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: 05-04 (93), 05-05 (93), 05-06 (93), 05-07 (93), 05-08 (93) — by astronomy; check the weather when the night is within four days.

2037-05-04astronomy score per night — click a bar for that night2037-06-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2037-05-20 Wed	57	—	unknown	22:40–01:50 (good, 3.17 h)	50.2° 21:55	5.3	34%	54.7°
2037-05-21 Thu	44	—	unknown	22:40–01:25 (good, 2.75 h)	50.2° 21:55	5.25	45%	40.6°
2037-05-22 Fri	31	—	unknown	22:45–02:10 (marginal, 3.42 h)	50.2° 21:50	5.21	56%	26.5°
2037-05-23 Sat	22	—	unknown	22:45–02:00 (marginal, 3.25 h)	50.2° 21:45	5.16	68%	12.2°
2037-05-24 Sun	16	—	unknown	22:45–01:45 (marginal, 3.0 h)	50.2° 21:40	5.11	78%	2.1°
2037-05-25 Mon	12	—	unknown	22:50–01:25 (marginal, 2.58 h)	50.1° 21:35	5.07	87%	16.4°
2037-05-26 Tue	11	—	unknown	22:50–01:10 (marginal, 2.33 h)	50.2° 21:35	5.02	93%	30.6°
2037-05-27 Wed	15	—	unknown	22:50–01:15 (marginal, 2.42 h)	50.2° 21:30	4.98	98%	44.7°
2037-05-28 Thu	20	—	unknown	22:55–01:25 (marginal, 2.5 h)	50.2° 21:25	4.94	100%	58.6°
2037-05-29 Fri	27	—	unknown	22:55–23:15 (good, 0.33 h)	50.2° 21:20	4.9	99%	72.2°
2037-05-30 Sat	35	—	unknown	22:55–00:35 (good, 1.67 h)	50.1° 21:20	4.86	96%	85.5°
2037-05-31 Sun	49	—	unknown	22:55–00:45 (good, 1.83 h)	50.2° 21:15	4.82	92%	98.5°
2037-06-01 Mon	50	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:10	4.78	85%	111.2°
2037-06-02 Tue	50	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:05	4.75	77%	123.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-04&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.