Velplot Error: Unequal coordinate increments (cdelt)

Is MIRIAD being a pain? Let us know your experience.

Moderator: Mark.Wieringa

Velplot Error: Unequal coordinate increments (cdelt)

Postby Elagali » Wed Aug 17, 2016 12:58 pm

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
Elagali
 
Posts: 4
Joined: Wed Jun 29, 2016 4:36 pm

Re: Velplot Error: Unequal coordinate increments (cdelt)

Postby Mark.Wieringa » Wed Aug 17, 2016 2:26 pm

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
Mark.Wieringa
ATCA Expert
 
Posts: 284
Joined: Mon Feb 08, 2010 1:37 pm

Re: Velplot Error: Unequal coordinate increments (cdelt)

Postby Elagali » Wed Aug 17, 2016 3:25 pm

Thanks heaps Mark! It is working now :-)

Cheers,
Elagali
Elagali
 
Posts: 4
Joined: Wed Jun 29, 2016 4:36 pm


Return to MIRIAD

Who is online

Users browsing this forum: No registered users and 1 guest

cron