[daip] coordinates in AIPS
Anna Bartkiewicz
annan at astro.uni.torun.pl
Tue Nov 23 09:16:21 EST 2010
Dear Eric,
Thank you for your willing help. In the meantime I just tried:
loading into AIPS the original file with a header:
SIMPLE = T / Written by IDL: 23-Oct-2009 16:29:30.00
BITPIX = -64 / IEEE double precision floating point
NAXIS = 2 /number of axes
NAXIS1 = 1305 /
NAXIS2 = 1306 /
EXTEND = T /file may contain extensions
DATE = '2009-10-21' / Creation date (DD/MM/YY) of FITS header
INSTRUME= 'NIRI ' /Instrument used to acquire data
OBJECT = 'G23.389+00.185' /Object Name
GEMPRGID= 'GN-2009B-Q-44' /Gemini Science Program ID
TELESCOP= 'Gemini-North' /Telescope
EPOCH = 2000.00 /Epoch for Target coordinates
RA = 278.30967 /RA of Target
DEC = -8.3992972 /Declination of Target
WAVELENG= 21200.0 /Effective Target Wavelength
RAWIQ = '20-percentile' /Raw Image Quality
RAWCC = '50-percentile' /Raw Cloud Cover
RAWWV = '50-percentile' /Raw Water Vapour/Transparency
RAWBG = '50-percentile' /Raw Background
PA = 0.000000 /Sky Position Angle at start of exposure
HUMIDITY= 26.0000 /The Relative Humidity (fraction, 0..101)
CAMERA = 'f32 ' /NIRI camera (f6|f14|f32)
COADDS = 35 /Number of coadds summed
DATE-OBS= '009-10-15' /Observation date (UT)
EXPTIME = 0.601000 /Exposure time (s) for each frame
FILTER1 = 'Kprime_G0206' /Filter 1 name
FILTER2 = 'open ' /Filter 2 name
FILTER3 = 'Pupil38_G5207' /Pupil mask, grism, or filter name
FPMASK = 'f14-cam_G5209' /Focal plane mask name
BEAMSPLT= 'f32 ' /Beam splitter position name
FRMSPCYC= 2 /Frames per cycle,1=sep,2=stare
MODE = 'STARE ' /Stare or sep
TIME = '05:39:40.3' /Beginning of Observation (UT)
AMSTART = 1.39900 /Airmass at start of exposure
AMEND = 1.40200 /Airmass at end of exposure
CTYPE1 = 'RA---TAN' /the coordinate type for the first axis
CTYPE2 = 'DEC--TAN' /the coordinate type for the second axis
CD1_1 = -6.089454412084e-006 /partial of first axis coord w.r.t. x
CD1_2 = 3.802123089418e-008 /partial of first axis coord w.r.t. y
CD2_1 = 2.450182223808e-008 /partial of second axis coord w.r.t. x
CD2_2 = 6.054210442537e-006 /partial of second axis coord w.r.t. y
FRAME = 'FK5 ' /Target coordinate system
CRPIX1 = 121.130 /Ref pix of axis 1
CRPIX2 = 345.380 /Ref pix of axis 2
CRVAL1 = 278.31204800 /RA at Ref pix in decimal degrees
CRVAL2 = -8.40106300 /DEC at Ref pix in decimal degrees
FLUXSCAL= 'mJy/pixel' /Flux scale of image
END
AIPS message was:
ring2 > FITLD1: Task FITLD (release of 31DEC10) begins
ring2 > FITLD1: WARNING: 64-bit input stored in 32 bits inside AIPS
ring2 > FITLD1: WARNING: 64-bit input stored in 32 bits inside AIPS
ring2 > FITLD1: Create FITLD .TEMP . 1 (MA) on disk 1 cno 49
ring2 > FITLD1: PCHDR: IMAGE APPEARS TO BE SKEWED: 179.77 NOT 179.64
ring2 > FITLD1: PCHDR: IMAGE SKEWED: 0.02192 -0.02180 NOT 0.01712 -0.02657
ring2 > FITLD1: RenamE G23.389_CLE .IMAP . 1 (MA) on disk 1 cno 49
ring2 > FITLD1: Image=G23.389+ (MA) Filename=G23.389_CLE .IMAP . 1
ring2 > FITLD1: Telescope=Gemini-N Receiver=NIRI
ring2 > FITLD1: Observer= User #= 101
