IRTF Image Quality Report for April 19, 2001


Daniel O'Connor




            Present: Griep, Sears, O'Connor

            Set-Up: TT cam (for wavefronts, ef) on NSFCam (for S&A data)

Data Set: 9 positions on the sky, wavefront data with ef reduction as well as Shift & Add data from NSFCam in K'.


1.) wavefront out of focus images: /benchmark/tiptilt/fits

            (1636.fits thru 1676.fits)

2.)  Ef reduced data, eg zern*.txt /benchmark/wavefront/010419

3.) Shift and Add images /benchmark/image/010419

            (fits images with .bin# extension)

4.) Jpeg images are stored in C:\projects\Image Quality



Shift & Add


Ef rms wavefront error (nm)

FWHM from xgfit


3 hrs. North

data0147.jpg /.bin4


0.40" (7.32)

2 hrs. North

data0129.jpg /.bin3


0.36" (6.58)


data0037.jpg /.bin4


0.26" (4.84)

2 hrs. South

data0088.jpg /.bin6


0.17" (3.15)

4 hrs. South

data0195.jpg /.bin4


0.25" (4.62)

30 deg. East

data0106.jpg /.bin5


0.43" (7.75)

60 deg. East

data0228.jpg /.bin4


0.33" (6.08)

30 deg. West

data0064.jpg /.bin4


0.25" (4.72)

60 deg. West

data0185.jpg /.bin4


0.28" (5.07)




            Wavefront errors are those given by `ef' data reduction software.

            FWHM data are from xgfit of `representative' image from Shift & Add.

            (Important note: These FWHM are not what is typically achieved by a long integration of a typical observer. These images are the result taking 1000 images, each with a 0.1 second integration time. We then sort the images by peak height and bin the images into 7 bins. The top bin (ie the bin with the largest average peak height) is then used to form a Shift & Add image. The resultant image formed from the largest peak height represents the situation where the aberrations due to the atmosphere are minimal, and thus is representative of the aberrations in the telescope optical train. It is further interesting to note that the S&A images are very peaky and a fit to a gaussian is perhaps not the best function to choose. 



            List of files of


                        Zernicke tables - 9 ea text files (could combine into one table)

                        Reconstructed images from ef - 9 ea fits files (could change to jpegs with IDL)







Zenith, 540 nm rms

0.26" FWHM


3 hr N, 400 nm rms

0.40" FWHM




2 hr N, 380 nm rms

0.36" FWHM


60d W, 560 nm rms

0.28" FWHM

30d W 360 nm rms

0.25" FWHM

30d E, 420 nm rms

0.43" FWHM



2 hr S, 660 nm rms

0.17" FWHM


60d E, 480 nm rms

0.33" FWHM








4 hr S, 500 nm rms

0.28" FWHM