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Re: reading header and manipulating according to the header information [message #70994 is a reply to message #70993]

Sun, 16 May 2010 07:31

sid
Messages: 50
Registered: January 1995

Member

On May 15, 9:21 pm, Craig Markwardt <craig.markwa...@gmail.com> wrote:
> On May 15, 12:02 pm, Craig Markwardt <craig.markwa...@gmail.com>
> wrote:
>
>
>
>> On May 15, 10:21 am, sid <gunvicsi...@gmail.com> wrote:> Hi,
>>> Since I am using huge data of several years, different kind of
>>> ccds are used on different days. I need to trim the data to a size
>>> which depends on ccd size, is there any method to read the header
>>> information and take the ccd size from there and then to proceed
>>> further, instead of giving the ccd size manually. Because it is really
>>> very tedious to check for the ccd size each time and then to proceed.
>>> Please help out.
>>> For example,
>>> in one of my data the ccd size that is 1K by 1k is given in header as,
>
>> ...
>
>> Anything you can do "manually," you can do in a program. The hard
>> part is usually to make it robust.
>
>> Based on the headers you provided, it looks like you have FITS image
>> files. If you don't already have it, get the IDL Astronomy Library.
>> It has many routines for reading FITS images and tables. The easiest
>> one to use is MRDFITS(). MRDFITS() returns the image array which you
>> can query using SIZE() and then trim as needed.
>
>> Simple example:
>> filename = 'myfile.fits'
>> img = mrdfits(filename) ;; Read image
>> sz = size(img, /dim) ;; Determine size of image
>> szx = sz(0) ;; Number of columns
>> szy = sz(1) ;; Number of rows
>> img = img( (0+2):(szx-3) , (0+2):(szy-3) ) ;; Remove outermost two
>> rows and columns
>
> Oh, and if you need other header keywords, then you need to read the
> header with a slightly different call to MRDFITS().
> img = mrdfits(filename,0,header)
> and then retrieve the keyword KEYNAME with FXPAR()
> value = fxpar(header, keyname)
>
> Craig

Thank you this works now i could able to read the size of ccd as a
variable.
In my data header I have a line like the one below,

COMMENT = 090222 Lat=40N exp=50s seeing 3",

in this line I need to read the lat=40N that is the value 40 as a idl
variable which I need use for further analysis,
but if I do the same process like,img = mrdfits(filename,0,header) and
value = fxpar(header, comment),
then it prints the whole sentence '090222 Lat=40N exp=50s seeing
3"' .
So can anyone suggest is there any way to read only the desired part
of the string.

regards
sid

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[Message index]

		Re: reading header and manipulating according to the header information By: sid on Fri, 21 May 2010 12:37
		Re: reading header and manipulating according to the header information By: Gray on Sun, 16 May 2010 09:13
		Re: reading header and manipulating according to the header information By: sid on Sun, 16 May 2010 07:31
		Re: reading header and manipulating according to the header information By: Jeremy Bailin on Sat, 15 May 2010 16:02
		Re: reading header and manipulating according to the header information By: Craig Markwardt on Sat, 15 May 2010 09:21
		Re: reading header and manipulating according to the header information By: Craig Markwardt on Sat, 15 May 2010 09:02
		Re: reading header and manipulating according to the header information By: Gray on Sat, 15 May 2010 08:02

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