Re: [APML] M31 Mosaic project

[Chris1011@aol.com]

In a message dated 9/16/2002 5:11:39 PM Central Daylight Time, jeffball@zoominternet.net writes:


> The Provia 400F at 2 hours is impressive.  The slide just has tons of
> info.  The Provia seems to keep recording well as my slightly shorter
> exposures of 90 minutes show less than the 105 minutes.  The E200 at 2
> hours did exactly what it was supposed to do-capture the H2 regions.
> They stand out like red islands in the sky.  Much more prominent than
> what the Provia shows.  I think a multiple stack of Provia and E200 for
> a luminance and then assigning the appropriate color channels from each
> film will make for a very smooth and moderate resolution image.  Keep us
> posted on the M31 mosaic.
> Jeff Ball


Thanks. We are learning as we go along. Film is infinitely easier to work with. The CCD camera is great for resolution, but requires lots of stacking to get a smooth result. If there is even one bright star in the field, it severely limits the maximum exposure because of blooming. Anti-blooming chips might sound like the way to go, but then you lose sensitivity big time. Besides, there is none available in the ST10 size. This image consists of several 5 minute exposures stacked and combined into a color image. Mark is re-shooting this pane with longer 30 minute exposures (blooms be damned) and hoping to get smoother detail in the fainter regions. The core will be burned to a crisp but we already have pretty good core data. 

We have about 5 panes now, and the memory requirements are running out of sight. Each pane is about 30 meg when all three scopes' data is combined, and I can just imagine what 20 panes will cost at full resolution. I have no idea how to present this on a monitor, but it will be great for printing. I have a full resolution 3 pane image on my monitor and scrolling from one side to the other is unreal - almost like flying through space on the Enterprise. The outer spiral arms with the blue supergiant stars are fully resolved with black sky between the stars. In fact, there are blue supergiant star clusters all over the middle of the galaxy as well. We've come a long way since it took the 100 inch reflector at Mount Wilson to resolve these spiral arms into individual stars.

Roland Christen