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Draco Dwarf is a dwarf spheroidal galaxy in a distance of about 270000 light years. It is one of the small satellite galaxies of our Milky Way. 

Position of Draco Dwarf on the sky:    RA: 17h 20m 12.4s Dec: +57°54'55" (Epoch 2000)

Grafic from "An Atlas of the Universe"

  image size 35' x 51'

Draco Dwarf (DDO208, UGC 10822, A1719), 130mm APQ f7.7, 30 5 min. exp., CCD ST-10XME hires, 33% image size

© Copyright by Bernhard Häusler + Ralf Mündlein, Germany

image in original size containing many back ground galaxies - 1683 KB JPEG,   to see many details click this reverse image  - 1955 KB JPEG. 
70 marked background galaxies: small size, original size,
take a look at this image taken by professional observers: SDSS Sloan Digital Sky Survey 2,5 meter telescope  

On the image you can't see a bright surface of the galaxy but individual stars which are merging with foreground stars of our galaxy. Only the light of the brightest members of Draco Dwarf with magnitudes between 19 and 22 mag is visible on the image. The  galaxy was investigated by Walter Baade, Henrietta H. Swope (1961) and Paul W. Hodge (1964), based on images of the Oschin Schmidt Mirror of the Palomar Observatory. In two years they found over 260 variable stars in the galaxy and measured 138 of them in the center. Of these all but five proved to be RR Lyrae type.

The galaxy is located right from the center and is filling about a quarter of the image.

Observation of the variable star V37  RA: 17h 20m 08.3s Dec: +57°52'02" (Epoch 2000) in an special project of the German Fachgruppe Astrofotografie (VdS).

During a series of four images we could recognize the steep rising of the magnitude of the Draco variable star  V37.

date of the image: 09-13-2002  19:32h - 21:04h UT
telescope type: Ritchey-Chrétien 3655mm f-10.35, integration of four 15 minutes images with CCD camera ST-10XME, low resolution and clear filter, taken by Bernhard Häusler + Ralf Mündlein, Germany

  finding chart

Animation of the steep rising of V37, 4 15min images, 15 minutes in reality are 1 second in the animation:

   animation original size

   animation 4 x larger

Fotometry: V-mag

The comparative photometry was performed by MaxIm DL Version 3, which also contains a tool for the plotting of light curves.
For doing the photometry I choosed the V-mags of the two reference stars H and M (Source of the reference stars from The Draco System, a Dwarf Galaxy, Walter Baade und Henrietta H. Swope, 1961).

Draco Dwarf DDO208, RC 3655mm f10.35, 1 900 sec. exp., CCD ST-10XME hires, © by Bernhard Häusler + Ralf Mündlein, Germany

Original image with many details in the center of the galaxy - 227 KB JPEG    reverse image 259 KB JPEG

Light curve performed by MaxIm DL: The red circles are the measured magnitudes of the RR-Lyrae star V37.
You can see the increase of the magnitude of around 1.2 mag in 1.5 hours.

Left: light curve of RR-Lyrae star V37 generated by  our own images taken at 09-02-2002  20:22h - 21:55h UT and 09-13-2002  19:32h - 21:04h UT

Right: light curve gained of images of the 5 meter telescope on the Mount Palomar between 1953 and 1954

The period of the variable star is 0,554524 days = 13:18 hours, the magnitude lies between 19.51 and 20.93 mag.

We talked about our exploration of Draco Dwarf variables at our annual meeting of the German Deep Sky amateurs on the mountain Eisenberg in Germany at April 11-13 2003 (Deep-Sky Tagung DST 2003). The Draco explorers are Peter Riepe, Ralf Mündlein and Bernhard Häusler.

meeting link: http://www.naa.net/deepsky/dst.htm or http://www.naa.net/deepsky/dst-2003.htm
meeting program: http://www.naa.net/deepsky/download/dst2003-programm.pdf

Author of this websites: Bernhard Häusler, Maidbronn, Germany, all rights reserved.

German VdS group "Visual Deep Sky Observation"
German VdS group "Astro Photography"

all images:

[Draco Dwarf DDO208 APQ 130mm f7.7 and CCD ST10-XME]
[Draco Dwarf DDO208 APQ 130mm f7.7 and CCD ST10-XME revers]
[Draco Dwarf DDO208 RC 3655mm f10.35 and CCD ST10-XME]
[Draco Dwarf DDO208 RC 3655mm f10.35 and CCD ST10-XME reverse]
[Draco Dwarf DDO208 APQ 130mm f7.7 and CCD ST10-XME revers with marked background galaxies]
[Draco Dwarf DDO208 APQ 130mm f7.7 and CCD ST10-XME revers with marked background galaxies, original image size]