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: 01-04 (3), 01-05 (2), 01-06 (2), 01-07 (1), 01-08 (1) — by astronomy; check the weather when the night is within four days.

2039-01-04astronomy score per night — click a bar for that night2039-02-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-01-04 Tue	3	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:30	11.42	74%	95.8°
2039-01-05 Wed	2	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:25	11.4	82%	104.0°
2039-01-06 Thu	2	—	unknown	18:50–18:55 (marginal, 0.08 h)	71.1° 13:20	11.39	88%	111.9°
2039-01-07 Fri	1	—	unknown	—	71.1° 13:15	11.38	94%	119.3°
2039-01-08 Sat	1	—	unknown	—	71.1° 13:10	11.36	98%	125.8°
2039-01-09 Sun	1	—	unknown	—	71.1° 13:10	11.34	100%	131.0°
2039-01-10 Mon	1	—	unknown	—	71.1° 13:05	11.33	100%	134.1°
2039-01-11 Tue	1	—	unknown	—	71.1° 13:00	11.31	98%	134.6°
2039-01-12 Wed	1	—	unknown	—	71.1° 12:55	11.29	94%	132.3°
2039-01-13 Thu	0	—	unknown	—	71.1° 12:50	11.27	88%	127.5°
2039-01-14 Fri	0	—	unknown	—	71.1° 12:50	11.25	80%	120.7°
2039-01-15 Sat	0	—	unknown	—	71.1° 12:45	11.23	70%	112.4°
2039-01-16 Sun	0	—	unknown	—	71.1° 12:40	11.21	59%	103.3°
2039-01-17 Mon	0	—	unknown	—	71.1° 12:35	11.18	48%	93.6°
2039-01-18 Tue	0	—	unknown	—	71.1° 12:35	11.16	37%	83.6°
2039-01-19 Wed	0	—	unknown	—	71.1° 12:30	11.14	26%	73.8°
2039-01-20 Thu	0	—	unknown	—	71.1° 12:25	11.11	17%	64.4°
2039-01-21 Fri	0	—	unknown	—	71.1° 12:20	11.09	9%	56.2°
2039-01-22 Sat	0	—	unknown	—	71.1° 12:15	11.06	4%	49.7°
2039-01-23 Sun	0	—	unknown	—	71.1° 12:15	11.03	1%	45.9°
2039-01-24 Mon	0	—	unknown	—	71.1° 12:10	11.01	0%	45.4°
2039-01-25 Tue	0	—	unknown	—	71.1° 12:05	10.98	2%	48.2°
2039-01-26 Wed	0	—	unknown	—	71.1° 12:00	10.95	7%	53.4°
2039-01-27 Thu	1	—	unknown	—	71.1° 11:55	10.92	13%	60.2°
2039-01-28 Fri	1	—	unknown	—	71.1° 11:50	10.89	20%	68.0°
2039-01-29 Sat	1	—	unknown	—	71.1° 11:45	10.86	29%	76.2°
2039-01-30 Sun	1	—	unknown	—	71.1° 11:40	10.83	38%	84.6°
2039-01-31 Mon	1	—	unknown	—	71.1° 11:40	10.79	48%	93.0°
2039-02-01 Tue	1	—	unknown	—	71.1° 11:35	10.76	57%	101.2°
2039-02-02 Wed	1	—	unknown	—	71.1° 11:30	10.73	66%	109.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-01-04&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.