Welcome to Preflight Training

If you need to learn how to use a new tool or brush up on some basics before launching off into a project or starting an Expedition, this is the place to be. The practice sessions are broken down into small chunks so you can pick just the skills and tools you need for your Voyage. 

Pre-flight training won’t tell you everything there is to know about a topic. These activities are built to get you using tools and concepts quickly. If you need an electric drill to build a bookshelf, you probably want to know where the power switch is and how attach a bit. You don’t need to know how the drill is put together or the history of drills. That is our philosophy here in Pre-Flight training; we’ll give you what you need to know so you don’t crash on take-off.


Locating Objects

Learning how to locate objects in the sky, as well as in the SDSS database and SkyServer, is a fundamental first step for embarking on Voyages activities. Only topics specific to the SDSS database are covered in these Preflights, but we encourage you to contact us at voyages@sdss.org if you would like to see a topic added.

Driving the SDSS Telescope

This activity provides an introduction to the sky coordinates of Right Ascension and Declination, how they are measured, and how the decimal degrees of RA and Dec are calculated.

Structured Query Language

This activity provides an introduction to how massive amounts of astronomy data are stored on computers in an organized manner.  The SDSS database can be accessed and queried using a coding language called SQL (structured query language). The activity demonstrates how a a simple SQL query works to retrieve specific information about objects in the vast SDSS database.


Asteroids are not intentional targets of the SDSS, but during the long exposures needed to capture faint galaxies and quasars, asteroids and other rapidly moving objects leave colored streaks or a series of colored dots in SDSS images. In this Preflight, you will learn how to identify asteroids in SDSS images and how the engineering goals of the telescope (i.e., targeting faint objects) result in clear images of stars and galaxies and streaked images of asteroids.  You may also use the information provided on this page as a starting place for thinking about how the SDSS telescope was designed by engineers to meet a particular goal: capturing the images and spectra of faint and distant objects, while also covering large portions of the sky.


This activity provides more examples of objects captured by the SDSS telescope and camera that were not the intended targets of the survey.


The nature and behavior of light is fascinating and complex. In this Preflight we offer you the SDSS twist on some key topics related to the electromagnetic spectrum.


This Preflight takes a detailed look at plots of SDSS spectra — the type of observational data that is required to understand the three-dimensional locations and detailed physical characteristics of stars, galaxies, and quasars.  Start here to learn about the types of data recorded on the spectrum graphs, the units used, and how to interpret what you see.

The information in this section is very dense, covering a large number of topics related to spectra. If you would like to discover more about the spectral properties of specific types of objects, we recommend Launch – Stellar Spectra for exploring the nature of the continuum curve, Launch – Stars as Blackbodies for interpreting temperature, and Launch – Redshift for a closer look at absorption and emission lines.


This Preflight provides an introduction to the concept of redshift and a generalized description of how it is measured in an SDSS spectrum. For more about redshift, Launch – Redshift provides a detailed investigation of how spectral lines are identified and used to calculate redshift.


This Preflight describes the function of a filter and how it blocks certain wavelengths of light. As with all Preflights, the information is presented in the context of the SDSS; no other filters or systems are discussed. The wavelength nature of light is introduced as it is essential to understanding the “colors” that we do not see and how filters function.


This Preflight provides a basic overview of apparent magnitudes in astronomy. This training provides the historical background for the development of the scale and numerous examples to ground this unit-less measurement to familiar objects like the moon.

Magnitude Calculation

This Preflight offers a short demonstration about how apparent magnitude (a unit-less measurement of an object’s apparent brightness) is determined by comparing the flux we receive from an object to that of the star Vega.

Capturing and Recording Light

Designing and building the SDSS required extensive engineering and technological innovations. In this section we offer some of the highlights of this work. Understanding how data were captured and made available via SkyServer lays the foundation for every other activity in Voyages.


The SDSS Telescope

The Sloan Foundation 2.5m Telescope, which was built and operated exclusively by the SDSS collaboration, has many unique design features. This Preflight provides information about the location, design, and dimensions of the telescope, which were chosen specifically to meet the science goals of the survey.

SDSS Instruments

This Preflight reviews the function of a telescope and introduces the idea of how light from objects in the sky is collected and analyzed. The CCD camera and spectrograph — the primary instruments that work with the SDSS telescope to do those jobs — are described in this section.

Related video resources:
Plugging the Plates
SDSS at Night

Types of Data

This Preflight emphasizes the two primary data types recorded by the SDSS: photometric (i.e., imaging) and spectroscopic. The reading shows how each type of data can be accessed using the Navigate tool in SkyServer and provides an overview of how to locate more detailed measurements through the QuickLook tool.

If want to know more, we highly recommend these resources for further information about basic concepts in astronomy: