Subject: WSMR AMBER IR update
From: cgarasi@NMSU.Edu
Submitted: Sun, 27 Aug 1995 20:51:58 -0600
Message number: 2
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All:
I had the pleasure of visiting the White Sands Missile Range (WSMR) base
yesterday with Jim Fowler to take a look at the AMBER detector and
its electronics. The electronics and detector combined are worth ~1 million dollars and is by far one of the most hi-tech systems you can find.
Jim Fowler has already had 1.5 days training with the detector and
there are plans for another 1.5 days training at WSMR once the dewer has
been created and returned. This may occur in late October/early November
and I myself will try to attend.
Jim and I tinkered with the detector quite a bit. I was introduced to the
design of the detector and electronics. Not to go into too much detail,
I will describe what I can below:
The detector consists of a 512x512 array of pixels which are read-out
using a multiplexer rather than your typical shift-register (bucket-brigade).
This means that individual pixels can be read/omitted and info. on each
pixel is recorded within the electronics in order to remove pixel-to-pixel
variations later on.
Pixels are read in groups of 4 (each pixel traveling down one of 4 channels)
into what is referred to as the "Pro-View" data acquisition system. The
data is converted (A/D) and if desired, non-uniformity corrections, intensity
transformations, and summations can occur within this circuit board. In short,
by placing a hot and cold source in front of the detector for calibration
frames, the electronics will take care of flat-fielding and bias levels.
Current plans are for WSMR to provide an adjustable blackbody source
to be used for these calibrations.
Data frames are placed in a display bus and carried to a storage area and then
to a video board. This video board is QUITE flexible and can manipulate the
color monitor display of your data without affecting the acquisition of your
data (it is an entirely separate entity). There are both manual and automated
settings which you can choose to change gains and offsets. In other words, you
will see a really NEAT color representation of your data on the screen and can
change things to see low brightness details. VERY FANCY! Note: manipulating
the screen output has no bearing on the stored data.
The storage area will consist of removable Gigabyte-sized disks (which are currently being obtained). The amount of data per pixel is
2 bytes per pixel. Depending on the size of the array which you will be
accessing, the frame rate can go from 800 frames/sec (128x128 max) to 70-78
frames/sec (512x512 max rate). Therefore, we are talking about acquiring
Gigabytes of data over the span of a night or 1 minute, depending on
your exposure times and the ability to sum data in the Proview Acquisition
board. Do not fret. More details will come later on.
Data storage will be an issue though, and Jim Fowler will be looking into
this. Apparently the WSMR people will store their data on removable
Gigabyte disks. All of their data, once it hits the disk, is "classified".
We will therefore have to obtain disks which are similar to the ones the WSMR
people will be using. Thought will have to be put in as to how much disk space
we will need and who will pay for the disks.
The raw images will be in byte array format, possibly with some basic header
information (time,alt,az.). This has to be looked into in more detail
and good observation notes will be a MUST with this detector.
Finally, considerations must be made concerning the utilization of this
instrument for astronomical purposes. It is unclear at which position
at the rear of the 3.5 meter this camera will be placed. The WSMR people
do not need to worry about sidereal rates or field rotation, however WE
DO. It is hoped that whatever position is chosen for the WSMR camera, that
it is done so that astronomical obsv. will be possible. With the amount of
data that is going to be obtained using this instrument, it would be
cumbersome to have to worry about field rotation for the hundreds of frames
you have spanning a few hours of the night.
!!!!!!!!!!!!!!!!_______________NOTE_________________________!!!!!!!!!!!!
What is needed right now is input from the ARC astro. community
concerning the AMBER detector and what is going to be needed in order for
it to be used for astronomy. I have already mentioned data storage
as well as tracking and field rotation potential problems, and I am sure
there are quite a few more things that need to be addressed. Jim Fowler
and I will be working on these dilemmas together, however we would
appreciate any comments/concerns you might have regarding this detector.
Please FEEL FREE to contact me or email the AMBER board
apo35-amber@astro.princeton.edu
with any comments. With some luck and support we will be able to have the
ability to use this MARVELOUS AMBER setup to do some great science.
The images which Jim and I made of buildings, mountains, people smoking
cigarettes were amazing, and done with relative ease. The possibilities
of using this detector for astronomical purposes should be taken
VERY seriously.
Please support this detector if you have the slightest interest in using it,
Christopher Garasi
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