ObservingDetails
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Constraints for ground-based observing
Please ignore this page until this notice is removed. [BA 1/23/2012].
Introduction
Seasonal observability (not sure this is an actual word) for an astronomical object refers to times of the year when that object is above a certain viewable height at night. In other words, you can see it easily. It is above your local horizon in the hours between sunset and sunrise. And, it is "sufficiently above" the horizon. When the object is low on the horizon, your line of sight will pass through much more atmosphere (air) compared to a line of sight looking straight up. The less airmass you see, the better the photometric quality of your observation. Hence, "sufficiently above" means its above the limit for the amount of air/atmosphere you are willing to tolerate.
See:
Most observatories have written their own code to calculate seasonal visibility. I used this one:
Seasonal Observability for BRC 27
RA & dec: 7 01 37.9, -11 18 48, epoch 1950.0 Site long&lat: 10 21 53.2 (h.m.s) West, 19 49 36 North.
| 2012Feb6 | F | -2 48 | 1.6 | 2 17 | 1.4 | 7 22 | down | 7.1 | 6.2 | 5.0 |
| 2012Feb21 | N | -1 43 | 1.3 | 3 16 | 1.9 | 8 14 | down | 6.0 | 5.2 | 4.2 |
| 2012Mar7 | F | -0 39 | 1.2 | 4 12 | 2.9 | 9 03 | down | 4.9 | 4.1 | 3.1 |
| 2012Mar21 | N | 0 21 | 1.2 | 5 04 | 6.3 | 9 46 | down | 3.9 | 3.1 | 2.1 |
| 2012Apr5 | F | 1 25 | 1.3 | 5 58 | down | 10 31 | down | 2.9 | 2.0 | 1.1 |
| 2012Apr20 | N | 2 30 | 1.5 | 6 54 | down | 11 17 | down | 1.8 | 1.0 | 0.0 |
| 2012May5 | F | 3 37 | 2.1 | 7 51 | down | -11 56 | down | 0.7 | 0.0 | 0.0 |
| 2012May20 | N | 4 45 | 4.3 | 8 50 | down | -11 05 | down | 0.0 | 0.0 | 0.0 |
| 2012Jun3 | F | 5 47 | down | 9 47 | down | -10 14 | down | 0.0 | 0.0 | 0.0 |
| 2012Jun18 | N | 6 52 | down | 10 49 | down | -9 14 | down | 0.0 | 0.0 | 0.0 |
| 2012Jul2 | F | 7 49 | down | 11 47 | down | -8 15 | down | 0.0 | 0.0 | 0.0 |
| 2012Jul18 | N | 8 48 | down | -11 08 | down | -7 04 | down | 0.0 | 0.0 | 0.0 |
| 2012Aug1 | F | 9 36 | down | -10 13 | down | -6 01 | down | 0.0 | 0.0 | 0.0 |
| 2012Aug16 | N | 10 24 | down | -9 16 | down | -4 55 | 5.2 | 0.0 | 0.0 | 0.0 |
| 2012Aug30 | F | 11 06 | down | -8 24 | down | -3 54 | 2.4 | 0.4 | 0.0 | 0.0 |
| 2012Sep15 | N | 11 53 | down | -7 27 | down | -2 46 | 1.6 | 1.5 | 0.7 | 0.0 |
| 2012Sep29 | F | -11 25 | down | -6 36 | down | -1 48 | 1.3 | 2.5 | 1.7 | 0.7 |
| 2012Oct14 | N | -10 38 | down | -5 41 | v.low | -0 45 | 1.2 | 3.5 | 2.7 | 1.7 |
| 2012Oct28 | F | -9 51 | down | -4 48 | 4.6 | 0 15 | 1.2 | 4.5 | 3.7 | 2.7 |
| 2012Nov12 | N | -8 57 | down | -3 49 | 2.3 | 1 20 | 1.3 | 5.6 | 4.8 | 3.8 |
| 2012Nov27 | F | -7 58 | down | -2 46 | 1.6 | 2 26 | 1.5 | 6.7 | 5.9 | 4.9 |
| 2012Dec12 | N | -6 54 | down | -1 40 | 1.3 | 3 34 | 2.1 | 7.8 | 6.9 | 5.0 |
| 2012Dec27 | F | -5 48 | down | -0 34 | 1.2 | 4 41 | 4.1 | 8.5 | 6.9 | 5.0 |
| 2013Jan10 | N | -4 45 | 4.3 | 0 28 | 1.2 | 5 40 | 81.1 | 8.5 | 6.9 | 5.0 |
