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 HD 189733: 02-08 (4), 02-09 (4), 02-06 (3), 02-07 (3), 02-05 (2) — by astronomy; check the weather when the night is within four days.

2040-01-11astronomy score per night — click a bar for that night2040-02-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-11 Wed	1	—	unknown	—	71.1° 13:00	11.31	7%	61.2°
2040-01-12 Thu	1	—	unknown	—	71.1° 12:55	11.29	2%	53.6°
2040-01-13 Fri	0	—	unknown	—	71.1° 12:55	11.27	0%	48.3°
2040-01-14 Sat	0	—	unknown	—	71.1° 12:50	11.25	1%	46.4°
2040-01-15 Sun	0	—	unknown	—	71.1° 12:45	11.23	5%	48.2°
2040-01-16 Mon	0	—	unknown	—	71.1° 12:40	11.21	11%	53.0°
2040-01-17 Tue	0	—	unknown	—	71.1° 12:40	11.19	19%	59.9°
2040-01-18 Wed	0	—	unknown	—	71.1° 12:35	11.17	28%	67.8°
2040-01-19 Thu	0	—	unknown	—	71.1° 12:30	11.14	38%	76.3°
2040-01-20 Fri	0	—	unknown	—	71.1° 12:25	11.12	48%	84.9°
2040-01-21 Sat	0	—	unknown	—	71.1° 12:20	11.09	58%	93.4°
2040-01-22 Sun	0	—	unknown	—	71.1° 12:20	11.07	68%	101.7°
2040-01-23 Mon	0	—	unknown	—	71.1° 12:15	11.04	76%	109.6°
2040-01-24 Tue	0	—	unknown	—	71.1° 12:10	11.01	84%	116.8°
2040-01-25 Wed	0	—	unknown	—	71.1° 12:05	10.98	90%	123.3°
2040-01-26 Thu	0	—	unknown	—	71.1° 12:00	10.96	95%	128.5°
2040-01-27 Fri	0	—	unknown	—	71.1° 11:55	10.93	98%	132.1°
2040-01-28 Sat	1	—	unknown	—	71.1° 11:50	10.9	100%	133.6°
2040-01-29 Sun	1	—	unknown	—	71.1° 11:45	10.87	100%	132.7°
2040-01-30 Mon	1	—	unknown	—	71.1° 11:45	10.83	97%	129.5°
2040-01-31 Tue	1	—	unknown	—	71.1° 11:40	10.8	93%	124.3°
2040-02-01 Wed	1	—	unknown	—	71.1° 11:35	10.77	88%	117.6°
2040-02-02 Thu	1	—	unknown	—	71.1° 11:30	10.74	80%	109.7°
2040-02-03 Fri	1	—	unknown	—	71.1° 11:25	10.7	71%	101.1°
2040-02-04 Sat	1	—	unknown	—	71.1° 11:25	10.67	61%	92.1°
2040-02-05 Sun	2	—	unknown	05:50–05:55 (marginal, 0.08 h)	71.1° 11:20	10.64	50%	82.7°
2040-02-06 Mon	3	—	unknown	05:45–05:55 (marginal, 0.17 h)	71.1° 11:15	10.6	39%	73.4°
2040-02-07 Tue	3	—	unknown	05:45–05:55 (marginal, 0.17 h)	71.1° 11:10	10.56	28%	64.5°
2040-02-08 Wed	4	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:05	10.53	18%	56.5°
2040-02-09 Thu	4	—	unknown	06:00–06:25 (marginal, 0.42 h)	71.1° 11:05	10.49	10%	50.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-11&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.