NEMO (Not Everybody Must Observe) is a toolkit for

stellar dynamics Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. The essential difference from celestial mechanics is that the number of body N \gg 10. Typica ...

. At its core it manipulates an ''n''-body system (snapshot), but can also derive or compute

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

s, derive

image An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensiona ...

s and extract

tables Table may refer to: * Table (furniture), a piece of furniture with a flat surface and one or more legs * Table (landform), a flat area of land * Table (information), a data arrangement with rows and columns * Table (database), how the table data ...

to take to other analysis systems.

Architecture

NEMO was developed on

Sun workstation The SUN workstation was a modular computer system designed at Stanford University in the early 1980s. It became the seed technology for many commercial products, including the original workstations from Sun Microsystems. History In 1979 Xerox do ...

s, but ports to most

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

-like systems. At its core NEMO defines a series of

objects Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ...

(SnapShot, Orbit, Image) and associated

header files Many programming languages and other computer files have a directive, often called include (sometimes copy or import), that causes the contents of the specified file to be inserted into the original file. These included files are called copybooks ...

and

libraries A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vir ...

to operate on them, and these mirror the stored data in a portable

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

-named and type-tagged

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...

-like format dubbed ''structured file''. The program tsf in NEMO will show the contents of such a file in a human readable way. Another feature of NEMO is that all its data can be piped from one task into the next, thus creating whole simulations in a simple

Unix pipe In Unix-like computer operating systems, a pipeline is a mechanism for inter-process communication using message passing. A pipeline is a set of processes chained together by their standard streams, so that the output text of each process (''stdou ...

. For example, mkplummer - 1000 , snapscale - - vscale=0.5 , hackcode1 - - tstop=10 , snaptrim - - times=10 , snapgrid - - , ccdfits - final.fits would create a 1000 particle Plummer sphere, scale the

velocities Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...

down to below virial equilibrium, integrate this for 10 virial times to see it collapse, and take the particle distribution of the last snapshot and turn that into a

FITS Flexible Image Transport System (FITS) is an open standard defining a digital file format useful for storage, transmission and processing of data: formatted as multi-dimensional arrays (for example a 2D image), or tables. FITS is the most com ...

file to view in another astronomical analysis package.

History

NEMO was conceived and written by Josh Barnes,

Piet Hut Piet Hut (born September 26, 1952) is a Dutch-American astrophysicist, who divides his time between research in computer simulations of dense stellar systems and broadly interdisciplinary collaborations, ranging from other fields in natural scien ...

and Peter Teuben in 1986, at the

Institute for Advanced Study The Institute for Advanced Study (IAS), located in Princeton, New Jersey, in the United States, is an independent center for theoretical research and intellectual inquiry. It has served as the academic home of internationally preeminent scholar ...

, prompted by the wish to have a toolkit built around the just developed

Barnes–Hut simulation The Barnes–Hut simulation (named after Josh Barnes and Piet Hut) is an approximation algorithm for performing an ''n''-body simulation. It is notable for having order O(''n'' log ''n'') compared to a direct-sum algorithm which would b ...

. NEMO wa
presented
at the 199
Astronomical Data Analysis Software and Systems (ADASS)
conference held in Baltimore, MD. NEMO is still in active use and development, and has been used in many publications. Peter Teuben maintains NEMO, whereas Josh Barnes maintains ZENO, a spin-off from NEMO.

References

External links

NEMO home page

(a NEMO derived toolkit) Astronomical imaging Astronomy software Fortran software C (programming language) software {{science-software-stub