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: 03-20 (93), 03-21 (93), 03-22 (93), 03-23 (93), 03-24 (93) — by astronomy; check the weather when the night is within four days.

2039-03-20astronomy score per night — click a bar for that night2039-04-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2039-03-23 Wed	93	—	unknown	21:00–04:40 (good, 7.67 h)	50.1° 00:45	8.57	1%	167.8°
2039-03-24 Thu	93	—	unknown	20:55–04:35 (good, 7.67 h)	50.1° 00:45	8.52	0%	179.6°
2039-03-25 Fri	93	—	unknown	20:50–04:30 (good, 7.67 h)	50.1° 00:40	8.47	2%	167.2°
2039-03-26 Sat	93	—	unknown	20:50–05:25 (good, 7.58 h)	50.1° 00:35	8.42	5%	155.0°
2039-03-27 Sun	93	—	unknown	21:45–05:25 (good, 7.67 h)	50.1° 01:30	8.36	10%	143.0°
2039-03-28 Mon	93	—	unknown	21:40–05:20 (good, 7.67 h)	50.1° 01:25	8.31	16%	131.1°
2039-03-29 Tue	93	—	unknown	21:40–05:15 (good, 7.58 h)	50.1° 01:25	8.25	23%	119.3°
2039-03-30 Wed	93	—	unknown	21:40–05:10 (good, 7.5 h)	50.1° 01:20	8.2	32%	107.4°
2039-03-31 Thu	92	—	unknown	21:40–05:05 (good, 7.42 h)	50.1° 01:15	8.15	41%	95.5°
2039-04-01 Fri	88	—	unknown	21:45–05:05 (good, 7.33 h)	50.1° 01:10	8.09	50%	83.5°
2039-04-02 Sat	83	—	unknown	22:25–05:00 (good, 6.58 h)	50.1° 01:10	8.04	60%	71.2°
2039-04-03 Sun	69	—	unknown	00:25–04:30 (good, 4.08 h)	50.1° 01:05	7.98	70%	58.7°
2039-04-04 Mon	53	—	unknown	21:30–05:20 (marginal, 7.83 h)	50.1° 01:00	7.93	79%	45.7°
2039-04-05 Tue	33	—	unknown	22:05–05:05 (marginal, 7.0 h)	50.1° 00:55	7.87	87%	32.3°
2039-04-06 Wed	24	—	unknown	00:45–04:45 (marginal, 4.0 h)	50.1° 00:50	7.81	93%	18.4°
2039-04-07 Thu	20	—	unknown	02:15–04:30 (marginal, 2.25 h)	50.1° 00:50	7.76	98%	4.2°
2039-04-08 Fri	21	—	unknown	21:35–00:35 (marginal, 3.0 h)	50.1° 00:45	7.7	100%	10.4°
2039-04-09 Sat	29	—	unknown	21:35–04:05 (marginal, 6.5 h)	50.1° 00:40	7.64	99%	25.3°
2039-04-10 Sun	75	—	unknown	21:35–21:50 (good, 0.25 h)	50.1° 00:35	7.59	95%	40.2°
2039-04-11 Mon	90	—	unknown	21:40–01:05 (good, 3.42 h)	50.1° 00:30	7.53	89%	55.1°
2039-04-12 Tue	93	—	unknown	21:40–03:20 (good, 5.67 h)	50.1° 00:30	7.47	80%	69.9°
2039-04-13 Wed	93	—	unknown	21:40–03:55 (good, 6.25 h)	50.1° 00:25	7.42	70%	84.3°
2039-04-14 Thu	93	—	unknown	21:45–04:00 (good, 6.25 h)	50.1° 00:20	7.36	59%	98.5°
2039-04-15 Fri	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.1° 00:15	7.3	48%	112.3°
2039-04-16 Sat	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.1° 00:15	7.24	37%	125.8°
2039-04-17 Sun	93	—	unknown	21:45–04:00 (good, 6.25 h)	50.1° 00:10	7.19	27%	138.9°
2039-04-18 Mon	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.1° 00:05	7.13	19%	151.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-03-20&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.