Before you start imaging and analyzing your own data, we suggest you use one of our tutorials and sample data sets to learn the steps for obtaining a raw instrument magnitude. We have created two sets of data that include a minimal number of images for this purpose. The Beginner data file was taken under ideal observing conditions and may be reduced by any Final Reduction Method. The Intermediate level data was taken at higher air mass and requires the Intermediate Level Final Reduction method to get good results. Both data sets may use either the AIP4WIN, IRIS, or MaximDL tutorial listed below to extract instrument magnitudes.
Digital images of a star field contain all the information needed to determine an accurate magnitude of the target star. Obtaining this magnitude is accomplished in a two-phase process. The tutorial refers to phase one as “Starting Analysis” and phase two as “Finishing Analysis”.
Starting Analysis: In this step of the tutorial we will use one of three software packages to obtain raw instrument magnitudes (a measure of the brightness of the stars that is camera-dependent) from our images.
The camera itself
While these tutorials focus on DSLR cameras, any digital camera will do as long as it meets the following criteria:
Produces images in a RAW data format.
Can manually select a shutter speed/exposure time of several seconds.
Has a wide enough field of view to get a variable star and comparison star in the image. A typical 50-90 mm lens will do just fine.Read more
Photometry by itself answers a single fundamental question: “How bright is it?” and if you do photometry over time you can answer another fundamental question: “How does brightness change with time?” These answers to these simple questions can be obtained from just visual inspection of a light curve, or through more advanced techniques, but the main reason why we do photometry is to gain additional insight to the behavior of various astronomical objects. In this tutorial we focus on stars, but the same approach we discuss here can be applied to planets, asteroids, comets, or even galaxies.
Measuring the Brightness of Stars
If you have observed the night sky, you have noticed that some stars are brighter than others. The brightest star in the northern hemisphere winter sky is Sirius, the "Dog Star" accompanying Orion on his nightly journey through the sky. In the constellation of Lyra the Harp, Vega shines the brightest in the summer sky. How bright is Sirius compared to its starry companions in the night sky? How does it compare to Vega, its counterpart in the summer sky? How bright are these stars compared to the light reflected from the surface of the Moon? From the surface of Venus?
While the goal of the AAVSO has been mainly concerned with magnitude determination of stars and star systems, spectroscopy is now on the threshold to add significant value to the AAVSO.
Photometry takes the pulse of a star or star system, where spectroscopy examines its soul.Read more
Photometry is a beautiful thing: equal parts science and art, equal parts frustration and reward. It is the core measurement technology of astronomy and provides much of the observational evidence behind the theories.
There are three main methods of doing photometry of a very bright star like epsilon Aurigae:Read more
- Single Channel Photoelectric Photometry (PEP): PEP was the first mainstream optical photometric technology and in widespread use in astronomy by the 1940's. It is not very sensitive, but it can work in very large fields of view. It is also very precise and simple to operate. Some modern PEP systems also have the unique capability of working in the near-infrared, a capability that may prove key to studies of epsilon Aurigae. Infrared measures dust (among other things) and epsilon Aurigae may be a dusty system. PEP was basically made for a project like this!
Data that covers multiple observations over a period of time is often referred to as time series data. Analysis of variable star data usually involves time series analysis because the observations are of a single star and spread out over a long time span.
One of the key goals of Citizen Sky is to teach participants how to analyse data - either your own or data contributed by other participants. We have three main projects underway to do this:Read more
Talks are a great way to spread the word about epsilon Aurigae and your participation in the project. Some good places to give talks are local amateur clubs, museums, observatories and schools (both K-12 and college). You may be surprised at how easy it is to simply call them up and offer to give a talk. Since astronomy is one of the most well attended topics, science outreach organizations are always on the lookout for interesting astronomy talks.Read more
This page will be populated with questions frequently asked of the project. Since the project just launched, we have few questions - whether frequently asked or not! Expect this page to expand over the coming weeks as we slowly populate the rest of the web site.
Until then, if you have a question feel free to contact us via this form.
Q: Do I need a telescope to participate?
A: No. This star is so bright that you don't even need binoculars to observe it.
Q: Do I need to be an expert?Read more