9.58	66%	98.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-09-10&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.