Thursday, October 09, 2014

blue data

Shared some observation notes with Mr Crinklaw. That both Ian and I had not been able to see (or image) NGC 7325. Asked where he obtained his galaxy dimension data. Greg replied:
This galaxy is indeed small.  If you download a blue next generation DSS image you can see that it is tiny, although it does have a roundish halo around it.  The dimensions of the galaxy are for the halo.  This galaxy has a very bright core (it was even picked up as a GSC star).  The magnitude reflects this bright core, which is very small.
So, the dimensions come from a slice of the spectrum. Perhaps not representative of full spectrum visual observing. Or one-shot colour. Once again, it means, while viewing charts in SkyTools, one must take the display with a grain of salt.

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