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 Great Orion Nebula: 09-02 (5), 08-28 (4), 09-01 (4), 08-25 (3), 08-26 (3) — by astronomy; check the weather when the night is within four days.

2045-08-04astronomy score per night — click a bar for that night2045-09-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-08-04 Fri	0	—	unknown	—	42.9° 10:00	6.04	61%	60.7°
2045-08-05 Sat	0	—	unknown	—	42.9° 10:00	6.09	51%	51.2°
2045-08-06 Sun	0	—	unknown	—	42.9° 09:55	6.15	40%	42.6°
2045-08-07 Mon	0	—	unknown	—	42.9° 09:50	6.21	30%	36.0°
2045-08-08 Tue	0	—	unknown	—	42.9° 09:45	6.26	20%	33.2°
2045-08-09 Wed	0	—	unknown	—	42.9° 09:40	6.32	11%	35.6°
2045-08-10 Thu	0	—	unknown	—	42.9° 09:40	6.38	5%	42.7°
2045-08-11 Fri	0	—	unknown	—	42.9° 09:35	6.44	1%	52.7°
2045-08-12 Sat	0	—	unknown	—	42.9° 09:30	6.49	0%	64.3°
2045-08-13 Sun	0	—	unknown	—	42.9° 09:25	6.55	2%	76.7°
2045-08-14 Mon	0	—	unknown	—	42.9° 09:20	6.61	7%	89.2°
2045-08-15 Tue	0	—	unknown	—	42.9° 09:20	6.67	14%	101.4°
2045-08-16 Wed	0	—	unknown	—	42.9° 09:15	6.72	24%	113.0°
2045-08-17 Thu	0	—	unknown	—	42.9° 09:10	6.78	34%	123.8°
2045-08-18 Fri	0	—	unknown	—	42.9° 09:05	6.84	44%	133.2°
2045-08-19 Sat	1	—	unknown	—	42.9° 09:05	6.9	55%	140.8°
2045-08-20 Sun	1	—	unknown	—	42.9° 09:00	6.95	64%	145.6°
2045-08-21 Mon	1	—	unknown	—	42.9° 08:55	7.01	74%	146.7°
2045-08-22 Tue	1	—	unknown	—	42.9° 08:50	7.07	82%	144.0°
2045-08-23 Wed	2	—	unknown	—	42.9° 08:45	7.13	88%	138.3°
2045-08-24 Thu	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.18	94%	130.8°
2045-08-25 Fri	3	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.24	98%	122.1°
2045-08-26 Sat	3	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.3	100%	112.9°
2045-08-27 Sun	3	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.35	100%	103.2°
2045-08-28 Mon	4	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:25	7.41	98%	93.2°
2045-08-29 Tue	3	—	unknown	04:45–05:10 (marginal, 0.42 h)	42.9° 08:25	7.47	95%	83.1°
2045-08-30 Wed	3	—	unknown	04:50–05:10 (marginal, 0.33 h)	42.9° 08:20	7.52	90%	73.1°
2045-08-31 Thu	3	—	unknown	04:50–05:10 (marginal, 0.33 h)	42.9° 08:15	7.58	83%	63.1°
2045-09-01 Fri	4	—	unknown	04:50–05:15 (marginal, 0.42 h)	42.9° 08:10	7.63	75%	53.5°
2045-09-02 Sat	5	—	unknown	04:45–05:15 (marginal, 0.5 h)	42.9° 08:10	7.69	66%	44.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-08-04&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.