Re: The youngest known galactic supernova remnant - Oct Astronomy

By the way, my subject "the youngest known galactic supernova remnant" is misleading -- in 2008, it was discovered that the expansion rate of a small, radio supernova remnant (G1.9+0.3) implied an age of only 100 years or so. This easily makes G1.9+0.3 the youngest SNR in the Galaxy, though I'm certain it's not a visual object as it is highly obscured by dust. The discovery preprint is at http://arxiv.org/PS_cache/arxiv/pdf/0803/0803.1487v2.pdf

--Steve

On Aug 29, 2010, at 1:59 PM, Mark Johnston wrote:

> 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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