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: 07-05 (5), 07-06 (4), 07-07 (3), 07-08 (2), 07-09 (2) — by astronomy; check the weather when the night is within four days.

2027-07-05astronomy score per night — click a bar for that night2027-08-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-05 Mon	5	—	unknown	22:20–22:50 (marginal, 0.5 h)	50.2° 19:00	4.63	5%	56.7°
2027-07-06 Tue	4	—	unknown	22:20–22:40 (marginal, 0.33 h)	50.2° 18:55	4.66	11%	42.1°
2027-07-07 Wed	3	—	unknown	22:15–22:35 (marginal, 0.33 h)	50.2° 18:50	4.69	20%	28.0°
2027-07-08 Thu	2	—	unknown	22:15–22:25 (marginal, 0.17 h)	50.2° 18:45	4.72	30%	15.3°
2027-07-09 Fri	2	—	unknown	—	50.2° 18:40	4.76	41%	9.2°
2027-07-10 Sat	1	—	unknown	—	50.2° 18:40	4.79	52%	17.4°
2027-07-11 Sun	1	—	unknown	—	50.2° 18:35	4.83	62%	29.4°
2027-07-12 Mon	1	—	unknown	—	50.2° 18:30	4.87	72%	41.6°
2027-07-13 Tue	1	—	unknown	—	50.2° 18:25	4.9	80%	53.9°
2027-07-14 Wed	1	—	unknown	—	50.2° 18:20	4.95	88%	66.0°
2027-07-15 Thu	1	—	unknown	—	50.2° 18:20	4.99	93%	77.9°
2027-07-16 Fri	1	—	unknown	—	50.2° 18:15	5.03	97%	89.8°
2027-07-17 Sat	1	—	unknown	—	50.2° 18:10	5.07	100%	101.6°
2027-07-18 Sun	1	—	unknown	—	50.2° 18:05	5.12	100%	113.2°
2027-07-19 Mon	1	—	unknown	—	50.2° 18:05	5.17	98%	124.9°
2027-07-20 Tue	1	—	unknown	—	50.2° 18:00	5.21	95%	136.5°
2027-07-21 Wed	1	—	unknown	—	50.2° 17:55	5.26	91%	148.0°
2027-07-22 Thu	0	—	unknown	—	50.2° 17:50	5.31	84%	159.1°
2027-07-23 Fri	0	—	unknown	—	50.2° 17:45	5.36	77%	168.7°
2027-07-24 Sat	0	—	unknown	—	50.2° 17:45	5.41	68%	169.4°
2027-07-25 Sun	0	—	unknown	—	50.2° 17:40	5.46	58%	159.8°
2027-07-26 Mon	0	—	unknown	—	50.2° 17:35	5.51	48%	147.8°
2027-07-27 Tue	0	—	unknown	—	50.2° 17:30	5.56	37%	134.9°
2027-07-28 Wed	0	—	unknown	—	50.2° 17:25	5.62	27%	121.5°
2027-07-29 Thu	0	—	unknown	—	50.2° 17:25	5.67	17%	107.5°
2027-07-30 Fri	0	—	unknown	—	50.2° 17:20	5.72	9%	93.1°
2027-07-31 Sat	0	—	unknown	—	50.2° 17:15	5.78	3%	78.3°
2027-08-01 Sun	0	—	unknown	—	50.2° 17:10	5.83	0%	63.4°
2027-08-02 Mon	0	—	unknown	—	50.2° 17:10	5.89	0%	48.4°
2027-08-03 Tue	0	—	unknown	—	50.2° 17:05	5.94	4%	33.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-05&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.