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ASCA Guest Observer Facility

ROLL V1.00 Installation Guide


UNIX users

Use anonymous ftp to legacy.gsfc.nasa.gov and copy roll1_00.tar.Z from /FTP/asca/software.

Copy the file to a suitable directory then


% zcat roll1_00.tar | tar xvf -

Unlike pimms and viewing, there is no 'sitespec.inc' file to edit!


% make arch=sun
if your machine is a Sun (other arch are 'dec' for DECstation running Ultrix, 'alpha' for DEC Alphas running OSF). It will leave the executable, roll, in the current directory.

A short description of the usage and limitation can be found here.

Known Make problem

If make complains that 'don't know how to make sys.o' then wait a few seconds and try again. Makefile specifies to make a link sys.f to the appropriate *.sys file, sometimes this does not appear to take effect until after you exit make.

System dependence?

This version of roll will probably compile on all different flavors of Suns (old SunOS or Solaris, various compiler versions etc). In fact, make arch=sun will probably work for many non-DEC UNIX platforms, not just Suns. Try it and let us know if you encounter problems.

VAX/VMS users

If you can ftp and unpack the compressed tar file, then do so. Follow the UNIX directions above, then type @make instead of 'make arch=***'. To use the various command line options, each user must specify viewing as an external command. E.g.,


$ roll :== $disk$user4:[utils.roll]roll.exe
Otherwise, contact mukai@lheavx.gsfc.nasa.gov to arrange an alternative method of file transfer.


ROLL V1.00 Users' Guide


Roll is an ASCA-specific program, necessiated by the square shape of the CCDs used for its SIS instruments.

For observations involving multiple objects or an extended source, the roll angle may be critical in necessary sky coverage. However, there are operational constraints on the roll angle.

The main constraint is that the spacecraft Y axis must point to within 25 degrees of the Sun: this is all that the program roll considers (it also knows about the viewing constraint on Z axis, but this is quasi-independnet).

There are two ways to use roll. One is to find out the range of roll angles available for your target. You can optionally constrain the time window by giveing a range of dates


example% roll from=1-sep-1996 to=30-sep-1996
(default is 1 year starting the day the program is run) or by giving a sun angle constraint

example% roll range=80-110
(appropriate for non-time-critical observations; default is range=75-112, appropriate for time-critical observations).

Conversely, you can find out when a specific roll might be available


example% roll roll=32.4
(but you're advised to consider roll=32.4+180=212.4, roll=32.4+90=122.4 etc. as well).

You should refer to Figure 4.5 of the technical appendex of the NRA (AO-5 version) to decipher what a given roll angle means. The ASCA GOF has an additional tool 'adcongra' developed at ISAS for the operation, which is very useful but not very portable; consult the GOF for details.

However, there are other constraints, including one on star trackers (they must not point too close to the Moon). For this reason, the program 'roll' should be taken to give guidelines, and the final decision will be made by the ASCA operations team at ISAS.



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This file was last modified on Monday, 13-Sep-1999 15:37:07 EDT

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