iraf.net

Hi!
I am trying to find radial velocity using FXCOR, but I would like to use synthethic spectra as template.I've created some synthetic spectra in ASCII format, and converted them into fits using rspectext command.Then I tried to use FXCOR on the real spectrum as object and the synthetic as template, but it gives the following error:ERROR: cannot convert to specified unitI've tried to use a real spectra instead of the synthetic one, but the error is the same. Could you please explain me how to solve this problem?I have also another question, how can I choose a particular range?
In the case I'm studying , I would like to use the range from 4000 to 4050 angstrom, because that is the one in common beetwen real and synthetic spectra.Thanks you for any help,Angela

The error about units means there is something strange in the WCS and the task isn't able to convert e.g. a TAN projection WCS to a spectral WCS. Please post the header for the object and template and I can be more specific about what is wrong, you can turn on the 'pixcorr' parameter to do a pixel-only correlation if all you want is a shift.As for setting ranges, set the 'osample' and 'rsample' parameter to the range string "4000-4050" (this can be a comma-delimited list if you have multiple ranges).Cheers,
-Mike

Hi Mike,
thank you for your answer. Here there are the headers:[b:2b576fe13b]Template header [/b:2b576fe13b]t05500g5.0ap00k0_br14.asc.fits[9872][real]:
No bad pixels, min=0., max=0. (old)
Line storage mode, physdim [9872], length of user area 1256 s.u.
Created Tue 16:50:47 10-Feb-2009, Last modified Tue 16:50:51 10-Feb-2009
Pixel file "t05500g5.0ap00k0_br14.asc.fits" [ok]
EXTEND = F / File may contain extensions
ORIGIN = 'NOAO-IRAF FITS Image Kernel July 2003' / FITS file originator
DATE = '2009-02-10T15:50:47' / Date FITS file was generated
IRAF-TLM= '16:50:51 (10/02/2009)' / Time of last modification
APNUM1 = '1 1 '
WCSDIM = 1
CTYPE1 = 'LINEAR '
CRVAL1 = 3854.013
CRPIX1 = 1.
CDELT1 = 0.019753520413332
CD1_1 = 0.019753520413332
LTM1_1 = 1.
WAT0_001= 'system=equispec'
WAT1_001= 'wtype=linear'
DC-FLAG = 0[b:2b576fe13b]Object header:[/b:2b576fe13b]BITPIX = 8 / 8-bit ASCII characters
NAXIS = 1 / Number of Image Dimensions
NAXIS1 = 56000 / Length of axis
ORIGIN = 'NOAO-IRAF: WTEXTIMAGE' /
IRAF-MAX= 0. / Max image pixel (out of date)
IRAF-MIN= 0. / Min image pixel (out of date)
IRAF-B/P= 32 / Image bits per pixel
IRAFTYPE= 'REAL FLOATING ' / Image datatype
OBJECT = 'HD117176 ' /
FILENAME= '/HOME/MEA/DESKTOP/ELODIE2/HD117176_NORM.FITS' /
FORMAT = '5G14.7 ' / Text line format
EXTEND = T / File may contain extensions
ORIGIN = 'NOAO-IRAF FITS Image Kernel July 2003' / FITS file originator
DATE = '2009-02-06T10:46:24' / Date FITS file was generated
IRAF-TLM= '11:45:53 (06/02/2009)' / Time of last modification
OBJECT = 'HD117176' / Name of the object observed
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
CRPIX1 = 1. / Reference pixel
CRVAL1 = 4000. / Coordinate at reference pixel
CDELT1 = 0.0500000007 / Coordinate increment (prefer CD)
VERSION = '1.3 ' / TACOS_VERSION
LASTCOMP= 'tacos_SunOS_5.4 - Thu Mar 7 14:46:32 WET 1996' / TACOS_LASTCOMP
INSTRUME= 'ELODIE ' / INSTRUME
CUMUL = 1.00000000E+00 / O_CUMUL
DATETU = '19991223' / O_DATETU
HDEBUT = 5.04111958E+00 / O_HDEBUT
HFIN = 5.20779896E+00 / O_HFIN
EXPTIME = 600.450012 / Exposure time
TIME1 = 1.99900000E+03 / O_TIME
TIME2 = 1.20000000E+01 / O_TIME
TIME3 = 2.30000000E+01 / O_TIME
TIME4 = 5.12451553E+00 / O_TIME
TIME5 = 6.00450012E+02 / O_TIME
CCDGAIN = 2.65000010E+00 / ELODIE_CCDGAIN
NUMGAIN = 3.00000000E+00 / ELODIE_NUMGAIN
NUMCCD = '1 ' / ELODIE_NUMCCD
NUMCORRE= '3 ' / ELODIE_NUMCORRE
POSCORRE= '35 ' / ELODIE_POSCORRE
CCDTEMP = '-90.00 ' / ELODIE_CCDTEMP
CCDPOWER= '74.60 ' / ELODIE_CCDPOWER
MAP = '1898 ' / ELODIE_MAP
OBSERVER= 'soubiran' / OBSERVER
NONUIT = 4.10000000E+01 / NONUIT
POS1 = 1.34733362E+01 / TEL_POS
POS2 = 1.37708330E+01 / TEL_POS
NOOBJET1= 1 / CAT_NOOBJET
NOOBJET2= 0 / CAT_NOOBJET
NOOBJET3= 117176 / CAT_NOOBJET
NOOBJET4= 0 / CAT_NOOBJET
REFNOCOD= 'HD ' / CAT_REFNOCODE
EQUINOX = 2.00000000E+03 / CAT_EQUINOX
ALPHA = '13:28:26' / CAT_ALPHA
DELTA = '+13:46:44' / CAT_DELTA
PROPERM1= 0.00000000E+00 / CAT_PROPERMVT
PROPERM2= 0.00000000E+00 / CAT_PROPERMVT
NOPROG = 100 / CAT_NOPROG
COMMENT = '* ' / COMMENT
IMATYP = 'OBJOd/S2D/CAL' / TACOS_IMATYP
IMALOC = 'n19991222/s2d/loco0003' / TACOS_IMALOC
NORDER = 6.70000000E+01 / TACOS_NORDER
DECLOC = 0.00000000E+00 / TACOS_DECLOC
DEGLOC1 = 4.00000000E+00 / TACOS_DEGLOC
DEGLOC2 = 2.50000000E+01 / TACOS_DEGLOC
DEGSIG1 = 3.00000000E+00 / TACOS_DEGSIG
DEGSIG2 = 4.00000000E+00 / TACOS_DEGSIG
OLIMLS = 1.00000000E+00 / TACOS_OLIMLS
EXTSTR = 3.00000000E+00 / TACOS_EXTSTR
JDB1 = 2.45153500E+06 / TACOS_JDB
JDB2 = 7.12275028E-01 / TACOS_JDB
BERV = 2.75154343E+01 / TACOS_BERV
BERVMX = 2.98112831E+01 / TACOS_BERVMX
DELCAL = 0.00000000E+00 / TACOS_DELCAL
DEGXLL = 3.00000000E+00 / TACOS_DEGXLL
DEGOLL = 5.00000000E+00 / TACOS_DEGOLL
OLIMLL = 1.00000000E+00 / TACOS_OLIMLL
LLOFFSET= 1.57015152E+02 / TACOS_LLOFFSET
LLPARS = -1.00000000E+00 / TACOS_LLPARS
LLCMOY = 0.00000000E+00 / TACOS_LLCMOY
LLCSIG = 0.00000000E+00 / TACOS_LLCSIG
IMACAL = 'n19991222/llo0018' / TACOS_IMACAL
LLCNRA = 1.01700000E+03 / TACOS_LLCNRA
FILERC = '/d1/gva/dqsrc/elodie/elodiehp' / TACOS_FILERC
PROXIM = 2.50000000E-01 / TACOS_PROXIM
FILENAME= 'elodie:19991222/0041' / Original filename
CD1_1 = 0.0500000007 / Coordinate increment per pixel
CREATOR = 'Pleinpot 1' / Written by Pleinpot (Hypercat)
DATE-OBS= '1999-12-23T05:07:28' / [CCYY-MM-DDThh:mm:ss] Date observation
MJD-OBS = 51535.213521 / [d] Modified JD when observ. start
AIRMASS = 1.26949573 / Airmass
CTYPE1 = 'WAVE-WAV' / Axis type
H_CONTXT= 'SPE ' / Spectrum
H_STATUS= 0 / No error on pipeline
COMMENT The ELODIE archive (OHP)
COMMENT Note: The telescope position (POS1,POS2) and the catalogue information
COMMENT (NOOBETn)
COMMENT may not be accurate. Please use instead the designation from keyword
COMMENT (OBJECT)
H_AFR000= 'elodie:19991222/0041' / Archive identifier of current frame
H_TYPE = 1 / Science object
SN = 322.8 / S/N-per-pixel of original spectrum at 550 nm
DIVUL = 0 / data fully public
CUNIT1 = '0.1 nm ' / Unit of coordinate
BTYPE = 'FLUX-INS' / Type of data
BUNIT = 'instrumental' / Unit of data
H_DBIAS = 0. / [ADU] Bias on the frame
H_WRESOL= 0.1321429 / [0.1nm] FWHM wavelength resolution
H_ASP002= 'fa:LL_ELODIE/99002' / File used for "strengthening"
H_HISTO = 'FFC000/WCA000/'
H_FCANOR= '[FCANOR]' / Pointer to the Flux calibration relation
SFIT = '1 '
SFITB = '1 '
END
Thanks a lot,
Angela

