1、Li, D., Velusamy, T., Goldsmith, P.F. & Langer, W., 2007,
“Massive Quiescent Cores in Orion part II – Core Mass Function”, The
Astrophysical Journal, Vol. 655, pp. 351.这篇文章就是从S/N图中寻找云核的
2、
http://docs.jach.hawaii.edu/star/sun255.htx/node18.html 中讲到如果假设噪音恒定,从S/N中寻找核要比从flux图中寻找核要好,如果没有S/N图可以采用,网页中给的方法计算S/N图。
我今天呈现了数据的3D图(
注意z轴的刻度)
x轴是赤纬(dec),y轴是赤经(ra),z轴是流量(flux)
x轴是赤纬(dec),y轴是赤经(ra),z轴是信噪比(s/n)
对图进行分析,可以发现流量高的地方信噪比大,流量图类似与信噪比图,显而易见,通过信噪比图更容易找核。数据可视化的程序
pro plo
ih = readfits("/root/data/ROPH_SWAS.37708-37914.extended.fits",EXTEN_NO=0)
im = readfits("/root/data/ROPH_SWAS.37708-37914.extended.fits",EXTEN_NO=1)
in = readfits("/root/data/ROPH_SWAS.37708-37914.extended.fits",EXTEN_NO=3)
iflux=fltarr(n_elements(im[*,1]),n_elements(im[1,*]))
istn=fltarr(n_elements(im[*,1]),n_elements(im[1,*]))
for i=0,n_elements(im[*,1])-1 do begin
for j=0,n_elements(im[1,*])-1 do begin
if finite(im[i,j]) ne 0 then begin
if im[i,j] ge 2.0 then begin
iflux[i,j]= ih[i,j]
istn[i,j]=in[i,j]
endif
endif
endfor
endfor
set_plot,'ps'
device,file='/root/data/3dimage/3dflux.ps'
shade_surf,iflux
device,/close
set_plot,'ps'
device,file='/root/data/3dimage/3dstn.ps'
shade_surf,istn
device,/close
end
同时通过下面的程序计算了流量图有效值的平均值和信噪比图的有效值的平均值
pro aver
ih = readfits("/root/data/ROPH_SWAS.37708-37914.extended.fits",Header1,EXTEN_NO=0)
im = readfits("/root/data/ROPH_SWAS.37708-37914.extended.fits",Header2,EXTEN_NO=1)
in = readfits("/root/data/ROPH_SWAS.37708-37914.extended.fits",Header2,EXTEN_NO=3)
a=0.0d
b=0.0d
n=0l
for i=0,n_elements(im[*,1])-1 do begin
for j=0,n_elements(im[1,*])-1 do begin
if finite(im[i,j]) ne 0 then begin
if im[i,j] ge 2.0 then begin
a=a+ih[i,j]
b=b+in[i,j]
n++
endif
endif
endfor
endfor
averflux=a/(n*1.0)
averstn=b/(n*1.0)
ratio=averstn/averflux
print,'average of flux =',averflux
print,'average of stn =',averstn
print,'averstn/averflux=',ratio
end
就算结果:
average of flux = 0.029920901
average of stn = 0.21340572
averstn/averflux= 7.1323292
从信噪比图中寻找到的云核