by Nikodem Poplawski

The 2011 Nobel prize in physics has been awarded to S. Perlmutter, A. Riess and B. Schmidt for their path breaking discovery that the rate of expansion of the universe is increasing with time. The trio used Type Ia supernovae (SNe Ia) as standard candles to estimate their luminosity-distances. To appreciate some of the far reaching implications of their work, I have provided an elementary exposition of general theory of relativity, accelerated expansion of the universe, luminosity-distance, SNe Ia and the cosmological constant problem.

The ATLAS3D Project (Cappellari et al. 2011) combines a multi-wavelength survey of a complete sample of 260 early-type galaxies within the local (42Mpc) volume (1.16×105 Mpc3) with numerical simulations and semi-analytic modeling of galaxy formation. This project aims to quantify the global stellar kinematics and dynamics of a statistically significant sample of objects to characterize the class of early-type galaxies, and relate this to their formation and evolution. Combining the stellar populations diagnostics from the multi-wavelength coverage, the ATLAS3D Project will derive the star formation history probing the mass-assembly epochs and timescales. In addition, the project will characterise the different phases of the interstellar medium linking the kinematics of molecular, atomic and ionised gas with the dynamical structure, star formation and environment of the host galaxies.

Shape is a morpho-kinematic modeling and reconstruction tool for astrophysical objects. With this software you can quickly construct 3D model structures and directly compare them with data in order to assist in the interpretation of observations. From such a 3D structure model with a model velocity field and emission properties, it generates images and position-velocity (pv) diagrams, channel maps, light echoes, light curves and one dimensional spectral line shape, to mention a few. Wavelength dependent radiation transfer for line emission and scattering on dust is also possible.

Now in its fourth edition, this highly regarded book is ideal for those who wish to solve a variety of practical and recreational problems in astronomy using a scientific calculator or spreadsheet. Updated and extended, this new edition shows you how to use spreadsheets to predict, with greater accuracy, solar and lunar eclipses, the positions of the planets, and the times of sunrise and sunset. Suitable for worldwide use, this handbook covers orbits, transformations and general celestial phenomena, and is essential for anyone wanting to make astronomical calculations for themselves. With clear, easy-to-follow instructions for use with a pocket calculator, shown alongside worked examples, it can be enjoyed by anyone interested in astronomy, and will be a useful tool for software writers and students studying introductory astronomy. High-precision spreadsheet methods for greater accuracy are available at www.cambridge.org/practicalastronomy.

This file contains Galactic stars known or suspected to be variable.
It lists all stars that have an entry in the AAVSO International
Variable Star Index (VSX; http://www.aavso.org/vsx).

The database consisted initially of the General Catalogue of Variable
Stars (GCVS) and the New Catalogue of Suspected Variables (NSV) and
was then supplemented with a large number of variable star catalogues,
as well as individual variable star discoveries or variables found in
the literature. Effort has also been invested to update the entries
with the latest information regarding position, type and period and to
remove duplicates. The VSX database is being continually updated and
maintained.

For historical reasons some objects outside of the Galaxy have been
included.

The AAVSO is an international non-profit organization of variable star observers whose mission is:

to observe and analyze variable stars
to collect and archive observations for worldwide access
to forge strong collaborations between amateur and professional astronomers
to promote scientific research and education using variable star data.

The GCVS is the only reference source on all known variable stars.
This version contains the electronically-readable version as
distributed by the Sternberg Astronomical Institute and Institute of
Astronomy (Russian Acad.Sci.), Moscow. It includes the catalog of
variable stars, updated and completed with the Name-Lists of Variables
Stars Nos. 67-79, the NSV (New catalog of Suspected Variable stars)
and Supplement to the NSV stars, and a catalog of extragalactic
variables. A cross-index makes possible to find out identifications
between the GCVS and the NSV catalogue.

Fv is the easy to use graphical program for viewing and editing any FITS format image or table. The Fv software is small, completely self-contained and ready to run on

PyEphem provides scientific-grade astronomical computations for the Python programming language. Given a date and location on the Earth’s surface, it can compute the positions of the Sun and Moon, of the planets and their moons, and of any asteroids, comets, or earth satellites whose orbital elements the user can provide. Additional functions are provided to compute the angular separation between two objects in the sky, to determine the constellation in which an object lies, and to find the times at which an object rises, transits, and sets on a particular day.

