YALO IR - February 2001

YALO IR color terms (Feb 2001)

The YALO types got some IR standards on 2,3,4 Feb 2001. There were only a few taken per night, and many of them were crap because the coords were entered incorrectly. I had to reduce all the three nights in a single reduction which is obviously stupid, but there was nothing else to be done. The solutions were based on data from 2,4 Feb 2001.

The output was:

3 INDICES:   K J-K H-K      
iras537w 0.861 9.9836 0.0093 2.9973 0.0240 1.0529 0.0182 13 14 14
lhs2026 0.449 11.1527 0.0123 0.9252 0.0208 0.3627 0.0178 6 7 7
lhs2397a 1.176 10.6765 0.0121 1.2185 0.0362 0.5008 0.0264 11 13 12
iras537sx 1.221 10.6703 0.0147 2.6456 0.0352 1.0104 0.0258 13 14 13
p9106x 0.473 11.9521 0.0150 0.4445 0.0213 0.0477 0.0212 7 7 6

 

The library values were:

iras537w 9.981 0.0130 2.993 0.0090 1.051 0.0090 Persson
lhs2026 11.129 0.0070 0.937 0.0060 0.368 0.0050 Persson
lhs2397a 10.691 0.0080 1.206 0.0080 0.499 0.0070 Persson
iras537sx 10.972 0.0140 2.883 0.0120 1.115 0.0090 Persson
p9106x 11.772 0.0100 0.381 0.0070 0.070 0.0050 Persson


The airmass range was [1.0,1.6] and the color range [0.9,3.0].

The calibration file was:
M1=I1+I2
M2=I1+I3
M3=I1
I1=M3
I2=M1-M3
I3=M2-M3
O1 = M1 + A0 + A1*I2 + A2*X + A3*T
O2 = M2 + B0 + B1*I2 + B2*X + B3*T
O3 = M3 + C0 + C1*I2 + C2*X + C3*T
A3 = 0 m:j,h,k
B3 = 0 i:K,J-K.H-K
C3 = 0
A2 = 0.1
B2 = 0.04
C2 = 0.08
A0 = 5.4748354 0.0325335 <<
A1 = -0.0399482 0.0152400 <<
B0 = 5.3961229 0.0229689 <<
B1 = 0.0210653 0.0109061 <<
C0 = 5.8853974 0.0154214 <<
C1 = 0.0745587 0.0072294 <<
S1 = 0.0743827 <<
S2 = 0.0556543 <<
S3 = 0.0346595 <<

This should be compared to last years data:

 

   ========================================  
     Feb 2000 Feb 2001    
  -----------------------------------------------------------------------------------  
  [J,J-K] = -0.028 +/- 0.005 -0.039 0.015  
  [H,J-K] = 0.010 +/- 0.005 0.021 0.011  
  [H,H-K] = 0.022 +/- 0.005      
  [K,J-K] = -0.003 +/- 0.005 0.074 0.010 <==??
  -----------------------------------------------------------------------------------  

For some reason the K term is much different, but there is no explanation. The 2000 data are much more accurate because they represent 5 nights, and on each night many more stars were observed.

Using the Persson and CIT standards from [J-K]=[0.0,1.0], I get the following proportionalities:

H-K = c + 0.33(J-K)
J-H = c + 0.65(J-K)

for which I will estimate the following color terms based on the 2000 data. I also put the measured Feb 2001 color terms, which are not very accurate:

  Feb 2000 Feb 2001
[J,J-H] = -0.043 +/- 0.005 -0.058  0.031
[H,J-H] = 0.015 +/- 0.005 0.031  0.026

 

Mag at 1 ct/sec in 11" aperture at x=1.25 and color=0.

 

  ===================
        2000 2001
  ----------------------------------------
  J 19.56 19.41
  H 19.62 19.55
  K 19.03 19.02
  ----------------------------------------

 

 

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