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.

2028-04-29astronomy score per night — click a bar for that night2028-05-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-04-29 Sat	74	—	unknown	01:45–04:35 (good, 2.83 h)	71.1° 06:50	6.45	27%	130.4°
2028-04-30 Sun	73	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:45	6.39	37%	136.2°
2028-05-01 Mon	75	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:40	6.33	48%	139.0°
2028-05-02 Tue	75	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:35	6.28	59%	137.9°
2028-05-03 Wed	74	—	unknown	01:40–04:25 (good, 2.75 h)	71.1° 06:35	6.22	70%	133.2°
2028-05-04 Thu	74	—	unknown	01:35–04:25 (good, 2.83 h)	71.1° 06:30	6.16	80%	125.6°
2028-05-05 Fri	74	—	unknown	01:35–04:25 (good, 2.83 h)	71.1° 06:25	6.1	89%	116.3°
2028-05-06 Sat	59	—	unknown	01:40–04:20 (good, 2.67 h)	71.1° 06:20	6.05	95%	106.0°
2028-05-07 Sun	52	—	unknown	01:40–04:20 (good, 2.67 h)	71.1° 06:15	5.99	99%	95.3°
2028-05-08 Mon	46	—	unknown	02:15–04:20 (good, 2.08 h)	71.1° 06:15	5.93	100%	84.7°
2028-05-09 Tue	40	—	unknown	02:50–04:15 (good, 1.42 h)	71.1° 06:10	5.88	98%	74.3°
2028-05-10 Wed	37	—	unknown	03:20–04:15 (good, 0.92 h)	71.1° 06:05	5.82	95%	64.7°
2028-05-11 Thu	35	—	unknown	03:35–04:15 (good, 0.67 h)	71.1° 06:00	5.77	89%	56.1°
2028-05-12 Fri	36	—	unknown	03:20–04:10 (good, 0.83 h)	71.1° 05:55	5.71	82%	48.9°
2028-05-13 Sat	46	—	unknown	01:50–04:10 (good, 2.33 h)	71.1° 05:55	5.66	73%	43.7°
2028-05-14 Sun	59	—	unknown	00:50–04:10 (good, 3.33 h)	71.1° 05:50	5.6	64%	41.0°
2028-05-15 Mon	67	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:45	5.55	55%	41.3°
2028-05-16 Tue	75	—	unknown	00:40–04:05 (good, 3.42 h)	71.1° 05:40	5.5	46%	44.2°
2028-05-17 Wed	82	—	unknown	00:35–04:05 (good, 3.5 h)	71.1° 05:40	5.45	36%	49.4°
2028-05-18 Thu	87	—	unknown	00:35–04:00 (good, 3.42 h)	71.1° 05:35	5.39	27%	56.1°
2028-05-19 Fri	93	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:30	5.34	19%	64.0°
2028-05-20 Sat	96	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:25	5.29	12%	72.6°
2028-05-21 Sun	97	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.24	6%	81.9°
2028-05-22 Mon	99	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:20	5.2	2%	91.5°
2028-05-23 Tue	100	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.15	0%	101.3°
2028-05-24 Wed	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.1	0%	111.1°
2028-05-25 Thu	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.06	3%	120.4°
2028-05-26 Fri	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	5.01	8%	128.8°
2028-05-27 Sat	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 05:00	4.97	15%	135.3°
2028-05-28 Sun	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.93	24%	138.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-29&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.