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: 06-06 (42), 06-07 (41), 06-08 (41), 06-05 (40), 06-09 (39) — by astronomy; check the weather when the night is within four days.

2042-05-30astronomy score per night — click a bar for that night2042-06-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-30 Fri	12	—	unknown	22:55–01:15 (marginal, 2.33 h)	50.1° 21:20	4.87	86%	19.7°
2042-05-31 Sat	11	—	unknown	22:55–01:05 (marginal, 2.17 h)	50.1° 21:15	4.83	92%	31.7°
2042-06-01 Sun	14	—	unknown	23:00–01:05 (marginal, 2.08 h)	50.1° 21:10	4.79	96%	43.8°
2042-06-02 Mon	17	—	unknown	23:00–01:10 (marginal, 2.17 h)	50.1° 21:05	4.76	99%	56.2°
2042-06-03 Tue	22	—	unknown	23:00–01:15 (marginal, 2.25 h)	50.1° 21:05	4.72	100%	68.8°
2042-06-04 Wed	28	—	unknown	23:00–00:05 (good, 1.08 h)	50.1° 21:00	4.69	99%	81.6°
2042-06-05 Thu	40	—	unknown	23:00–00:25 (good, 1.42 h)	50.1° 20:55	4.66	95%	94.7°
2042-06-06 Fri	42	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:50	4.63	90%	108.0°
2042-06-07 Sat	41	—	unknown	23:05–00:35 (good, 1.5 h)	50.1° 20:45	4.6	82%	121.4°
2042-06-08 Sun	41	—	unknown	23:05–00:35 (good, 1.5 h)	50.1° 20:45	4.58	73%	135.1°
2042-06-09 Mon	39	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:40	4.55	62%	148.9°
2042-06-10 Tue	38	—	unknown	23:05–00:25 (good, 1.33 h)	50.1° 20:35	4.53	51%	162.8°
2042-06-11 Wed	35	—	unknown	23:10–00:25 (good, 1.25 h)	50.1° 20:30	4.51	40%	175.9°
2042-06-12 Thu	34	—	unknown	23:10–00:20 (good, 1.17 h)	50.1° 20:30	4.49	29%	168.1°
2042-06-13 Fri	33	—	unknown	23:10–00:15 (good, 1.08 h)	50.1° 20:25	4.48	19%	154.0°
2042-06-14 Sat	31	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:20	4.46	11%	139.6°
2042-06-15 Sun	29	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:15	4.45	5%	125.3°
2042-06-16 Mon	28	—	unknown	23:10–00:05 (good, 0.92 h)	50.1° 20:10	4.44	1%	111.2°
2042-06-17 Tue	27	—	unknown	23:10–00:00 (good, 0.83 h)	50.1° 20:10	4.43	0%	97.2°
2042-06-18 Wed	26	—	unknown	23:10–23:55 (good, 0.75 h)	50.1° 20:05	4.43	2%	83.5°
2042-06-19 Thu	24	—	unknown	23:10–23:50 (good, 0.67 h)	50.1° 20:00	4.42	6%	70.2°
2042-06-20 Fri	21	—	unknown	23:15–23:50 (good, 0.58 h)	50.1° 19:55	4.42	11%	57.2°
2042-06-21 Sat	17	—	unknown	23:15–23:40 (good, 0.42 h)	50.1° 19:50	4.42	18%	44.6°
2042-06-22 Sun	14	—	unknown	23:15–23:30 (good, 0.25 h)	50.1° 19:50	4.42	26%	32.3°
2042-06-23 Mon	11	—	unknown	22:20–00:05 (marginal, 1.75 h)	50.1° 19:45	4.43	36%	20.2°
2042-06-24 Tue	9	—	unknown	23:15–00:00 (marginal, 0.75 h)	50.1° 19:40	4.44	45%	8.6°
2042-06-25 Wed	7	—	unknown	23:15–23:55 (marginal, 0.67 h)	50.1° 19:35	4.44	54%	5.0°
2042-06-26 Thu	5	—	unknown	23:15–23:45 (marginal, 0.5 h)	50.1° 19:35	4.46	64%	16.0°
2042-06-27 Fri	4	—	unknown	23:15–23:35 (marginal, 0.33 h)	50.1° 19:30	4.47	72%	27.8°
2042-06-28 Sat	3	—	unknown	23:15–23:30 (marginal, 0.25 h)	50.1° 19:25	4.48	81%	39.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-30&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.