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: 01-10 (93), 01-11 (93), 01-12 (93), 01-13 (93), 01-14 (93) — by astronomy; check the weather when the night is within four days.

2040-01-02astronomy score per night — click a bar for that night2040-01-31

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-02 Mon	19	—	unknown	02:35–06:10 (marginal, 3.58 h)	50.1° 06:05	11.44	90%	46.3°
2040-01-03 Tue	17	—	unknown	02:30–06:10 (marginal, 3.67 h)	50.1° 06:00	11.43	83%	34.1°
2040-01-04 Wed	20	—	unknown	02:10–06:10 (marginal, 4.0 h)	50.1° 05:55	11.42	75%	21.7°
2040-01-05 Thu	28	—	unknown	01:50–06:10 (marginal, 4.33 h)	50.1° 05:50	11.41	66%	9.0°
2040-01-06 Fri	39	—	unknown	01:35–06:10 (marginal, 4.58 h)	50.1° 05:45	11.39	56%	3.9°
2040-01-07 Sat	52	—	unknown	02:20–06:10 (good, 3.83 h)	50.1° 05:45	11.38	45%	17.2°
2040-01-08 Sun	73	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:40	11.36	34%	30.8°
2040-01-09 Mon	87	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:35	11.35	24%	45.0°
2040-01-10 Tue	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.1° 05:30	11.33	15%	59.5°
2040-01-11 Wed	93	—	unknown	01:40–06:10 (good, 4.5 h)	50.1° 05:25	11.31	7%	74.4°
2040-01-12 Thu	93	—	unknown	01:35–06:10 (good, 4.58 h)	50.1° 05:25	11.29	2%	89.5°
2040-01-13 Fri	93	—	unknown	01:35–06:10 (good, 4.58 h)	50.1° 05:20	11.27	0%	104.8°
2040-01-14 Sat	93	—	unknown	01:30–06:10 (good, 4.67 h)	50.1° 05:15	11.25	1%	119.9°
2040-01-15 Sun	93	—	unknown	01:25–06:10 (good, 4.75 h)	50.1° 05:10	11.23	5%	134.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-02&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.