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: 02-21 (93), 02-22 (93), 02-23 (93), 02-24 (93), 02-25 (93) — by astronomy; check the weather when the night is within four days.

2039-02-21astronomy score per night — click a bar for that night2039-03-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-02-21 Mon	93	—	unknown	23:00–05:35 (good, 6.58 h)	50.1° 02:45	10.01	2%	132.5°
2039-02-22 Tue	93	—	unknown	22:55–05:35 (good, 6.67 h)	50.1° 02:40	9.96	0%	146.0°
2039-02-23 Wed	93	—	unknown	22:50–05:35 (good, 6.75 h)	50.1° 02:35	9.92	1%	159.1°
2039-02-24 Thu	93	—	unknown	22:45–05:35 (good, 6.83 h)	50.1° 02:35	9.88	4%	172.0°
2039-02-25 Fri	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.1° 02:30	9.83	8%	175.4°
2039-02-26 Sat	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.1° 02:25	9.79	14%	163.1°
2039-02-27 Sun	93	—	unknown	22:35–05:30 (good, 6.92 h)	50.1° 02:20	9.74	22%	151.0°
2039-02-28 Mon	93	—	unknown	22:35–05:25 (good, 6.83 h)	50.1° 02:15	9.7	30%	139.1°
2039-03-01 Tue	93	—	unknown	22:30–05:25 (good, 6.92 h)	50.1° 02:15	9.65	39%	127.2°
2039-03-02 Wed	93	—	unknown	22:30–05:25 (good, 6.92 h)	50.1° 02:10	9.61	48%	115.4°
2039-03-03 Thu	93	—	unknown	22:30–05:20 (good, 6.83 h)	50.1° 02:05	9.56	58%	103.5°
2039-03-04 Fri	91	—	unknown	22:40–05:20 (good, 6.67 h)	50.1° 02:00	9.52	67%	91.4°
2039-03-05 Sat	86	—	unknown	23:35–05:20 (good, 5.75 h)	50.1° 02:00	9.47	76%	79.1°
2039-03-06 Sun	81	—	unknown	01:45–05:15 (good, 3.5 h)	50.1° 01:55	9.42	84%	66.5°
2039-03-07 Mon	50	—	unknown	22:15–05:15 (marginal, 7.0 h)	50.1° 01:50	9.38	91%	53.5°
2039-03-08 Tue	32	—	unknown	00:00–05:15 (marginal, 5.25 h)	50.1° 01:45	9.33	96%	40.1°
2039-03-09 Wed	20	—	unknown	02:45–05:10 (marginal, 2.42 h)	50.1° 01:40	9.28	99%	26.4°
2039-03-10 Thu	19	—	unknown	03:25–05:10 (marginal, 1.75 h)	50.1° 01:40	9.23	100%	12.4°
2039-03-11 Fri	21	—	unknown	22:00–00:35 (marginal, 2.58 h)	50.1° 01:35	9.18	98%	2.0°
2039-03-12 Sat	31	—	unknown	21:35–05:05 (marginal, 7.5 h)	50.1° 01:30	9.13	93%	16.4°
2039-03-13 Sun	64	—	unknown	21:40–21:55 (good, 0.25 h)	50.1° 01:25	9.08	86%	30.9°
2039-03-14 Mon	86	—	unknown	21:35–01:25 (good, 3.83 h)	50.1° 01:20	9.03	77%	45.4°
2039-03-15 Tue	92	—	unknown	21:30–04:10 (good, 6.67 h)	50.1° 01:20	8.98	67%	59.8°
2039-03-16 Wed	93	—	unknown	21:30–04:45 (good, 7.25 h)	50.1° 01:15	8.93	56%	74.0°
2039-03-17 Thu	93	—	unknown	21:25–04:50 (good, 7.42 h)	50.1° 01:10	8.88	44%	88.0°
2039-03-18 Fri	93	—	unknown	21:20–04:55 (good, 7.58 h)	50.1° 01:05	8.83	33%	101.8°
2039-03-19 Sat	93	—	unknown	21:15–04:50 (good, 7.58 h)	50.1° 01:05	8.78	24%	115.4°
2039-03-20 Sun	93	—	unknown	21:10–04:50 (good, 7.67 h)	50.1° 01:00	8.73	15%	128.8°
2039-03-21 Mon	93	—	unknown	21:10–04:45 (good, 7.58 h)	50.1° 00:55	8.68	8%	142.0°
2039-03-22 Tue	93	—	unknown	21:05–04:45 (good, 7.67 h)	50.1° 00:50	8.63	4%	155.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-02-21&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.