Masil-Astro-Imaging is the home for astro-photos taken by Sheldon Faworski & Sean Walker.
Sean works in Massachusetts and I live in Illinois, hence the name "MASIL". We collaborate
on many of the images that are posted on this site.

Overwhelming collection of old star maps and celestial atlasses.

How was the world created? People have asked this ever since they could ask anything, and answers have come from all sides: from religion, tradition, philosophy, mysticism... and science. While this does not seem like a problem amenable to scientific measurement, it has led scientists to come up with fascinating ideas and observations: the Big Bang, the concept of inflation, the fact that most of the world is made up of dark matter and dark energy which we can not perceive, and more.
Of course scientists cannot claim to know the definitive truth. But we can approach the question from a scientific viewpoint and see what we find out. How do we do that? First, we look to the data. Thanks to modern technology, we have much more information than did people of previous ages who asked the same question. Then we can use scientific methods and techniques to analyze the data, organize them in a coherent way and try and extract an answer. This process and its main findings will be described in the article.

This paper presents a hands-on introduction to the medieval astrolabe, based around a working model which can be constructed from photocopies of the supplied figures. As well as describing how to assemble the model, I also provide a brief explanation of how each of its various parts might be used. The printed version of this paper includes only the parts needed to build a single model prepared for use at latitudes around 52{deg}N, but an accompanying electronic file archive includes equivalent images which can be used to build models prepared for use at any other latitude. The vector graphics scripts used to generate the models are also available for download, allowing customised astrolabes to be made.

PyAST is a collection of modules that allows the facilities of the Starlink AST library to be used within Python (version 2.7 or later) scripts.
The AST library provides a comprehensive range of facilities for attaching world coordinate systems to astronomical data, for retrieving and interpreting that information and for generating graphical output based on it. AST is written in ANSI C but has wrappers for various other languages, including Fortran, Java, Perl, and now Python.

The Revista Mexicana de Astronomia y Astrofisica, founded in 1974, publishes original research papers in all branches of Astronomy, Astrophysics and closely related fields. Two numbers per year are issued and are distributed free of charge to all institutions engaged in the fields covered by the RevMexAA.

The Habitable Sun - One of Herschel, William's Stranger Ideas

Title:
The Habitable Sun - One of Herschel, William's Stranger Ideas
Authors:
Kawaler, S.; Veverka, J.
Publication:
Journal of the Royal Astronomical Society of Canada, Vol. 75, P. 46, 1981
Publication Date:
02/1981
Origin:
KNUDSEN
Comment:
A&AA ID. AAA029.004.032
Bibliographic Code:
1981JRASC..75...46K

The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of intergalactic gas, but its mass, heavy element enrichment, and relation to galaxy properties are poorly constrained by observations. In a survey of the outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we detected ubiquitous, large (150-kiloparsec) halos of ionized oxygen surrounding star-forming galaxies; we found much less ionized oxygen around galaxies with little or no star formation. This ionized CGM contains a substantial mass of heavy elements and gas, perhaps far exceeding the reservoirs of gas in the galaxies themselves. Our data indicate that it is a basic component of nearly all star-forming galaxies that is removed or transformed during the quenching of star formation and the transition to passive evolution.

To our best knowledge, there are no problem books on cosmology yet, that would include its spectacular recent achievements. We believe there is a strong need for such now, when cosmology is swiftly becoming a strict and vast science, and the book would be extremely useful for the youth pouring in this area of research. Indeed, the only way to rise over the popular level in any science is to master its alphabet, that is, to learn to solve problems.
Of course, most of modern textbooks on cosmology include problems. However, a reader, exhausted by high theory, may often be thwarted by the lack of time and strength to solve them. Might it be worth sometimes to change the tactics and just throw those who wish to learn to swim into the water?
The proposed problems constitute our contribution to this cause. There are over 1000 problems, divided into 14 chapters, covering topics from the dynamics of the expanding Universe and CMB to cosmology beyond the Lambda-CDM model and holography. We intend to publish their solutions in later editions. The reader, however, is encouraged to look for answers independently, even though - or especially so because - the problems range from easy to not quite and from elements of scientific folklore already to those with answers not quite settled.

