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: 01-16 (93), 01-17 (93), 01-18 (93), 01-19 (93), 01-20 (93) — by astronomy; check the weather when the night is within four days.

2040-01-16astronomy score per night — click a bar for that night2040-02-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-16 Mon	93	—	unknown	01:20–06:10 (good, 4.83 h)	50.1° 05:10	11.21	11%	149.3°
2040-01-17 Tue	93	—	unknown	01:15–06:10 (good, 4.92 h)	50.1° 05:05	11.19	19%	163.4°
2040-01-18 Wed	93	—	unknown	01:15–06:10 (good, 4.92 h)	50.1° 05:00	11.17	28%	176.9°
2040-01-19 Thu	93	—	unknown	01:10–06:10 (good, 5.0 h)	50.1° 04:55	11.14	38%	170.0°
2040-01-20 Fri	93	—	unknown	01:05–06:10 (good, 5.08 h)	50.1° 04:50	11.12	48%	157.3°
2040-01-21 Sat	93	—	unknown	01:05–06:05 (good, 5.0 h)	50.1° 04:50	11.09	58%	144.9°
2040-01-22 Sun	93	—	unknown	01:05–06:05 (good, 5.0 h)	50.1° 04:45	11.07	68%	132.8°
2040-01-23 Mon	93	—	unknown	01:00–06:05 (good, 5.08 h)	50.1° 04:40	11.04	76%	120.8°
2040-01-24 Tue	93	—	unknown	01:05–06:05 (good, 5.0 h)	50.1° 04:35	11.01	84%	109.0°
2040-01-25 Wed	92	—	unknown	01:15–06:05 (good, 4.83 h)	50.1° 04:30	10.98	90%	97.2°
2040-01-26 Thu	67	—	unknown	02:35–06:05 (good, 3.5 h)	50.1° 04:30	10.96	95%	85.3°
2040-01-27 Fri	52	—	unknown	04:25–06:05 (good, 1.67 h)	50.1° 04:25	10.93	98%	73.4°
2040-01-28 Sat	38	—	unknown	00:45–06:05 (marginal, 5.33 h)	50.1° 04:20	10.9	100%	61.4°
2040-01-29 Sun	27	—	unknown	01:20–06:00 (marginal, 4.67 h)	50.1° 04:15	10.87	100%	49.3°
2040-01-30 Mon	19	—	unknown	03:25–06:00 (marginal, 2.58 h)	50.1° 04:10	10.83	97%	37.0°
2040-01-31 Tue	16	—	unknown	04:00–06:00 (marginal, 2.0 h)	50.1° 04:10	10.8	93%	24.5°
2040-02-01 Wed	20	—	unknown	00:30–06:00 (marginal, 5.5 h)	50.1° 04:05	10.77	88%	11.9°
2040-02-02 Thu	28	—	unknown	00:05–06:00 (marginal, 5.92 h)	50.1° 04:00	10.74	80%	0.9°
2040-02-03 Fri	41	—	unknown	23:50–06:00 (marginal, 6.17 h)	50.1° 03:55	10.7	71%	14.0°
2040-02-04 Sat	58	—	unknown	01:25–02:50 (good, 1.42 h)	50.1° 03:55	10.67	61%	27.3°
2040-02-05 Sun	85	—	unknown	00:00–05:55 (good, 5.92 h)	50.1° 03:50	10.64	50%	40.9°
2040-02-06 Mon	91	—	unknown	00:00–05:55 (good, 5.92 h)	50.1° 03:45	10.6	39%	54.8°
2040-02-07 Tue	93	—	unknown	23:55–05:55 (good, 6.0 h)	50.1° 03:40	10.56	28%	69.0°
2040-02-08 Wed	93	—	unknown	23:50–05:55 (good, 6.08 h)	50.1° 03:35	10.53	18%	83.5°
2040-02-09 Thu	93	—	unknown	23:45–05:50 (good, 6.08 h)	50.1° 03:35	10.49	10%	98.3°
2040-02-10 Fri	93	—	unknown	23:40–05:50 (good, 6.17 h)	50.1° 03:30	10.45	4%	113.2°
2040-02-11 Sat	93	—	unknown	23:40–05:50 (good, 6.17 h)	50.1° 03:25	10.42	1%	128.0°
2040-02-12 Sun	93	—	unknown	23:35–05:50 (good, 6.25 h)	50.1° 03:20	10.38	0%	142.7°
2040-02-13 Mon	93	—	unknown	23:30–05:50 (good, 6.33 h)	50.1° 03:15	10.34	3%	157.2°
2040-02-14 Tue	93	—	unknown	23:25–05:45 (good, 6.33 h)	50.1° 03:15	10.3	7%	171.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-16&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.