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: 04-21 (93), 04-22 (93), 04-23 (93), 04-24 (93), 04-25 (93) — by astronomy; check the weather when the night is within four days.

2044-04-21astronomy score per night — click a bar for that night2044-05-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-04-21 Thu	93	—	unknown	21:55–03:40 (good, 5.75 h)	50.1° 23:50	6.91	36%	132.8°
2044-04-22 Fri	93	—	unknown	21:55–03:40 (good, 5.75 h)	50.1° 23:45	6.85	27%	145.2°
2044-04-23 Sat	93	—	unknown	22:00–03:35 (good, 5.58 h)	50.1° 23:40	6.79	18%	157.8°
2044-04-24 Sun	93	—	unknown	22:00–03:30 (good, 5.5 h)	50.1° 23:40	6.73	11%	169.9°
2044-04-25 Mon	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:35	6.67	5%	171.5°
2044-04-26 Tue	93	—	unknown	22:00–03:20 (good, 5.33 h)	50.1° 23:30	6.62	1%	159.1°
2044-04-27 Wed	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.1° 23:25	6.56	0%	145.0°
2044-04-28 Thu	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:25	6.5	2%	130.5°
2044-04-29 Fri	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.1° 23:20	6.44	6%	115.8°
2044-04-30 Sat	92	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:15	6.38	14%	101.1°
2044-05-01 Sun	88	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:10	6.33	23%	86.5°
2044-05-02 Mon	83	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:05	6.27	33%	72.2°
2044-05-03 Tue	73	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:05	6.21	44%	58.2°
2044-05-04 Wed	54	—	unknown	22:15–02:25 (good, 4.17 h)	50.1° 23:00	6.15	56%	44.5°
2044-05-05 Thu	37	—	unknown	22:15–03:15 (marginal, 5.0 h)	50.1° 22:55	6.1	66%	31.2°
2044-05-06 Fri	28	—	unknown	22:20–03:00 (marginal, 4.67 h)	50.1° 22:50	6.04	76%	18.4°
2044-05-07 Sat	22	—	unknown	22:20–02:50 (marginal, 4.5 h)	50.1° 22:45	5.98	84%	7.6°
2044-05-08 Sun	18	—	unknown	22:20–02:35 (marginal, 4.25 h)	50.1° 22:45	5.93	91%	10.5°
2044-05-09 Mon	17	—	unknown	22:25–02:25 (marginal, 4.0 h)	50.1° 22:40	5.87	96%	21.9°
2044-05-10 Tue	20	—	unknown	22:25–02:20 (marginal, 3.92 h)	50.1° 22:35	5.81	99%	33.9°
2044-05-11 Wed	28	—	unknown	22:25–02:25 (marginal, 4.0 h)	50.1° 22:30	5.76	100%	46.0°
2044-05-12 Thu	38	—	unknown	22:30–23:00 (good, 0.5 h)	50.1° 22:30	5.7	99%	57.9°
2044-05-13 Fri	68	—	unknown	22:30–00:40 (good, 2.17 h)	50.1° 22:25	5.65	96%	69.8°
2044-05-14 Sat	77	—	unknown	22:30–01:40 (good, 3.17 h)	50.1° 22:20	5.6	92%	81.6°
2044-05-15 Sun	80	—	unknown	22:35–01:50 (good, 3.25 h)	50.1° 22:15	5.54	86%	93.4°
2044-05-16 Mon	82	—	unknown	22:35–01:50 (good, 3.25 h)	50.1° 22:10	5.49	79%	105.1°
2044-05-17 Tue	83	—	unknown	22:35–01:55 (good, 3.33 h)	50.1° 22:10	5.44	71%	116.9°
2044-05-18 Wed	81	—	unknown	22:40–01:55 (good, 3.25 h)	50.1° 22:05	5.39	62%	128.8°
2044-05-19 Thu	79	—	unknown	22:40–01:50 (good, 3.17 h)	50.1° 22:00	5.34	52%	140.9°
2044-05-20 Fri	77	—	unknown	22:40–01:50 (good, 3.17 h)	50.1° 21:55	5.29	42%	153.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-04-21&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.