MEMORIE della Società Astronomica Italiana is a professional quarterly journal devoted exclusively to the publication of Conference Proceedings and invited review papers. MEMORIE publishes only papers written in English. The journal is distributed to all members of the SAIt and to over one hundred subscribers abroad, including the main astronomical institutions. Since 1986 more than 30 conferences have been published.

Follow the adventures in the life of a Welsh astrophysicist sent into exile to a small island in the middle of the ocean. A blog by a scientist that almost certainly won't be about science, but will be very facetious.

Astro-WISE stands for Astronomical Wide-field Imaging System for Europe. Astro-WISE is an environment consisting of hardware and software which is federated over about a dozen institutes all over Europe. It has been developed to scientifically exploit the ever increasing avalanche of data produced by science experiments. We call such an environment an information system. As the name suggests, Astro-WISE started out as a system geared towards astronomy, but is now also being used for projects outside astronomy. Astro-WISE is an all-in-one system: it allows a scientist to archive raw data, calibrate data, perform post-calibration scientific analysis and archive all results in one environment. The system architecture links together all these commonly discrete steps in data analysis.

GNU Data Language (GDL) is a free/libre/open source incremental compiler compatible with IDL and to some extent with PV-WAVE. Together with its library routines it serves as a tool for data analysis and visualization in such disciplines as astronomy, geosciences and medical imaging. GDL is free software licensed under the GPL. GDL is developed by an international team of volunteers led by Marc Schellens - the project's founder

This command acts as a standard Unix filter: it takes a list of FITS file names in input and outputs their headers to stdout. Convenient to browse headers in directories. See fitsort to classify data from a list of FITS headers produced by dfits.

This handbook is designed to provide a selection of the most important and frequently used atomic spectroscopic data in an easily accessible format. The compilation includes data for the neutral and singly-ionized atoms of all elements hydrogen through einsteinium (Z = 1-99). The wavelengths, intensities, and spectrum assignments are given in a table for each element, and the data for the approximately 12,000 lines of all elements are also collected into a single table, sorted by wavelength (a "finding list").

The general idea is that we meet up on Twitter at a prearranged day and time and discuss an interesting piece of astronomy research. This will generally take the form of an academic paper, but we could also include some articles too. Everyone’s welcome to participate, whether you’re an expert in the topic or not – as long as you’ve read the paper. We hope that the real-time aspect of Twitter will make it a suitable platform for an online discussion. Check out the Next Meeting page for information about the next meeting, including the paper that we will be discussing.

Im Jahr 1992 gründete sich innerhalb der Astronomischen Gesellschaft ein Arbeitskreis Astronomiegeschichte.
Im Auftrag dieses Arbeitskreises geben nun seit 1998 die bekannten Astronomiehistoriker Wolfgang R. Dick und Jürgen Hamel die Buchreihe Acta Historica Astronomiae heraus (ISSN 1422-8521)
Im Vorwort zum ersten Band dieser Reihe schreiben Dick und Hamel:

"Besonders nach der Einstellung der Zeitschrift Die Sterne fehlt es im deutschsprachigen Raum an Möglichkeiten zur Publikation wissenschaftlicher Aufsätze auf dem Gebiet der Geschichte der Astronomie. In dem nunmehr mit dem ersten Band vorliegenden Acta Historica Astronomiae sollen Bücher und Broschüren verschiedenster Art publiziert werden: Monographien, Sammel- und Tagungsbände, Editionen von Handschriften, Bibliographien und Nachlassverzeichnisse sowie astronomiehistorische Dissertationen. Denkbar sind auch Nachdrucke interessanter historischer Werke."

