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: 02-11 (5), 02-07 (4), 02-08 (4), 02-09 (4), 02-10 (4) — by astronomy; check the weather when the night is within four days.

2028-01-13astronomy score per night — click a bar for that night2028-02-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-01-13 Thu	0	—	unknown	—	71.1° 12:55	11.28	95%	138.4°
2028-01-14 Fri	0	—	unknown	—	71.1° 12:50	11.26	89%	135.0°
2028-01-15 Sat	0	—	unknown	—	71.1° 12:45	11.24	80%	128.2°
2028-01-16 Sun	0	—	unknown	—	71.1° 12:40	11.21	70%	119.6°
2028-01-17 Mon	0	—	unknown	—	71.1° 12:35	11.19	60%	110.0°
2028-01-18 Tue	0	—	unknown	—	71.1° 12:35	11.17	49%	100.1°
2028-01-19 Wed	0	—	unknown	—	71.1° 12:30	11.14	38%	90.1°
2028-01-20 Thu	0	—	unknown	—	71.1° 12:25	11.12	28%	80.4°
2028-01-21 Fri	0	—	unknown	—	71.1° 12:20	11.09	20%	71.1°
2028-01-22 Sat	0	—	unknown	—	71.1° 12:20	11.07	12%	62.5°
2028-01-23 Sun	0	—	unknown	—	71.1° 12:15	11.04	7%	54.7°
2028-01-24 Mon	0	—	unknown	—	71.1° 12:10	11.01	3%	48.3°
2028-01-25 Tue	0	—	unknown	—	71.1° 12:05	10.99	0%	43.7°
2028-01-26 Wed	0	—	unknown	—	71.1° 12:00	10.96	0%	41.5°
2028-01-27 Thu	0	—	unknown	—	71.1° 11:55	10.93	2%	42.0°
2028-01-28 Fri	1	—	unknown	—	71.1° 11:50	10.9	5%	45.2°
2028-01-29 Sat	1	—	unknown	—	71.1° 11:45	10.87	10%	50.4°
2028-01-30 Sun	1	—	unknown	—	71.1° 11:40	10.84	16%	57.2°
2028-01-31 Mon	1	—	unknown	—	71.1° 11:40	10.81	23%	65.0°
2028-02-01 Tue	1	—	unknown	—	71.1° 11:35	10.77	32%	73.6°
2028-02-02 Wed	1	—	unknown	—	71.1° 11:30	10.74	41%	82.6°
2028-02-03 Thu	2	—	unknown	06:25–06:30 (marginal, 0.08 h)	71.1° 11:25	10.71	51%	92.1°
2028-02-04 Fri	2	—	unknown	06:20–06:30 (marginal, 0.17 h)	71.1° 11:25	10.67	62%	101.8°
2028-02-05 Sat	3	—	unknown	06:20–06:30 (marginal, 0.17 h)	71.1° 11:20	10.64	72%	111.5°
2028-02-06 Sun	3	—	unknown	06:15–06:30 (marginal, 0.25 h)	71.1° 11:15	10.6	81%	120.9°
2028-02-07 Mon	4	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:10	10.57	90%	129.3°
2028-02-08 Tue	4	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:05	10.53	96%	135.7°
2028-02-09 Wed	4	—	unknown	05:35–05:50 (marginal, 0.25 h)	71.1° 11:05	10.49	99%	138.6°
2028-02-10 Thu	4	—	unknown	05:30–05:50 (marginal, 0.33 h)	71.1° 11:00	10.46	100%	137.0°
2028-02-11 Fri	5	—	unknown	05:25–05:50 (marginal, 0.42 h)	71.1° 10:55	10.42	97%	131.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-01-13&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.