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: 08-13 (55), 08-14 (55), 08-12 (53), 08-11 (51), 08-10 (49) — by astronomy; check the weather when the night is within four days.

2027-07-25astronomy score per night — click a bar for that night2027-08-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-25 Sun	7	—	unknown	03:30–04:15 (marginal, 0.75 h)	72.5° 08:55	5.46	58%	36.1°
2027-07-26 Mon	9	—	unknown	03:20–04:15 (marginal, 0.92 h)	72.5° 08:50	5.51	48%	23.2°
2027-07-27 Tue	12	—	unknown	04:05–04:15 (good, 0.17 h)	72.5° 08:45	5.56	37%	9.9°
2027-07-28 Wed	17	—	unknown	03:50–04:20 (good, 0.5 h)	72.5° 08:40	5.62	27%	4.0°
2027-07-29 Thu	21	—	unknown	03:40–04:20 (good, 0.67 h)	72.5° 08:40	5.67	17%	18.1°
2027-07-30 Fri	25	—	unknown	03:30–04:20 (good, 0.83 h)	72.5° 08:35	5.72	9%	32.7°
2027-07-31 Sat	29	—	unknown	03:25–04:25 (good, 1.0 h)	72.5° 08:30	5.78	3%	47.6°
2027-08-01 Sun	31	—	unknown	03:20–04:25 (good, 1.08 h)	72.5° 08:25	5.83	0%	62.8°
2027-08-02 Mon	32	—	unknown	03:15–04:25 (good, 1.17 h)	72.5° 08:25	5.89	0%	78.0°
2027-08-03 Tue	35	—	unknown	03:15–04:30 (good, 1.25 h)	72.5° 08:20	5.94	4%	93.2°
2027-08-04 Wed	37	—	unknown	03:10–04:30 (good, 1.33 h)	72.5° 08:15	6.0	9%	108.0°
2027-08-05 Thu	38	—	unknown	03:05–04:30 (good, 1.42 h)	72.5° 08:10	6.06	17%	122.5°
2027-08-06 Fri	41	—	unknown	03:00–04:35 (good, 1.58 h)	72.5° 08:05	6.11	26%	136.5°
2027-08-07 Sat	43	—	unknown	02:55–04:35 (good, 1.67 h)	72.5° 08:05	6.17	37%	150.1°
2027-08-08 Sun	45	—	unknown	02:55–04:35 (good, 1.67 h)	72.5° 08:00	6.23	47%	163.2°
2027-08-09 Mon	48	—	unknown	02:50–04:40 (good, 1.83 h)	72.5° 07:55	6.28	57%	175.8°
2027-08-10 Tue	49	—	unknown	02:45–04:40 (good, 1.92 h)	72.5° 07:50	6.34	67%	171.6°
2027-08-11 Wed	51	—	unknown	02:40–04:40 (good, 2.0 h)	72.5° 07:45	6.4	76%	159.4°
2027-08-12 Thu	53	—	unknown	02:40–04:40 (good, 2.0 h)	72.5° 07:45	6.46	84%	147.4°
2027-08-13 Fri	55	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:40	6.51	90%	135.5°
2027-08-14 Sat	55	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:35	6.57	95%	123.7°
2027-08-15 Sun	46	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:30	6.63	98%	111.8°
2027-08-16 Mon	41	—	unknown	02:45–04:50 (good, 2.08 h)	72.5° 07:30	6.69	100%	100.0°
2027-08-17 Tue	34	—	unknown	03:30–04:50 (good, 1.33 h)	72.5° 07:25	6.74	100%	88.1°
2027-08-18 Wed	27	—	unknown	04:40–04:50 (good, 0.17 h)	72.5° 07:20	6.8	98%	76.1°
2027-08-19 Thu	22	—	unknown	02:05–04:55 (marginal, 2.83 h)	72.5° 07:15	6.86	94%	63.9°
2027-08-20 Fri	18	—	unknown	02:05–04:55 (marginal, 2.83 h)	72.5° 07:10	6.92	88%	51.7°
2027-08-21 Sat	16	—	unknown	02:05–04:55 (marginal, 2.83 h)	72.5° 07:10	6.97	81%	39.2°
2027-08-22 Sun	17	—	unknown	01:55–05:00 (marginal, 3.08 h)	72.5° 07:05	7.03	72%	26.6°
2027-08-23 Mon	24	—	unknown	01:40–05:00 (marginal, 3.33 h)	72.5° 07:00	7.09	62%	13.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-25&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.