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: 05-02 (93), 05-03 (93), 05-04 (93), 05-05 (93), 05-06 (93) — by astronomy; check the weather when the night is within four days.

2037-04-20astronomy score per night — click a bar for that night2037-05-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-04-20 Mon	92	—	unknown	21:50–03:45 (good, 5.92 h)	50.2° 23:55	6.98	27%	92.7°
2037-04-21 Tue	88	—	unknown	21:55–03:45 (good, 5.83 h)	50.2° 23:50	6.93	37%	79.2°
2037-04-22 Wed	83	—	unknown	21:55–03:40 (good, 5.75 h)	50.2° 23:45	6.87	48%	65.5°
2037-04-23 Thu	66	—	unknown	22:30–03:15 (good, 4.75 h)	50.2° 23:45	6.81	59%	51.5°
2037-04-24 Fri	44	—	unknown	22:00–04:00 (marginal, 6.0 h)	50.2° 23:40	6.75	70%	37.2°
2037-04-25 Sat	29	—	unknown	22:00–03:45 (marginal, 5.75 h)	50.2° 23:35	6.69	80%	22.7°
2037-04-26 Sun	21	—	unknown	22:00–03:25 (marginal, 5.42 h)	50.2° 23:30	6.64	89%	8.1°
2037-04-27 Mon	16	—	unknown	22:05–03:05 (marginal, 5.0 h)	50.1° 23:25	6.58	95%	6.7°
2037-04-28 Tue	17	—	unknown	22:05–02:50 (marginal, 4.75 h)	50.2° 23:25	6.52	99%	21.3°
2037-04-29 Wed	24	—	unknown	22:05–02:50 (marginal, 4.75 h)	50.2° 23:20	6.46	100%	35.8°
2037-04-30 Thu	39	—	unknown	22:10–03:10 (marginal, 5.0 h)	50.2° 23:15	6.4	98%	50.1°
2037-05-01 Fri	79	—	unknown	22:10–00:25 (good, 2.25 h)	50.2° 23:10	6.34	94%	64.0°
2037-05-02 Sat	93	—	unknown	22:10–02:05 (good, 3.92 h)	50.2° 23:10	6.29	88%	77.5°
2037-05-03 Sun	93	—	unknown	22:15–02:35 (good, 4.33 h)	50.2° 23:05	6.23	80%	90.5°
2037-05-04 Mon	93	—	unknown	22:15–02:40 (good, 4.42 h)	50.2° 23:00	6.17	72%	103.2°
2037-05-05 Tue	93	—	unknown	22:15–02:40 (good, 4.42 h)	50.2° 22:55	6.11	62%	115.6°
2037-05-06 Wed	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.2° 22:50	6.06	53%	127.7°
2037-05-07 Thu	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.2° 22:50	6.0	43%	139.7°
2037-05-08 Fri	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.2° 22:45	5.94	34%	151.5°
2037-05-09 Sat	93	—	unknown	22:25–02:30 (good, 4.08 h)	50.2° 22:40	5.89	25%	163.4°
2037-05-10 Sun	93	—	unknown	22:25–02:30 (good, 4.08 h)	50.2° 22:35	5.83	18%	175.3°
2037-05-11 Mon	93	—	unknown	22:25–02:25 (good, 4.0 h)	50.1° 22:30	5.78	11%	172.7°
2037-05-12 Tue	93	—	unknown	22:30–02:20 (good, 3.83 h)	50.2° 22:30	5.72	6%	160.5°
2037-05-13 Wed	92	—	unknown	22:30–02:15 (good, 3.75 h)	50.2° 22:25	5.67	2%	148.1°
2037-05-14 Thu	90	—	unknown	22:30–02:10 (good, 3.67 h)	50.2° 22:20	5.61	0%	135.4°
2037-05-15 Fri	87	—	unknown	22:35–02:10 (good, 3.58 h)	50.2° 22:15	5.56	1%	122.5°
2037-05-16 Sat	86	—	unknown	22:35–02:05 (good, 3.5 h)	50.1° 22:15	5.51	3%	109.3°
2037-05-17 Sun	83	—	unknown	22:35–02:00 (good, 3.42 h)	50.2° 22:10	5.46	8%	95.9°
2037-05-18 Mon	77	—	unknown	22:40–01:55 (good, 3.25 h)	50.2° 22:05	5.4	15%	82.3°
2037-05-19 Tue	69	—	unknown	22:40–01:55 (good, 3.25 h)	50.2° 22:00	5.35	24%	68.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-04-20&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.