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: 07-11 (2), 07-12 (2), 07-13 (2), 07-14 (2), 07-15 (1) — by astronomy; check the weather when the night is within four days.

2042-07-11astronomy score per night — click a bar for that night2042-08-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-07-11 Fri	2	—	unknown	22:15–22:25 (marginal, 0.17 h)	50.1° 18:35	4.84	31%	143.3°
2042-07-12 Sat	2	—	unknown	22:15–22:20 (marginal, 0.08 h)	50.1° 18:30	4.88	21%	129.3°
2042-07-13 Sun	2	—	unknown	—	50.1° 18:25	4.92	13%	115.4°
2042-07-14 Mon	2	—	unknown	22:10–22:15 (marginal, 0.08 h)	50.1° 18:20	4.96	6%	101.7°
2042-07-15 Tue	1	—	unknown	—	50.1° 18:20	5.0	2%	88.1°
2042-07-16 Wed	1	—	unknown	—	50.1° 18:15	5.05	0%	74.8°
2042-07-17 Thu	1	—	unknown	—	50.1° 18:10	5.09	1%	61.8°
2042-07-18 Fri	1	—	unknown	—	50.1° 18:05	5.14	3%	49.0°
2042-07-19 Sat	1	—	unknown	—	50.1° 18:00	5.18	8%	36.5°
2042-07-20 Sun	1	—	unknown	—	50.1° 18:00	5.23	14%	24.3°
2042-07-21 Mon	0	—	unknown	—	50.1° 17:55	5.28	21%	12.4°
2042-07-22 Tue	0	—	unknown	—	50.1° 17:50	5.33	29%	3.4°
2042-07-23 Wed	0	—	unknown	—	50.1° 17:45	5.38	38%	12.3°
2042-07-24 Thu	0	—	unknown	—	50.1° 17:40	5.43	47%	23.9°
2042-07-25 Fri	0	—	unknown	—	50.1° 17:40	5.48	57%	35.8°
2042-07-26 Sat	0	—	unknown	—	50.1° 17:35	5.53	66%	47.8°
2042-07-27 Sun	0	—	unknown	—	50.1° 17:30	5.58	75%	60.1°
2042-07-28 Mon	0	—	unknown	—	50.1° 17:25	5.64	84%	72.7°
2042-07-29 Tue	0	—	unknown	—	50.1° 17:25	5.69	90%	85.7°
2042-07-30 Wed	0	—	unknown	—	50.1° 17:20	5.74	96%	99.1°
2042-07-31 Thu	0	—	unknown	—	50.1° 17:15	5.8	99%	112.8°
2042-08-01 Fri	0	—	unknown	—	50.1° 17:10	5.85	100%	126.8°
2042-08-02 Sat	0	—	unknown	—	50.1° 17:05	5.91	98%	141.1°
2042-08-03 Sun	0	—	unknown	—	50.1° 17:05	5.97	93%	155.5°
2042-08-04 Mon	0	—	unknown	—	50.1° 17:00	6.02	86%	169.7°
2042-08-05 Tue	0	—	unknown	—	50.1° 16:55	6.08	77%	174.0°
2042-08-06 Wed	0	—	unknown	—	50.1° 16:50	6.13	67%	160.5°
2042-08-07 Thu	0	—	unknown	—	50.1° 16:45	6.19	56%	146.4°
2042-08-08 Fri	0	—	unknown	—	50.1° 16:45	6.25	44%	132.4°
2042-08-09 Sat	0	—	unknown	—	50.1° 16:40	6.3	34%	118.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-07-11&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.