Amateur

 Virtual Observatory

Updated 8th May 2011

Updates highlighted in pale yellow or by red text

 Exercises using the Virtual Observatory

Following the lecture I have delivered to a number of societies about the Amateur Virtual Observatory the questions asked and subsequent discussions indicated that there is so much in the Virtual Observatory that people don't know where to start. As a result I have written a number of exercises that are designed to 'break the ice' and to aid you getting familiar with the various facilities of the virtual observatory. The exercises start with a very gentle introduction and then build on this. Most exercises assume familiarity with the material covered in the previous exercises so it is best to attempt them in order.

Introduction

The following exercises are designed to introduce you to some of the facilities available to Amateur Astronomers in the Virtual Observatory. The first exercises are designed to introduce you to the AVO. The initial exercises will concentrate on one of the graphical front ends to the VO called Aladin as this has a powerful graphical interface that allows you to explore large sections of the VO as well as using the facilities for your own projects. Where possible hyperlinks to the various programmes and websites have been included as clickable links.

For some exercises you will require additional images or software. These will be shown at the start of each exercise.

Earlier versions of Aladin were limited in the area of the Sky which they would show to the size of the images in held in the server - often a fraction of a degree. This also created problems if the area you were interested on was in the border of several images. Attempting to download catalogues for large areas ran into problems due to the large amount of data. In version Aladin Version 7 a new mode was introduced - the progressive mode that allows you to download large areas of the sky and also makes this the default option if you just enter an object in the 'Location' box. Indeed if you do not enter an object you will get an image of the whole sky. A number of quick load buttons have been provided for the 'progressive' mode just above the image area. There are three images All Sky Optical (coloured), All Sky Infrared & Digital Sky Survey (monochrome). In addition buttons provide access to the Simbad, NED, PPMX & 2 Mass catalogues in progressive mode. Further images and catalogues are available under the new 'File' - 'All Sky' option.

The original mode is still available by loading the images and catalogues using the functions on the file menu. In this mode a lot more images and catalogues are available but the images are limited by the size of individual images held on the server - there is no automatic tiling mode. .Also a lot of images taken by surveys only cover part of the sky so don’t be surprised if your favourite images or survey are not available for the area you are looking at.

There have been a number of other changes that have effected the exercises below - I have put some notes against these until I can re-write them

In addition to the exercise number the list below shows the programme that you will learn about and brief summary of what the exercise is designed to teach you

Equipment:

To run Aladin you need a computer that has Java installed (most have). There are no special hardware requirements though a large monitor running at high resolution is helpful to see some of the fine detail. The exercises should run under Windows, Mac and Linux Operating Systems though the methods of installing Aladin are different. You will also need a high speed Internet connection as some of the images and catalogues are quite large. You will also need a reasonable amount of spare space on your hard disc as the uncompressed FITS format images tend to be quite large.

VO Software Changes:

The exercises are designed around the current version of the software – currently in July 2009 Aladin V6. Due to the rate of change of the VO the software may have been upgraded and additional functionality added by the time you try these exercises.

 The exercises below are in draft and any feedback would be welcome. Exercises 1 to 5 are available, the others will be added as I write them and verify them. The exercises in purple Italics have yet to be written and may be changed.

Note: 8/5/2011 - Exercise 10 has been added - the exercise to plot all the Globular Clusters is now an additional activity at the end of exercise 10 so exercise 9 which was out of order is no longer required.

Update 8/1/2011 Virtual Observatory Examples on EuroVO:

A large number of examples on how to use the Virtual Observatory can be found on the EuroVO Aida/WP5 page. The examples are at the bottom of the page - the plain text links to the english version. They are copied below to show you what is available but you should go to the source page on the link above to ensure you get the latest updates.

1.		The sky (apparent motion, coordinates, constellations, light pollution)
2.		The stars (color and luminosity: the Hertzsprung-Russell diagram)
3.		The shape of galaxies (the Hubble morphological sequence)
4.		The Pleiades open cluster (parallax, HR-diagram)
5.		Proper motion of the Barnard's star
6.		Confirmation of an apparent supernova    * download the image ngc6946.fits
7.		Distance of the Andromeda galaxy (variable stars: cepheids)
8.		Distance of the Crab Nebula     (linear and angular size, expansion velocity of the nebula)
9.		Asteroids in the Solar System   (asteroids distribution, orbital elements, risonances)
10.		Planetary conjunctions (conjunctions, the Star of Bethlehem and the end of the world in 2012)
11.		Introduction to Stellarium for prescholars     (Celestial sphere, light pollution, constellations)
12.		Planetary motion (Geocentric and heliocentric models, retrograde motion, Kepler's Laws)

Update 28/4/2011 - Practice Using Aladin to download & analyse images & data

The Aladin Website has a number of exercises available to help you develop your skills using Aladin and to show some of the features of the programme. The exercises are colour coded to show you the easier and more difficult ones. Some of the instructions are a bit terse but try them and see how you get on. In due course I hope to expand this section to give you some tips on the exercises and some information on other things to try.

One thing to note with Aladin is that you should be very careful with the delete (X) function. There is no sure' warning and it is very easy to accidentally delete several image & data planes - I know I have done it !

The exercises require at least Aladin V7 so if you have an older version delete this before you start. In addition I think you need to run the Standalone version to allow you to download your own image in exercise 3.

When you have tried an exercise experiment by changing some of the parameters or varying the conditions in the filters. Only by trying things yourself will you learn what it is all about and become an Aladin Wizard !

John Murrell

Clicking on the Home logo will return you to the home page