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This might help you: http://starlink.eao.hawaii.edu/docs/sun95.htx/sun95se12.html#x13-950001 You need to understand the difference between PIXEL and GRID coordinate frames. On Wed, Nov 6, 2019 at 4:21 PM Helen Kirk <[log in to unmask]> wrote: > 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 >> > >> > ---- >> > Starlink User Support list >> > For list configuration, including subscribing to and unsubscribing >> > from the list, see >> > https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=STARLINK >> >> ---- >> Starlink User Support list >> For list configuration, including subscribing to and unsubscribing from >> the list, see >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=STARLINK >> > ---- Starlink User Support list For list configuration, including > subscribing to and unsubscribing from the list, see > https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=STARLINK > > > ---- Starlink User Support list For list configuration, including > subscribing to and unsubscribing from the list, see > https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=STARLINK ---- Starlink User Support list For list configuration, including subscribing to and unsubscribing from the list, see https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=STARLINK