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 3C 273: 07-12 (2), 07-13 (1), 07-14 (1), 07-15 (1), 07-16 (1) — by astronomy; check the weather when the night is within four days.

2040-07-12astronomy score per night — click a bar for that night2040-08-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-12 Thu	2	—	unknown	—	50.1° 18:30	4.9	11%	35.7°
2040-07-13 Fri	1	—	unknown	—	50.1° 18:25	4.94	18%	23.7°
2040-07-14 Sat	1	—	unknown	—	50.1° 18:20	4.98	26%	11.5°
2040-07-15 Sun	1	—	unknown	—	50.1° 18:15	5.02	35%	1.1°
2040-07-16 Mon	1	—	unknown	—	50.1° 18:10	5.07	45%	13.7°
2040-07-17 Tue	0	—	unknown	—	50.1° 18:10	5.11	56%	26.8°
2040-07-18 Wed	0	—	unknown	—	50.1° 18:05	5.16	66%	40.3°
2040-07-19 Thu	0	—	unknown	—	50.1° 18:00	5.21	77%	54.3°
2040-07-20 Fri	0	—	unknown	—	50.1° 17:55	5.25	86%	68.7°
2040-07-21 Sat	0	—	unknown	—	50.1° 17:50	5.3	93%	83.5°
2040-07-22 Sun	0	—	unknown	—	50.1° 17:50	5.35	98%	98.6°
2040-07-23 Mon	0	—	unknown	—	50.1° 17:45	5.4	100%	113.8°
2040-07-24 Tue	0	—	unknown	—	50.1° 17:40	5.45	99%	129.1°
2040-07-25 Wed	0	—	unknown	—	50.1° 17:35	5.5	95%	144.1°
2040-07-26 Thu	0	—	unknown	—	50.1° 17:35	5.56	88%	158.8°
2040-07-27 Fri	0	—	unknown	—	50.1° 17:30	5.61	80%	173.1°
2040-07-28 Sat	0	—	unknown	—	50.1° 17:25	5.66	70%	173.1°
2040-07-29 Sun	0	—	unknown	—	50.1° 17:20	5.72	60%	159.7°
2040-07-30 Mon	0	—	unknown	—	50.1° 17:15	5.77	49%	146.8°
2040-07-31 Tue	0	—	unknown	—	50.1° 17:15	5.83	39%	134.2°
2040-08-01 Wed	0	—	unknown	—	50.1° 17:10	5.88	30%	122.0°
2040-08-02 Thu	0	—	unknown	—	50.1° 17:05	5.94	22%	109.9°
2040-08-03 Fri	0	—	unknown	—	50.1° 17:00	5.99	14%	98.0°
2040-08-04 Sat	0	—	unknown	—	50.1° 16:55	6.05	8%	86.1°
2040-08-05 Sun	0	—	unknown	—	50.1° 16:55	6.1	4%	74.3°
2040-08-06 Mon	0	—	unknown	—	50.1° 16:50	6.16	1%	62.5°
2040-08-07 Tue	0	—	unknown	—	50.1° 16:45	6.22	0%	50.6°
2040-08-08 Wed	0	—	unknown	—	50.1° 16:40	6.28	1%	38.6°
2040-08-09 Thu	0	—	unknown	—	50.1° 16:40	6.33	4%	26.6°
2040-08-10 Fri	0	—	unknown	—	50.1° 16:35	6.39	8%	14.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-12&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.