The Great Observatories Origins Deep Survey (GOODS) is a public, multiwavelength survey which originally covered two 150 square arcmin fields, centered around the HDF-N (Hubble Deep Field North) and the CDF-S (Chandra Deep Field South). It is a coordinated effort to combine the deepest survey data over the widest wavelength range (from X-ray through radio) from NASA’s Great Observatories (HST, Chandra, Sptizer), ESA’s XMM-Newton, and the largest ground-based observatories, namely ESO-VLT, Keck, Gemini in the optical/nearIR region, VLA in the radio, etc. Observations were designed to promote major advances in following primary science areas:

Strong damped Lyman alpha absorption (DLA) lines seen spectra of distant quasar are believed to arise when the sight line to the quasar goes trough the disc of a galaxy or a proto galaxy. Most of the neutral matter in the universe is contained in these clouds of neutral hydrogen that cause the absorption lines. Hence these DLAs are reservoirs for the formation of stars and galaxies throughout the universe. Despite intensive efforts over more than two decades only few galaxies responsible for the DLAs have been found. The problem is that the galaxies that harbour the neutral clouds are not necessarily bright, and selecting galaxies based on absorption lines could well select different types of galaxies than found in large surveys. If we are to understand how galaxies form out of neutral gas clouds it is essential to locate the galaxies in which DLAs reside.

This thesis explores the use of integral field spectroscopy (IFS) to observe quasars known to have strong absorption lines in their spectra. IFS allows us to obtain a spectrum at many spatial points close to the quasar, thus providing images and spectroscopy simultaneously. From the imaging part, we can directly identify objects, and from the spectroscopy we can calculate the distances to the objects. When the distance of the object found in emission matches the distance to the object that cause the DLA line, we have identified the absorbing galaxy.

Using this technique, we have showed that we can successfully recover a few DLA galaxies known previously from the literature. In a survey aimed to increase the number of DLA galaxies we have identified eight new candidate DLA galaxies. The projected distances from the candidates to the quasar sight lines indicate that the DLA galaxies have sizes similar to local disc galaxies. Hence our results suggest that large discs may be present when the universe was just 2 billion years old. We furthermore find no differences between the sizes of the very distant DLA galaxies and those that are not so distant. The large sizes imply that their neutral hydrogen masses are also similar to those in local galaxies, but we argue that the DLA galaxies are not necessarily as luminous as the present day disc galaxies.

Taking advantage of the three-dimensional view provided by the IFS data, the second part of this thesis investigates extended emission line regions arising in the quasar neighborhood. We find that extended emission line nebulae are common around quasars, and explore the effects that may be the cause. Some quasars are known to be powerful radio emitters while others are not detected at radio wavelengths. We find that significantly larger and brighter emission line nebulae are found around the quasars which have the brightest radio emission, and in particular those that have large radio jets. The existence of the nebulae can be interpreted as an interaction of the radio jet with the surrounding medium, but we can not rule out a scenario where there are density or temperature differences in the surrounding environment. Only for the brightest object, where additional velocity information can be derived from the IFS data, can we argue for an interaction.

In conclusion the use of IFS to search for faint emission lines, both from point sources and extended nebulae provides exciting new results within the scientific areas studied here.

Vereiningung für Jugendarbeit in der Astronomie e.V.

Las Cumbres Observatory Global Telescope Network is a private operating foundation, building a global network of telescopes for professional research and citizen investigations

The Special Astrophysical Observatory (SAO) was founded in 1966. At present it is the largest Russian astronomical center for ground-based observations of objects in the Universe.

Astrobites is a daily literature journal summarizing new astrophysical research posted to astroph. Astrobites is written by graduate students for undergraduates. Read more about our goals.

The PASEO group aims at the development of new data analysis tools in the space imaging domain. Probabilistic approaches are used to model complex datasets (multispectral, multiple sources), and to solve the inverse problems related to their analysis.

PASEO is currently a research group within the MIV team (LSIIT, Illkirch), in close collaboration with the CDS (Strasbourg Observatory), mainly funded by CNRS, ULP and various national and European projects.

This company offers tot their clients management, design and developments of technological projects with scientific goals, software developments and consultancy in astronomical instrumentation.

