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View Full Version : Object of the Week August 4, 2013 - NGC 7252 and the littlest Voorwerpje



Jimi Lowrey
August 4th, 2013, 07:46 PM
NGC 7252 AKA Arp 226

Aquarius

RA
22 20 44

Dec
-24 40 42

Mag 12.1 V

Type (R)SA(r)

This is a famous galaxy in the late stages of recovery from a merger - NGC 7252, also known as the "Atoms for Peace" galaxy after a resemblance to a 1960s-era logo. It is also in the Arps catalog of peculiar galaxies as #226 "Amorphous spiral arms". It has listed in NED 247 references so this is one well studied galaxy. I have viewed this galaxy many times over the years and must say that the long tidal tails that show up well in images are hard to see visually.

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Francois Schweizer of the Carnegie Observatories and Pat Seitzer of the University of Michigan have studied NGC 7252 off and on for 20 years. In a new paper, they and additional colleagues Danial Kelson, Edward Villanueva, and Gregory Walth report a new facet of this system - it hosts the Littlest Voorwerpje (so far). Link to paper http://arxiv.org/abs/1307.2233

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This new O III object looked fairly bright on the DSS so I thought I would give it a go this week. I viewed it twice this week @ 697 X the O III cloud was easy to see at this power but the knot near the end (little Hanny) was tough to see. I tried a O III but it darked the field to much. I then tried a Sloan G filter which works well on "Hanny's Voowearp"and had no response to this filter. Not deterred I then tried a DGM galaxy contrast filter which works well on some H II knots in other galaxies. This filter worked great on"little Hanny's" it really lit it up! It looked like a dim star blinking in and out with the seeing. As with other objects once I saw "little Hanny" I could see its faint glow unfiltered in moments of steady seeing. This is a object that has just been released so if you want to be one of the first to see it visually" Give it a Go"

There is another object that is a real challenge associated with NGC 7252 that is the star clusters W-3 it is a cluster that I have read is 100 times larger than our globular clusters which some think it is a UCD or the striped out core of a dwarf galaxy that has merged with NGC 7252. I know of no visual observations of this object so you could be the first if you can catch it!

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So here are some real challenging object for you deep sky hounds so as always,

“Give it a go and let us know!”

Good luck and great viewing!

hajuem
August 7th, 2013, 07:48 AM
Hi Jim

Thank you for the interesting presentation of this object!!
IT`s a new object for me and i hope for a good observation next weekend.
The HII region "Little Hanny" is really a big challenge!!
I try the galaxy with my 16" telescope and look what goes.
Your observation with the Sloane G Filter is very interesting!!
I did not know this filter!!

Regards from germany
Hajü
www.astromerk.de

Jimi Lowrey
August 7th, 2013, 05:50 PM
Hi Haju,

The Sloan filters are photometric filters that were used on the Sloan telescope for the Sloan survey. This is a link that shows the band pass of the filter http://www.astrodon.com/products/filters/astrodon_photometrics_-_sloan/

Dr William Keel who is the lead astronomer on Hanny's Voorwerp suggested to me to try the Sloan G on Hanny's, he thought from the spectrometry on the object that the slow G would enhance the visual view of this unusual object. He was right this filter lights up this small and unusual object. Like I posted above the Sloan G filter had little to no response on the Little Hanny's object in NGC 7252.

Ivan Maly
August 7th, 2013, 07:29 PM
Interesting object. Funny name... I see the use of Dutch in astronomy is expanding; it's becoming advanced ;)