Scale in ArcSeconds?
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- Asternaut
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- Joined: Mon Feb 28, 2011 9:56 pm
Scale in ArcSeconds?
Is there any way that I can find the scale in ArcSeconds directly on the Picture for the APOD?
- Chris Peterson
- Abominable Snowman
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Re: Scale in ArcSeconds?
Generally not. If you know the sensor details and the focal length of the lens, you can calculate the pixel scale. Those things can be found in the EXIF header if the image was made with a digital camera, and if the header was preserved. For most astronomical images, you usually need to perform a plate solve to recover the pixel scale, although this information is occasionally provided in the caption or in linked data.DavidBartlett wrote:Is there any way that I can find the scale in ArcSeconds directly on the Picture for the APOD?
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com
*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com
-
- Asternaut
- Posts: 2
- Joined: Mon Feb 28, 2011 9:56 pm
Re: Scale in ArcSeconds?
Thank you Chris. Is there a standard pixel scale for the Hubble Advanced Camera for Surveys?
- Chris Peterson
- Abominable Snowman
- Posts: 18459
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
- Contact:
Re: Scale in ArcSeconds?
For the WCS, the plate scale is 0.05 arcsec/pixel. You have to be careful with released images, and those published on APOD, since they are sometimes resampled to different resolutions. Don't automatically assume you are seeing an image at the native resolution of the camera.DavidBartlett wrote:Thank you Chris. Is there a standard pixel scale for the Hubble Advanced Camera for Surveys?
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com
*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com