ring2 > FITLD1: Observ. date=BAD DATE Map date=23-NOV-2010
ring2 > FITLD1: Minimum=-1.17929012E-03 Maximum= 1.95409203E+00
ring2 > FITLD1:
----------------------------------------------------------------
ring2 > FITLD1: Type Pixels Coord value at Pixel Coord incr Rotat
ring2 > FITLD1: RA---TAN 1305 18 33 14.892 121.13 0.019522 0.00
ring2 > FITLD1: DEC--TAN 1306 -08 24 03.827 345.38 -0.024182 179.70
ring2 > FITLD1:
----------------------------------------------------------------
ring2 > FITLD1: Coordinate equinox 2000.00
ring2 > FITLD1: Maximum version number of extension files of type HI is 1
ring2 > FITLD1: Appears to have ended successfully
ring2 > FITLD1: ring2 31DEC10 TST: Cpu= 0.1 Real= 0 IO= 8
Then FITTP on the disc and the header of the file is:
SIMPLE = T /
BITPIX = -32 /
NAXIS = 2 /
NAXIS1 = 1305 /
NAXIS2 = 1306 /
EXTEND = T /Tables following main image
BLOCKED = T /Tape may be blocked
OBJECT = 'G23.389+' /Source name
TELESCOP= 'Gemini-N' /
INSTRUME= 'NIRI ' /
OBSERVER= ' ' /
DATE-OBS= '009--10--1' /Obs start date YYYY-MM-DD
DATE-MAP= '2010-11-23' /Last processing date YYYY-MM-DD
BSCALE = 1.00000000000E+00 /REAL = TAPE * BSCALE + BZERO
BZERO = 0.00000000000E+00 /
BUNIT = ' ' /Units of flux
EQUINOX = 2.000000000E+03 /Epoch of RA DEC
DATAMAX = 1.954092026E+00 /Maximum pixel value
DATAMIN = -1.179290120E-03 /Minimum pixel value
CTYPE1 = 'RA---TAN' /
CRVAL1 = 2.78312048000E+02 /
CDELT1 = 5.422718914E-06 /
CRPIX1 = 1.211299973E+02 /
CROTA1 = 0.000000000E+00 /
CTYPE2 = 'DEC--TAN' /
CRVAL2 = -8.40106300000E+00 /
CDELT2 = -6.717182259E-06 /
CRPIX2 = 3.453800049E+02 /
CROTA2 = 1.797048187E+02 /
And then correct by hand: CDELT1 = 6.083333333E-06 / and CDELT2 =
-6.083333333E-06 / (as it should be 0.0219" and -0.0219" )
And again FITLD into AIPS. The message from AIPS:
ring2 > FITLD1: Task FITLD (release of 31DEC10) begins
ring2 > FITLD1: Create FITLD .TEMP . 2 (MA) on disk 1 cno 52
ring2 > FITLD1: RenamE G23.389_CLE2.IMAP . 2 (MA) on disk 1 cno 52
ring2 > FITLD1: Image=G23.389+ (MA) Filename=G23.389_CLE2.IMAP . 2
ring2 > FITLD1: Telescope=Gemini-N Receiver=NIRI
ring2 > FITLD1: Observer= User #= 101
ring2 > FITLD1: Observ. date=BAD DATE Map date=23-NOV-2010
ring2 > FITLD1: Minimum=-1.17929012E-03 Maximum= 1.95409203E+00
ring2 > FITLD1:
----------------------------------------------------------------
ring2 > FITLD1: Type Pixels Coord value at Pixel Coord incr Rotat
ring2 > FITLD1: RA---TAN 1305 18 33 14.892 121.13 0.021900 0.00
ring2 > FITLD1: DEC--TAN 1306 -08 24 03.827 345.38 -0.021900 179.70
ring2 > FITLD1:
----------------------------------------------------------------
ring2 > FITLD1: Coordinate equinox 2000.00
ring2 > FITLD1: Maximum version number of extension files of type HI is 1
ring2 > FITLD1: Appears to have ended successfully
ring2 > FITLD1: ring2 31DEC10 TST: Cpu= 0.1 Real= 0 IO= 8
So, the pixel size are ok, but that is probably a problem of skewing as
you wrote (can it be related to 32/64 bits) since now the coordinates are
little bit shifted.
