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: 02-20 (14), 02-21 (14), 02-19 (13), 02-18 (11), 02-17 (9) — by astronomy; check the weather when the night is within four days.

2031-01-23astronomy score per night — click a bar for that night2031-02-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-01-23 Thu	0	—	unknown	—	71.1° 12:15	11.03	1%	37.7°
2031-01-24 Fri	0	—	unknown	—	71.1° 12:10	11.01	4%	41.2°
2031-01-25 Sat	0	—	unknown	—	71.1° 12:05	10.98	10%	48.0°
2031-01-26 Sun	0	—	unknown	—	71.1° 12:00	10.95	18%	56.7°
2031-01-27 Mon	1	—	unknown	—	71.1° 11:55	10.92	27%	66.3°
2031-01-28 Tue	1	—	unknown	—	71.1° 11:50	10.89	36%	76.1°
2031-01-29 Wed	1	—	unknown	—	71.1° 11:45	10.86	46%	85.9°
2031-01-30 Thu	1	—	unknown	—	71.1° 11:40	10.83	56%	95.6°
2031-01-31 Fri	1	—	unknown	—	71.1° 11:40	10.8	65%	105.0°
2031-02-01 Sat	1	—	unknown	—	71.1° 11:35	10.76	74%	114.0°
2031-02-02 Sun	1	—	unknown	—	71.1° 11:30	10.73	82%	122.5°
2031-02-03 Mon	2	—	unknown	05:55–06:00 (marginal, 0.08 h)	71.1° 11:25	10.7	88%	130.2°
2031-02-04 Tue	2	—	unknown	06:20–06:30 (marginal, 0.17 h)	71.1° 11:20	10.66	94%	136.6°
2031-02-05 Wed	2	—	unknown	05:50–05:55 (marginal, 0.08 h)	71.1° 11:20	10.63	97%	140.9°
2031-02-06 Thu	3	—	unknown	05:45–05:55 (marginal, 0.17 h)	71.1° 11:15	10.59	100%	142.4°
2031-02-07 Fri	3	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:10	10.56	100%	140.5°
2031-02-08 Sat	4	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:05	10.52	98%	135.5°
2031-02-09 Sun	4	—	unknown	05:35–05:50 (marginal, 0.25 h)	71.1° 11:00	10.48	94%	128.3°
2031-02-10 Mon	4	—	unknown	05:30–05:50 (marginal, 0.33 h)	71.1° 11:00	10.45	88%	119.6°
2031-02-11 Tue	5	—	unknown	05:25–05:50 (marginal, 0.42 h)	71.1° 10:55	10.41	81%	109.8°
2031-02-12 Wed	5	—	unknown	05:20–05:50 (marginal, 0.5 h)	71.1° 10:50	10.37	72%	99.5°
2031-02-13 Thu	5	—	unknown	05:20–05:45 (marginal, 0.42 h)	71.1° 10:45	10.33	61%	88.8°
2031-02-14 Fri	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	71.1° 10:40	10.29	50%	77.9°
2031-02-15 Sat	7	—	unknown	05:10–05:45 (marginal, 0.58 h)	71.1° 10:40	10.25	39%	67.1°
2031-02-16 Sun	8	—	unknown	05:05–06:15 (marginal, 1.17 h)	71.1° 10:35	10.21	28%	56.8°
2031-02-17 Mon	9	—	unknown	05:35–05:40 (good, 0.08 h)	71.1° 10:30	10.17	18%	47.6°
2031-02-18 Tue	11	—	unknown	05:30–05:40 (good, 0.17 h)	71.1° 10:25	10.13	10%	40.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-23&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.