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: 03-15 (33), 03-14 (32), 03-13 (31), 03-12 (30), 03-10 (29) — by astronomy; check the weather when the night is within four days.

2040-02-15astronomy score per night — click a bar for that night2040-03-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-02-15 Wed	9	—	unknown	05:40–05:45 (good, 0.08 h)	71.1° 10:40	10.26	14%	72.8°
2040-02-16 Thu	10	—	unknown	05:35–05:45 (good, 0.17 h)	71.1° 10:35	10.22	22%	81.6°
2040-02-17 Fri	11	—	unknown	05:30–05:45 (good, 0.25 h)	71.1° 10:30	10.18	31%	90.4°
2040-02-18 Sat	11	—	unknown	05:25–05:40 (good, 0.25 h)	71.1° 10:30	10.14	41%	98.9°
2040-02-19 Sun	12	—	unknown	05:25–05:40 (good, 0.25 h)	71.1° 10:25	10.1	50%	107.0°
2040-02-20 Mon	14	—	unknown	05:20–05:40 (good, 0.33 h)	71.1° 10:20	10.06	60%	114.6°
2040-02-21 Tue	14	—	unknown	05:15–05:35 (good, 0.33 h)	71.1° 10:15	10.02	69%	121.3°
2040-02-22 Wed	15	—	unknown	05:10–05:35 (good, 0.42 h)	71.1° 10:10	9.97	77%	127.0°
2040-02-23 Thu	16	—	unknown	05:15–05:35 (good, 0.33 h)	71.1° 10:10	9.93	84%	131.1°
2040-02-24 Fri	15	—	unknown	05:10–05:35 (good, 0.42 h)	71.1° 10:05	9.89	91%	133.3°
2040-02-25 Sat	15	—	unknown	05:10–05:30 (good, 0.33 h)	71.1° 10:00	9.84	96%	133.2°
2040-02-26 Sun	15	—	unknown	05:05–05:30 (good, 0.42 h)	71.1° 09:55	9.8	99%	130.6°
2040-02-27 Mon	16	—	unknown	05:00–05:30 (good, 0.5 h)	71.1° 09:50	9.75	100%	126.0°
2040-02-28 Tue	16	—	unknown	05:00–05:25 (good, 0.42 h)	71.1° 09:50	9.71	99%	119.6°
2040-02-29 Wed	15	—	unknown	05:00–05:25 (good, 0.42 h)	71.1° 09:45	9.66	96%	111.9°
2040-03-01 Thu	15	—	unknown	05:00–05:25 (good, 0.42 h)	71.1° 09:40	9.62	91%	103.4°
2040-03-02 Fri	13	—	unknown	05:00–05:20 (good, 0.33 h)	71.1° 09:35	9.57	84%	94.3°
2040-03-03 Sat	14	—	unknown	04:55–05:20 (good, 0.42 h)	71.1° 09:35	9.53	75%	85.0°
2040-03-04 Sun	15	—	unknown	04:50–05:20 (good, 0.5 h)	71.1° 09:30	9.48	65%	75.7°
2040-03-05 Mon	16	—	unknown	04:45–05:15 (good, 0.5 h)	71.1° 09:25	9.43	54%	66.8°
2040-03-06 Tue	18	—	unknown	04:35–05:15 (good, 0.67 h)	71.1° 09:20	9.39	43%	58.7°
2040-03-07 Wed	21	—	unknown	04:25–05:15 (good, 0.83 h)	71.1° 09:15	9.34	32%	52.1°
2040-03-08 Thu	25	—	unknown	04:10–05:10 (good, 1.0 h)	71.1° 09:15	9.29	22%	47.8°
2040-03-09 Fri	28	—	unknown	04:10–05:10 (good, 1.0 h)	71.1° 09:10	9.24	13%	46.6°
2040-03-10 Sat	29	—	unknown	04:05–05:10 (good, 1.08 h)	71.1° 09:05	9.19	6%	48.7°
2040-03-11 Sun	29	—	unknown	04:00–05:05 (good, 1.08 h)	71.1° 09:00	9.15	2%	53.7°
2040-03-12 Mon	30	—	unknown	03:55–05:05 (good, 1.17 h)	71.1° 08:55	9.1	0%	60.8°
2040-03-13 Tue	31	—	unknown	03:50–05:05 (good, 1.25 h)	71.1° 08:55	9.05	1%	69.0°
2040-03-14 Wed	32	—	unknown	03:50–05:00 (good, 1.17 h)	71.1° 08:50	9.0	4%	77.8°
2040-03-15 Thu	33	—	unknown	03:45–05:00 (good, 1.25 h)	71.1° 08:45	8.95	10%	86.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-02-15&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.