Northern Prairie Star PartyBlack Nugget LakeSeptember 15, 2012

Brian MartinThe King’s University College

Three Fundamental “Sciences”

• Measuring “Distance”, Position & “Scale” Astrometry

• Measuring Brightness and Intensity Photometry

• Measuring “Colour” Spectroscopy

Exciting science that you can do from the back yard!

Astrometry

How big are the lunar features in this image?

August 29, 2012H-alpha filter0.001 s exposureED80Atik 314L+ cameraTKUCO

Some Math …

q

R S

The Small Angle Formula Rq* = S where:• R = distance from object• q = angle that the object subtends in the sky• S = distance across the object

* Angle in radians

The Scale of Your Telescope• Scale in (seconds of arc)/mm found by:

• In the previous image a ED80 telescope was used so the scale is (206265)/(600 mm) = 343.8 “/mm

• The Atik 314L+ has 6.45 mm pixels, so each pixel has a scale of 342.8”/mm × 0.00645mm/px = 2.22 “/px when used with the ED80

• By measuring the number of pixels you can measure the angle that an object or feature subtends

scalefocal length206,265

850 px = 3457 km(0.5% error)

304 px = 1236 km

Some other images…

• Capuanus Crater:– December 26,2009– C14, f/11 – Imaging source DMK2104 – 2000 frames– Scale = 0.20”/px – Distance = 0.002523 AU

• Apennines (Eratsothenes, Archimedes)– March 1, 2012– C14, f/7– Atik 314L+– 20 frames (0.005 s)– Scale = 0.52”/px– Distance = 0.00262 AU

• Jupiter– November 5, 2011– C14, f/11– Imaging Source DMK2104– LRGB (~2000 frames each)– Scale = 0.26”/px

• M57– August 26, 2011– C14 f/7– ST7E– LRGB– Scale 1.49”/px– Distance = 2300 ly

• M15– August 21, 2011– C14 f/7– ST7E– LRGB– Scale 1.49”/px– Distance = 33 Kly

Photometry – Measuring Changes in Brightness

• Intrinsic Variables– d Scuti– SX Phe

• Novae and Supernovae• Cataclysmic Variables

Consumer grade CCD cameras…• Capable of doing excellent science!• Modest cost (< $2000)• Excellent software support• Monochrome with no anti-blooming is

preferred• Pixel size should be carefully matched

to image scale – need to oversample• Capable of milli-magnitude precision

photometry

Atik 314L+

SBIG ST7E

SX Phoenicis Variables

• BL Camelopardalis– Average mag 13.1 – Period

• 0.0389d• 56 minutes – this is

an exciting system to watch!!

40 s integration, C14 f/7ST7E camera – KAF400 detector

November 9, 2009

The Light-Curve…

November 9, 2009, s (C2-C1) = 0.007 mag

BL CamTeff 7730 KAge ~4GaMetal poorPeriod shows a Small change over time!