Technical and Other Data
for the #5383-17-7 CCD

We have used the 1st of the interim EEV CCD42 devices at the prime focus of the William Herschel Telescope. The data illustrated here is a 1200 second R band image.

Click on the Thumbnail for the full image(97k)

The second image is a 300s exposure of object GRB9708, taken again at the WHT prime, no filter this time. Its a 2400 high 2148 wide window at x=0, y=900. The horizontal under and overscans can be clearly seen along with one or two 'interesting' objects..

Click on the Thumbnail for the full image(154k)

EEV CCD42-80 Spectral Response Data

Spectral Response Data taken im Imaging mode (we still havent figured a way to measure response in 'DC Mode', though discussions about this are taking place with EEV. To view the full image(14.5k), click on the Thumbnail...

Response Curve

Peak QE is ~80%, ~60% at 350nm, 55% at 800nm and 25% at 900nm.

EEV CCD42-80 Spectral Response for 2 AR Coatings

The Response Curve shown here illustrates what we expect in terms of peak response from the 2 CCD42 devices we have tested which have different AR coatings applied. One is 'Blue' optimised and the other is 'Red' optimised.

It has been our intention to measure Response data for a variety of AR coatings on a single device, indeed we have asked EEV to supply such a CCD, this would enable us to measure the QE at different coating peaks and then select the AR coating we want. From the data her it looks as if the optimised blue coating is okay for our needs in the UV. I still feel we could do better with a coating peaked further over for the red optimised coating..

Comparison Response Curves

Flat Field Spots at 380 and 950nm

Two frames showing the response of the CCD to flat spot illumination at 380nm and 950nm. The fringing at 950nm can be clearly seen. See the data below for details of the fringe amplitudes at different wavelengths...

380 nm Response, OR

D'load 380nm Data File(918kb PKZIP'd, IRAF FITS file)

950nm Response, OR

D'load 950nm Data File(932kb PKZIP'd, IRAF FITS file)

EEV CCD42-80 Device Quantification

Other miscellaneous items of data obtained during the June Run are given below - 

Point-spread function

 With the UES slit width matched to two pixels, the best focus resulted
 in a FWHM of arc lines of 2.4 pixels (in the X direction). Although
 the chip tilt was not even optimized, the FWMH over the chip degraded
 no more than 0.3 pixels from the best value. This confirms that the 
 flatness of the device is at least of good quality.
 The FWHM was not seen to depend on light level, nor on wavelength.




Fringing

 This was measured from tungsten lamp exposures at different orders.
 
 wavelength     amplitude
 < 6000             - 
   6500             5 %
   7000            10 %
   7500            25 %
   8000            30 %
   9000            40 %
  10000            40 %




Read-Out times

speed         total time    minimum time     sampling(us)

standard        7' 20"         ~5'            8 + 8
quick           5' 45"         ~3' 30"        4 + 4
turbo           5' 10"         ~3'            2 + 2
non-astro       4' 55"         ~2' 40"        1 + 1


NOTE:: as the read-out noise does not vary much at the slower speeds, we
use Turbo read-out speed as default.





Point Spread Function



With the UES slit width matched to two pixels, the best focus resulted
in a FWHM of arc lines of 2.4 pixels (in the X direction). Although
the chip tilt was not even optimized, the FWMH over the chip degraded
no more than 0.3 pixels from the best value. This confirms that the 
flatness of the device is at least of good quality.
The FWHM was not seen to depend on light level, nor on wavelength.

The PSF in the Y direction could not be checked accurately from the
arc line data, but the performance that could be measured from the
dekker edge looks okay.

Further assessment of the PSF awaits the analysis of the interferometry
lab data, and imaging tests under good seeing conditions, but from 
the tests so far it's safe to conclude that the PSF is of excellent
quality and allows astronomers to really exploit the small pixels,
unlike the Loral CCDs.

EEV CCD42-80 Sequencing Waveforms and DC Biases

We now have one of the 'interim' (with the low-level CTE problem) devices on the telescope to evaluate its scientific performance. I have now down-loaded the sequencer waveforms from our CCD controller, we use to operate this device, and this information appears on the following page-

EEV Configs Page

I hope this may be of some use to the community. I will add further information to this page as it becomes available.

Somewhere to go for a vacation...

I am... apo