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: 02-20 (66), 02-21 (66), 02-22 (66), 02-19 (64), 02-23 (64) — by astronomy; check the weather when the night is within four days.

2040-01-31astronomy score per night — click a bar for that night2040-02-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-31 Tue	25	—	unknown	04:50–06:00 (good, 1.17 h)	87.1° 10:15	10.8	93%	100.8°
2040-02-01 Wed	25	—	unknown	04:55–06:00 (good, 1.08 h)	87.1° 10:10	10.77	88%	95.5°
2040-02-02 Thu	25	—	unknown	04:50–06:00 (good, 1.17 h)	87.1° 10:05	10.74	80%	90.0°
2040-02-03 Fri	27	—	unknown	04:40–06:00 (good, 1.33 h)	87.1° 10:05	10.7	71%	84.4°
2040-02-04 Sat	28	—	unknown	04:30–05:55 (good, 1.42 h)	87.1° 10:00	10.67	61%	78.9°
2040-02-05 Sun	32	—	unknown	04:20–05:55 (good, 1.58 h)	87.1° 09:55	10.64	50%	73.8°
2040-02-06 Mon	37	—	unknown	04:10–05:55 (good, 1.75 h)	87.1° 09:50	10.6	39%	69.5°
2040-02-07 Tue	42	—	unknown	04:00–05:55 (good, 1.92 h)	87.1° 09:45	10.56	28%	66.3°
2040-02-08 Wed	48	—	unknown	03:50–05:55 (good, 2.08 h)	87.1° 09:45	10.53	18%	64.6°
2040-02-09 Thu	52	—	unknown	03:45–05:50 (good, 2.08 h)	87.1° 09:40	10.49	10%	64.6°
2040-02-10 Fri	54	—	unknown	03:40–05:50 (good, 2.17 h)	87.1° 09:35	10.45	4%	66.3°
2040-02-11 Sat	55	—	unknown	03:35–05:50 (good, 2.25 h)	87.1° 09:30	10.42	1%	69.8°
2040-02-12 Sun	57	—	unknown	03:35–05:50 (good, 2.25 h)	87.1° 09:25	10.38	0%	74.4°
2040-02-13 Mon	59	—	unknown	03:30–05:50 (good, 2.33 h)	87.1° 09:25	10.34	3%	79.9°
2040-02-14 Tue	58	—	unknown	03:25–05:45 (good, 2.33 h)	87.1° 09:20	10.3	7%	85.8°
2040-02-15 Wed	60	—	unknown	03:20–05:45 (good, 2.42 h)	87.1° 09:15	10.26	14%	91.7°
2040-02-16 Thu	62	—	unknown	03:15–05:45 (good, 2.5 h)	87.1° 09:10	10.22	22%	97.3°
2040-02-17 Fri	63	—	unknown	03:15–05:45 (good, 2.5 h)	87.1° 09:10	10.18	31%	102.4°
2040-02-18 Sat	63	—	unknown	03:10–05:40 (good, 2.5 h)	87.1° 09:05	10.14	41%	106.9°
2040-02-19 Sun	64	—	unknown	03:05–05:40 (good, 2.58 h)	87.1° 09:00	10.1	50%	110.6°
2040-02-20 Mon	66	—	unknown	03:00–05:40 (good, 2.67 h)	87.1° 08:55	10.06	60%	113.3°
2040-02-21 Tue	66	—	unknown	03:05–05:35 (good, 2.5 h)	87.1° 08:50	10.02	69%	115.0°
2040-02-22 Wed	66	—	unknown	03:05–05:35 (good, 2.5 h)	87.1° 08:50	9.97	77%	115.6°
2040-02-23 Thu	64	—	unknown	03:00–05:35 (good, 2.58 h)	87.1° 08:45	9.93	84%	115.0°
2040-02-24 Fri	57	—	unknown	03:00–05:35 (good, 2.58 h)	87.1° 08:40	9.89	91%	113.3°
2040-02-25 Sat	53	—	unknown	03:00–05:30 (good, 2.5 h)	87.1° 08:35	9.84	96%	110.5°
2040-02-26 Sun	50	—	unknown	03:05–05:30 (good, 2.42 h)	87.1° 08:30	9.8	99%	106.7°
2040-02-27 Mon	47	—	unknown	03:05–05:30 (good, 2.42 h)	87.1° 08:30	9.75	100%	102.2°
2040-02-28 Tue	42	—	unknown	03:25–05:25 (good, 2.0 h)	87.1° 08:25	9.71	99%	97.1°
2040-02-29 Wed	40	—	unknown	03:45–05:25 (good, 1.67 h)	87.1° 08:20	9.66	96%	91.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-31&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.