M101 "Pinwheel galaxy". The 100 galaxies image. A 23h deep sky image

Object Information:

I called this image "The 100 galaxies image" because, although it's not obvious, more than 100 galaxies were caugh in this deep sky image. M101 is the most prominent, but... can you guess were the other 99 galaxies are hidden?

Annotated image with tens of galaxies all around the image:

This wide field image of the Ursa Majoris region shows more than one hundred galaxies. The most distant are 3500 million light years away and occupy only a few pixels. The most prominent, The Pinwheel Galaxy (M101), it's a Milky Way like galaxy "only" 21 million light years from us.

M101, is also known as the Pinwheel Galaxy. It's a face-on spiral galaxy located in the constellation Ursa Major, the Great Bear. The galaxy appears face-on and occupies an area of 28.8 by 26.9 arc minutes of apparent sky, which corresponds to a linear diameter of about 170,000 light years. The galaxy is quite large, but has a low surface brightness and requires exceptionally clear, moonless skies to be seen, even in medium-sized telescopes.

Another galaxy that becomes evident is the NGC 5474.

NGC 5474 is a peculiar dwarf galaxy in the constellation Ursa Major. It is one of several companion galaxies of the Pinwheel Galaxy (M101), a grand-design spiral galaxy. Among the Pinwheel Galaxy's companions, this galaxy is the closest to the Pinwheel Galaxy itself. The gravitational interaction between NGC 5474 and the Pinwheel Galaxy has strongly distorted the former. As a result, the disk is offset relative to the nucleus. The star formation in this galaxy (as traced by hydrogen spectral line emission) is also offset from the nucleus. NGC 5474 shows some signs of a spiral structure. As a result, this galaxy is often classified as a dwarf spiral galaxy, a relatively rare group of dwarf galaxies.

Here we can see a detail of NGC 5474:

Crop of the M101 grand design galaxy:

Detail of another highlight of the image,


Link to the high resolution image here.

Exposure Information:

23h05 minutes exposure

L: 300x180" bin1
RGB: 30x90" each bin2
Halpha: 35x600" bin1

23h total exposure for this wide field image

Darks: 30
Flats: 30 (in L and Ha)
Bias: 50

Sensor temperature -20ºC
Moon phase around 0%


M101, The Pinwheel Galaxy, imaged from PRADES during 7 nights from 22nd of May until 2nd of June.
Halpha has been used to enhance the HII regions.

Image taken with a 8,5cm aperture telescope from Prades, Spain.

All the images were taken with automated sessions using SGP software.

Imaged at: Prades, Tarragona, CATALUNYA - SPAIN

Optics - Takahashi FSQ 85 - Focal lenght: 450mm - Diameter: 85mm
Camera - ASI 1600 MM-Cooled + ZWO 8pos 31mm Filter Wheel + ZWO OAG

Mount - Mesu 200
Guiding and planetary camera – ASI 174MC

Software: Sequence Generator Pro (SGP), PHD2, DSS, PIX

Image date: May 22th to June 2nd, 2017