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: 05-27 (100), 05-28 (100), 05-29 (100), 05-30 (100), 05-31 (100) — by astronomy; check the weather when the night is within four days.

2038-05-02astronomy score per night — click a bar for that night2038-05-31

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-05-02 Sun	76	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:40	6.3	2%	84.4°
2038-05-03 Mon	77	—	unknown	01:35–04:25 (good, 2.83 h)	71.1° 06:35	6.24	0%	92.9°
2038-05-04 Tue	78	—	unknown	01:30–04:25 (good, 2.92 h)	71.1° 06:30	6.19	0%	101.3°
2038-05-05 Wed	79	—	unknown	01:25–04:25 (good, 3.0 h)	71.1° 06:25	6.13	2%	109.6°
2038-05-06 Thu	80	—	unknown	01:20–04:20 (good, 3.0 h)	71.1° 06:25	6.07	6%	117.4°
2038-05-07 Fri	81	—	unknown	01:20–04:20 (good, 3.0 h)	71.1° 06:20	6.01	11%	124.5°
2038-05-08 Sat	83	—	unknown	01:15–04:20 (good, 3.08 h)	71.1° 06:15	5.96	18%	130.4°
2038-05-09 Sun	83	—	unknown	01:10–04:15 (good, 3.08 h)	71.1° 06:10	5.9	27%	134.3°
2038-05-10 Mon	84	—	unknown	01:10–04:15 (good, 3.08 h)	71.1° 06:05	5.85	37%	135.7°
2038-05-11 Tue	85	—	unknown	01:05–04:15 (good, 3.17 h)	71.1° 06:05	5.79	47%	134.0°
2038-05-12 Wed	84	—	unknown	01:05–04:10 (good, 3.08 h)	71.1° 06:00	5.73	58%	129.3°
2038-05-13 Thu	85	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 05:55	5.68	69%	122.3°
2038-05-14 Fri	75	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 05:50	5.63	79%	113.5°
2038-05-15 Sat	65	—	unknown	01:05–04:05 (good, 3.0 h)	71.1° 05:50	5.57	88%	103.6°
2038-05-16 Sun	56	—	unknown	01:20–04:05 (good, 2.75 h)	71.1° 05:45	5.52	95%	93.0°
2038-05-17 Mon	47	—	unknown	02:10–04:05 (good, 1.92 h)	71.1° 05:40	5.47	99%	82.3°
2038-05-18 Tue	39	—	unknown	03:00–04:00 (good, 1.0 h)	71.1° 05:35	5.42	100%	71.8°
2038-05-19 Wed	35	—	unknown	03:40–04:00 (good, 0.33 h)	71.1° 05:30	5.37	98%	62.2°
2038-05-20 Thu	34	—	unknown	00:10–04:00 (marginal, 3.83 h)	71.1° 05:30	5.32	94%	54.1°
2038-05-21 Fri	36	—	unknown	00:00–04:00 (marginal, 4.0 h)	71.1° 05:25	5.27	87%	48.1°
2038-05-22 Sat	56	—	unknown	01:40–03:55 (good, 2.25 h)	71.1° 05:20	5.22	78%	44.9°
2038-05-23 Sun	69	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.17	69%	44.8°
2038-05-24 Mon	80	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.12	59%	47.5°
2038-05-25 Tue	90	—	unknown	00:05–03:55 (good, 3.83 h)	71.1° 05:10	5.08	49%	52.4°
2038-05-26 Wed	98	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.03	40%	58.8°
2038-05-27 Thu	100	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	4.99	31%	66.1°
2038-05-28 Fri	100	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.95	22%	74.0°
2038-05-29 Sat	100	—	unknown	23:50–03:50 (good, 4.0 h)	71.1° 04:55	4.91	15%	82.2°
2038-05-30 Sun	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:50	4.87	9%	90.6°
2038-05-31 Mon	100	—	unknown	23:45–03:45 (good, 4.0 h)	71.1° 04:45	4.83	4%	99.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-05-02&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.