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: 03-20 (37), 03-19 (34), 03-18 (29), 03-17 (26), 03-04 (24) — by astronomy; check the weather when the night is within four days.

2031-02-19astronomy score per night — click a bar for that night2031-03-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-02-19 Wed	13	—	unknown	05:20–05:40 (good, 0.33 h)	71.1° 10:25	10.09	4%	37.6°
2031-02-20 Thu	14	—	unknown	05:20–05:40 (good, 0.33 h)	71.1° 10:20	10.05	1%	39.2°
2031-02-21 Fri	14	—	unknown	05:15–05:35 (good, 0.33 h)	71.1° 10:15	10.01	0%	44.8°
2031-02-22 Sat	15	—	unknown	05:10–05:35 (good, 0.42 h)	71.1° 10:10	9.96	2%	52.9°
2031-02-23 Sun	17	—	unknown	05:05–05:35 (good, 0.5 h)	71.1° 10:05	9.92	7%	62.4°
2031-02-24 Mon	18	—	unknown	05:00–05:35 (good, 0.58 h)	71.1° 10:05	9.88	13%	72.4°
2031-02-25 Tue	18	—	unknown	05:00–05:30 (good, 0.5 h)	71.1° 10:00	9.83	20%	82.5°
2031-02-26 Wed	19	—	unknown	04:55–05:30 (good, 0.58 h)	71.1° 09:55	9.79	29%	92.4°
2031-02-27 Thu	20	—	unknown	04:50–05:30 (good, 0.67 h)	71.1° 09:50	9.75	38%	102.1°
2031-02-28 Fri	20	—	unknown	04:45–05:25 (good, 0.67 h)	71.1° 09:45	9.7	48%	111.3°
2031-03-01 Sat	21	—	unknown	04:40–05:25 (good, 0.75 h)	71.1° 09:45	9.66	57%	120.1°
2031-03-02 Sun	23	—	unknown	04:40–05:25 (good, 0.75 h)	71.1° 09:40	9.61	66%	128.1°
2031-03-03 Mon	23	—	unknown	04:35–05:20 (good, 0.75 h)	71.1° 09:35	9.56	75%	134.9°
2031-03-04 Tue	24	—	unknown	04:30–05:20 (good, 0.83 h)	71.1° 09:30	9.52	83%	140.0°
2031-03-05 Wed	24	—	unknown	04:35–05:20 (good, 0.75 h)	71.1° 09:30	9.47	89%	142.4°
2031-03-06 Thu	21	—	unknown	04:30–05:15 (good, 0.75 h)	71.1° 09:25	9.42	95%	141.5°
2031-03-07 Fri	22	—	unknown	04:30–05:15 (good, 0.75 h)	71.1° 09:20	9.38	98%	137.4°
2031-03-08 Sat	22	—	unknown	04:25–05:15 (good, 0.83 h)	71.1° 09:15	9.33	100%	130.6°
2031-03-09 Sun	22	—	unknown	04:20–05:10 (good, 0.83 h)	71.1° 09:10	9.28	99%	122.1°
2031-03-10 Mon	21	—	unknown	04:20–05:10 (good, 0.83 h)	71.1° 09:10	9.23	96%	112.4°
2031-03-11 Tue	19	—	unknown	04:25–05:10 (good, 0.75 h)	71.1° 09:05	9.18	91%	102.0°
2031-03-12 Wed	18	—	unknown	04:25–05:05 (good, 0.67 h)	71.1° 09:00	9.14	84%	91.1°
2031-03-13 Thu	18	—	unknown	04:20–05:05 (good, 0.75 h)	71.1° 08:55	9.09	75%	80.1°
2031-03-14 Fri	18	—	unknown	04:15–05:05 (good, 0.83 h)	71.1° 08:50	9.04	65%	69.3°
2031-03-15 Sat	19	—	unknown	04:10–05:00 (good, 0.83 h)	71.1° 08:50	8.99	54%	59.0°
2031-03-16 Sun	22	—	unknown	04:00–05:00 (good, 1.0 h)	71.1° 08:45	8.94	42%	49.6°
2031-03-17 Mon	26	—	unknown	03:50–05:00 (good, 1.17 h)	71.1° 08:40	8.89	31%	42.2°
2031-03-18 Tue	29	—	unknown	03:35–04:55 (good, 1.33 h)	71.1° 08:35	8.84	21%	38.0°
2031-03-19 Wed	34	—	unknown	03:30–04:55 (good, 1.42 h)	71.1° 08:35	8.78	13%	38.0°
2031-03-20 Thu	37	—	unknown	03:30–04:55 (good, 1.42 h)	71.1° 08:30	8.73	6%	42.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-02-19&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.