Life is unique in nature in complexity and in its drive for self-propagation. We are part of life, implying a human purpose to safeguard and propagate life. For this purpose we may settle the Solar System, and seed with life new solar systems, solar nebulae and star-forming interstellar clouds. Directed panspermia to these targets can carry colonizing cyanobacteria, extremophile microorganisms, and eggs of multicellular rotifers to start higher evolution. The technical requirements for launching, targeting, deceleration and capture, and the probability of success were evaluated. The results show that directed panspermia can be accomplished with present technology. These programs will also serve the drive of life to occupy all habitats, and protect life from various threats, including ultimately the red giant Sun. ...

Manually labeling features in a crowed plot can be very time consuming. Functions in this module can be used to automatically place labels without the labels overlapping each other. This is useful, for example, in creating plots of spectrum with lines identified with labels.

Line Identification Plots v0.1 documentation
Line identification plots with automatic label layout

FITS Manager (FM) is a desktop application for astronomers to manage FITS files hosted in their personal computers. This toolkit is a collaboration project between Chinese Virtual Observatory (China-VO) and Virtual Observatory India (VO-India).

Dr. Hans Vehrenberg war in den 60er Jahren des letzten Jahrhunderts vielleicht der weltweit bekannteste, sicher aber erfolgreichste Astrofotograf. Mit seinen Zeiss Astrokameras erstellte er den ersten fotografischen Sternatlas, der den ganzen Himmel komplett abbildete, den Falkauer Atlas. Mit einem 120mm Zeiss Sonnefeld Astrovierlinser fotografierte er den gesamten Himmel im doppelten Maßstab ein zweites Mal, um seinen Atlas Stellarum zu erstellen. Darüber hinaus veröffentlichte Dr. Vehrenberg ein Milchstraßenmosaik, den Atlas of Selected Areas (zusammen mit den französischen Astronomen A. Brun), sein Messier-Buch und den Atlas Galaktischer Nebel (zusammen mit Dr. Neckel).

p3d is a general data-reduction tool that is intended to be used with data of fiber-fed integral field spectrographs (IFSs). This tool can be useful for people who have access to astronomical data of such an instrument. Data-reduction tasks, which are performed by p3d, convert raw data of CCD detectors into extracted spectra that can thereafter be used for scientific purposes.

Astro-ph discussions

This page provides links to an overview of deep fields. The focus here is on imaging surveys and we maintain two different lists: One is a manually assembled list of deep fields typically with multi-wavelength imaging and the other is an automatically generated list of all deep fields observed by HST.

SDSS images of selected RC3 galaxies

If you have astronomical imaging of the sky with celestial coordinates you do not know—or do not trust—then Astrometry.net is for you. Input an image and we'll give you back astrometric calibration meta-data, plus lists of known objects falling inside the field of view.

Urania’s Mirror is a boxed set of 32 constellation cards first published by Samuel Leigh of the Strand, London, in or shortly before 1825. The engraver was Sidney Hall but authorship was coyly attributed to “a lady”. Peter Hingley, librarian of the Royal Astronomical Society in London, has established that the true author was almost certainly the Reverend Richard Rouse Bloxam of Rugby (Journal of the British Astronomical Association, vol. 104, p. 238, 1994).

If you are looking for a screen-based astronomical ephemeris program with that retro look, or just want something very small and efficient, try ephem. It was written about 20 years ago in C and still compiles on just about any UNIX platform (including Linux and Mac OS X) and even VMS and Windows. The output is always 24 rows and 80 columns, just like the old glass TTYs.

The 110 galaxies, star clusters and nebulae catalogued by the comet hunter Charles Messier in the late 1700s are still the most widely observed celestial wonders in the heavens. They are the favourite targets of amateur astronomers, with such rich variety and detail that they never cease to fascinate. This book provides new and experienced observers with a fresh perspective on the Messier objects. Stephen James O'Meara has prepared a visual feast for the observer. Using the finest optical telescopes available for amateur work, superior eyepieces and the darkest site on Earth, he describes and sketches the view from the telescope as never before. There are new drawings, improved finder charts, and new astronomical data on each object, including findings from the Hubble Space Telescope. This is truly the Messier Guide for the modern age.

