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 Vega: 08-22 (100), 08-23 (100), 08-24 (100), 08-25 (100), 08-26 (100) — by astronomy; check the weather when the night is within four days.

2027-08-22astronomy score per night — click a bar for that night2027-09-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-22 Sun	100	—	unknown	21:55–03:30 (good, 5.58 h)	87.1° 21:55	7.03	72%	93.7°
2027-08-23 Mon	100	—	unknown	21:55–03:30 (good, 5.58 h)	87.1° 21:50	7.09	62%	99.3°
2027-08-24 Tue	100	—	unknown	21:50–03:35 (good, 5.75 h)	87.1° 21:50	7.15	52%	104.6°
2027-08-25 Wed	100	—	unknown	21:50–03:35 (good, 5.75 h)	87.1° 21:45	7.2	41%	109.3°
2027-08-26 Thu	100	—	unknown	21:50–03:35 (good, 5.75 h)	87.1° 21:40	7.26	30%	113.1°
2027-08-27 Fri	100	—	unknown	21:45–03:35 (good, 5.83 h)	87.1° 21:35	7.32	20%	115.6°
2027-08-28 Sat	100	—	unknown	21:45–03:30 (good, 5.75 h)	87.1° 21:30	7.37	11%	116.3°
2027-08-29 Sun	100	—	unknown	21:40–03:25 (good, 5.75 h)	87.1° 21:30	7.43	5%	115.2°
2027-08-30 Mon	100	—	unknown	21:40–03:25 (good, 5.75 h)	87.1° 21:25	7.49	1%	112.3°
2027-08-31 Tue	100	—	unknown	21:40–03:20 (good, 5.67 h)	87.1° 21:20	7.54	0%	107.8°
2027-09-01 Wed	100	—	unknown	21:35–03:15 (good, 5.67 h)	87.1° 21:15	7.6	2%	102.3°
2027-09-02 Thu	100	—	unknown	21:35–03:10 (good, 5.58 h)	87.1° 21:10	7.65	7%	96.3°
2027-09-03 Fri	100	—	unknown	21:30–03:10 (good, 5.67 h)	87.1° 21:10	7.71	14%	90.0°
2027-09-04 Sat	100	—	unknown	21:30–03:05 (good, 5.58 h)	87.1° 21:05	7.76	22%	84.0°
2027-09-05 Sun	100	—	unknown	21:30–03:00 (good, 5.5 h)	87.1° 21:00	7.82	32%	78.5°
2027-09-06 Mon	100	—	unknown	21:25–02:55 (good, 5.5 h)	87.1° 20:55	7.87	42%	73.6°
2027-09-07 Tue	100	—	unknown	21:25–02:50 (good, 5.42 h)	87.1° 20:55	7.93	52%	69.5°
2027-09-08 Wed	95	—	unknown	21:20–02:50 (good, 5.5 h)	87.1° 20:50	7.98	61%	66.4°
2027-09-09 Thu	87	—	unknown	21:20–02:45 (good, 5.42 h)	87.1° 20:45	8.04	70%	64.4°
2027-09-10 Fri	78	—	unknown	21:20–02:40 (good, 5.33 h)	87.1° 20:40	8.09	79%	63.6°
2027-09-11 Sat	62	—	unknown	21:15–01:00 (good, 3.75 h)	87.1° 20:35	8.15	86%	64.0°
2027-09-12 Sun	56	—	unknown	21:15–23:40 (good, 2.42 h)	87.1° 20:35	8.2	92%	65.6°
2027-09-13 Mon	53	—	unknown	21:10–23:00 (good, 1.83 h)	87.1° 20:30	8.25	96%	68.3°
2027-09-14 Tue	54	—	unknown	21:10–23:00 (good, 1.83 h)	87.1° 20:25	8.31	99%	71.9°
2027-09-15 Wed	57	—	unknown	21:10–23:20 (good, 2.17 h)	87.1° 20:20	8.36	100%	76.3°
2027-09-16 Thu	63	—	unknown	21:05–23:45 (good, 2.67 h)	87.1° 20:15	8.41	99%	81.4°
2027-09-17 Fri	71	—	unknown	21:05–00:20 (good, 3.25 h)	87.1° 20:15	8.46	96%	86.8°
2027-09-18 Sat	82	—	unknown	21:00–01:00 (good, 4.0 h)	87.1° 20:10	8.52	91%	92.5°
2027-09-19 Sun	86	—	unknown	21:00–01:35 (good, 4.58 h)	87.1° 20:05	8.57	84%	98.1°
2027-09-20 Mon	100	—	unknown	21:00–01:40 (good, 4.67 h)	87.1° 20:00	8.62	76%	103.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-22&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.