What is 1/2 Terabyte?
With the NOAO Save the bits archive now in
full operation (and including images from the WIYN telescope),
NOAO/Tucson archives 1/2 Terabyte of imaging data yearly
(1993-94 archive statistics).
To help visualize this number:
- 1/2 Terabyte = 1/4 trillion pixels = one image 500,000 pixels square
- A 500,000 square CCD chip with 21 micron pixels would be 10 meters
on a side.
- If it takes 2 minutes to read out a 2048x2048 CCD at a nominal gain
through one amplifier, it would take 83 days to read out a CCD this size
(but only 2 days to read out an NOAO IR detector of the same size).
- 1/2 Terabyte = 60,000 2048x2048 CCD exposures. Given the 70
arcminute field of the Burrell Schmidt telescope, this many images is
equivalent to a two arcsecond full sky survey every year - including
flats and biases.
- 1/2 Terabyte/year = 16 Kilobytes/second. The archive could
keep sixteen 9600 baud modems busy 24 hours a day, 365 days a year.