[daip] aips question

[Ashley King]

Thanks Eric,

That did it!


On Mon, Feb 24, 2014 at 11:01 AM, Eric Greisen <egreisen at nrao.edu> wrote:

> Ashley King wrote:
>
>> Hi,
>>
>> I am having a problem where I'm finding it difficult to convert the X
>> axis pixel scale from an IMAGR output to the correct RA. The Y axis pixel
>> scale appears to be fine.
>>
>> I find in my images, that the distance between two knots in RA is about
>> 2e-4 seconds, which I convert to arcsecs to 3e-3''. However the distance
>> between the knots in the X-direction is 30 pixels which the pixel scale i
>> used to make the image is 4e-5 arcsecs, which corresponds to 1.2e-3. It
>> seems that I am off by almost a factor of pi. Is this a  known problem with
>> aips or am I converting between RA and arcsec wrong.
>>
>
> The increment in RA is the increment in arc seconds divided by
> cos(declination).  Try TVLOD and then point at the two objects in the verb
> IMXY.
>
> ERic Greisen
>
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