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.