problem with ccfind
Nakisa Nooraee wrote on Oct 05, 2009
hello
I want use ccfind and then ccmap to do astrometry with HST data. (according to this recipe http://iraf.noao.edu/irafnews/apr98/irafnews.14.html ).
I use GSC.1 which is the guide star cataloge of HST observation.
and write
ccfind GCS1.txt new.txt j9ju05kbq_drz.fits[SCI] usewcs+
This command produce an output but wrongly. all the sky positions are the same number
00 : 51 : 30.18 +41 : 13 : 54.7 2117.438 2105.056
00 : 40 : 48.77 +40 : 11 : 24.1 2117.438 2105.056
00 : 51 : 30.14 +41 : 13 : 54.8 2117.438 2105.056
00 : 40 : 48.82 +40 : 11 : 23.1 2117.438 2105.056
00 : 40 : 49.22 +40 : 11 : 14.1 2117.438 2105.056
00 : 50 : 26.61 +40 : 48 : 29.5 2117.438 2105.056
and when I omit usewcs , IRAF doesn't produce data in the output. It just writes some texts on the file without any data included.
Can anyboyd say where my mistake is ?
best,Nakisa
I want use ccfind and then ccmap to do astrometry with HST data. (according to this recipe http://iraf.noao.edu/irafnews/apr98/irafnews.14.html ).
I use GSC.1 which is the guide star cataloge of HST observation.
and write
ccfind GCS1.txt new.txt j9ju05kbq_drz.fits[SCI] usewcs+
This command produce an output but wrongly. all the sky positions are the same number
00 : 51 : 30.18 +41 : 13 : 54.7 2117.438 2105.056
00 : 40 : 48.77 +40 : 11 : 24.1 2117.438 2105.056
00 : 51 : 30.14 +41 : 13 : 54.8 2117.438 2105.056
00 : 40 : 48.82 +40 : 11 : 23.1 2117.438 2105.056
00 : 40 : 49.22 +40 : 11 : 14.1 2117.438 2105.056
00 : 50 : 26.61 +40 : 48 : 29.5 2117.438 2105.056
and when I omit usewcs , IRAF doesn't produce data in the output. It just writes some texts on the file without any data included.
Can anyboyd say where my mistake is ?
best,Nakisa
emma wrote on Oct 05, 2009
Hi Nakisa,
Does it work if you don't have the [SCI] part included?
ccfind GCS1.txt new.txt j9ju05kbq_drz.fits usewcs+
If you don't use usewcs+ you need to make sure the parameters for xref, yref, xmag, ymag, xrotation, yrotation, lngref, latref, lngrefunits, latrefunits, refsystem, and projection are correct. You can look at the help file (help ccfind) for more info on these parameters.
Thanks,
Emma :)
Does it work if you don't have the [SCI] part included?
ccfind GCS1.txt new.txt j9ju05kbq_drz.fits usewcs+
If you don't use usewcs+ you need to make sure the parameters for xref, yref, xmag, ymag, xrotation, yrotation, lngref, latref, lngrefunits, latrefunits, refsystem, and projection are correct. You can look at the help file (help ccfind) for more info on these parameters.
Thanks,
Emma :)
Nakisa Nooraee wrote on Oct 05, 2009
Hi Emma
whit omitting [SCI] it doesn't work. IRAF sends an error that the file extention is needed.
I had read the help file ,but it doens't help much ! because ccfind doesn't work for me to test some new options from the help or not
Best,Nakisa
whit omitting [SCI] it doesn't work. IRAF sends an error that the file extention is needed.
I had read the help file ,but it doens't help much ! because ccfind doesn't work for me to test some new options from the help or not
Best,Nakisa
emma wrote on Oct 05, 2009
Hi again :)
What version of IRAF are you using? The latest patch (2.14.1) had a bug fix for ccfind (see http://iraf.noao.edu/iraf/ftp/iraf/v214/v2141revs.txt) ... maybe that's the problem?
