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: 07-25 (100), 07-26 (100), 07-27 (100), 07-28 (100), 07-29 (100) — by astronomy; check the weather when the night is within four days.

2027-07-17astronomy score per night — click a bar for that night2027-08-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-17 Sat	70	—	unknown	23:00–04:00 (good, 5.0 h)	87.2° 02:40	5.07	100%	72.7°
2027-07-18 Sun	62	—	unknown	22:55–04:05 (good, 5.17 h)	87.3° 02:35	5.12	100%	66.9°
2027-07-19 Mon	57	—	unknown	22:55–00:35 (good, 1.67 h)	87.3° 02:30	5.17	98%	61.9°
2027-07-20 Tue	57	—	unknown	22:55–00:30 (good, 1.58 h)	87.2° 02:25	5.21	95%	58.0°
2027-07-21 Wed	61	—	unknown	22:50–00:55 (good, 2.08 h)	87.2° 02:25	5.26	91%	55.6°
2027-07-22 Thu	68	—	unknown	22:50–01:45 (good, 2.92 h)	87.2° 02:20	5.31	84%	54.7°
2027-07-23 Fri	96	—	unknown	22:50–03:20 (good, 4.5 h)	87.3° 02:15	5.36	77%	55.7°
2027-07-24 Sat	99	—	unknown	22:50–04:15 (good, 5.42 h)	87.2° 02:10	5.41	68%	58.4°
2027-07-25 Sun	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.2° 02:05	5.46	58%	62.7°
2027-07-26 Mon	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.2° 02:05	5.51	48%	68.4°
2027-07-27 Tue	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.3° 02:00	5.56	37%	75.1°
2027-07-28 Wed	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.3° 01:55	5.62	27%	82.7°
2027-07-29 Thu	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.2° 01:50	5.67	17%	90.9°
2027-07-30 Fri	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.2° 01:45	5.72	9%	99.2°
2027-07-31 Sat	100	—	unknown	22:35–04:25 (good, 5.83 h)	87.2° 01:45	5.78	3%	107.4°
2027-08-01 Sun	100	—	unknown	22:35–04:25 (good, 5.83 h)	87.3° 01:40	5.83	0%	114.7°
2027-08-02 Mon	100	—	unknown	22:35–04:25 (good, 5.83 h)	87.3° 01:35	5.89	0%	120.5°
2027-08-03 Tue	100	—	unknown	22:30–04:30 (good, 6.0 h)	87.2° 01:30	5.94	4%	124.2°
2027-08-04 Wed	100	—	unknown	22:30–04:30 (good, 6.0 h)	87.2° 01:30	6.0	9%	125.2°
2027-08-05 Thu	100	—	unknown	22:30–04:30 (good, 6.0 h)	87.2° 01:25	6.06	17%	123.7°
2027-08-06 Fri	100	—	unknown	22:25–04:35 (good, 6.17 h)	87.3° 01:20	6.11	26%	120.0°
2027-08-07 Sat	100	—	unknown	22:25–04:35 (good, 6.17 h)	87.2° 01:15	6.17	37%	114.7°
2027-08-08 Sun	100	—	unknown	22:25–04:35 (good, 6.17 h)	87.2° 01:10	6.23	47%	108.5°
2027-08-09 Mon	100	—	unknown	22:20–04:40 (good, 6.33 h)	87.2° 01:10	6.28	57%	101.7°
2027-08-10 Tue	100	—	unknown	22:20–04:40 (good, 6.33 h)	87.3° 01:05	6.34	67%	94.7°
2027-08-11 Wed	100	—	unknown	22:15–04:40 (good, 6.42 h)	87.3° 01:00	6.4	76%	87.7°
2027-08-12 Thu	100	—	unknown	22:15–04:40 (good, 6.42 h)	87.2° 00:55	6.46	84%	80.8°
2027-08-13 Fri	100	—	unknown	22:15–04:45 (good, 6.5 h)	87.2° 00:50	6.51	90%	74.3°
2027-08-14 Sat	95	—	unknown	22:10–04:45 (good, 6.58 h)	87.2° 00:50	6.57	95%	68.3°
2027-08-15 Sun	64	—	unknown	01:50–04:45 (good, 2.92 h)	87.3° 00:45	6.63	98%	63.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-17&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.