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: 05-17 (84), 05-18 (83), 05-19 (80), 05-20 (78), 05-21 (77) — by astronomy; check the weather when the night is within four days.

2047-05-17astronomy score per night — click a bar for that night2047-06-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-05-17 Fri	84	—	unknown	22:35–02:05 (good, 3.5 h)	50.1° 22:10	5.48	38%	153.5°
2047-05-18 Sat	83	—	unknown	22:35–02:00 (good, 3.42 h)	50.1° 22:05	5.42	29%	164.1°
2047-05-19 Sun	80	—	unknown	22:40–01:55 (good, 3.25 h)	50.1° 22:05	5.37	21%	170.2°
2047-05-20 Mon	78	—	unknown	22:40–01:50 (good, 3.17 h)	50.1° 22:00	5.32	14%	165.2°
2047-05-21 Tue	77	—	unknown	22:40–01:45 (good, 3.08 h)	50.1° 21:55	5.27	8%	155.2°
2047-05-22 Wed	74	—	unknown	22:45–01:45 (good, 3.0 h)	50.1° 21:50	5.23	4%	144.1°
2047-05-23 Thu	72	—	unknown	22:45–01:40 (good, 2.92 h)	50.1° 21:45	5.18	1%	132.6°
2047-05-24 Fri	70	—	unknown	22:45–01:35 (good, 2.83 h)	50.1° 21:45	5.13	0%	120.8°
2047-05-25 Sat	68	—	unknown	22:50–01:30 (good, 2.67 h)	50.1° 21:40	5.09	1%	108.9°
2047-05-26 Sun	66	—	unknown	22:50–01:25 (good, 2.58 h)	50.1° 21:35	5.04	4%	96.9°
2047-05-27 Mon	63	—	unknown	22:50–01:25 (good, 2.58 h)	50.1° 21:30	5.0	9%	84.6°
2047-05-28 Tue	58	—	unknown	22:50–01:20 (good, 2.5 h)	50.1° 21:30	4.96	16%	72.1°
2047-05-29 Wed	51	—	unknown	22:55–01:15 (good, 2.33 h)	50.1° 21:25	4.91	24%	59.5°
2047-05-30 Thu	43	—	unknown	22:55–01:10 (good, 2.25 h)	50.1° 21:20	4.87	33%	46.7°
2047-05-31 Fri	34	—	unknown	22:55–00:45 (good, 1.83 h)	50.1° 21:15	4.84	44%	33.7°
2047-06-01 Sat	25	—	unknown	22:55–01:30 (marginal, 2.58 h)	50.1° 21:10	4.8	55%	21.1°
2047-06-02 Sun	20	—	unknown	23:00–01:25 (marginal, 2.42 h)	50.1° 21:10	4.76	66%	10.9°
2047-06-03 Mon	15	—	unknown	23:00–01:10 (marginal, 2.17 h)	50.1° 21:05	4.73	77%	13.9°
2047-06-04 Tue	12	—	unknown	23:00–01:00 (marginal, 2.0 h)	50.1° 21:00	4.7	86%	26.3°
2047-06-05 Wed	12	—	unknown	23:00–00:55 (marginal, 1.92 h)	50.1° 20:55	4.67	93%	40.3°
2047-06-06 Thu	15	—	unknown	23:05–00:55 (marginal, 1.83 h)	50.1° 20:50	4.64	98%	54.8°
2047-06-07 Fri	19	—	unknown	23:05–01:00 (marginal, 1.92 h)	50.1° 20:50	4.61	100%	69.4°
2047-06-08 Sat	23	—	unknown	23:05–23:55 (good, 0.83 h)	50.1° 20:45	4.58	99%	83.9°
2047-06-09 Sun	28	—	unknown	23:05–00:10 (good, 1.08 h)	50.1° 20:40	4.56	95%	98.0°
2047-06-10 Mon	35	—	unknown	23:05–00:15 (good, 1.17 h)	50.1° 20:35	4.54	90%	111.7°
2047-06-11 Tue	35	—	unknown	23:10–00:20 (good, 1.17 h)	50.1° 20:35	4.52	82%	125.0°
2047-06-12 Wed	34	—	unknown	23:10–00:20 (good, 1.17 h)	50.1° 20:30	4.5	73%	137.7°
2047-06-13 Thu	33	—	unknown	23:10–00:15 (good, 1.08 h)	50.1° 20:25	4.48	64%	149.8°
2047-06-14 Fri	31	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:20	4.47	54%	161.0°
2047-06-15 Sat	29	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:15	4.45	44%	169.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-05-17&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.