[daip] autoboxing

[Eric Greisen]

Lynn D. Matthews wrote:
>     Eric,
> 
> I agree that having the option to write out a series of OBOX files would 
> be useful. Personally I would also like a record of each channel's boxes 
> in the history file, although it would make it long. Previously I had 
> done the equivalent of all this through a POPS script I wrote to read a 
> series of pre-made box files, clean one plane at a time, record the 
> boxes in the HI file using HINOTE, insert the plane into a cube using 
> MCUBE, etc.

For my hand reduction of NGC6503 - my script used a input BOXFILE from 
channel N-1 for channel N and then wrote a new OBOXFILE.  I used the TV 
to adjust the boxes as needed.  I did not put all in the HI file but did 
save the many boxfiles.  Eventually I used MCUBE to put the cube 
together.  I need to think about the cube reduction issue more deeply.

> Meanwhile I have been putting the autoboxing option to the test using 
> some VLBA maser data. I found I needed to set IM2PARM(1) to a very low 
> number to prevent initial boxing of sidelobes, so I chose IM2PARM(1)=1 
> and left the rest of the array as zeros.  I wasn't clear as to what 
> IM2PARM(5) was doing when left to the default, but 0 worked, so I didn't 
> alter it.

IM2PARM(4) is meant to help with sidelobes so that IM2PARM(1) could be 
larger.
> 
> The results are very encouraging. When cleaned to the same limiting flux 
> as my hand-boxed image, the autoboxed image has slightly higher noise, 
> but manages to avoid the production of annoying artifacts around the 
> bright, spatially extended masers.  IMAGR also finished 20% faster with 
> the autoboxing. I compared with an image that Bill Cotton made using 
> OBIT's autoboxing some time ago, and the AIPS/OBIT results are virtually 
> identical. Some screen shots are attached for two test cases I tried if 
> you're interested. E and K refer to two observational epochs.
> 
> I did however run into one problem. When I had IMAGRPRM(8), (9), and 
> (10) set for the second test, IMAGR crashed after filtering with the 
> messages below. This did not happen during the first test.
> 

I suspect the failure below is a consequence of problems handling 
filtered output and only accidentally related to the auto-boxing.  The 
filtered data were so like the non-filtered data that there was nothing 
left to Clean.  Somehow this did not get passed properly and so it tried 
an illegal subtraction and everything fell apart.  I will have to look 
at this - it may come from my adding a continue Cleaning after the 
"final" filtering in case the filtering mattered.  When it doesn't - 
which is what one hopes for a "final" it should then complete gracefully.

> 
> wrest > IMAGR1: Filter abs value below  0.001000 Jy in 13-pixel diameter 
> area
> wrest > IMAGR1: Field    1 filtered       6814 components of   643.163 Jy
> wrest > IMAGR1:                 to       6811 components of   643.176 Jy
> wrest > IMAGR1: All fields totaled       6814 components of   643.163 Jy
> wrest > IMAGR1:          now total       6811 components of   643.176 Jy
> wrest > IMAGR1: VISDFT: Begin DFT component subtraction
> wrest > IMAGR1: VISDFT: fields 1 - 1 chns 1 - 1 in 1 CC models
> wrest > IMAGR1: I Polarization model processed
> wrest > IMAGR1: Field    1 min = -165.5 MilliJy,max =  192.2 MilliJy
> wrest > IMAGR1: Resuming Clean with     6811 filtered components
> wrest > IMAGR1: CLRHIS: NO FIELDS THIS PASS ABOVE MINIMUM FLUX
> wrest > IMAGR1: VISDFT: Begin DFT component subtraction
> wrest > IMAGR1: VISDFT: fields 1 - 1 chns 1 - 1 in 1 CC models
> wrest > IMAGR1: VISDFT: ERROR    1 NO POINT COMPONENTS FOUND
> wrest > IMAGR1: OUMSUB: ERROR SUBTRACTING CLEAN field number 0001
> wrest > IMAGR1: OUMSUB: FROM UVdata work object
> wrest > IMAGR1: UVSUBM: ERROR SUBTRACTING CLEAN field number 0001
> wrest > IMAGR1: UVSUBM: FROM UVdata work object
> wrest > IMAGR1: CLNUV1 : ERROR CLEANING CLEAN process object
> wrest > IMAGR1: CLNUV : ERROR CLEANING CLEAN process object
> wrest > IMAGR1: Deleting UV work file:
> wrest > IMAGR1: Destroyed  1 extension files of type AN
> wrest > IMAGR1: Destroyed  1 extension files of type FQ
> wrest > IMAGR1: Destroyed UV image file: catno=    319 disk= 3
> wrest > IMAGR1: Purports to die of UNNATURAL causes
> wrest > IMAGR1: wrest 31DEC09 TST: Cpu=   1307.2  Real=   1346  IO= 94614

Eric Greisen