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.

2039-01-09astronomy score per night — click a bar for that night2039-02-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-01-09 Sun	49	—	unknown	04:15–06:10 (good, 1.92 h)	50.1° 05:35	11.34	100%	82.7°
2039-01-10 Mon	37	—	unknown	01:45–06:10 (marginal, 4.42 h)	50.1° 05:30	11.33	100%	70.1°
2039-01-11 Tue	27	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.1° 05:25	11.31	98%	57.2°
2039-01-12 Wed	20	—	unknown	02:05–06:10 (marginal, 4.08 h)	50.1° 05:20	11.29	94%	44.2°
2039-01-13 Thu	16	—	unknown	02:55–06:10 (marginal, 3.25 h)	50.1° 05:20	11.27	88%	31.0°
2039-01-14 Fri	21	—	unknown	01:35–06:10 (marginal, 4.58 h)	50.1° 05:15	11.25	80%	17.6°
2039-01-15 Sat	29	—	unknown	01:10–06:10 (marginal, 5.0 h)	50.1° 05:10	11.23	70%	4.0°
2039-01-16 Sun	43	—	unknown	00:55–06:10 (marginal, 5.25 h)	50.1° 05:05	11.21	59%	9.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-01-09&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.