This page, updated monthly, will let you know some of the things that you can look out for in the night sky. It lists the phases of the Moon, where you will see the naked-eye planets and describes some of the prominent constellations in the night sky during the month

The goal of astrometry is to determine positions and motions of celestial objects such as stars and planets, as well as artificial satellites. Astrometry is the oldest branch of astronomy and until the 19th century all of professional astronomy was astrometry (see ASTROMETRY: HISTORY). One of the main astrometric objectives is to measure angular separations of stars and other celestial objects r...

The Kapteyn Package is a collection of Python modules and applications developed by the computer group of the Kapteyn Astronomical Institute, University of Groningen, The Netherlands. The purpose of the package is to provide tools for the development of astronomical applications with Python.

CFITSIO is a library of C and Fortran subroutines for reading and writing data files in FITS (Flexible Image Transport System) data format. CFITSIO provides simple high-level routines for reading and writing FITS files that insulate the programmer from the internal complexities of the FITS format. CFITSIO also provides many advanced features for manipulating and filtering the information in FITS files.

The Virtual Astronomy Multimedia ProjecThe Virtual Astronomy Multimedia Project (VAMP) will enable access to, and vastly multiply the use of, astronomy image resources. VAMP will enable innovative future exploitation of all kinds of outreach media by systematically linking resource archives worldwide.t (VAMP) will enable access to, and vastly multiply the use of, astronomy image resources. VAMP will enable innovative future exploitation of all kinds of outreach media by systematically linking resource archives worldwide.

Montage is a toolkit for assembling Flexible Image Transport System (FITS) images into custom mosaics.

Duncan is a postdoctoral research fellow at the Institute for Astronomy, part of the University of Edinburgh. His research focuses on numerical simulations of protoplanetary discs, the spawning grounds of the planets. He came to fame (and infamy) through a research sideline – numerical astrobiology. His work on attempting to model life in the Galaxy became a hot topic in the blogosphere, and was picked up by the major news networks across the globe.

On the heels of the International Year of Astronomy 2009, celebrating the famed peek into the cosmos through Galileo's first telescope, the question arises: What is next for science education and outreach?

Providing a forum for reflection, for sharing lessons learned, and for shaping resolve, the Astronomical Society of the Pacific (ASP) hosted a conference for astronomy and space science professionals in Millbrae, California from September 12 to 16, 2009. During the conference, participants discussed current education and outreach research and practice and shared perspectives about the future of this field. This conference, the proceedings of which are contained in this volume, was divided into a series of conference strands that each represent an important aspect of this time of contemplation and decision about the future of education and public outreach (EPO) in astronomy:

SAOImage DS9 is an astronomical imaging and data visualization application. DS9 supports FITS images and binary tables, multiple frame buffers, region manipulation, and many scale algorithms and colormaps. It provides for easy communication with external analysis tasks and is highly configurable and extensible via XPA and SAMP.

The Annual Review of Astronomy and Astrophysics, in publication since 1963, covers the significant developments in the field of Astronomy and Astrophysics, including: the sun; solar system and extrasolar planets; stars; the interstellar medium; galaxy and galaxies; active galactic nuclei; cosmology; and instrumentation and techniques, andthe history of the development of new areas of research.

We review our current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang. Modern large telescopes discovered galaxies at redshifts greater than seven, whereas theoretical studies have just reached the degree of sophistication necessary to make meaningful predictions. A crucial ingredient is the feedback exerted by the first generation of stars, through UV radiation, supernova blast waves, and chemical enrichment. The key goal is to derive the signature of the first galaxies to be observed with upcoming or planned next-generation facilities, such as the James Webb Space Telescope or Atacama Large Millimeter Array. From the observational side, ongoing deep-field searches for very high-redshift galaxies begin to provide us with empirical constraints on the nature of the first galaxies.

The purpose of this web site is to act as a community knowledge base for performing astronomy research with Python. It provides lists of useful resources, a forum for general discussion, advice, or relevant news items, collecting users' code snippets or scripts, and longer tutorials on specific topics. The topics within these pages are presented in a list view with the ability to sort by date or topic. A traditional "blog" view of the most recently posted topics is visible from the site Home page.

