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 (7), 04-02 (5), 04-03 (3), 04-04 (2), 04-05 (2) — by astronomy; check the weather when the night is within four days.

2036-04-01astronomy score per night — click a bar for that night2036-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-04-01 Tue	7	—	unknown	21:25–22:05 (marginal, 0.67 h)	42.9° 18:15	8.05	27%	24.8°
2036-04-02 Wed	5	—	unknown	21:25–22:00 (marginal, 0.58 h)	42.9° 18:10	8.0	38%	25.3°
2036-04-03 Thu	3	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:10	7.94	49%	32.1°
2036-04-04 Fri	2	—	unknown	21:30–21:40 (marginal, 0.17 h)	42.9° 18:05	7.88	61%	42.4°
2036-04-05 Sat	2	—	unknown	—	42.9° 18:00	7.83	72%	54.3°
2036-04-06 Sun	2	—	unknown	—	42.9° 17:55	7.77	81%	66.9°
2036-04-07 Mon	1	—	unknown	—	42.9° 17:50	7.72	89%	79.9°
2036-04-08 Tue	1	—	unknown	—	42.9° 17:50	7.66	95%	92.8°
2036-04-09 Wed	1	—	unknown	—	42.9° 17:45	7.6	99%	105.6°
2036-04-10 Thu	1	—	unknown	—	42.9° 17:40	7.55	100%	118.0°
2036-04-11 Fri	1	—	unknown	—	42.9° 17:35	7.49	98%	129.8°
2036-04-12 Sat	1	—	unknown	—	42.9° 17:35	7.43	95%	140.5°
2036-04-13 Sun	1	—	unknown	—	42.9° 17:30	7.38	89%	149.4°
2036-04-14 Mon	0	—	unknown	—	42.9° 17:25	7.32	82%	154.9°
2036-04-15 Tue	0	—	unknown	—	42.9° 17:20	7.26	74%	155.2°
2036-04-16 Wed	0	—	unknown	—	42.9° 17:15	7.2	66%	150.4°
2036-04-17 Thu	0	—	unknown	—	42.9° 17:15	7.14	56%	142.6°
2036-04-18 Fri	0	—	unknown	—	42.9° 17:10	7.09	47%	133.2°
2036-04-19 Sat	0	—	unknown	—	42.9° 17:05	7.03	37%	123.1°
2036-04-20 Sun	0	—	unknown	—	42.9° 17:00	6.97	28%	112.5°
2036-04-21 Mon	0	—	unknown	—	42.9° 16:55	6.91	20%	101.6°
2036-04-22 Tue	0	—	unknown	—	42.9° 16:55	6.85	13%	90.3°
2036-04-23 Wed	0	—	unknown	—	42.9° 16:50	6.8	7%	78.8°
2036-04-24 Thu	0	—	unknown	—	42.9° 16:45	6.74	3%	67.0°
2036-04-25 Fri	0	—	unknown	—	42.9° 16:40	6.68	0%	55.3°
2036-04-26 Sat	0	—	unknown	—	42.9° 16:40	6.62	0%	43.9°
2036-04-27 Sun	0	—	unknown	—	42.9° 16:35	6.56	3%	33.5°
2036-04-28 Mon	0	—	unknown	—	42.9° 16:30	6.5	8%	26.1°
2036-04-29 Tue	0	—	unknown	—	42.9° 16:25	6.45	15%	24.7°
2036-04-30 Wed	0	—	unknown	—	42.9° 16:20	6.39	25%	30.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-04-01&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.