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: 12-29 (12), 12-30 (11), 12-31 (9), 01-01 (8), 01-02 (7) — by astronomy; check the weather when the night is within four days.

2042-12-29astronomy score per night — click a bar for that night2043-01-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-12-29 Mon	12	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:50	11.48	88%	132.8°
2042-12-30 Tue	11	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:45	11.47	80%	129.8°
2042-12-31 Wed	9	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:45	11.46	72%	124.8°
2043-01-01 Thu	8	—	unknown	18:10–19:15 (marginal, 1.08 h)	71.1° 13:40	11.45	62%	118.5°
2043-01-02 Fri	7	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	53%	111.3°
2043-01-03 Sat	6	—	unknown	18:10–18:40 (marginal, 0.5 h)	71.1° 13:30	11.43	44%	103.7°
2043-01-04 Sun	5	—	unknown	18:10–18:35 (marginal, 0.42 h)	71.1° 13:30	11.42	34%	95.7°
2043-01-05 Mon	3	—	unknown	18:15–18:30 (marginal, 0.25 h)	71.1° 13:25	11.4	26%	87.6°
2043-01-06 Tue	3	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:20	11.39	18%	79.4°
2043-01-07 Wed	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.38	11%	71.5°
2043-01-08 Thu	1	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:10	11.36	6%	63.9°
2043-01-09 Fri	1	—	unknown	—	71.1° 13:10	11.34	2%	57.0°
2043-01-10 Sat	1	—	unknown	—	71.1° 13:05	11.33	0%	51.4°
2043-01-11 Sun	1	—	unknown	—	71.1° 13:00	11.31	1%	47.7°
2043-01-12 Mon	1	—	unknown	—	71.1° 12:55	11.29	3%	46.6°
2043-01-13 Tue	0	—	unknown	—	71.1° 12:50	11.27	8%	48.5°
2043-01-14 Wed	0	—	unknown	—	71.1° 12:50	11.25	15%	53.1°
2043-01-15 Thu	0	—	unknown	—	71.1° 12:45	11.23	24%	59.8°
2043-01-16 Fri	0	—	unknown	—	71.1° 12:40	11.21	34%	67.9°
2043-01-17 Sat	0	—	unknown	—	71.1° 12:35	11.18	45%	77.0°
2043-01-18 Sun	0	—	unknown	—	71.1° 12:35	11.16	56%	86.6°
2043-01-19 Mon	0	—	unknown	—	71.1° 12:30	11.14	67%	96.3°
2043-01-20 Tue	0	—	unknown	—	71.1° 12:25	11.11	78%	105.8°
2043-01-21 Wed	0	—	unknown	—	71.1° 12:20	11.09	86%	114.7°
2043-01-22 Thu	0	—	unknown	—	71.1° 12:15	11.06	93%	122.6°
2043-01-23 Fri	0	—	unknown	—	71.1° 12:15	11.03	98%	128.7°
2043-01-24 Sat	0	—	unknown	—	71.1° 12:10	11.0	100%	132.5°
2043-01-25 Sun	0	—	unknown	—	71.1° 12:05	10.98	99%	133.4°
2043-01-26 Mon	0	—	unknown	—	71.1° 12:00	10.95	97%	131.4°
2043-01-27 Tue	0	—	unknown	—	71.1° 11:55	10.92	92%	127.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-12-29&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.