ASTRO: M51

Don't know if M51 is in Arp's catalogue, if it is I should have mentioned
that name to hide that I have been imaging what everybody does :-)

I spent some days under OK skies in the north of Germany last week. Two
streetlights about 50m away each were shining on my scope, otherwise there
was little light pollution.
Conditions weren't too good with sometimes gusty winds and sometimes thin
clouds and also northern lights brightening the sky considerably on March
17. I didn't mind the northern lights though, it was the first time I have
seen them.
On the last of three semi-clear nights I had a bit more than an hour left
till astronomical dawn, which I filled with some luminance frames of M51.
Got the colour data one night later in Berlin. The colour data was sharper
than luminance, so I mixed the city colour into the country luminance.

Image scale is 0,46 arcseconds/pixel.

Taken from Neu Göhren (Lum) and Berlin (colour) with a 10" Meade ACF at f/8
on a G11 mount, Trius SX694 camera, 11x10 minutes each for LRGB.

Stefan

Very nice. I've never had the seeing needed to do it at that image scale. Even at 1" it has always been rather iffy for me.

And yes, it is Arp 85 in his "LARGE, HIGH SURFACE BRIGHTNESS COMPANIONS" category.
Links you might find useful
By category
http://arpgalaxy.com/arpord.html
By RA
http://arpgalaxy.com/arplist.html
Arp's images
http://ned.ipac.caltech.edu/level5/A..._contents.html
PDF of Arp's paper with his comments (he had none for some objects) Includes his film data and seeing estimates.
http://www.astrosurf.com/luxorion/Do...laxies-ned.pdf

Rick

Originally Posted by Stefan Lilge

Don't know if M51 is in Arp's catalogue, if it is I should have mentioned
that name to hide that I have been imaging what everybody does :-)

I spent some days under OK skies in the north of Germany last week. Two
streetlights about 50m away each were shining on my scope, otherwise there
was little light pollution.
Conditions weren't too good with sometimes gusty winds and sometimes thin
clouds and also northern lights brightening the sky considerably on March
17. I didn't mind the northern lights though, it was the first time I have
seen them.
On the last of three semi-clear nights I had a bit more than an hour left
till astronomical dawn, which I filled with some luminance frames of M51.
Got the colour data one night later in Berlin. The colour data was sharper
than luminance, so I mixed the city colour into the country luminance.

Image scale is 0,46 arcseconds/pixel.

Taken from Neu Göhren (Lum) and Berlin (colour) with a 10" Meade ACF at f/8
on a G11 mount, Trius SX694 camera, 11x10 minutes each for LRGB.

Stefan