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: 05-23 (100), 05-24 (100), 05-25 (100), 05-26 (100), 05-27 (100) — by astronomy; check the weather when the night is within four days.

2031-05-01astronomy score per night — click a bar for that night2031-05-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-01 Thu	72	—	unknown	01:50–04:30 (good, 2.67 h)	71.1° 06:45	6.38	70%	136.1°
2031-05-02 Fri	72	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:40	6.32	79%	128.9°
2031-05-03 Sat	72	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:35	6.26	87%	120.0°
2031-05-04 Sun	59	—	unknown	01:45–04:25 (good, 2.67 h)	71.1° 06:30	6.2	94%	109.9°
2031-05-05 Mon	52	—	unknown	01:50–04:25 (good, 2.58 h)	71.1° 06:30	6.14	98%	99.0°
2031-05-06 Tue	44	—	unknown	02:20–04:25 (good, 2.08 h)	71.1° 06:25	6.09	100%	87.6°
2031-05-07 Wed	37	—	unknown	03:10–04:20 (good, 1.17 h)	71.1° 06:20	6.03	99%	76.1°
2031-05-08 Thu	32	—	unknown	03:55–04:20 (good, 0.42 h)	71.1° 06:15	5.97	96%	64.8°
2031-05-09 Fri	30	—	unknown	00:50–04:15 (marginal, 3.42 h)	71.1° 06:10	5.92	89%	54.3°
2031-05-10 Sat	31	—	unknown	00:45–04:15 (marginal, 3.5 h)	71.1° 06:10	5.86	81%	45.4°
2031-05-11 Sun	37	—	unknown	02:55–04:15 (good, 1.33 h)	71.1° 06:05	5.81	71%	39.3°
2031-05-12 Mon	55	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 06:00	5.75	60%	37.2°
2031-05-13 Tue	65	—	unknown	00:55–04:10 (good, 3.25 h)	71.1° 05:55	5.7	48%	39.5°
2031-05-14 Wed	75	—	unknown	00:50–04:10 (good, 3.33 h)	71.1° 05:55	5.64	38%	45.4°
2031-05-15 Thu	82	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:50	5.59	27%	53.4°
2031-05-16 Fri	89	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:45	5.54	18%	62.7°
2031-05-17 Sat	93	—	unknown	00:40–04:05 (good, 3.42 h)	71.1° 05:40	5.48	11%	72.4°
2031-05-18 Sun	94	—	unknown	00:35–04:05 (good, 3.5 h)	71.1° 05:35	5.43	6%	82.4°
2031-05-19 Mon	94	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:35	5.38	2%	92.4°
2031-05-20 Tue	96	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:30	5.33	0%	102.2°
2031-05-21 Wed	98	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:25	5.28	0%	111.6°
2031-05-22 Thu	98	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.23	2%	120.5°
2031-05-23 Fri	100	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.18	6%	128.6°
2031-05-24 Sat	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:15	5.14	12%	135.4°
2031-05-25 Sun	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.09	18%	140.4°
2031-05-26 Mon	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.05	26%	142.7°
2031-05-27 Tue	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:00	5.0	35%	141.9°
2031-05-28 Wed	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 04:55	4.96	45%	138.0°
2031-05-29 Thu	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.92	55%	131.7°
2031-05-30 Fri	100	—	unknown	23:55–03:45 (good, 3.83 h)	71.1° 04:50	4.88	65%	123.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-01&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.