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 Problems with Standard and Calibrate IRAF task
   
Marckelson
 11/20/2015 06:58PM (Read 1216 times)  
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Registered: 11/20/2015
Posts: 1
Hi there,

I'm actually working on xshooter long-slit and ifu data. Regarding to long-slit, everything is done by the pipeline provided by ESO, but ifu data is just reduced, ESO doesn't provide a recipe to perform the ifu flux calibration so I thought to use IRAF to do it.
Aiming to flux calibrate the ifu data I also taken some ifu standard stars and after to obtain the standard 3D spectrum I extracted the one-dimensional spectrum from each star to use in standard IRAF task, however when I try to run the task no points are identified in the standard star spectrum. Looking at the long-slit spectrum I realised that CTYPE1 = 'LINEAR' while the ifu one-dimensional spectrum (from standard stars) shows CTYPE1 ='WAVE' so when I change this field in the header the standard task can identify all of the points in the spectrum. Would be it correct? Bellow you can see part of the header of standard one-dimensional spectrum from NIR arm:
SIMPLE = T / file does conform to FITS standard
BITPIX = -32
NAXIS = 1
NAXIS1 = 24750
EXTEND = T / FITS dataset may contain extensions
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
DATE = '2015-11-19T15:17:43' / file creation date (YYYY-MM-DDThh:mm:ss UT)
ORIGIN = 'ESO ' / European Southern Observatory
TELESCOP= 'ESO-VLT-U2' / ESO Telescope Name
INSTRUME= 'XSHOOTER' / Instrument used.
OBJECT = 'STD,FLUX' / Original target.
RA = 245.891154 / 16:23:33.8 RA (J2000) pointing (deg)
DEC = -39.22973 / -39:13:47.0 DEC (J2000) pointing (deg)
EQUINOX = 2000. / Standard FK5 (years)
RADECSYS= 'FK5 ' / Coordinate reference frame
EXPTIME = 120. / Integration time
SPECSYS = 'TOPOCENT' / Coordinate reference frame
CTYPE1 = 'WAVE '
CRPIX1 = 1.
CRVAL1 = 994
CDELT1 = 0.0599999986588955
CUNIT1 = 'nm '

After that I can use the sensfunc task normally but when I try to use calibrate task I get a warning saying that all of the pixels are outside of flux calibration limits, i. e., if I try to flux calibrate the data cube (science object with dimension 3 x 20 x 24750) it says that "495000 pixels outside of flux calibration limits" so if I extract a one-dimensional spectrum from the science object (dimension = 24750) it says that "24750 pixels outside..." I really don't know what to do about it because I using at least 6 stars and the results are very different from long-slit results so I think that something is going well. Bellow is part of the science object header.

SIMPLE = T / Fits standard
BITPIX = -32 / Bits per pixel
NAXIS = 3 / Number of axes
NAXIS1 = 3 / Axis length
NAXIS2 = 20 / Axis length
NAXIS3 = 24750 / Axis length
EXTEND = T / File may contain extensions
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
DATE = '2015-10-29T23:27:20' / file creation date (YYYY-MM-DDThh:mm:ss UT)
ORIGIN = 'NOAO-IRAF FITS Image Kernel July 2003' / FITS file originator
IRAF-TLM= '2015-11-02T23:28:50' / Time of last modification
TELESCOP= 'ESO-VLT-U2' / ESO Telescope Name
INSTRUME= 'SHOOT ' / Instrument used.
OBJECT = 'MRC0943-242' / Original target.
RA = 146.386349 / 09:45:32.7 RA (J2000) pointing (deg)
DEC = -24.48049 / -24:28:49.7 DEC (J2000) pointing (deg)
EQUINOX = 2000. / Standard FK5 (years)
RADECSYS= 'FK5 ' / Coordinate reference frame
EXPTIME = 600. / Integration time
CD1_3 = 0. / CD rotation matrix
CD2_3 = 0. / CD rotation matrix
CD3_1 = 0. / CD rotation matrix
CD3_2 = 0. / CD rotation matrix
CD3_3 = 0.0599999986588955 / CD rotation matrix
CD1_1 = -0.000555555555555556 / CD rotation matrix
CD1_2 = -0. / CD rotation matrix
CD2_1 = -0. / CD rotation matrix
CD2_2 = 5.83333315120803E-05 / CD rotation matrix
CTYPE3 = 'WAVE ' / wavelength axis in nm
CRPIX3 = 0. / Reference pixel in z
CRVAL3 = 994. / central wavelength
CDELT3 = 0.0599999986588955 / nm per pixel
CUNIT3 = 'nm ' / spectral unit
SPECSYS = 'TOPOCENT' / Coordinate reference frame
CTYPE1 = 'RA---TAN' / Projected Rectascension
CRPIX1 = 1. / Reference pixel in RA
CRVAL1 = 146.3814625 / Reference RA
CDELT1 = -0.000555555555555556 / pixel scale
CUNIT1 = 'deg ' / RA-UNIT
CTYPE2 = 'DEC--TAN' / Projected Declination
CRPIX2 = 10. / Reference pixel in DEC
CRVAL2 = -24.4829305555556 / Reference DEC
CDELT2 = 5.83333315120803E-05 / pixel scale
CUNIT2 = 'deg ' / DEC-UNIT
MJD-OBS = 54955.99319961 / Obs start 2009-05-05T00:10:53.096
DATE-OBS= '2009-05-04T23:50:12.4464' / Observing date
UTC = 85810. / 00:10:51.000 UTC at start (sec)
LST = 36031.484 / 10:21:15.881 LST at start (sec)
PI-COI = 'UNKNOWN ' / PI-COI name.
OBSERVER= 'UNKNOWN ' / Name of observer.
HDRVER = '2009-10-20T16:43:06.403' / Header timetag
BUNIT = 'ADU '
HDUCLASS= 'ESO ' / hdu classification
HDUDOC = 'DICD ' / hdu reference document
HDUVERS = 'DICD V6.0' / hdu reference document version
HDUCLAS1= 'IMAGE ' / hdu format classification
HDUCLAS2= 'DATA ' / hdu type classification
ERRDATA = 'ERRS ' / name of errs extension
QUALDATA= 'QUAL ' / name of qual extension

Thanks in advance for anyone who can help me!

Best Regards,
Marckelson Big Grin

 
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