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: 05-26 (57), 05-27 (48), 06-08 (40), 06-09 (39), 05-28 (38) — by astronomy; check the weather when the night is within four days.

2031-05-26astronomy score per night — click a bar for that night2031-06-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-26 Mon	57	—	unknown	22:50–01:25 (good, 2.58 h)	50.2° 21:35	5.05	26%	59.5°
2031-05-27 Tue	48	—	unknown	22:50–01:25 (good, 2.58 h)	50.2° 21:30	5.0	35%	47.8°
2031-05-28 Wed	38	—	unknown	22:50–01:00 (good, 2.17 h)	50.2° 21:25	4.96	45%	36.0°
2031-05-29 Thu	28	—	unknown	22:55–00:05 (good, 1.17 h)	50.2° 21:25	4.92	55%	24.3°
2031-05-30 Fri	22	—	unknown	22:55–01:35 (marginal, 2.67 h)	50.2° 21:20	4.88	65%	13.4°
2031-05-31 Sat	17	—	unknown	22:55–01:25 (marginal, 2.5 h)	50.2° 21:15	4.84	74%	9.5°
2031-06-01 Sun	13	—	unknown	22:55–01:10 (marginal, 2.25 h)	50.2° 21:10	4.8	83%	18.8°
2031-06-02 Mon	11	—	unknown	23:00–01:00 (marginal, 2.0 h)	50.2° 21:10	4.77	91%	31.8°
2031-06-03 Tue	13	—	unknown	23:00–01:00 (marginal, 2.0 h)	50.2° 21:05	4.73	96%	45.8°
2031-06-04 Wed	17	—	unknown	23:00–01:05 (marginal, 2.08 h)	50.2° 21:00	4.7	100%	60.3°
2031-06-05 Thu	22	—	unknown	23:00–23:10 (good, 0.17 h)	50.2° 20:55	4.67	100%	75.1°
2031-06-06 Fri	27	—	unknown	23:05–00:15 (good, 1.17 h)	50.2° 20:50	4.64	97%	90.1°
2031-06-07 Sat	33	—	unknown	23:05–00:25 (good, 1.33 h)	50.2° 20:50	4.61	91%	104.9°
2031-06-08 Sun	40	—	unknown	23:05–00:30 (good, 1.42 h)	50.2° 20:45	4.59	83%	119.6°
2031-06-09 Mon	39	—	unknown	23:05–00:25 (good, 1.33 h)	50.2° 20:40	4.56	74%	133.8°
2031-06-10 Tue	38	—	unknown	23:05–00:30 (good, 1.42 h)	50.2° 20:35	4.54	63%	147.5°
2031-06-11 Wed	35	—	unknown	23:10–00:25 (good, 1.25 h)	50.2° 20:30	4.52	52%	160.3°
2031-06-12 Thu	35	—	unknown	23:10–00:20 (good, 1.17 h)	50.2° 20:30	4.5	41%	170.1°
2031-06-13 Fri	33	—	unknown	23:10–00:15 (good, 1.08 h)	50.2° 20:25	4.48	31%	167.6°
2031-06-14 Sat	31	—	unknown	23:10–00:10 (good, 1.0 h)	50.2° 20:20	4.47	22%	156.9°
2031-06-15 Sun	29	—	unknown	23:10–00:10 (good, 1.0 h)	50.2° 20:15	4.46	14%	145.1°
2031-06-16 Mon	29	—	unknown	23:10–00:05 (good, 0.92 h)	50.2° 20:15	4.44	8%	133.1°
2031-06-17 Tue	27	—	unknown	23:10–00:00 (good, 0.83 h)	50.2° 20:10	4.44	4%	121.2°
2031-06-18 Wed	26	—	unknown	23:10–23:55 (good, 0.75 h)	50.2° 20:05	4.43	1%	109.4°
2031-06-19 Thu	24	—	unknown	23:10–23:55 (good, 0.75 h)	50.2° 20:00	4.43	0%	97.6°
2031-06-20 Fri	22	—	unknown	23:15–23:50 (good, 0.58 h)	50.2° 19:55	4.42	1%	85.9°
2031-06-21 Sat	21	—	unknown	23:15–23:45 (good, 0.5 h)	50.2° 19:55	4.42	4%	74.3°
2031-06-22 Sun	19	—	unknown	23:15–23:40 (good, 0.42 h)	50.2° 19:50	4.42	8%	62.6°
2031-06-23 Mon	17	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:45	4.43	14%	50.9°
2031-06-24 Tue	14	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:40	4.43	21%	39.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-26&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.