DATA REDUCTION


Magnetic Tapes

Please remember that magnetic tapes cannot be loaned away from the Observatory. If you wish to take data home on tape, please provide your own blank tapes, or purchase them at the Office Supply Room in the Central Facilities Operations area downtown during regular working hours. Tapes can also be purchased on the Mountain by contacting any OT or the Mountain Receptionist. Exabytes (8mm), and DAT (4mm) are stocked.

Each telescope at KPNO is equipped with both Exabyte (8mm) and DAT (4mm) tape drives. If you bring tapes to the mountain, bring only computer grade (i.e., certified for Digital Data Storage) tapes. Audio grade tapes are not to be used as they now have significantly lower quality and do not produce reliable results.

KPNO orders and stocks the following types of tapes for use on the mountain:

Type Capacity Cost
Exabyte 112M 5GB uncompressed $5
DAT 90 DDS-1 2GB uncompressed $4
DAT 150 DDS-4 20GB uncompressed $25
DLT 40GB uncompressed $70
CD-R (WIYN only) 700MB uncompressed $1
DVD DVD-R 4x $2

If you want to import data on tape to use during your run, please use lowest-common-denominator recording techniques. For Exabytes, record in 8200 mode (as opposed to 8500 mode) with no compression. For DAT tapes, record 90m DDS tapes with no compression.

One final word: as you may have deduced from articles in the NOAO Newsletter, the era of 9-track tapes at KPNO is over. There are no active 9-track drives on the mountain.

Similarly, as of Feb. 1, 2006, we will not support Exabyte drives in any of the domes, but DAT tapes will still be available.

Taping Data

It is the responsibility of each observer to tape his/her own data. Each observer must make the necessary copies of both raw and reduced data to take home with him/her. Lost data mean lost telescope time! Observers are expected to have their data on tape before Noon on the last morning of their run. To ready the system for the next observer, disks are normally initialized around 1:00 pm. NOAO no longer provides or holds backup tapes (known as T-tapes) for observers. If an emergency arises and some data are lost, there is a good chance that your data have been recorded by the "Save-the-Bits" project. Contact Daryl Willmarth for assistance (dwillmarth@noao.edu).



Updated 26 September 2005