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| | == Seasonal Observability for BRC 27 == | | == Seasonal Observability for BRC 27 == |
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| − | RA & dec: 7 01 37.9, -11 18 48, epoch 1950.0
| + | 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. | | Site long&lat: 10 21 53.2 (h.m.s) West, 19 49 36 North. |
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| − | Shown: local eve. date, moon phase, hr ang and sec.z at (1) eve. twilight,
| + | {| border="1" |
| − | (2) natural center of night, and (3) morning twilight; then comes number of
| + | |+BRC 27 |
| − | nighttime hours during which object is at sec.z less than 3, 2, and 1.5.
| + | |-bgcolor=grey |
| − | Night (and twilight) is defined by sun altitude < -18.0 degrees.
| + | |} |
| − | | |
| − | Date (eve) moon eve cent morn night hrs@sec.z:
| |
| − | HA sec.z HA sec.z HA sec.z <3 <2 <1.5
| |
| − | 2012 Feb 6 F -2 48 1.6 2 17 1.4 7 22 down 7.1 6.2 5.0
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| − | 2012 Feb 21 N -1 43 1.3 3 16 1.9 8 14 down 6.0 5.2 4.2
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| − | 2012 Mar 7 F -0 39 1.2 4 12 2.9 9 03 down 4.9 4.1 3.1
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| − | 2012 Mar 21 N 0 21 1.2 5 04 6.3 9 46 down 3.9 3.1 2.1
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| − | 2012 Apr 5 F 1 25 1.3 5 58 down 10 31 down 2.9 2.0 1.1
| |
| − | 2012 Apr 20 N 2 30 1.5 6 54 down 11 17 down 1.8 1.0 0.0
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| − | 2012 May 5 F 3 37 2.1 7 51 down -11 56 down 0.7 0.0 0.0
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| − | 2012 May 20 N 4 45 4.3 8 50 down -11 05 down 0.0 0.0 0.0
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| − | 2012 Jun 3 F 5 47 down 9 47 down -10 14 down 0.0 0.0 0.0
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| − | 2012 Jun 18 N 6 52 down 10 49 down -9 14 down 0.0 0.0 0.0
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| − | 2012 Jul 2 F 7 49 down 11 47 down -8 15 down 0.0 0.0 0.0
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| − | 2012 Jul 18 N 8 48 down -11 08 down -7 04 down 0.0 0.0 0.0
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| − | 2012 Aug 1 F 9 36 down -10 13 down -6 01 down 0.0 0.0 0.0
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| − | 2012 Aug 16 N 10 24 down -9 16 down -4 55 5.2 0.0 0.0 0.0
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| − | 2012 Aug 30 F 11 06 down -8 24 down -3 54 2.4 0.4 0.0 0.0
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| − | 2012 Sep 15 N 11 53 down -7 27 down -2 46 1.6 1.5 0.7 0.0
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| − | 2012 Sep 29 F -11 25 down -6 36 down -1 48 1.3 2.5 1.7 0.7
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| − | 2012 Oct 14 N -10 38 down -5 41 v.low -0 45 1.2 3.5 2.7 1.7
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| − | 2012 Oct 28 F -9 51 down -4 48 4.6 0 15 1.2 4.5 3.7 2.7
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| − | 2012 Nov 12 N -8 57 down -3 49 2.3 1 20 1.3 5.6 4.8 3.8
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| − | 2012 Nov 27 F -7 58 down -2 46 1.6 2 26 1.5 6.7 5.9 4.9
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| − | 2012 Dec 12 N -6 54 down -1 40 1.3 3 34 2.1 7.8 6.9 5.0
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| − | 2012 Dec 27 F -5 48 down -0 34 1.2 4 41 4.1 8.5 6.9 5.0
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| − | 2013 Jan 10 N -4 45 4.3 0 28 1.2 5 40 81.1 8.5 6.9 5.0
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| − | | |
| − | | |
| − | >><<
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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.
