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: 01-20 (93), 01-21 (93), 01-22 (93), 01-23 (93), 01-24 (93) — by astronomy; check the weather when the night is within four days.

2039-01-17astronomy score per night — click a bar for that night2039-02-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-01-17 Mon	58	—	unknown	01:40–06:10 (good, 4.5 h)	50.1° 05:05	11.18	48%	23.8°
2039-01-18 Tue	83	—	unknown	01:10–06:10 (good, 5.0 h)	50.1° 05:00	11.16	37%	37.9°
2039-01-19 Wed	90	—	unknown	01:10–06:10 (good, 5.0 h)	50.1° 04:55	11.14	26%	52.2°
2039-01-20 Thu	93	—	unknown	01:05–06:10 (good, 5.08 h)	50.1° 04:50	11.11	17%	66.6°
2039-01-21 Fri	93	—	unknown	01:00–06:05 (good, 5.08 h)	50.1° 04:45	11.09	9%	81.1°
2039-01-22 Sat	93	—	unknown	00:55–06:05 (good, 5.17 h)	50.1° 04:45	11.06	4%	95.5°
2039-01-23 Sun	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.1° 04:40	11.03	1%	109.8°
2039-01-24 Mon	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.1° 04:35	11.01	0%	123.8°
2039-01-25 Tue	93	—	unknown	00:45–06:05 (good, 5.33 h)	50.1° 04:30	10.98	2%	137.6°
2039-01-26 Wed	93	—	unknown	00:40–06:05 (good, 5.42 h)	50.1° 04:25	10.95	7%	151.0°
2039-01-27 Thu	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.1° 04:25	10.92	13%	164.1°
2039-01-28 Fri	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.1° 04:20	10.89	20%	176.7°
2039-01-29 Sat	93	—	unknown	00:30–06:00 (good, 5.5 h)	50.1° 04:15	10.86	29%	170.9°
2039-01-30 Sun	93	—	unknown	00:25–06:00 (good, 5.58 h)	50.1° 04:10	10.83	38%	158.8°
2039-01-31 Mon	93	—	unknown	00:25–06:00 (good, 5.58 h)	50.1° 04:10	10.79	48%	146.9°
2039-02-01 Tue	93	—	unknown	00:20–06:00 (good, 5.67 h)	50.1° 04:05	10.76	57%	135.0°
2039-02-02 Wed	93	—	unknown	00:20–06:00 (good, 5.67 h)	50.1° 04:00	10.73	66%	123.2°
2039-02-03 Thu	93	—	unknown	00:20–06:00 (good, 5.67 h)	50.1° 03:55	10.7	75%	111.3°
2039-02-04 Fri	92	—	unknown	00:30–05:55 (good, 5.42 h)	50.1° 03:50	10.66	83%	99.2°
2039-02-05 Sat	89	—	unknown	01:25–05:55 (good, 4.5 h)	50.1° 03:50	10.63	89%	86.9°
2039-02-06 Sun	61	—	unknown	03:15–05:55 (good, 2.67 h)	50.1° 03:45	10.59	95%	74.3°
2039-02-07 Mon	44	—	unknown	00:00–05:55 (marginal, 5.92 h)	50.1° 03:40	10.56	98%	61.5°
2039-02-08 Tue	30	—	unknown	00:55–05:55 (marginal, 5.0 h)	50.1° 03:35	10.52	100%	48.3°
2039-02-09 Wed	19	—	unknown	03:25–05:50 (marginal, 2.42 h)	50.1° 03:30	10.48	99%	34.9°
2039-02-10 Thu	17	—	unknown	04:05–05:50 (marginal, 1.75 h)	50.1° 03:30	10.45	96%	21.2°
2039-02-11 Fri	20	—	unknown	23:50–05:50 (marginal, 6.0 h)	50.1° 03:25	10.41	91%	7.4°
2039-02-12 Sat	30	—	unknown	23:25–05:50 (marginal, 6.42 h)	50.1° 03:20	10.37	83%	6.6°
2039-02-13 Sun	44	—	unknown	23:05–05:45 (marginal, 6.67 h)	50.1° 03:15	10.33	74%	20.7°
2039-02-14 Mon	81	—	unknown	23:25–03:25 (good, 4.0 h)	50.1° 03:10	10.29	63%	34.8°
2039-02-15 Tue	88	—	unknown	23:20–05:45 (good, 6.42 h)	50.1° 03:10	10.25	52%	48.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-01-17&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.