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 which step lets iraf know the exposure time of your source and the standard star?
   
haha
 08/24/2014 12:09PM (Read 1389 times)  
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Chatty

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For specral reduction,there is a parameter 'exptime' in 'calibrate'. The exptime is the exposure time of your star or the standard star?

How does iraf know the exposure time of your source and the standard star?


 
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fitz
 08/24/2014 10:10PM  
AAAAA
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The 'exptime' parameter refers to the exposure time of the image, i.e. the value read from the 'exptime' keyword in the image header or if that can't be found, then the response you give when prompted for a value for the image. So there isn't just one value, it is the value for each image.

If the exposure time is stored in a different keyword then you can use the HEDIT task to add an EXPTIME keyword with the value. For example:

cl\$this->_split2($m[0]) hedit *.fits EXPTIME '(otime)' add+ ver-

would add a new EXPTIME keyword to every image using the value stored in the OTIME keyword.

 
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haha
 08/26/2014 02:48PM  
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Chatty

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Registered: 10/25/2013
Posts: 39
Quote by: fitz


The 'exptime' parameter refers to the exposure time of the image, i.e. the value read from the 'exptime' keyword in the image header or if that can't be found, then the response you give when prompted for a value for the image. So there isn't just one value, it is the value for each image.

If the exposure time is stored in a different keyword then you can use the HEDIT task to add an EXPTIME keyword with the value. For example:

cl\$this->_split2($m[0]) hedit *.fits EXPTIME '(otime)' add+ ver-

would add a new EXPTIME keyword to every image using the value stored in the OTIME keyword.




Thank you~

 
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