Aperture Photometry
From BYU Astro Docs
NOTE: This documents contains footnotes (pause for dramatic effect) they are VERY important. Please read them as you come to them. Thank you for your participation in the reduction process. Comments or suggestions welcome.
Contents |
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Aperture Photometry
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Transfer / Load Data
- SFTP data to correct directory if not burned onto a CD
- Open an xgterm
- Open DS91
- Type cl in the xgterm to get started2
- Copy a .cmds file using the cp command
- Edit the cmds file in the text editor of your choice3
- If your files are burned onto a CD4, type:
rfits /media/cdrom0/date/file.fts
to convert from fits files to .imh files5
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Header Editing
- Type
noao astutil
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Pictor Images Using Pictor Software
- Type:6
hselect star*.imh date-obs yes > time epar asthedit
- Make sure that colname says 'ut'7. Type:
asthedit star*.imh star.cmds setjd star*.imh setairmass star*.imh
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Apogee Images or Any Images Using MaxIm software
- Type:6
epar asthedit
- Make sure that colname says 'time-obs'8. Type:
asthedit star*.imh star.cmds table=time setjd star*.imh setairmass star*.imh
- The headers are now updated. To view one of the headers type:
imhead star0001.imh
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Calibration
Type:
imred ccdred hedit zero*.imh imagetyp zero zerocombine zero*.imh hedit dark*.imh imagetyp dark epar ccdproc
- Change ccdtype to dark
- Change darkcor and flatcor to no (zerocor should be yes).
- Type:
ccdproc dark*.imh darkcombine dark*.imh hedit flat*.imh imagetyp flat hedit flat*.imh subset V epar ccdproc
- Change ccdtype to flat
- Change darkcor to yes (zerocor should be yes and flatcor should be no).
- Type:
ccdproc flat*.imh flatcombine flat*.imh epar ccdproc
- Change ccdtype to object
- Change flatcor to yes (zerocor and darkcor should be yes).
- Type
ccdproc star*.imh
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Photing
- Type:
digi apphot newton9 disp star0001 110
- After selecting the stars you want to use and saving the coordinate file correctly you may phot, type
phot star0001
- Repeat this step until you are finished11
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Use Varstar
- Type:
txdump star*.mag.1 id,mag,otime,xairmass,ifilter yes > star.lst varstar12
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Plot the data
- Type:
graph star*.dat (you may need to epar graph)13
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Print the Graph
- Type:
graph star*.dat >G star.plt14 stdplot star.plt
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Footnotes
- There have been some troubles displaying in DS9 when DS9 was opened using an xterm. If this occurs, try opening DS9 in a konsole (KDE), gnome-terminal (Gnome), or eterm.
- Remember to NOT delete your fits files unless they have been burned onto a CD. Also remember that IRAF is case sensitive.
- Edit: star name, RA, Dec and date if necessary --- date only needs to be edited if you are using a pictor image. See document on the different cmds files.
- If you are reducing data and the fits files are on the hard drive you don't need the extensions. (/mnt/cdrom/date/file.fts) you only need file.fts could be .fts, .fit, .fits)
- Be sure to do each type separately: darks, flats, zeros, and object.
- Do this only after you have rfitsed all the files you need.
- Check document on cmds files for the pictor cmds format.
- Check document on cmds files for the apogee/maxim cmds format.
- This step only needs to be done the first time you reduce. If you change any settings you can use it to change them back.
- See the document on using DS9 (this is important to your photing abilities!)
- If you get an error when you are photing you must redisplay and remark the stars you are using; be sure to do this in the SAME order every time. Also be sure to delete the mag file (star0001.mag.1).
- See the varstar document.
- This will graph all the stars that you photted. To graph only the variable star type graph star001.dat assuming your variable star was the first star you marked when photing. If not, replace the 1 with the correct number.
- This will print the graph of all the stars you photted. See above footnote to only print (graph) one star.
