M88 lies in the Virgo Cluster of galaxies at a distance of about 50-60 mly and it's found in the constellation Coma Berenices.  It has an apparent magnitude of 9.6 and a size of 6.9' x 3.7'.  It has a morphological classification of SBc, which puts it between a medium and a loosely wound spiral galaxy.  M88 is classified as a type 2 Seyfert galaxy because of it's strong narrowband emissions.  A super massive black hole with a mass of 80million solar masses lies at its core.  With that mass, the Schwartzchild radius is 146,843,891 miles, which is about 13 light minutes or 1.58 astronomical units.  Still, the black hole at the core of M88 is far from the largest.  Nearby M87 has a black hole that is nearly two orders of magnitude more massive with a mass of 7.22 billion[i] [/i]solar masses!  The physics of super massive black holes is absolutely fascinating and it is mind boggling to think of an object that massive.  

I started this imaging project late in May when M88 was already pretty high above the horizon at sunset.  I gathered 27.8 hours of LRGB data over a period of 9 days as the generally good Chilean Fall seeing conditions fell apart.  SubFrameSelector analysis showed that none of the data that I gathered had FWHM values better than 2.0".  That's right, NONE.  Whew...that's pretty bad even considering that M88 was mostly pretty low in the northern sky.  Undaunted, I set an acceptance threshold at 2.4" and managed to salvage just shy of 6.5 hours worth of data.  I can't even remember the last time I processed a galaxy image with this little data!

As @Adam Block pointed out in his M88 image, M88 can be a tricky galaxy to process and starting with so little data didn't make it any easier.  I started out by making a couple of false starts in an effort to get the colors properly calibrated.  One clue to a good SPCC color calibration run is that the White Balance chart should show a good linear fit with low scatter.  So it's important to be careful about picking the proper wavelet scale and magnitude limits so that the software can achieve a good fit to the satellite photometric database.  I was finally able to get 30 good star fits in this field for calibrating the color and the results pass the basic sanity check that the colors jive with what might be expected relative to stellar populations.  Looking through various M88 images here on AB, I found colors that were all over the place.  Adam used the same SPCC method that I used and our results mostly agree so I went with it.  I verified that this is one galaxy where using the whole galaxy as a SBc white balanced reference gives a radically different result--and you can quickly see why.  The younger, hot blue stars lie in the extreme outer regions so the bight yellow, large core will pull the color balance pretty far into the blue if you use this method.  So, M88 is a particularly good example of where SPCC does its job very nicely to produce a more accurate color rendition.  I think that this is an interesting result because it shows that most of the galaxy is composed of older, cooler yellow stars with the younger stars concentrated in the extreme outer regions of the structure.

I used BXT to pull out the details in the inner structure and it worked extremely well.  The nice thing about BXT is that it pulls out detail without adding any significant noise.   It's my nature to push pretty hard on the detail, which may disappoint anyone bent on extreme pixel peeping.  At normal display sizes, I think that the detail level is acceptable.  The hardest part of the processing came down to deciding on the saturation levels.  With so little data, it was easy to push the star colors over the edge to create odd posterization effects so I had to find a balance where the stars look natural without strange color shapes or other subtle halo effects.  I tend to like colorful images but I'm slowly coming around to the idea that for objects like M88, too much saturation might not be the best.   My original version is more colorful and my final version has the saturation dialed down a bit.   I'm still torn over which presents better so I'll be curious to hear opinions on which works better on various monitors.

I'll have to revisit M88 next year.  It is a really interesting galaxy and I'd like to see if I can gather more high-quality data to get a cleaner result.

As always, C&C is always welcome so let me know what you thiink.

John