AIPS IMSTAT gives the pixel maximum:
RA 18 33 14.32431 DEC -08 23 57.2654
and it should be (info from collaborators) something like:
RA 18 33 14.323 DEC -08 23 57.30
I will be waiting patiently when you find time for this small thing. I
really appreciate your help!
Greetings,
Anna
On Mon, 22 Nov 2010, Eric Greisen wrote:
> Anna Bartkiewicz wrote:
>>
>> Dear Eric,
>>
>> Please, help me finding what should I change in the FITS file that will
>> enable AIPS to obtain a proper pixel size.
>>
>> I got the map (FITS file) of Gemini data with a header:
>> [...]
>> CTYPE1 = 'RA---TAN' /the coordinate type for the first axis
>> CTYPE2 = 'DEC--TAN' /the coordinate type for the second axis
>> CD1_1 = -6.089454412084e-006 /partial of first axis coord w.r.t. x
>> CD1_2 = 3.802123089418e-008 /partial of first axis coord w.r.t. y
>> CD2_1 = 2.450182223808e-008 /partial of second axis coord w.r.t. x
>> CD2_2 = 6.054210442537e-006 /partial of second axis coord w.r.t. y
>> FRAME = 'FK5 ' /Target coordinate system
>> CRPIX1 = 121.130 /Ref pix of axis 1
>> CRPIX2 = 345.380 /Ref pix of axis 2
>> CRVAL1 = 278.31204800 /RA at Ref pix in decimal degrees
>> CRVAL2 = -8.40106300 /DEC at Ref pix in decimal degrees
>> [...]
>>
>> When I load it to the AIPS the header is:
>>> AIPS 1: Image=G23.389+ (MA) Filename=G23.389_KCOR.IMAP . 1
>>> AIPS 1: Telescope=Gemini-N Receiver=NIRI
>>> AIPS 1: Observer= User #= 101
>>> AIPS 1: Observ. date=BAD DATE Map date=25-OCT-2010
>>> AIPS 1: Minimum=-1.17929012E-03 Maximum= 1.95409203E+00
>>> AIPS 1: ----------------------------------------------------------------
>>> AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
>>> AIPS 1: RA---TAN 1305 18 33 14.892 121.13 0.019522 0.00
>>> AIPS 1: DEC--TAN 1306 -08 24 03.827 345.38 -0.024182 179.70
>>> AIPS 1: ----------------------------------------------------------------
>>> AIPS 1: Coordinate equinox 2000.00
>>
>> Is the "coord incr" values the pixels scale for the two axes?
>> If so, they should be 0.0219 and -0.0219 arcsec/pixel as I got the
>> informations from my Collaborators.
>>
>> I read the page:
>> http://tdc-www.harvard.edu/wcstools/wcstools.wcs.html
>> but still I do not know how AIPS determines the "coord incr" values? Should
>> I add CRPIX1 and CRPIX2? Please, reply if you find time for my question.
>>
>> I will appreciate your help.
>>
>> Best regards,
>>
>> Anna
> I am just back from 24 days vacation - please let me look in more detail.
> The CD2_1 and CD1_2 indicate that there is some skew but only at a small
> level so I am surprised that aips gets this much difference between the 2
> axes. It will be a couple of days until I can get to this.
>
> Eric Greisen
>
More information about the Daip
mailing list