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: 02-23 (16), 02-27 (16), 02-22 (15), 02-24 (15), 02-25 (15) — by astronomy; check the weather when the night is within four days.

2040-01-29astronomy score per night — click a bar for that night2040-02-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2040-02-10 Fri	5	—	unknown	05:30–05:50 (marginal, 0.33 h)	71.1° 11:00	10.45	4%	46.8°
2040-02-11 Sat	6	—	unknown	05:25–05:50 (marginal, 0.42 h)	71.1° 10:55	10.42	1%	46.9°
2040-02-12 Sun	7	—	unknown	05:25–06:20 (marginal, 0.92 h)	71.1° 10:50	10.38	0%	50.4°
2040-02-13 Mon	8	—	unknown	05:45–05:50 (good, 0.08 h)	71.1° 10:45	10.34	3%	56.5°
2040-02-14 Tue	8	—	unknown	05:40–05:45 (good, 0.08 h)	71.1° 10:45	10.3	7%	64.2°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-29&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.