Tuesday, August 29, 2017

centred on NGC 7550 (Halifax)

We viewed a number of Arp objects last week. I thought I'd ask the BGO robot to centre on NGC 7550 or Arp 99 in Pegasus. This is a group of galaxies also known as Hickson 93.

galaxy group Hickson 93 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

Sadly two satellites went through the image. The middle one was a tumbler...

NGC 7550 aka MCG 3-59-15 and PGC 70830 is in the centre of the image. It appears to be a large elliptical galaxy. It is nearly round with a bright core.

Due north is the fantastic barred spiral with extended arms. This is NGC 7549 aka MCG 3-59-14 and PGC 70832. The north arm is very long arcing away from 7550. The southern arm seems diffuse and flattened.

NGC 7547 is west of 7550. It is a canted spiral galaxy. It does not appear uniform with an enlarged region to the east. It too has a bright central region. aka MCG 3-59-13 and PGC 70819.

Where SkyTools 3 Professional shows star J231442.7+184940, I see a faint oval fuzzy. This is south-west of 7550, near the bottom-right corner, near the pair of stars with TYC 01715-2104 1.

To the south-east of 7550, and more distant, is the small round elliptical galaxy of NGC 7558 aka MCG 3-59-16 and PGC 70844. It does not have the Arp 99 designation according to ST3P.

East of 7550 there is a pair of objects. SkyTools shows these as stars. At least one of them is a fuzzy galaxy.

To the north-east of 7550 and due east of 7549 there is another elliptical. NGC 7553 or PGC 70834. This has a slight oval shape. It is slightly brighter than 7558.

I suspect there are many more galaxies in this image.


Imaged again the following night. No satellites; but more noise.

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