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Images are Blank (all white)

CMJA's picture
CMJA
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Joined: 2010-10-01

I just uploaded some fits files and they are displayiing all white. The fits header seems to be OK. I can open and view these fits files in AIP4WIN and MaxIm DL. The fits files pass fitsverify (http://fits.gsfc.nasa.gov/).

I tried using Tools > Image Display in Vphot, but hat does not have any effect.

An example fits file is attached.

AttachmentSize
V380-Oph.fits18.01 MB
Images are Blank (all white)
kge's picture
kge
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Joined: 2010-07-19

If you select 'Pixel/ADU mode' and click anywhere in the image you will see that all pixels have ADU = 0. So the image is in fact blank.

I can't say why, though. Perhaps something happened during calibration?

Geir

Images are Blank (all white)
CMJA's picture
CMJA
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Joined: 2010-10-01

The CALIBRATED images display fine in AIP4WIN, MaxIm DL, Aladin, . Also, the fits header shows:

 

CBLACK 1957
CWHITE 2532

If I download the image from VPhot, I can display the images with no problem.

Images are Blank (all white)
kge's picture
kge
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Joined: 2010-07-19

VPHOT uses the CFITSIO library for reading FITS files (http://heasarc.gsfc.nasa.gov/fitsio/), and it gives the following error message on your image:

BAD_ELEM_NUM 308 illegal starting element number in vector

I have no idea what that means, so I'm afraid I won't get any further. Could be a bug in the library.

Geir

fits image
HQA's picture
HQA
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Joined: 2010-05-10

This is a 1536x1024 QSI 516ws (KAF-1603 sensor).  The FITS image itself is a floating-point file, with three tiles.  These all look like V images of the field; I don't know why you have made it a 3-plane image.  You might try uploading each V image separately and see if that takes care of the problem; I don't know if VPHOT understands the 3rd dimension.

BTW - each plane has reasonable pixel values, ranging from a hard minimum of 0 (this is unphysical, BTW, after processing, so your software is truncating your file, something that would be important for short exposures where there is little sky background) to about 34K.  I also notice that your flat exposures indicate subsecond values; I do not recommend this, even with something like the QSI's photometric shutter.

Arne

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