NGC5746 - B&W

[rfdesigner]

NGC5746 is a large edge on spiral in virgo, about 95 million miles away and around 150,000 light years in diameter, physically larger than M31. It is unsual in having a central bulge that appears closer to square rather than the normal hump shape, a possible indication that the galaxy is in fact a barred spiral. The star on the left of the image is 19VIR a 3.7 magnitude brute. The galaxy in the bottom right is NGC5740, 12th magnitude and only a little further from us that NGC5746.

This image took too long to set up so I only got a fraction of the data I wanted. 14 x 3 minutes. All processed in IRIS, just found the selective wavelet noise suppression routine.. which I've used here to keep what was a badly noisy image respectable.

North is up

thanks for looking

Derek

[rfdesigner]

NGC5746 is a large edge on spiral in virgo, about 95 million miles away and around 150,000 light years in diameter, physically larger than M31. It is unsual in having a central bulge that appears closer to square rather than the normal hump shape, a possible indication that the galaxy is in fact a barred spiral. The star on the left of the image is 19VIR a 3.7 magnitude brute. The galaxy in the bottom right is NGC5740, 12th magnitude and only a little further from us that NGC5746.

This image took too long to set up so I only got a fraction of the data I wanted. 14 x 3 minutes. All processed in IRIS, just found the selective wavelet noise suppression routine.. which I've used here to keep what was a badly noisy image respectable.

North is up

thanks for looking

Derek

[acey]

I checked to see if I had observed these two objects (NGC 5746, 5740) - I did, earlier this year with my 12” f4.9 flextube. Here are my notes from then:

19th February 2012. SQ 21.3, temperature 0.7C. Clear, very blustery.

3.00am NGC 5746 Very easy (sweepable at low/medium power). Pretty bright, considerably large, much extended, gradually brighter towards the middle. Very thin ray, aligned approximately North-South. North end markedly brighter than South.

3.30am NGC 5740 Moderate difficulty (sweepable at medium/high power). Faint, extended, brighter in the middle. Low surface brightness, best seen at medium power.

Between viewing those two I was distracted by a bright auroral display on the northern horizon.

NGC 5746 is a Herschel Class I (“Bright”) object and is in the “Herschel 400” selection, as well as O’Meara’s “Hidden Treasures”. NGC 5740 is Herschel Class II (“Faint”). Both galaxies were observed by the astronomer Holetschek in 1897 using a 6” refractor. By comparison with out-of-focus stars he estimated their visual magnitudes as 11.0 for 5740 and 9.5 for 5746.

Here's the link to the image, for any observers who fancy going for it:

http://stargazerslounge.com/showthread.php?t=189486

After those two, the next that I viewed was NGC 5738, which Herschel missed completely. I rated it "Extremely difficult - glimpsed as an extremely faint spot among many faint field stars." In all I viewed 27 new galaxies that night, plus some others I'd viewed previously. Can't wait for the long nights to return!

[Gina]

Great!

[acey]

Lovely image. I've observed both these galaxies visually with a 12" scope.

http://stargazerslounge.com/showpost.php?p=2303722&postcount=2

[rfdesigner]

thanks acey

Fantastic write up, and amazingly accurate estimates of the brightness all done by eye. (amazing to my uneducated eye)

I never actually saw them, my scope is now really an astrograph although I'm still using the finder scope to align it the 60mm refractor isn't really enough to pick these up.

Derek

[acey]

Holetschek's magnitude estimates amaze me too: he was a professional astronomer and his figures remained standard until about the 1930s when photographic data took over.

I had a look at O'Meara's entry for 5746 in "Hidden Treasures". He says he was able to see all three galaxies - 5746, 5740 and 5738 - with his 4" scope! Testimony to his incredible skies and extraordinary visual ability. 5738 (which O'Meara says is listed as magnitude 14) was at the very limit of what I can manage with the 12" at my dark site - though I have in the past seen galaxies listed as 15th magnitude. A reminder that these figures can never be taken as absolute.

[Quatermass]

Really like this one looks like the needle galaxy I think.