Usage of findPixel

Return to directory of Todd's CASA extensions

Takes an image and converts a list of pixels to a list of RA,Decs and (optionally) the separation (in arcseconds) from a reference position. See also findRADec.

Usage

au.findPixel(image, pixelfile='', pixel='', referencePosition=None, precision=2, 
        outputfile=None, getvalue=False, beam=None, format='sexagesimal'):
Inputs:
  • Image should be recognizable to casa (FITS or casa native image or cube).
  • pixelfile: expects a text file containing lines in any of these formats:
    • sourcename1 '243, 347'\n
    • sourcename2 "243, 347"\n
    • sourcename3 243, 347\n
  • Pixels can be integers or floating point values.
  • pixel: this parameter must be a string of the format: 'x,y', (integers or floats), or a list of length 2
  • Ignores lines with '#' as the first character, and lines lacking a comma.
  • Reference Position should be a tuple: [RA,Dec] each in degrees
  • getvalue: if True, then print the pixel value
  • beam: if not None, then interpret this as the FHWM beam in arcsec, assume the image is in MJy/sr, and compute the Jy/beam at this pixel
  • format: 'sexagesimal', 'radians', or 'degrees'
Returns:
  • format = 'sexagesimal':
    • if one pixel: a single sexagesimal string: HH:MM:SS.SSS +DD:MM:SS.SS
    • if more than one pixel: a list of strings
  • format = 'radians' or 'degrees':
    • if one pixel: [ra, dec]
    • if more than one pixel: a list of [ra,dec] values

See this example pixelfile.

Examples

CASA <3>: au.findPixel('Juno0.apcal_R1.image.imsmooth',pixel=au.imageCentroid('Juno0.apcal_R1.image.imsmooth',fractionalThreshold=0.1),format='degrees')
Set threshold to 0.002833
Image statistics: mean=0.000026 median=0.000000 max=0.028327 min=0.000000
   488.150885 500.625473   08:14:46.277534 +06:19:11.80024
  Out[3]: [123.69282306005104, 6.319944510915164]

CASA <2>: au.findPixel('/net/shadowfax/export/data_2/30Dor_ALMA/Line_cubes/30DorBand3.ms.HCOp.image.pbcor.CONV', 
                       /users/thunter/pixelfile',referencePosition=[84.6779,-69.1009] )
Far_east       81 313   05:38:56.41 -69:04:16.809  129.315741
NE_Dark        178 292   05:38:50.98 -69:04:23.123  109.509072
Bright_E       132 250   05:38:53.56 -69:04:35.718  105.086109
Bright_W       145 243   05:38:52.83 -69:04:37.819  101.199849
Center         208 229   05:38:49.30 -69:04:42.025  88.585214
Center_south   207 222   05:38:49.36 -69:04:44.125  86.786799
South_center   215 211   05:38:48.91 -69:04:47.425  82.796170
H2O_maser      256 219   05:38:46.62 -69:04:45.026  80.979839
NE_ofmaser     248 235   05:38:47.06 -69:04:40.226  86.244302
Double_E       281 233   05:38:45.22 -69:04:40.825  83.511075
Double_W       287 237   05:38:44.88 -69:04:39.625  84.428012
North_Pillar   249 168   05:38:47.01 -69:05:00.326  67.013816
Southern       282 146   05:38:45.16 -69:05:06.925  57.837019
Far_west       412 168   05:38:37.88 -69:05:00.311  68.013238
NF_north       242 366   05:38:47.40 -69:04:00.926  124.880434
NF_center      247 356   05:38:47.12 -69:04:03.926  121.642743
NF_south       243 347   05:38:47.34 -69:04:06.626  119.240012
Output file =  /users/thunter/pixelfile.radec

-- ToddHunter - 2012-12-04
Topic revision: r6 - 2014-12-02, ToddHunter
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding NRAO Public Wiki? Send feedback