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J/ApJ/707/89            Variation of mid-IR extinction              (Gao+, 2009)
Mid-infrared extinction and its variation with galactic longitude.
    Gao J., Jiang B.W., Li A.
   <Astrophys. J., 707, 89-102 (2009)>
   =2009ApJ...707...89G
ADC_Keywords: Extinction ; Galactic plane ; Interstellar medium ; Stars, giant ;
              Photometry, infrared ; Surveys
Keywords: dust, extinction - Galaxy: bulge - Galaxy: structure - infrared: ISM -
          infrared: stars

Abstract:
    Based on the data obtained from the Spitzer/Galactic Legacy Infrared
    Midplane Survey Extraordinaire (GLIPMSE) Legacy Program and the Two
    Micron All Sky Survey (2MASS) project, we derive the extinction in the
    four IRAC bands, [3.6], [4.5], [5.8], and [8.0]um, relative to the
    2MASS Ks band (at 2.16um) for 131 GLIPMSE fields along the Galactic
    plane within |l|≤65°, using red giants and red clump giants as
    tracers. As a whole, the mean extinction in the IRAC bands (normalized
    to the 2MASS Ks band), A[3.6]/AKs∼0.63±0.01,
    A[4.5]/AKs∼0.57±0.03, A[5.8]/AKs_∼0.49±0.03,
    A[8.0]/AKs∼0.55±0.03, exhibits little variation with wavelength
    (i.e., the extinction is somewhat flat or gray). As far as individual
    sightline is concerned, however, the wavelength dependence of the
    mid-infrared interstellar extinction Aλ/AKs varies from one
    sightline to another, suggesting that there may not exist a
    "universal" IR extinction law.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table3.dat       126      131   Extinction ratios A(λ)/A(Ks) of the 131
                             GLIMPSE fields


See also:
   II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
   II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
   J/ApJ/658/1264  : IR-excess sources in GLIMPSE and MSX (Uzpen+, 2007)
   J/A+A/446/551   : Extinctions at 7um + 15um from ISOGAL survey (Jiang+, 2006)
   J/MNRAS/338/253 : K extinction near the Galactic Centre (Dutra+, 2003)
   J/A+A/349/L69   : Interstellar extinction (Schultheis+, 1999)
   http://www.astro.wisc.edu/sirtf/glimpsedata.html : GLIMPSE data home page


Byte-by-byte Description of file: table3.dat

   Bytes Format Units   Label    Explanations

   1- 11  A11   ---     FName    Field name (1)
  13- 17  F5.1  deg     GLONl    Lower Galactic longitude degree
  19- 23  F5.1  deg     GLONu    Upper Galactic longitude degree
  25- 28  F4.1  deg     GLATl    Lower Galactic latitude degree
  30- 33  F4.1  deg     GLATu    Upper Galactic latitude degree
  35- 39  F5.3  ---     GA3.6    IRAC [3.6] band to Ks band extinction ratio
                                 from Red Giants (2)
  41- 45  F5.3  ---     e_GA3.6  Uncertainty in GA3.6
  47- 51  F5.3  ---     GA4.5    IRAC [4.5] band to Ks band extinction ratio
                                 from Red Giants (2)
  53- 57  F5.3  ---     e_GA4.5  Uncertainty in GA4.5
  59- 63  F5.3  ---     GA5.8    IRAC [5.8] band to Ks band extinction ratio
                                 from Red Giants (2)
  65- 69  F5.3  ---     e_GA5.8  Uncertainty in GA5.8
  71- 75  F5.3  ---     GA8.0    IRAC [8.0] band to Ks band extinction ratio
                                 from Red Giants (2)
  77- 81  F5.3  ---     e_GA8.0  Uncertainty in GA8.0
  83- 86  F4.2  ---     CA3.6    IRAC [3.6] band to Ks band extinction ratio
                                 from Red Clump Giants  (2)
  88- 91  F4.2  ---     e_CA3.6  Uncertainty in CA3.6
  93- 96  F4.2  ---     CA4.5    IRAC [4.5] band to Ks band extinction ratio
                                 from Red Clump Giants (2)
  98-101  F4.2  ---     e_CA4.5  Uncertainty in CA4.5
 103-106  F4.2  ---     CA5.8    IRAC [5.8] band to Ks band extinction ratio
                                 from Red Clump Giants (2)
 108-111  F4.2  ---     e_CA5.8  Uncertainty in CA5.8
 113-116  F4.2  ---     CA8.0    IRAC [8.0] band to Ks band extinction ratio
                                 from Red Clump Giants (2)
 118-121  F4.2  ---     e_CA8.0  Uncertainty in CA8.0
 123-126  F4.1  mag     Ksmax    Maximum Ks band magnitude for Red Clump Giants

Note (1): GLMXC_l009, GLMXC_l350, GLMIC_l064 and GLMIC_l295 are the combined
          fields (see Section 2 in the paper).
Note (2): The effective wavelengths of the four Spitzer/IRAC bands [3.6],
          [4.5], [5.8] and [8.0] are actually 3.545, 4.442, 5.675 and 7.760
          microns, respectively.


History:
    From electronic version of the journal
(End)                 Greg Schwarz [AAS], Emmanuelle Perret [CDS]    29-Dec-2011