Hi Sarah,

Ah, thanks!  I did not think to look near the centre of the image when adding something in at 1,1, but I do see the changed pixel now.  (Interestingly, it doesn't show up in gaia's maximum pixel value listing, which I was using as a second indicator of whether the change had worked.)

If you have some insight as to how I convert from pixel coordinates in gaia to pixel coordinates in kappa (when you are at the right computer), that would be really helpful for me to figure out how to code up what I'm eventually trying to do with chpix.

thanks very much to you and Malcolm for all of your help!

Helen

On 11/06/2019 03:12 PM, Sarah Graves wrote:

Hi Helen,

I'm not sure but I think the issue might be that the coordinates Gaia displays are not the same pixel coordinates that kappa is using.

Based on your email, 1,1 in kappa will be near the center of the array. There is an option in Gaia to bring up another window displaying more pixel coordinates, I think it's under the change coordinate option. I'll be on my computer later and can check properly then,

Sarah

On Thu, Nov 7, 2019, 06:26 Helen Kirk <[log in to unmask]> wrote:

Thanks, Malcolm -- as far as I can tell, the pixel is in the bounds of
the NDF.  ndftrace gives the following:

   Shape:
       No. of dimensions:  2
       Dimension size(s):  801 x 800
       Pixel bounds     :  -399:401, -398:401

When I hover my mouse over the pixels in gaia, the RA and dec fields
start giving values at (0,0).  For completeness, I also just tried
changing a pixel at (401,401) which is near the apparent centre of the
image and should be visible even if there are 0-point issues -  nothing
appears for that either.

Helen


On 11/06/2019 02:14 PM, Malcolm J. Currie wrote:
> Helen,
>
> Is the pixel you want to change inside the bounds of your NDF? You
> selected pixel indices (1,1). "ndftrace test" will tell you. You can
> also supply WCS co-ordinates too.  Parameter SECTION uses the same
> syntax as NDF sections to access a subset, or indeed a superset, of
> your NDF.
>
> By the way, in KAPPA V2.6, you can supply a text file listing many
> sections and their replacement values.  I found that I needed this
> facility to mask some transient narrow artefacts in HARP time-series
> cubes.
>
> Malcolm
>
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