Re: The youngest known galactic supernova remnant - Oct Astronomy

Correction: October version of Astronomy that came in mail just now, NOT
Sept version.
(These guys are so far ahead of the calendar)

Mark Johnston wrote:
> The Sept 2010 Astronomy mag has Cassiopeia A being discussed with an
> extremely enhanced picture on page 49 in the context of the compact
> central neutron star it holds at it's center.
> Marko
>
> Steve Gottlieb wrote:
>> If you're going to take a look, Marko, I realized I left off the
>> position! Cas A is plotted on the U2000 atlas as a radio/x-ray
>> source but there is no catalogue listing in the companion Deep Sky
>> Field Guide and I couldn't find a listing within Megastar or SkyTools
>> 3. The center of the shell is at 23 23 24 +58 48.9 (2000) and the
>> filament I described about 1.5' north of this position.
>>
>> --Steve
>>
>> On Aug 25, 2010, at 12:59 AM, Mark Johnston wrote:
>>
>>
>>> Steve throws another kool object out for a challange. Thanks, I
>>> have been building a list for next month mostly in Pegasus.
>>>
>>> Steve Gottlieb wrote:
>>>
>>>> That would be Cas A, the strongest radio source in the sky (besides
>>>> the sun). Based on the expansion rate of the filaments light from
>>>> this supernova must have reached earth ~340 years ago ( roughly
>>>> 1667). Although it was not recognized as a nova at the time, it
>>>> may have been catalogued as a 6th magnitude "star" by Astronomer
>>>> Royal John Flamsteed in 1680, as there is no known counterpart
>>>> today for his "star" Cassiopeia 3.
>>>>
>>>> Available images have traditionally been at radio wavelengths
>>>> (http://images.nrao.edu/395) or x-ray
>>>> (http://chandra.harvard.edu/photo/1999/0237/), though HST captured
>>>> it in 2006 (http://spacetelescope.org/news/heic0609/). So, it was
>>>> never known as a visual target and the first observation was
>>>> probably made in the last couple of years. So, this object was
>>>> high on my observing list earlier this month when I observed with
>>>> Ray Cash, Mark Wagner, Richard Navarette, Ken Archuleta and Mina
>>>> Reyes at Lassen on the peak of the Perseids. But I really didn't
>>>> know what to expect.
>>>>
>>>> Here's the good news -- using a 21mm Ethos (108x) and an OIII
>>>> filter, I was surprised to easily pick up the brightest filament in
>>>> my 18-inch Starmaster. With this combination a small, elongated,
>>>> fairly low surface brightness glow was immediately noticed,
>>>> ~1.2'x0.4', extended ~E-W. The SNR was not seen unfiltered at 108x
>>>> or at 175x, so it responded strongly to the OIII filter. The visual
>>>> filament I picked up forms the northern edge of the 4' diameter
>>>> supernova remnant. The glow is situated at the vertex of an
>>>> isosceles triangle with a mag 11.4 star 2.5' SW and a mag 11.7 star
>>>> 2.5' NNW. The 56' field includes a number of mag 10 stars and is
>>>> fairly rich, but there are no brighter stars. Give it a try!
>>>>
>>>> --Steve
>>>>
>>>>
>>> --
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>>>
>>
>>
>>
>
>

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