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Suzaku Guest Observer Facility

RollRange - an alternative to Maki

It may be desirable to perform a Suzaku observation at a certain roll angle, if the target is extended or near a bright source. Maki is a tool for the user to investigate the range of observable dates and the range of roll angles for a given date. Unfortunately, the current version of Maki does not work on 64-bit machines.

We therefore provide a simpler, text-only, perl script, RollRange as an alternative to Maki.

Note that both Maki and RollRange consider only the Sun angle. Additional constraints often exist, due to the availability (or not) of suitable stars in the star-tracker filed-of-view. For accepted observations, the mission scheduling team will provide the definitive range of allowed roll angles to the PI.


The package can be downloaded from

  • The tar file contains the main perl script, as well as 3 packages,,, and
  • The first line of all 4 files should be edited, if necessary, to point to the correct location of perl.
  • The main script will find the three packages if (a) they are placed anywhere in the perl library path, or (b) by specifying the directory path using the -I option (followed by the path) in the first line of Otherwise the user will see an error message indicating the script could not locate
  • In addition, the module requires a series of data files. Change the value of $ROOT to the directory where the SolarSystemVanFlandern subdirectory is (in our tar file, this is the same directory as the location of the perl modules).

Usage takes three arguments: the right ascension and declination of the pointing direction in decimal degrees, and the MJD of interest (which can be calculated using the HEASARC xTime tool).

Two types of outputs are possible:

example> 200.0 30.0 56505.0

     *** Target falls outside observation window! ***

     Target - sun angle = 63.00
     Acceptable range is 70 - 110
(this location is not observable with Suzaku on 2013 August 1), or
example> 200.0 30.0 56651.0

Target roll range at 56655.0:    96.4 - 135.4
(it is on 2013 December 25).

At roll angle of 0.0, spacecraft Y axis is pointing north; at 90.0, it points east (i.e., counterclockwise rotation looking up at the sky). One can subtract the roll angle from 90.0 to obtain the 3rd Euler angle.

If you have any questions concerning Suzaku, visit the Feedback form.

This file was last modified on Wednesday, 20-Oct-2021 08:44:57 EDT

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