Emma :)
What version of IRAF are you using? The latest patch (2.14.1) had a bug fix for ccfind (see http://iraf.noao.edu/iraf/ftp/iraf/v214/v2141revs.txt) ... maybe that's the problem?
Emma :)
Nakisa Nooraee wrote on Oct 05, 2009
hi
I am using the last version. it is not my problem. The problem is when I use
usewcs =yes , then all sources in the text file recoginzed in the image with the same (x,y) coordinate ! and when I turn it off , then no source be recognized by software !!!!!
it is crazy
I am using the last version. it is not my problem. The problem is when I use
usewcs =yes , then all sources in the text file recoginzed in the image with the same (x,y) coordinate ! and when I turn it off , then no source be recognized by software !!!!!
it is crazy
emma wrote on Oct 05, 2009
Ok, it was worth a try :)
As I said in my first message, if you want to set the usewcs parameter equal to no then you need to fill in the xref, yref, xmag, ymag, xrotation, yrotation, lngref, latref, lngrefunits, latrefunits, refsystem, and projection parameters correctly.
Choose an object in your image that has an RA and Dec in your input celestial coordinate file (preferably a point source). Determine the x and y pixel coordinates for this object and put the values into the parameters xref and yref, respectively.
xmag and ymag are the pixel scales of your image in arcseconds per pixel for the x and y axis, respectively.
Find out which direction is east in your image. If east is up, set xrotation to 90, if down set to 270, if left set to 180 and if right set to 0.
Then find out which direction is north in your image. If north is up, set yrotation to 0, if down set to 180, if left set to 90 and if right set to 270.
Now, go to your input celestial coordinate file and find the RA and Dec for the object you took the pixel coordinates for earlier. Put the RA and Dec values into the parameters lngref and latref, respectively. Make sure the units for these parameters are correct (the parameters lngrefunits and latrefunits should be used to put in the units for the RA and Dec values).
Also, check that the columns in your input celestial coordinate file that contains the RA and Dec positions of each of your targets are set correctly (use the parameters lngcolumn and latcolumn, respectively for this).
I hope this helps.
Thanks,
Emma :)
As I said in my first message, if you want to set the usewcs parameter equal to no then you need to fill in the xref, yref, xmag, ymag, xrotation, yrotation, lngref, latref, lngrefunits, latrefunits, refsystem, and projection parameters correctly.
Choose an object in your image that has an RA and Dec in your input celestial coordinate file (preferably a point source). Determine the x and y pixel coordinates for this object and put the values into the parameters xref and yref, respectively.
xmag and ymag are the pixel scales of your image in arcseconds per pixel for the x and y axis, respectively.
Find out which direction is east in your image. If east is up, set xrotation to 90, if down set to 270, if left set to 180 and if right set to 0.
Then find out which direction is north in your image. If north is up, set yrotation to 0, if down set to 180, if left set to 90 and if right set to 270.
Now, go to your input celestial coordinate file and find the RA and Dec for the object you took the pixel coordinates for earlier. Put the RA and Dec values into the parameters lngref and latref, respectively. Make sure the units for these parameters are correct (the parameters lngrefunits and latrefunits should be used to put in the units for the RA and Dec values).
Also, check that the columns in your input celestial coordinate file that contains the RA and Dec positions of each of your targets are set correctly (use the parameters lngcolumn and latcolumn, respectively for this).
I hope this helps.
Thanks,
Emma :)
Nakisa Nooraee wrote on Oct 05, 2009
hi
It was my mistake. My observation on HST is form small area of sky and the list was from the whole galaxy, and there is no star common in the list and my observation !!!
I find a point source in the observation and use its coordinate as the input of ccfind instead of the pervious list and suprisingly it works fine !
thanks for help.
Nakisa
It was my mistake. My observation on HST is form small area of sky and the list was from the whole galaxy, and there is no star common in the list and my observation !!!
I find a point source in the observation and use its coordinate as the input of ccfind instead of the pervious list and suprisingly it works fine !
thanks for help.
Nakisa
emma wrote on Oct 05, 2009
Glad you managed to get it working :)
Last post on Oct 05, 2009