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: 08-21 (76), 08-20 (74), 08-19 (71), 08-18 (68), 08-17 (66) — by astronomy; check the weather when the night is within four days.

2039-07-23astronomy score per night — click a bar for that night2039-08-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2039-07-28 Thu	24	—	unknown	03:35–04:20 (good, 0.75 h)	72.5° 08:45	5.62	52%	157.2°
2039-07-29 Fri	25	—	unknown	03:35–04:20 (good, 0.75 h)	72.5° 08:40	5.68	64%	170.1°
2039-07-30 Sat	27	—	unknown	03:30–04:20 (good, 0.83 h)	72.5° 08:35	5.73	74%	171.2°
2039-07-31 Sun	28	—	unknown	03:25–04:25 (good, 1.0 h)	72.5° 08:30	5.78	84%	158.2°
2039-08-01 Mon	30	—	unknown	03:30–04:25 (good, 0.92 h)	72.5° 08:25	5.84	92%	143.9°
2039-08-02 Tue	28	—	unknown	03:25–04:25 (good, 1.0 h)	72.5° 08:25	5.89	97%	129.4°
2039-08-03 Wed	27	—	unknown	03:25–04:30 (good, 1.08 h)	72.5° 08:20	5.95	100%	114.9°
2039-08-04 Thu	23	—	unknown	03:30–04:30 (good, 1.0 h)	72.5° 08:15	6.01	100%	100.6°
2039-08-05 Fri	19	—	unknown	04:10–04:30 (good, 0.33 h)	72.5° 08:10	6.06	97%	86.6°
2039-08-06 Sat	17	—	unknown	02:45–04:35 (marginal, 1.83 h)	72.5° 08:05	6.12	92%	73.0°
2039-08-07 Sun	14	—	unknown	02:45–04:35 (marginal, 1.83 h)	72.5° 08:05	6.18	85%	59.8°
2039-08-08 Mon	14	—	unknown	02:40–04:35 (marginal, 1.92 h)	72.5° 08:00	6.23	77%	47.0°
2039-08-09 Tue	14	—	unknown	02:35–04:40 (marginal, 2.08 h)	72.5° 07:55	6.29	68%	34.6°
2039-08-10 Wed	18	—	unknown	02:25–04:40 (marginal, 2.25 h)	72.5° 07:50	6.35	58%	22.6°
2039-08-11 Thu	23	—	unknown	04:25–04:40 (good, 0.25 h)	72.5° 07:50	6.4	49%	11.5°
2039-08-12 Fri	31	—	unknown	03:00–04:45 (good, 1.75 h)	72.5° 07:45	6.46	40%	6.2°
2039-08-13 Sat	38	—	unknown	02:50–04:45 (good, 1.92 h)	72.5° 07:40	6.52	30%	15.0°
2039-08-14 Sun	45	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:35	6.58	22%	26.4°
2039-08-15 Mon	53	—	unknown	02:25–04:45 (good, 2.33 h)	72.5° 07:30	6.63	15%	38.1°
2039-08-16 Tue	61	—	unknown	02:20–04:50 (good, 2.5 h)	72.5° 07:30	6.69	9%	50.1°
2039-08-17 Wed	66	—	unknown	02:20–04:50 (good, 2.5 h)	72.5° 07:25	6.75	4%	62.3°
2039-08-18 Thu	68	—	unknown	02:15–04:50 (good, 2.58 h)	72.5° 07:20	6.81	1%	74.8°
2039-08-19 Fri	71	—	unknown	02:10–04:55 (good, 2.75 h)	72.5° 07:15	6.86	0%	87.5°
2039-08-20 Sat	74	—	unknown	02:05–04:55 (good, 2.83 h)	72.5° 07:10	6.92	1%	100.5°
2039-08-21 Sun	76	—	unknown	02:05–04:55 (good, 2.83 h)	72.5° 07:10	6.98	5%	113.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-07-23&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.