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: 01-05 (3), 01-06 (2), 02-03 (2), 01-07 (1), 01-08 (1) — by astronomy; check the weather when the night is within four days.

2044-01-05astronomy score per night — click a bar for that night2044-02-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-01-05 Tue	3	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	27%	55.3°
2044-01-06 Wed	2	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:20	11.39	37%	62.4°
2044-01-07 Thu	1	—	unknown	—	71.1° 13:15	11.38	47%	70.8°
2044-01-08 Fri	1	—	unknown	—	71.1° 13:15	11.36	58%	80.1°
2044-01-09 Sat	1	—	unknown	—	71.1° 13:10	11.35	69%	89.9°
2044-01-10 Sun	1	—	unknown	—	71.1° 13:05	11.33	80%	100.0°
2044-01-11 Mon	0	—	unknown	—	71.1° 13:00	11.31	88%	109.9°
2044-01-12 Tue	0	—	unknown	—	71.1° 12:55	11.29	95%	119.1°
2044-01-13 Wed	0	—	unknown	—	71.1° 12:55	11.27	99%	126.9°
2044-01-14 Thu	0	—	unknown	—	71.1° 12:50	11.25	100%	132.3°
2044-01-15 Fri	0	—	unknown	—	71.1° 12:45	11.23	98%	134.5°
2044-01-16 Sat	0	—	unknown	—	71.1° 12:40	11.21	94%	133.0°
2044-01-17 Sun	0	—	unknown	—	71.1° 12:40	11.19	87%	128.6°
2044-01-18 Mon	0	—	unknown	—	71.1° 12:35	11.17	79%	122.1°
2044-01-19 Tue	0	—	unknown	—	71.1° 12:30	11.14	70%	114.5°
2044-01-20 Wed	0	—	unknown	—	71.1° 12:25	11.12	60%	106.4°
2044-01-21 Thu	0	—	unknown	—	71.1° 12:20	11.09	50%	98.0°
2044-01-22 Fri	0	—	unknown	—	71.1° 12:20	11.07	41%	89.5°
2044-01-23 Sat	0	—	unknown	—	71.1° 12:15	11.04	32%	81.2°
2044-01-24 Sun	0	—	unknown	—	71.1° 12:10	11.01	24%	73.2°
2044-01-25 Mon	0	—	unknown	—	71.1° 12:05	10.98	16%	65.6°
2044-01-26 Tue	0	—	unknown	—	71.1° 12:00	10.95	10%	58.6°
2044-01-27 Wed	0	—	unknown	—	71.1° 11:55	10.93	5%	52.6°
2044-01-28 Thu	1	—	unknown	—	71.1° 11:50	10.9	2%	48.2°
2044-01-29 Fri	1	—	unknown	—	71.1° 11:45	10.86	0%	45.8°
2044-01-30 Sat	1	—	unknown	—	71.1° 11:45	10.83	1%	45.9°
2044-01-31 Sun	1	—	unknown	—	71.1° 11:40	10.8	3%	48.7°
2044-02-01 Mon	1	—	unknown	—	71.1° 11:35	10.77	8%	53.8°
2044-02-02 Tue	1	—	unknown	—	71.1° 11:30	10.74	14%	60.6°
2044-02-03 Wed	2	—	unknown	06:25–06:30 (marginal, 0.08 h)	71.1° 11:25	10.7	22%	68.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-01-05&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.