Whirlpool Galaxy (M51)

This photo comprises images taken on April 15th (previous post) and April 22nd, a total exposure time of 153 minutes.  The set up on the 22nd was the same as that on the 15th.  The increased exposure time yields improved detail.

Whirlpool Galaxy (M51)

This photo was taken on April 15th, the first clear night since returning from Arizona.  It is the first photo from the Plateau Observatory.  The photo consists of 30 3-minute exposures with the UHC-S filter and is somewhat grainy. More exposure time is needed.


The photo shows two interacting galaxies NGC 5194 (the Whirlpool) and NGC 5195 (the smaller eliptical) located in Canes Venatici just to the west of Alkaid (the final star in the handle of the Big Dipper).  The spiral structure of the Whirlpool is thought to be due to the interaction with 5195.  The galaxies may be in the process of merging - perhaps over the next billion years.  They are about 23 million light-years away from Earth.  The angular diameter is is about 11 arc-minutes.  The bright circular disc at the center of 5194 has a radius of about 38,000 light-years.


The Whirlpool was discovered by Charles Messier in 1774 (using a 3 inch diameter refractor telescope), but it was not until 1845 that it was recognized as a spiral (by Lord Rosse using a 72 inch Newtonian telescope). 


No change in equipment from the previous images.