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: 05-29 (60), 05-30 (58), 05-31 (56), 06-01 (55), 06-02 (52) — by astronomy; check the weather when the night is within four days.

2027-05-29astronomy score per night — click a bar for that night2027-06-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-05-29 Sat	60	—	unknown	22:55–01:15 (good, 2.33 h)	50.2° 21:25	4.92	37%	165.3°
2027-05-30 Sun	58	—	unknown	22:55–01:10 (good, 2.25 h)	50.2° 21:20	4.88	27%	171.2°
2027-05-31 Mon	56	—	unknown	22:55–01:10 (good, 2.25 h)	50.2° 21:15	4.84	19%	163.7°
2027-06-01 Tue	55	—	unknown	22:55–01:05 (good, 2.17 h)	50.2° 21:10	4.8	11%	151.5°
2027-06-02 Wed	52	—	unknown	23:00–01:00 (good, 2.0 h)	50.2° 21:10	4.77	5%	138.1°
2027-06-03 Thu	50	—	unknown	23:00–00:55 (good, 1.92 h)	50.2° 21:05	4.73	1%	124.2°
2027-06-04 Fri	49	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:00	4.7	0%	109.8°
2027-06-05 Sat	47	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 20:55	4.67	2%	95.2°
2027-06-06 Sun	44	—	unknown	23:05–00:45 (good, 1.67 h)	50.2° 20:50	4.64	6%	80.4°
2027-06-07 Mon	40	—	unknown	23:05–00:40 (good, 1.58 h)	50.2° 20:50	4.61	14%	65.8°
2027-06-08 Tue	35	—	unknown	23:05–00:35 (good, 1.5 h)	50.2° 20:45	4.59	23%	51.4°
2027-06-09 Wed	28	—	unknown	23:05–00:20 (good, 1.25 h)	50.2° 20:40	4.56	33%	37.4°
2027-06-10 Thu	22	—	unknown	23:05–00:05 (good, 1.0 h)	50.2° 20:35	4.54	44%	24.0°
2027-06-11 Fri	17	—	unknown	23:10–00:50 (marginal, 1.67 h)	50.2° 20:30	4.52	55%	12.3°
2027-06-12 Sat	13	—	unknown	23:10–00:45 (marginal, 1.58 h)	50.2° 20:30	4.5	66%	10.1°
2027-06-13 Sun	10	—	unknown	23:10–00:30 (marginal, 1.33 h)	50.2° 20:25	4.48	76%	20.1°
2027-06-14 Mon	9	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.2° 20:20	4.47	84%	32.1°
2027-06-15 Tue	9	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.2° 20:15	4.45	91%	44.4°
2027-06-16 Wed	10	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.2° 20:15	4.44	96%	56.7°
2027-06-17 Thu	12	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.2° 20:10	4.44	99%	68.8°
2027-06-18 Fri	14	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.2° 20:05	4.43	100%	80.9°
2027-06-19 Sat	15	—	unknown	23:10–23:30 (good, 0.33 h)	50.2° 20:00	4.42	99%	92.8°
2027-06-20 Sun	17	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:55	4.42	97%	104.5°
2027-06-21 Mon	18	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:55	4.42	92%	116.2°
2027-06-22 Tue	19	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:50	4.42	87%	127.9°
2027-06-23 Wed	17	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:45	4.43	80%	139.5°
2027-06-24 Thu	16	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:40	4.43	72%	150.9°
2027-06-25 Fri	14	—	unknown	23:15–23:30 (good, 0.25 h)	50.2° 19:35	4.44	62%	162.0°
2027-06-26 Sat	13	—	unknown	23:15–23:25 (good, 0.17 h)	50.2° 19:35	4.45	53%	170.4°
2027-06-27 Sun	12	—	unknown	23:15–23:20 (good, 0.08 h)	50.2° 19:30	4.46	43%	167.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-29&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.