APLpy (the Astronomical Plotting Library in Python) is a Python module aimed at producing publication-quality plots of astronomical imaging data in FITS format. The module uses Matplotlib, a powerful and interactive plotting package. It is capable of creating output files in several graphical formats, including EPS, PDF, PS, PNG, and SVG.

More impressive ground based images of the STS-133 mission, this time, Amateur astronomer Ralf Vandebergh of the Netherlands took images during one of the spacewalks for the mission, and likely captured astronaut Steve Bowen at work on the end of the Canadarm 2!

The transmission rate of communication between radio telescopes on Earth and extraterrestrial intelligence (ETI) has been calculated up to the distances 1000 light years. Phase-shift-keying (PSK) and frequency-shift keying (FSK) modulation schemes are both considered here. It has been demonstrated that M-ary FSK is advantageous in terms of energy. Narrow-band pulses scattered over the spectrum can be the probable signals of ETI and modern SETI spectrum analyzers are well suited to searching for these types of signals. Such signals can be detected using the Hough transform which is a dedicated tool for detecting patterns on an image. The time-frequency plane representing the power output of the spectrum analyzer during the search for ETI gives an image from which the Hough transform (HT) can detect signal patterns with frequency drift.

astLib is a set of Python modules that provides some tools for research astronomers. It can be used for astronomical plots, some statistics, common calculations, coordinate conversions, and manipulating FITS images with World Coordinate System (WCS) information through PyWCSTools - a simple wrapping of WCSTools by Doug Mink. PyWCSTools is distributed (and developed) as part of astLib.

On this website you will find information about AstrOmatic software, including download links to the latest versions and documentation, as well as access to the discussion forum and to development repositories.

We go through the many considerations involved in fitting a model to data, using as an example the fit of a straight line to a set of points in a two-dimensional plane. Standard weighted least-squares fitting is only appropriate when there is a dimension along which the data points have negligible uncertainties, and another along which all the uncertainties can be described by Gaussians of known variance; these conditions are rarely met in practice. We consider cases of general, heterogeneous, and arbitrarily covariant two-dimensional uncertainties, and situations in which there are bad data (large outliers), unknown uncertainties, and unknown but expected intrinsic scatter in the linear relationship being fit. Above all we emphasize the importance of having a "generative model" for the data, even an approximate one. [...]

IDLWAVE is an add-on mode for GNU Emacs and XEmacs which enables feature-rich development and interaction with IDL®, the Interactive Data Language, produced by ITT Visual Information Solutions. It provides a compelling, full-featured alternative to the IDLDE development environment bundled with IDL.

The expansion of the observed universe appears to be accelerating. A simple explanation of this phenomenon is provided by the non-vanishing of the cosmological constant in the Einstein equations. Arguments are commonly presented to the effect that this simple explanation is not viable or not sufficient, and therefore we are facing the "great mystery" of the "nature of a dark energy". We argue that these arguments are unconvincing, or ill-founded.

Emission lines provide a powerful tool to study the physical properties and chemical compositions of astrophysical objects in the Universe, from the first stars to objects in our Galaxy. The analysis of emission lines allows us to estimate the star formation rate and initial mass function of ionizing stellar populations, and the properties of active galactic nuclei. This book presents lectures from the eighteenth Winter School of the Canary Islands Astrophysics Institute (IAC), devoted to emission lines and the astrophysical objects that produce them. Written by prestigious researchers and experienced observers, it covers the formation of emission lines and the different sources that produce them. It shows how emission lines in different wavelengths, from ultraviolet to near infrared, can provide essential information on understanding the formation and evolution of astrophysical objects. It also includes practical tutorials for data reduction, making this a valuable reference

The Galaxy Zoo citizen science website invites anyone with an Internet connection to participate in research by classifying galaxies from the Sloan Digital Sky Survey. As of April 2009, more than 200,000 volunteers had made more than 100 million galaxy classifications. In this paper, we present results of a pilot study into the motivations and demographics of Galaxy Zoo volunteers, and define a technique to determine motivations from free responses that can be used in larger multiple-choice surveys with similar populations. Our categories form the basis for a future survey, with the goal of determining the prevalence of each motivation