SCUBA-2 with FTS and 80K blackbody source
SCUBA-2 with FTS and 80K blackbody source
SCUBA-2 with FTS and 80K blackbody source
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8. Variation of NEFD <strong>and</strong> total background power <strong>with</strong> sky transmission<br />
Compute, background <strong>and</strong> photon noise for the instrument (this is fixed irrespective of the PWV)<br />
k := 2.. ( nr − 2)<br />
Pinst := ⎛ Tel ⎞⋅pW Total instrument background power ⎜ k, 6⎟⎠<br />
Pinst = 10.21pW<br />
⎝ k<br />
Total instrument NEP NEP inst<br />
:=<br />
⎛<br />
⎜<br />
⎝<br />
∑<br />
k<br />
⎞<br />
⎟<br />
⎠<br />
∑<br />
0.5 − 16 watt<br />
Tel ⋅10<br />
⋅<br />
k, 7<br />
Hz<br />
NEPinst 7.46710 17 − watt<br />
=<br />
⋅<br />
Hz<br />
Now vary the airmass (in order to vary the sky transmission) <strong>and</strong> calculate the background power, photon noise<br />
limited NEP <strong>and</strong> NEFD for a range of sky transmission.<br />
airm :=<br />
⎛<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎜<br />
⎝<br />
1<br />
1.3<br />
1.6<br />
2.1<br />
2.6<br />
3.2<br />
3.9<br />
4.7<br />
5.6<br />
6.6<br />
7.7<br />
8.9<br />
10.2<br />
11.5<br />
13<br />
15<br />
⎞<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎟<br />
⎠<br />
pwv1 := 0.5<br />
( )<br />
Telpower( am)<br />
p am kg m 2 sec -3<br />
:= ← ⋅<br />
for x ∈ 0.. ( rows( am)<br />
− 1)<br />
p<br />
( )<br />
p ← P<br />
x water am , pwv1,<br />
Tel ⋅K,<br />
ν , Δν , Tel ⋅Tel<br />
x 1, 1<br />
1, 4 1, 5<br />
( )<br />
NEPph( am)<br />
nepph am kg m 2 sec -2.5<br />
:= ← ⋅<br />
for x ∈ 0.. ( rows( am)<br />
− 1)<br />
( ) 0.5<br />
nepph ← Photnsq am , pwv1,<br />
Tel ⋅K,<br />
ν , Δν , Tel ⋅Tel<br />
, Tel<br />
x<br />
x 1, 1<br />
1, 4 1, 5 1, 5<br />
nepph
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