Hi there,
I am interested in making position-velocity maps of my images. To do this I am using Velplot Miriad task. However, I keep getting this Error:
velplot: Revision 1.11, 2011/10/27 04:18:03 UTC
file: pbcorr
Array dimensions are: nx,ny,nc = 71 71 6
Array size is: nx*ny*nc = 30246
Maximum array dimension is 32768
### Fatal Error: Unequal coordinate increments (cdelt).
I have tried to solve this problem by changing the "cell" parameter in Invert Task, I have set it to (cell=5,5,res). Even though, I keep getting the same error!
Just to show you the header of my file:
naxis = 4
naxis1 = 1024
naxis2 = 1024
naxis3 = 76
naxis4 = 1
crpix1 = 513
crpix2 = 513
crpix3 = 1
crpix4 = 1
cdelt1 = -7.125374395e-06
cdelt2 = 1.693949525e-05
cdelt3 = 25
cdelt4 = 1
crval1 = 0.633001831
crval2 = -0.432633185
crval3 = 2000
crval4 = 1
ctype1 = RA---NCP
ctype2 = DEC--NCP
ctype3 = VELO-HEL
ctype4 = STOKES
bmaj = 0.0002760005591
bmin = 6.624137313e-05
bpa = -0.8444800973
btype = intensity
bunit = JY/BEAM
cellscal = 1/F
epoch = 2000
ltype = velocity
lstart = 2000
lstep = 25
lwidth = 25
niters = 19341
object = j0224_s1
observer = Wong
obstime = 2456659.095
restfreq = 1.420405712
specsys = BARYCENT
telescop = ATCA
vobs = 21.9204464
pbtype = SINGLE
history (text data, 10869 elements)
image (real data, 79691776 elements)
mask (integer data, 2570703 elements)
It is clear that cdelt1/cdelt2 are not similar which is the source of the problem! So, I am basically asking how to solve this issue?
Thanks very much for your help in advance.
Cheers,
Elagali
Velplot Error: Unequal coordinate increments (cdelt)
Moderator: Mark.Wieringa
-
- ATCA Expert
- Posts: 297
- Joined: Mon Feb 08, 2010 1:37 pm
Re: Velplot Error: Unequal coordinate increments (cdelt)
Hi Elagali,
you can force the cell size in ra and dec to be the same by specifying them directly:
cell=5,5
without the "res", this will give 5 arcsec cellsize in both directions. The 'res' option will take the declination into account.
Cheers,
Mark
you can force the cell size in ra and dec to be the same by specifying them directly:
cell=5,5
without the "res", this will give 5 arcsec cellsize in both directions. The 'res' option will take the declination into account.
Cheers,
Mark
Re: Velplot Error: Unequal coordinate increments (cdelt)
Thanks heaps Mark! It is working now
Cheers,
Elagali
Cheers,
Elagali