A quick guess until I have more time to look at this: The object CUNIT value of "0.1 nm" looks suspicious to me. First thing I'd try is to HEDIT the header to delete this keyword (on a copy, of course) since the units default to Angstroms anyway.-Mike

I've tried to change CUNIT1 = '0.1 nm ' into CUNIT1 = 'Angstrom' in two elodie spectra and then I've used them as object and template, but the error is the same

I believe the correct value is the plural "Angstroms", not "Angstrom". You can use HEDIT to simply delete the keyword and get the same default value. One other test is to auto-correlate your synthetic template (i.e. the one without the CUNIT keyword), my guess is that will work.-Mike

I've deleted the CUNIT keyword in all my spectra and FXCOR seems working Thank you very much for your helpAngela

I've tried to add the following keywords to the synthetic template spectra: DATE-OBS= '1993-03-17T04:56:38.0'
RA = '12:00:00'
DEC = '12:00:00'
EPOCH = 1993.0
OBSERVAT= 'KPNO' but in the correlation plot V_0=INDEF and V_h=INDEF +/- ... !!!I can I solve this problem?

I've added to the synthetic template the keyword EXPTIME =5, and now V_o and V_h aren't INDEF, but now I've HJD=INDEF, and V_r=V_o !!! What could I do?

Once the correlation is complete, use the 'v' keystroke to print the verbose logfile. At the end of the output will be any complaints about missing/malformed keywords.-Mike