[daip] issues with task CONVL

[Eric Greisen]

Sayali Avachat wrote:
> Hello, 
> I want to convolve optical maps to the resolution of radio maps, using 
> task CONVL.
> It looks like it is doing everything else fine, except that the flux 
> minimum and maximum values in the header are changing by an order. (e.g 
> previously maximum is 1.23e+2 and later it changes to 2.24e+3)
> I am not sure why CONVL would do that?
> 
> Here are the inputs I used - 
> 
> INNAME - optical map
> IN2NAME - radio map
> OPCODE '  '  (was left blank as I am using IN2NAME)
> BMAJ, BMIN and BPA - taken from header of IN2NAME
> FACTOR - 0, but also tried with 1

First microJy is a flux density not a brightness and so cannot be the 
units of your optical image.  microJy per pixel perhaps, but a 
brightness is power/area.

CONVL should not increase the maximum unless you use it to hyper-resolve 
and that is a questionable operation on radio images and beyond dubious 
on optical.  You do NOT want to convolve the optical image with the 
radio image - you want to convolve the optical image so that its 
resolution becomes that of the radio image.  Note that OPCODE ' ' means 
GAUS not some image convolution.  IN2NAME should be blank actually 
although GAUS would ignore the adverbs I expect.  If the optical image 
does not have BMAJ, BMIN, and BPA in its header, CONVL will not know 
what exactly to do to make the output image be the desired resolution.
Use PUTHEAD to put correct values in the optical image header.

Eric Greisen