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.

2039-05-16astronomy score per night — click a bar for that night2039-06-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-05-16 Mon	89	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:45	5.53	32%	59.0°
2039-05-17 Tue	93	—	unknown	00:40–04:05 (good, 3.42 h)	71.1° 05:40	5.48	23%	66.3°
2039-05-18 Wed	94	—	unknown	00:35–04:05 (good, 3.5 h)	71.1° 05:35	5.43	15%	74.3°
2039-05-19 Thu	94	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:35	5.38	9%	82.5°
2039-05-20 Fri	96	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:30	5.33	4%	90.8°
2039-05-21 Sat	98	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:25	5.28	1%	99.1°
2039-05-22 Sun	98	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.23	0%	107.1°
2039-05-23 Mon	100	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.18	1%	114.6°
2039-05-24 Tue	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:15	5.13	3%	121.5°
2039-05-25 Wed	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.09	7%	127.3°
2039-05-26 Thu	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.04	13%	131.6°
2039-05-27 Fri	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	5.0	20%	133.8°
2039-05-28 Sat	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	4.96	28%	133.7°
2039-05-29 Sun	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.92	38%	131.0°
2039-05-30 Mon	100	—	unknown	23:55–03:45 (good, 3.83 h)	71.1° 04:50	4.88	48%	126.0°
2039-05-31 Tue	100	—	unknown	23:50–03:45 (good, 3.92 h)	71.1° 04:45	4.84	59%	119.2°
2039-06-01 Wed	100	—	unknown	23:50–03:45 (good, 3.92 h)	71.1° 04:40	4.8	69%	110.9°
2039-06-02 Thu	97	—	unknown	23:55–03:45 (good, 3.83 h)	71.1° 04:40	4.77	79%	101.6°
2039-06-03 Fri	75	—	unknown	00:00–03:45 (good, 3.75 h)	71.1° 04:35	4.73	88%	91.6°
2039-06-04 Sat	63	—	unknown	00:50–03:45 (good, 2.92 h)	71.1° 04:30	4.7	95%	81.3°
2039-06-05 Sun	51	—	unknown	01:45–03:40 (good, 1.92 h)	71.1° 04:25	4.67	99%	71.1°
2039-06-06 Mon	44	—	unknown	02:40–03:40 (good, 1.0 h)	71.1° 04:20	4.64	100%	61.7°
2039-06-07 Tue	40	—	unknown	23:05–03:40 (marginal, 4.58 h)	71.1° 04:20	4.61	98%	53.7°
2039-06-08 Wed	42	—	unknown	23:05–03:40 (marginal, 4.58 h)	71.1° 04:15	4.58	93%	48.3°
2039-06-09 Thu	69	—	unknown	00:50–03:00 (good, 2.17 h)	71.1° 04:10	4.56	86%	46.0°
2039-06-10 Fri	84	—	unknown	23:05–03:40 (good, 4.58 h)	71.1° 04:05	4.54	77%	47.1°
2039-06-11 Sat	94	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:05	4.52	67%	51.1°
2039-06-12 Sun	98	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 04:00	4.5	57%	57.2°
2039-06-13 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:55	4.48	47%	64.4°
2039-06-14 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:50	4.47	37%	72.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-05-16&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.