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: 01-21 (93), 01-22 (93), 01-23 (93), 01-24 (93), 01-25 (93) — by astronomy; check the weather when the night is within four days.

2037-01-21astronomy score per night — click a bar for that night2037-02-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-01-21 Wed	93	—	unknown	01:00–06:05 (good, 5.08 h)	50.2° 04:45	11.07	25%	176.4°
2037-01-22 Thu	93	—	unknown	00:55–06:05 (good, 5.17 h)	50.2° 04:40	11.05	34%	171.6°
2037-01-23 Fri	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:35	11.02	43%	159.5°
2037-01-24 Sat	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:35	10.99	53%	147.1°
2037-01-25 Sun	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:30	10.96	63%	134.3°
2037-01-26 Mon	93	—	unknown	00:45–06:05 (good, 5.33 h)	50.2° 04:25	10.93	73%	121.1°
2037-01-27 Tue	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:20	10.9	82%	107.4°
2037-01-28 Wed	92	—	unknown	01:15–06:05 (good, 4.83 h)	50.2° 04:15	10.87	90%	93.3°
2037-01-29 Thu	63	—	unknown	03:05–06:00 (good, 2.92 h)	50.2° 04:15	10.84	96%	78.7°
2037-01-30 Fri	44	—	unknown	00:30–06:00 (marginal, 5.5 h)	50.2° 04:10	10.81	99%	63.7°
2037-01-31 Sat	28	—	unknown	01:05–06:00 (marginal, 4.92 h)	50.2° 04:05	10.78	100%	48.5°
2037-02-01 Sun	18	—	unknown	03:40–06:00 (marginal, 2.33 h)	50.2° 04:00	10.75	97%	33.3°
2037-02-02 Mon	18	—	unknown	02:30–06:00 (marginal, 3.5 h)	50.2° 04:00	10.71	92%	18.2°
2037-02-03 Tue	24	—	unknown	00:05–06:00 (marginal, 5.92 h)	50.2° 03:55	10.68	84%	3.4°
2037-02-04 Wed	37	—	unknown	23:45–05:55 (marginal, 6.17 h)	50.2° 03:50	10.64	74%	11.1°
2037-02-05 Thu	53	—	unknown	23:30–05:55 (marginal, 6.42 h)	50.2° 03:45	10.61	64%	25.1°
2037-02-06 Fri	83	—	unknown	23:55–05:55 (good, 6.0 h)	50.2° 03:40	10.57	53%	38.8°
2037-02-07 Sat	89	—	unknown	23:50–05:55 (good, 6.08 h)	50.2° 03:40	10.54	43%	52.0°
2037-02-08 Sun	93	—	unknown	23:45–05:50 (good, 6.08 h)	50.2° 03:35	10.5	33%	64.8°
2037-02-09 Mon	93	—	unknown	23:45–05:50 (good, 6.08 h)	50.2° 03:30	10.46	24%	77.4°
2037-02-10 Tue	93	—	unknown	23:40–05:50 (good, 6.17 h)	50.2° 03:25	10.43	16%	89.8°
2037-02-11 Wed	93	—	unknown	23:35–05:50 (good, 6.25 h)	50.2° 03:20	10.39	9%	101.9°
2037-02-12 Thu	93	—	unknown	23:30–05:50 (good, 6.33 h)	50.2° 03:20	10.35	4%	114.0°
2037-02-13 Fri	93	—	unknown	23:30–05:45 (good, 6.25 h)	50.2° 03:15	10.31	1%	125.9°
2037-02-14 Sat	93	—	unknown	23:25–05:45 (good, 6.33 h)	50.2° 03:10	10.27	0%	137.8°
2037-02-15 Sun	93	—	unknown	23:20–05:45 (good, 6.42 h)	50.2° 03:05	10.23	0%	149.6°
2037-02-16 Mon	93	—	unknown	23:15–05:45 (good, 6.5 h)	50.2° 03:05	10.19	3%	161.4°
2037-02-17 Tue	93	—	unknown	23:10–05:40 (good, 6.5 h)	50.2° 03:00	10.15	7%	173.3°
2037-02-18 Wed	93	—	unknown	23:10–05:40 (good, 6.5 h)	50.2° 02:55	10.11	12%	174.8°
2037-02-19 Thu	93	—	unknown	23:05–05:40 (good, 6.58 h)	50.2° 02:50	10.07	19%	162.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-01-21&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.