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: 07-20 (1) — by astronomy; check the weather when the night is within four days.

2028-07-20astronomy score per night — click a bar for that night2028-08-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-07-20 Thu	1	—	unknown	—	50.2° 17:55	5.25	2%	83.2°
2028-07-21 Fri	0	—	unknown	—	50.2° 17:50	5.3	0%	68.9°
2028-07-22 Sat	0	—	unknown	—	50.2° 17:50	5.35	1%	54.5°
2028-07-23 Sun	0	—	unknown	—	50.2° 17:45	5.4	5%	40.0°
2028-07-24 Mon	0	—	unknown	—	50.2° 17:40	5.45	11%	25.9°
2028-07-25 Tue	0	—	unknown	—	50.2° 17:35	5.5	20%	13.5°
2028-07-26 Wed	0	—	unknown	—	50.2° 17:30	5.55	30%	11.0°
2028-07-27 Thu	0	—	unknown	—	50.2° 17:30	5.6	41%	21.6°
2028-07-28 Fri	0	—	unknown	—	50.2° 17:25	5.66	52%	34.4°
2028-07-29 Sat	0	—	unknown	—	50.2° 17:20	5.71	63%	47.5°
2028-07-30 Sun	0	—	unknown	—	50.2° 17:15	5.77	73%	60.5°
2028-07-31 Mon	0	—	unknown	—	50.2° 17:15	5.82	82%	73.3°
2028-08-01 Tue	0	—	unknown	—	50.2° 17:10	5.88	89%	85.8°
2028-08-02 Wed	0	—	unknown	—	50.2° 17:05	5.93	94%	98.2°
2028-08-03 Thu	0	—	unknown	—	50.2° 17:00	5.99	98%	110.4°
2028-08-04 Fri	0	—	unknown	—	50.2° 16:55	6.04	100%	122.4°
2028-08-05 Sat	0	—	unknown	—	50.2° 16:55	6.1	100%	134.2°
2028-08-06 Sun	0	—	unknown	—	50.2° 16:50	6.16	98%	145.7°
2028-08-07 Mon	0	—	unknown	—	50.2° 16:45	6.21	94%	156.8°
2028-08-08 Tue	0	—	unknown	—	50.2° 16:40	6.27	88%	166.5°
2028-08-09 Wed	0	—	unknown	—	50.2° 16:35	6.33	82%	169.9°
2028-08-10 Thu	0	—	unknown	—	50.2° 16:35	6.38	74%	162.7°
2028-08-11 Fri	0	—	unknown	—	50.2° 16:30	6.44	65%	152.0°
2028-08-12 Sat	0	—	unknown	—	50.2° 16:25	6.5	56%	140.4°
2028-08-13 Sun	0	—	unknown	—	50.2° 16:20	6.56	46%	128.3°
2028-08-14 Mon	0	—	unknown	—	50.2° 16:20	6.61	35%	115.7°
2028-08-15 Tue	0	—	unknown	—	50.2° 16:15	6.67	26%	102.7°
2028-08-16 Wed	0	—	unknown	—	50.2° 16:10	6.73	16%	89.2°
2028-08-17 Thu	0	—	unknown	—	50.2° 16:05	6.79	9%	75.2°
2028-08-18 Fri	0	—	unknown	—	50.2° 16:00	6.84	3%	60.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-07-20&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.