SDSS Show and Tell

A set of images from the latest runs of the 2.5-m telescope, in early March, 2000.

Scan mosaic of run 1239, fields 171 to 180

These images were taken March 4, 2000. Look at the galaxy in column 5, near the bottom of the initial page.
Closeup of galaxy in col 5
Overlay of detected objects
NED information on UGC 5238
Image of UGC 5238 from digitized Palomar Sky Survey

Scan mosaic of run 1239, fields 151 to 160

Note the satellite passing through the middle fields of column 2 -- it appears blue, so it was recorded in the 'g' filter.
Closeup of satellite trail

One example of the power of color, which the SDSS provides via five different passbands. In this small area of the sky, there are a number of very small, very faint, little fuzzy objects. You can see them both in the Palomar Sky Survey photograph of this area, and in the SDSS scan of the corresponding patch of sky. Click on the SDSS picture to see a more impressive version of it :-)

Data Rates

When the mosaic camera is mounted on the telescope, it gathers information at a very high rate. We put data onto tapes each night, and send them to Fermilab via FedEx the next morning.

main CCDs in camera 30

astrometric CCDs 24

columns per CCD 2048

rows read out each second 38

pixels per CCD per second 77,824

total pixels per second 4,202,496

total data per second 8.4 MB

total data per hour 30 GB

It's a good thing that Fermilab has experience dealing with such high data rates!

Data Products

The SDSS will produce a lot of information:

raw pixel data 12000 GB

merged pixel maps 8000 GB

atlas images 250 GB

object catalog 25 GB

spectroscopic catalog 1 GB

main CCDs in camera	30
astrometric CCDs	24
columns per CCD	2048
rows read out each second	38
pixels per CCD per second	77,824
total pixels per second	4,202,496
total data per second	8.4 MB
total data per hour	30 GB

raw pixel data	12000 GB
merged pixel maps	8000 GB
atlas images	250 GB
object catalog	25 GB
spectroscopic catalog	1 GB