SlideShare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy.
SlideShare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our Privacy Policy and User Agreement for details.
Successfully reported this slideshow.
Activate your 14 day free trial to unlock unlimited reading.
ASSA imaging group DSLR Photometry Talk 27 Nov 2015
These are the slides for a talk I gave to the imaging group of the Astronomical Society of South Australia about DSLR photometry of variable stars on November 27 2015.
These are the slides for a talk I gave to the imaging group of the Astronomical Society of South Australia about DSLR photometry of variable stars on November 27 2015.
ASSA imaging group DSLR Photometry Talk 27 Nov 2015
1.
DSLR
Photometry
of Variable Stars
David Benn, Nov 2015
2.
Outline
Brief overview of variable stars
The varieties of variable star observing
What’s the goal?
Getting started with DSLR photometry
My setup
Procedure
3.
Introduction to Variables
Source: Society for popular astronomy
5.
Introduction to Variables
https://en.wikipedia.org/wiki/File:Eclipsing_binary_star_animation_2.gif
6.
Introduction to Variables
http://www.citizensky.org
7.
Introduction to Variables
http://www.astrosurf.com/aras/novae/Nova2013Del.html
8.
Variable Star Observing Varieties
Visual variable star estimation since 2009
Mostly binocular
Simple (technique, equipment) & quick
Great for long period variables, novae
~0.1 magnitude precision
Wide-field DSLR photometry since late 2014
~0.01 magnitude precision
Can quantify error
Not as precise as CCD or PEP but 10x lower cost
Repeatability; data re-use in future, e.g. for B, R
20.
Some Considerations
B, V, R possible from a single image
May be more than one variable per image
ISO 100 or 200 or 400 for high dynamic range
Exposure: depends upon tripod vs tracked
Turn off auto features
noise reduction
lens cleaning
21.
Procedure
Finder chart & photometry table
Locate field, take test frame to verify
Make notes, e.g. of conditions!
Deliberately under-focus for photometry
Convert RAW to software’s format, e.g. FITS
Calibration: lights, biases, flats, darks (maybe)
Stellar registration, for automatic photometry
22.
Procedure
Extract green (or blue or red) channels
Determine photometry radii
Local coordinates of target, reference stars
Some software may automate via plate solve
Photometry on individual or stacked images
Look at error, residuals; change one or more reference
(comparison, check) stars if too high
Ensemble-based transformation to V (or B or R)
23.
Photometry Table from Finder
Have to consider:
• Magnitude
• B-V
when choosing reference stars.