photometry

Now that you have the basics of photometry down you are ready to try several projects:

Observing Open Clusters and Making H-R Diagrams
How to Make a Light Curve for an Exoplanet
Observing Supernovae
Observing Variable Stars

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How to Use SalsaJ for Photometry

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SalsaJ (Until further notice, please download version 1.4, not version 2.0, which does not yet have full photometry features.) and APT (Aperture Photometry Tool) are both free java based photometry software packages you can install on your computer to use for this project and any project that uses photometry. SalsaJ is a bit simpler and does more

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radius

Introduction to Photometry

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Photometry and CCDs

Photometry is a technique that measures the brightness of a star in an image. Each pixel on a CCD will have had a certain number of photons fall on it during an exposure. This number of photons translates to a number of electrons that are stored in the CCD until it is read out. The more photons hit a certain pixel, the more electrons will be stored there.

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brightness

Introduction to Photometry

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This guide will take you through the steps you need to do basic photometry. Photometry is useful for projects where you need to measure the amount of light coming from a star or other celestial object. These projects include open clusters, supernovae, planet transits and many others. You can do this with sample data available from the public archive, or with data from your own observations if you have an account. After doing this activity you should be able to:

* Use SalsaJ to measure the brightness of stars in an image

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sky subtraction

Photometry of an Exoplanet Transit with SalsaJ

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Download SalsaJ from the European Hands On Universe Website. (Until further notice, please download version 1.4, not version 2.0, which does not yet have full photometry features.)

Launch SalsaJ and the Light Curve Plotter , or a spreadsheet such as Excel, OpenOffice Spreadsheet or Numbers.

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How to Make a Light Curve for an Exoplanet Transit

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This guide describes how to create a light curve for an exoplanet transit by measuring the brightness of the target star and a comparison star in several frames. You can do this with sample data available from the Faulkes Telescopes, or with data from your own observation if you have an account. After doing this activity you should be able to:

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exoplanets

The TAOS Project: High-Speed Crowded Field Aperture Photometry

We have devised an aperture photometry pipeline for data reduction of image data from the Taiwanese-American Occultation Survey (TAOS). The photometry pipeline has high computational performance, and is capable of real-time photometric reduction of images containing up to 1000 stars, within the sampling rate of 5 Hz. The pipeline is optimized for both speed and signal-to-noise performance, and in the latter category it performs nearly as well as DAOPHOT. This paper provides a detailed description of the TAOS aperture photometry pipeline.

Publications of the Astronomical Society of the Pacific, 121:1429–1439, 2009 December

Photometry of Star Clusters with SalsaJ

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Download SalsaJ from the Hands On Universe Website.

Launch SalsaJ.

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open clusters

Photometry to Find the Color of a Star

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Photometry is the measurement of the intensity or brightness of an astronomical object, such as a star or galaxy by adding up all of the light from the object. For example, a star looks like a point of light when you look at it just with your eyes but the Earth’s atmosphere smears it out into something that looks like a round blob when you use a telescope to look at it. In order to measure the total light coming from the star, we must add up all of the light from the smeared out star. Photometry is generally used to generate light curves of objects such as variable stars and

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Open Clusters Background Information

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An open cluster, sometimes called a Galactic Cluster, is a group of 10s or 100s of stars that were born from the same initial cloud of gas (mainly Hydrogen) and dust. When they are young - a few million or tens of millions of years old - these clusters contain some very large, bright stars (called O or B-type stars). The very youngest clusters (usually less than 10 million years old) often still contain the remains of the gas cloud from which the stars were born – this is seen as nebulosity.

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open clusters