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 Great Orion Nebula: 04-01 (11), 04-02 (10), 04-03 (8), 04-04 (7), 04-05 (6) — 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	11	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:20	8.08	7%	97.5°
2038-04-02 Fri	10	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:15	8.02	3%	86.9°
2038-04-03 Sat	8	—	unknown	21:25–21:30 (good, 0.08 h)	42.9° 18:10	7.97	1%	76.3°
2038-04-04 Sun	7	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.91	0%	65.9°
2038-04-05 Mon	6	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.86	2%	55.8°
2038-04-06 Tue	5	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.8	5%	46.1°
2038-04-07 Wed	3	—	unknown	21:35–21:45 (marginal, 0.17 h)	42.9° 17:55	7.74	9%	37.4°
2038-04-08 Thu	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:50	7.69	16%	30.5°
2038-04-09 Fri	1	—	unknown	—	42.9° 17:45	7.63	23%	26.9°
2038-04-10 Sat	1	—	unknown	—	42.9° 17:40	7.57	32%	28.2°
2038-04-11 Sun	1	—	unknown	—	42.9° 17:40	7.52	42%	34.0°
2038-04-12 Mon	0	—	unknown	—	42.9° 17:35	7.46	52%	42.8°
2038-04-13 Tue	0	—	unknown	—	42.9° 17:30	7.4	62%	53.4°
2038-04-14 Wed	0	—	unknown	—	42.9° 17:25	7.35	73%	65.1°
2038-04-15 Thu	0	—	unknown	—	42.9° 17:25	7.29	82%	77.7°
2038-04-16 Fri	0	—	unknown	—	42.9° 17:20	7.23	90%	90.7°
2038-04-17 Sat	0	—	unknown	—	42.9° 17:15	7.17	96%	104.1°
2038-04-18 Sun	0	—	unknown	—	42.9° 17:10	7.11	99%	117.4°
2038-04-19 Mon	0	—	unknown	—	42.9° 17:05	7.06	100%	130.2°
2038-04-20 Tue	0	—	unknown	—	42.9° 17:05	7.0	96%	141.7°
2038-04-21 Wed	0	—	unknown	—	42.9° 17:00	6.94	91%	150.1°
2038-04-22 Thu	0	—	unknown	—	42.9° 16:55	6.88	83%	153.1°
2038-04-23 Fri	0	—	unknown	—	42.9° 16:50	6.82	74%	149.6°
2038-04-24 Sat	0	—	unknown	—	42.9° 16:45	6.77	64%	141.7°
2038-04-25 Sun	0	—	unknown	—	42.9° 16:45	6.71	53%	132.0°
2038-04-26 Mon	0	—	unknown	—	42.9° 16:40	6.65	43%	121.5°
2038-04-27 Tue	0	—	unknown	—	42.9° 16:35	6.59	34%	110.8°
2038-04-28 Wed	0	—	unknown	—	42.9° 16:30	6.53	25%	100.1°
2038-04-29 Thu	0	—	unknown	—	42.9° 16:30	6.47	17%	89.5°
2038-04-30 Fri	0	—	unknown	—	42.9° 16:25	6.42	11%	78.9°

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.