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 Seven Sisters: 07-27 (21), 07-26 (20), 07-25 (18), 07-24 (16), 07-23 (13) — by astronomy; check the weather when the night is within four days.

2039-06-28astronomy score per night — click a bar for that night2039-07-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-06-28 Tue	0	—	unknown	—	72.5° 10:40	4.48	44%	119.9°
2039-06-29 Wed	0	—	unknown	—	72.5° 10:35	4.5	55%	133.4°
2039-06-30 Thu	0	—	unknown	—	72.5° 10:35	4.51	66%	147.1°
2039-07-01 Fri	0	—	unknown	—	72.5° 10:30	4.53	77%	160.9°
2039-07-02 Sat	0	—	unknown	—	72.5° 10:25	4.56	86%	173.0°
2039-07-03 Sun	0	—	unknown	—	72.5° 10:20	4.58	93%	167.0°
2039-07-04 Mon	0	—	unknown	—	72.5° 10:15	4.61	98%	152.9°
2039-07-05 Tue	0	—	unknown	—	72.5° 10:15	4.63	100%	138.1°
2039-07-06 Wed	0	—	unknown	—	72.5° 10:10	4.66	99%	123.4°
2039-07-07 Thu	0	—	unknown	—	72.5° 10:05	4.69	95%	108.9°
2039-07-08 Fri	0	—	unknown	—	72.5° 10:00	4.73	89%	94.7°
2039-07-09 Sat	0	—	unknown	—	72.5° 10:00	4.76	81%	81.1°
2039-07-10 Sun	1	—	unknown	—	72.5° 09:55	4.79	72%	67.8°
2039-07-11 Mon	1	—	unknown	—	72.5° 09:50	4.83	62%	55.1°
2039-07-12 Tue	1	—	unknown	—	72.5° 09:45	4.87	52%	42.7°
2039-07-13 Wed	1	—	unknown	—	72.5° 09:40	4.91	42%	30.7°
2039-07-14 Thu	1	—	unknown	—	72.5° 09:40	4.95	33%	19.0°
2039-07-15 Fri	2	—	unknown	04:40–04:50 (marginal, 0.17 h)	72.5° 09:35	4.99	24%	8.7°
2039-07-16 Sat	3	—	unknown	04:30–04:50 (marginal, 0.33 h)	72.5° 09:30	5.03	17%	8.3°
2039-07-17 Sun	4	—	unknown	04:25–04:50 (marginal, 0.42 h)	72.5° 09:25	5.08	10%	18.5°
2039-07-18 Mon	6	—	unknown	04:20–04:50 (marginal, 0.5 h)	72.5° 09:20	5.12	5%	29.9°
2039-07-19 Tue	7	—	unknown	04:10–04:50 (marginal, 0.67 h)	72.5° 09:20	5.17	2%	41.7°
2039-07-20 Wed	8	—	unknown	04:10–04:55 (marginal, 0.75 h)	72.5° 09:15	5.22	0%	53.8°
2039-07-21 Thu	10	—	unknown	04:05–04:10 (good, 0.08 h)	72.5° 09:10	5.27	0%	66.0°
2039-07-22 Fri	11	—	unknown	04:00–04:10 (good, 0.17 h)	72.5° 09:05	5.31	3%	78.4°
2039-07-23 Sat	13	—	unknown	03:55–04:10 (good, 0.25 h)	72.5° 09:00	5.36	7%	91.1°
2039-07-24 Sun	16	—	unknown	03:55–04:15 (good, 0.33 h)	72.5° 09:00	5.41	13%	103.9°
2039-07-25 Mon	18	—	unknown	03:50–04:15 (good, 0.42 h)	72.5° 08:55	5.47	21%	117.0°
2039-07-26 Tue	20	—	unknown	03:45–04:15 (good, 0.5 h)	72.5° 08:50	5.52	30%	130.2°
2039-07-27 Wed	21	—	unknown	03:40–04:15 (good, 0.58 h)	72.5° 08:45	5.57	41%	143.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-06-28&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.