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: 06-16 (29), 06-17 (27), 06-18 (26), 06-19 (24), 06-20 (22) — by astronomy; check the weather when the night is within four days.

2031-06-16astronomy score per night — click a bar for that night2031-07-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-06-16 Mon	29	—	unknown	23:10–00:05 (good, 0.92 h)	50.2° 20:15	4.44	8%	133.1°
2031-06-17 Tue	27	—	unknown	23:10–00:00 (good, 0.83 h)	50.2° 20:10	4.44	4%	121.2°
2031-06-18 Wed	26	—	unknown	23:10–23:55 (good, 0.75 h)	50.2° 20:05	4.43	1%	109.4°
2031-06-19 Thu	24	—	unknown	23:10–23:55 (good, 0.75 h)	50.2° 20:00	4.43	0%	97.6°
2031-06-20 Fri	22	—	unknown	23:15–23:50 (good, 0.58 h)	50.2° 19:55	4.42	1%	85.9°
2031-06-21 Sat	21	—	unknown	23:15–23:45 (good, 0.5 h)	50.2° 19:55	4.42	4%	74.3°
2031-06-22 Sun	19	—	unknown	23:15–23:40 (good, 0.42 h)	50.2° 19:50	4.42	8%	62.6°
2031-06-23 Mon	17	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:45	4.43	14%	50.9°
2031-06-24 Tue	14	—	unknown	23:15–23:35 (good, 0.33 h)	50.2° 19:40	4.43	21%	39.2°
2031-06-25 Wed	11	—	unknown	22:20–23:55 (marginal, 1.58 h)	50.2° 19:35	4.44	30%	27.6°
2031-06-26 Thu	9	—	unknown	23:15–23:55 (marginal, 0.67 h)	50.2° 19:35	4.45	39%	16.4°
2031-06-27 Fri	7	—	unknown	23:15–23:50 (marginal, 0.58 h)	50.2° 19:30	4.46	49%	8.9°
2031-06-28 Sat	5	—	unknown	23:15–23:40 (marginal, 0.42 h)	50.2° 19:25	4.48	60%	14.7°
2031-06-29 Sun	4	—	unknown	23:10–23:30 (marginal, 0.33 h)	50.2° 19:20	4.5	70%	26.6°
2031-06-30 Mon	3	—	unknown	23:10–23:20 (marginal, 0.17 h)	50.2° 19:20	4.51	80%	40.0°
2031-07-01 Tue	3	—	unknown	23:10–23:20 (marginal, 0.17 h)	50.2° 19:15	4.53	88%	54.0°
2031-07-02 Wed	3	—	unknown	23:10–23:20 (marginal, 0.17 h)	50.2° 19:10	4.56	95%	68.6°
2031-07-03 Thu	3	—	unknown	23:10–23:20 (marginal, 0.17 h)	50.2° 19:05	4.58	99%	83.5°
2031-07-04 Fri	3	—	unknown	23:10–23:20 (marginal, 0.17 h)	50.2° 19:00	4.6	100%	98.5°
2031-07-05 Sat	4	—	unknown	22:20–22:40 (marginal, 0.33 h)	50.2° 19:00	4.63	98%	113.6°
2031-07-06 Sun	3	—	unknown	22:20–22:40 (marginal, 0.33 h)	50.2° 18:55	4.66	93%	128.4°
2031-07-07 Mon	3	—	unknown	22:15–22:40 (marginal, 0.42 h)	50.2° 18:50	4.69	86%	142.8°
2031-07-08 Tue	3	—	unknown	22:15–22:40 (marginal, 0.42 h)	50.2° 18:45	4.72	77%	156.4°
2031-07-09 Wed	3	—	unknown	22:15–22:35 (marginal, 0.33 h)	50.2° 18:40	4.76	66%	168.1°
2031-07-10 Thu	2	—	unknown	22:15–22:30 (marginal, 0.25 h)	50.2° 18:40	4.79	56%	169.8°
2031-07-11 Fri	2	—	unknown	22:15–22:25 (marginal, 0.17 h)	50.2° 18:35	4.83	45%	159.8°
2031-07-12 Sat	2	—	unknown	22:15–22:20 (marginal, 0.08 h)	50.2° 18:30	4.87	36%	147.9°
2031-07-13 Sun	2	—	unknown	22:15–22:20 (marginal, 0.08 h)	50.2° 18:25	4.91	26%	136.0°
2031-07-14 Mon	2	—	unknown	22:10–22:15 (marginal, 0.08 h)	50.2° 18:25	4.95	18%	124.0°
2031-07-15 Tue	1	—	unknown	—	50.2° 18:20	4.99	12%	112.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-16&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.