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Astronomical Data Analysis Software and Systems IV
ASP Conference Series, Vol. 77, 1995
R. A. Shaw, H. E. Payne, and J. J. E. Hayes, eds.
Distributed Software for Observations in the Near Infrared
V. Gavryusev 1 and C. Baffa
Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, Firenze, 50125
Italy
E. Giani
Dipartamento di Astronomia, Universit`a di Firenze
Abstract. We have developed an integrated system that performs as­
tronomical observations in Near Infrared bands operating two­dimensional
instruments at the Italian National Infrared Facility's ARNICA 1 and
LONGSP 2 . This software consists of several communicating processes,
generally executed across a network, as well as on a single computer. The
user interface is organized as widget­based X11 client. The interprocess
communication is provided by sockets and uses TCP/IP.
The processes denoted for control of hardware (telescope and other
instruments) should be executed currently on a PC dedicated for this task
under DESQview/X, while all other components (user interface, tools
for the data analysis, etc.) can also work under UNIX. The hardware
independent part of software is based on the Athena Widget Set and is
compiled by GNU C to provide maximum portability.
1. Design
The design of a data acquisition package is, as always, a long struggle between
many different and contrasting needs. Also, we have to bear in mind the funda­
mental consideration that software which gives the user fast operation and an
immediate feeling for data quality raises the total (system + operator) efficiency.
This has the same effect of a bigger telescope or a more sensitive instrument.
For effective support of the observations of the Arcetri two­dimensional
infrared instruments, we need to put together cheap hardware, an easy and
intuitive user interface, the fastest data acquisition, the best quick look possible,
complete data documentation, infinite and safe data storage, code portability,
and the possibility of shifting to a more powerful platform.
As usual, we were forced to choose a middle path between these conflicting
requirements. As a start, we used an AT­Bus based machine for hardware
1
Visiting Astronomer, Nuclear Physics Institute of Moscow State University, Moscow, Russia
1 http://helios.arcetri.astro.it:/home/idefix/Mosaic/instr/arnica/arnica.html
2 http://helios.arcetri.astro.it:/home/idefix/Mosaic/instr/longsp/longsp.html
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construction. However, we found that neither DOS or Windows will do the
work (Baffa 1991). This is due to a number of reasons; DOS is short of memory
and lacks multi­tasking, while Windows is slow and completely lacks the code
portability we wanted. We finally chose to use DESQview/X and the GNU C
compiler as a reasonable compromise between our different needs (Gavryusev et
al. 1993; Di Giacomo et al. 1993).
From DESQview/X, we get an X server, so we have excellent code portabil­
ity, a native DOS Extender to have fewer memory problems, and the ability to
run in a DOS­like exclusive task mode, which gives us a workable time control
over our data acquisition (DESQview 1993). We can compile and run most of
our modules on different platforms---PC's and workstations, under DESQview/X
and UNIX. We can spread our processes over a network, so we can get data at
a telescope, control the instrument from Firenze in Italy, and display the data
on a computer in Baltimore.
2. Structure
It is always the best choice to solve independent tasks by independent software.
Independently executed parts can be compiled by different compilers (if neces­
sary), debugged separately, and their subsequent versions not influence other
pieces of the software (if interface demands are followed). The situation is the
same as with the use of DLL libraries. Moreover, if the interprocess communica­
tion interface includes support for networking, the software immediately becomes
network distributed software. Such organization of the program can, in princi­
ple, cause some complexity from the point of view of the user, but this problem
can be covered by providing well chosen default options and the permission to
easily change them only for experienced users.
In our case we have to differentiate between a number of tasks: (1) a graph­
ical user interface, (2) the display of images, (3) the hardware interface, and (4)
data transfer between computers. These tasks are solved by different processes,
generally more then one for each task when it is possible. The interprocess com­
munication is provided by sockets and uses TCP/IP if the processes are executed
on different computers.
It is important to remember that we plan to use the same control program
(without recompilation) for the two different infrared instruments: the camera
ARNICA (Lisi et al. 1993) and the long slit spectrograph LONGSP (Gennari
et al. 1993). This should be possible because the instrument dependent parts
of the software can start or finish their work dynamically, or depending on their
contents, an easily editable resource file for the current session.
Figure 1 shows the typical view of the screen during an observation. There
is the window with main menu (marked xnir), the control/information window
during the acquisition process (marked ACQUISITION ) with an open display of
the current image, obtained from ARNICA during the ``Single Frame'' measure­
ments (marked Image (acquisition)). The menu for starting the frame viewer
(marked Display Frame) is shown with a submenu that has a default list of
the hosts where the display can be sent. In addition the view­window (here,
SAOimage) is open as well.

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Figure 1. The typical view of screen during the observations.
Acknowledgments. We are grateful to R. Stanga and F. Lisi for useful
discussions, to A. Di Giacomo for some of the preparation work, and to Professor
F. Pacini who invited one of us (VG) to Arcetri.
References
Baffa, C. 1991, Arcetri Technical Report
DESQview/X User Guide 1993, Quarterdeck
Di Giacomo, A., Giani, E., & Baffa, C. 1993, Arcetri Technical Report
Gavryusev, V., Giani, E., & Baffa, C. 1993, Arcetri Technical Report
Gennari, S., & Vanzi, L. 1993, UCLA Conference
Lisi, F., Baffa, C., & Hunt, L. K. 1993, SPIES International Symposium on op­
tical Engineering and Photonics in Aerospace and Remote Sensing (Or­
lando, SPIE)