The FITS image accompanying this readme, Vmedianflat.fits is a flat image which I have been using in analyzing Tom's Mk IV images. It was for the V camera. I can upload one for the I camera if anyone is interested.
Here's a GIF version of the image, binned 4x4. The greyscale
runs from white = 3200 counts per pixel to black = 3500 counts
per pixel.
MWR 12/15/1999
The image was produced from the first 21 images on disk 5, which had each been dark-subtracted using file Vdark15.fts. The value of each pixel in the image is the median of the values for that pixel in the 15 input files, after each file had been normalized. (Only the "sky" portion of the image was done. The border pixels were not processed.)
If you have any questions, please e-mail me at:
twoodh@junction.net
Ted Woodhouse
This readme file is intended to accompany two flat
images produced from data taken by the TASS MkIV cameras,
and distributed on disk 6.
Feb 3, 2000
There are two files, Vflat.fits and Iflat.fits, for the V and I cameras respectively. These are median flats. Each was produced from 24 sky images HnR1544.500 to HnR1544.592, where n is 3 for the V camera and 4 for the I camera. Each image had been dark-subtracted using the appropriate dark image on disk 6.
Here's a GIF version of the V-band image, binned 4x4.
The greyscale runs from white = 4300 counts per pixel to
black = 4800 counts per pixel.
MWR 2/4/2000
Here's a GIF version of the I-band image, binned 4x4.
The greyscale runs from white = 13000 counts per pixel to
black = 15000 counts per pixel.
MWR 2/4/2000
To produce the flats:
1. The median brightness of each input image was measured, and a weighting factor assigned to the image, to compensate for variations in brightness among the images.
2. For each pixel, the 24 values were read, adjusted by the weighting factor, their medians taken, and written to that pixel position in the output file. That is, the median was calculated for each of the 4-million-odd pixels.
3. Only those pixels representing the image of the sky were used (i.e. 2032*2032). The "border" was copied from the first file.
If you have any questions, please direct the to me at:
twoodh@junction.net