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Although there will probably be considerable dupli-
cation of software development over the next few years,
an active committee with the cooperation of the National
Centers could result in the availability of a standard
baseline of software by the mid-1980's. If the program-
mers have done a good job, the software will be accepted
and used by the community, leading to gradual development
and (more importantly) acceptance of community-wide
software and data-format standards.
VI. DATA ARCHIVING
Data archives (usually in the form of plate collections)
have traditionally been exceedingly valuable in advancing
astronomical research. A recent example is the determi-
nation of historical light curves of optical objects
identified with newly discovered x-ray sources. Such
data have not only assisted with the identifications but
have also provided valuable clues to the nature of the
x-ray sources. As another example, where would we be
today without ready access to the Palomar Sky Survey?
The large volume of digital images that will be
produced in the coming years provides a valuable resource
for future generations of astronomers and should be
archived. There is more to archiving than simply storing
the data. There must be a means for users of the archives
to locate data stored in the archives quickly and easily.
Not only must the user be able to search indices to deter-
mine the availability of images containing the objects of
interest to him or her, but in addition, the user must
have a means of viewing the images identified by the
index search to determine if they are appropriate for the
intended research program. Finally, archives should
provide protection against data degradation or loss.
At present, the only available archival medium suit-
able for storing the volume of data described in the
previous section is the high-density magnetic tape.
However, tapes have several disadvantages. Tape archives
must be a manually operated system and are subject to
error. The access functions are cumbersome to perform
with tape archives.
ing the shelf life of tapes.
And there is some question concern-
In the near future (1982-1983), video disks are
expected to become available and promise to revolutionize
mass storage systems. Estimates are that initially a
read-write unit will cost about $150,000; a read unit,
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325
approximately $50,000; and the disk, about $1,000.
eral years after their introduction, the costs are
expected to drop to around $50,000, $6,000, and $100,
respectively. Video disks are about the size of an
ordinary phonograph album and will initially have
capacities of 101 bits per disk increasing to 1012
bits per disk after they have been on the market for a
few years. Video disks will also facilitate wide dis-
tribution of selected data bases. From an original disk
it will be possible to make a die that is then used to
press multiple copies of the original disk in much the
same way that phonograph records are reproduced.
For the immediate future, we expect that digital image
data will continue to be archived as part of individual
astronomers' private tape collections. This is unfor-
tunate, because such data are often not preserved for
future generations of astronomers. However, when video
disks (or other suitable media) become available, funds
should be provided to establish formal archives. This
process should start slowly so that we gain some experi-
ence before making too many mistakes. In particular, one
of the National Astronomy Centers should take the lead in
developing and implementing an archive. Once the problems
are understood, archives can be implemented at other
National Centers and then at other major observatories.
These implementations should be coordinated by a perma-
nent committee, perhaps the same committee suggested in
the previous section. Some of the major problems that
must be solved are questions of policy rather than tech-
nical problems. In particular, it must be recognized
that data obtained with public funds are public property
and, after a reasonable period following the original
observations, must be made available to all qualified
users. An important role of the committee will be to
promote discussions of these kinds of policy questions
throughout the astronomical community.
In addition to hardware acquisition, implementation of
archives will require some software development (although
commercially available data-base-management systems may
provide most of the necessary capabilities). Thus the
cost of establishing the first archives may be expected
to be on the order of $300,000 with the cost of later
archives approximately $200,000. In addition, operation
of the archives will orobablv require the services of one
_ , ~
or two full-time employees to oversee deposition of data
into the archives and to fulfill requests for data from
the archives. Thus we estimate that for expenditures of
Representative terms from entire chapter:
software development
