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: 04-30 (74), 04-29 (73), 04-28 (70), 04-27 (66), 04-26 (58) — by astronomy; check the weather when the night is within four days.

2038-04-01astronomy score per night — click a bar for that night2038-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-04-01 Thu	47	—	unknown	03:40–05:30 (good, 1.83 h)	71.1° 08:40	8.08	7%	55.3°
2038-04-02 Fri	46	—	unknown	03:35–05:25 (good, 1.83 h)	71.1° 08:35	8.02	3%	62.3°
2038-04-03 Sat	48	—	unknown	03:30–05:25 (good, 1.92 h)	71.1° 08:35	7.97	1%	70.0°
2038-04-04 Sun	50	—	unknown	03:30–05:25 (good, 1.92 h)	71.1° 08:30	7.91	0%	78.1°
2038-04-05 Mon	50	—	unknown	03:25–05:20 (good, 1.92 h)	71.1° 08:25	7.86	2%	86.6°
2038-04-06 Tue	51	—	unknown	03:20–05:20 (good, 2.0 h)	71.1° 08:20	7.8	5%	95.1°
2038-04-07 Wed	52	—	unknown	03:15–05:20 (good, 2.08 h)	71.1° 08:15	7.74	9%	103.5°
2038-04-08 Thu	52	—	unknown	03:10–05:15 (good, 2.08 h)	71.1° 08:15	7.69	16%	111.7°
2038-04-09 Fri	54	—	unknown	03:10–05:15 (good, 2.08 h)	71.1° 08:10	7.63	23%	119.4°
2038-04-10 Sat	54	—	unknown	03:05–05:10 (good, 2.08 h)	71.1° 08:05	7.57	32%	126.2°
2038-04-11 Sun	55	—	unknown	03:00–05:10 (good, 2.17 h)	71.1° 08:00	7.52	42%	131.8°
2038-04-12 Mon	56	—	unknown	03:00–05:10 (good, 2.17 h)	71.1° 07:55	7.46	52%	135.2°
2038-04-13 Tue	55	—	unknown	02:55–05:05 (good, 2.17 h)	71.1° 07:55	7.4	62%	135.7°
2038-04-14 Wed	56	—	unknown	02:55–05:05 (good, 2.17 h)	71.1° 07:50	7.35	73%	133.0°
2038-04-15 Thu	51	—	unknown	02:55–05:00 (good, 2.08 h)	71.1° 07:45	7.29	82%	127.4°
2038-04-16 Fri	49	—	unknown	02:50–05:00 (good, 2.17 h)	71.1° 07:40	7.23	90%	119.3°
2038-04-17 Sat	44	—	unknown	02:55–05:00 (good, 2.08 h)	71.1° 07:40	7.17	96%	109.7°
2038-04-18 Sun	38	—	unknown	03:00–04:55 (good, 1.92 h)	71.1° 07:35	7.11	99%	99.1°
2038-04-19 Mon	33	—	unknown	03:40–04:55 (good, 1.25 h)	71.1° 07:30	7.06	100%	88.2°
2038-04-20 Tue	29	—	unknown	04:15–04:50 (good, 0.58 h)	71.1° 07:25	7.0	96%	77.5°
2038-04-21 Wed	27	—	unknown	04:35–04:50 (good, 0.25 h)	71.1° 07:20	6.94	91%	67.3°
2038-04-22 Thu	28	—	unknown	04:30–04:50 (good, 0.33 h)	71.1° 07:20	6.88	83%	58.4°
2038-04-23 Fri	30	—	unknown	03:45–04:45 (good, 1.0 h)	71.1° 07:15	6.82	74%	51.2°
2038-04-24 Sat	37	—	unknown	02:35–04:45 (good, 2.17 h)	71.1° 07:10	6.77	64%	46.3°
2038-04-25 Sun	49	—	unknown	02:05–04:40 (good, 2.58 h)	71.1° 07:05	6.71	53%	44.3°
2038-04-26 Mon	58	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:00	6.65	43%	45.1°
2038-04-27 Tue	66	—	unknown	01:55–04:40 (good, 2.75 h)	71.1° 07:00	6.59	34%	48.6°
2038-04-28 Wed	70	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:55	6.53	25%	53.9°
2038-04-29 Thu	73	—	unknown	01:50–04:35 (good, 2.75 h)	71.1° 06:50	6.47	17%	60.6°
2038-04-30 Fri	74	—	unknown	01:45–04:35 (good, 2.83 h)	71.1° 06:45	6.42	11%	68.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-04-01&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.