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: 07-03 (100), 07-04 (100), 07-05 (100), 07-06 (100), 07-07 (100) — by astronomy; check the weather when the night is within four days.

2040-07-03astronomy score per night — click a bar for that night2040-08-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-03 Tue	100	—	unknown	23:10–03:45 (good, 4.58 h)	87.2° 03:30	4.6	25%	77.4°
2040-07-04 Wed	100	—	unknown	23:10–03:45 (good, 4.58 h)	87.2° 03:25	4.63	17%	82.8°
2040-07-05 Thu	100	—	unknown	23:10–03:50 (good, 4.67 h)	87.2° 03:25	4.66	10%	88.3°
2040-07-06 Fri	100	—	unknown	23:10–03:50 (good, 4.67 h)	87.2° 03:20	4.69	5%	93.8°
2040-07-07 Sat	100	—	unknown	23:05–03:50 (good, 4.75 h)	87.2° 03:15	4.72	2%	99.1°
2040-07-08 Sun	100	—	unknown	23:05–03:50 (good, 4.75 h)	87.2° 03:10	4.75	0%	104.1°
2040-07-09 Mon	100	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 03:05	4.79	0%	108.6°
2040-07-10 Tue	100	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 03:05	4.82	2%	112.3°
2040-07-11 Wed	100	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 03:00	4.86	6%	115.2°
2040-07-12 Thu	100	—	unknown	23:05–03:55 (good, 4.83 h)	87.2° 02:55	4.9	11%	116.9°
2040-07-13 Fri	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:50	4.94	18%	117.4°
2040-07-14 Sat	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:45	4.98	26%	116.6°
2040-07-15 Sun	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:45	5.02	35%	114.4°
2040-07-16 Mon	100	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:40	5.07	45%	111.0°
2040-07-17 Tue	100	—	unknown	22:55–04:05 (good, 5.17 h)	87.2° 02:35	5.11	56%	106.5°
2040-07-18 Wed	100	—	unknown	22:55–04:05 (good, 5.17 h)	87.2° 02:30	5.16	66%	101.0°
2040-07-19 Thu	100	—	unknown	22:55–04:05 (good, 5.17 h)	87.2° 02:30	5.21	77%	94.9°
2040-07-20 Fri	100	—	unknown	22:55–04:10 (good, 5.25 h)	87.2° 02:25	5.25	86%	88.3°
2040-07-21 Sat	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.2° 02:20	5.3	93%	81.6°
2040-07-22 Sun	75	—	unknown	22:50–04:10 (good, 5.33 h)	87.2° 02:15	5.35	98%	75.2°
2040-07-23 Mon	68	—	unknown	22:50–04:10 (good, 5.33 h)	87.2° 02:10	5.4	100%	69.6°
2040-07-24 Tue	66	—	unknown	22:45–04:15 (good, 5.5 h)	87.2° 02:10	5.45	99%	65.5°
2040-07-25 Wed	69	—	unknown	22:45–02:20 (good, 3.58 h)	87.2° 02:05	5.5	95%	63.0°
2040-07-26 Thu	97	—	unknown	22:45–03:40 (good, 4.92 h)	87.2° 02:00	5.56	88%	62.6°
2040-07-27 Fri	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.2° 01:55	5.61	80%	64.0°
2040-07-28 Sat	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.2° 01:50	5.66	70%	66.9°
2040-07-29 Sun	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.2° 01:50	5.72	60%	71.0°
2040-07-30 Mon	100	—	unknown	22:35–04:25 (good, 5.83 h)	87.2° 01:45	5.77	49%	75.9°
2040-07-31 Tue	100	—	unknown	22:35–04:25 (good, 5.83 h)	87.2° 01:40	5.83	39%	81.2°
2040-08-01 Wed	100	—	unknown	22:35–04:25 (good, 5.83 h)	87.2° 01:35	5.88	30%	86.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-03&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.