[APML] New Planetary Nebula Film Images

["John Boudreau" <jeboud@attbi.com>]

Finally, I have some recent images!

I shot M57 for 90 minutes back in June, and recently attempted to get some
additional frames to combine with the June shot. But operator error has kept
me from getting any more M57 shots--- I've fallen asleep only to wake up to
sunrise with the shutter still open <G>, and recently an exposure that was
timed
as 90 minutes under a very good sky inexplicably looks like a 30 minute
exposure. Maybe the cable release lock failed, but I don't recall that
happening
in the 10 years or so I've had this cable. First time for everything , I
guess.  ;o(

However my single June M57 exposure processed out very well. It beats my old
Provia 100F shot of it taken last year. The new M57 image is at:
http://home.attbi.com/~jeboud/m57.htm

On the same night I experienced what may have been the cable failure on M57,
I
shot a 20 and then a 30 minute exposure of NGC6826, the "Blinking"
Planetary. The result of the 2 exposures is at:
http://home.attbi.com/~jeboud/ngc6826.htm
Keep in mind that this planetary is less than 30 arcsecs, or approximately
1/3 the size of M57.

On many of these planetaries their surface brightness is strong enough to
record well in such short exposures, but with this NGC6826 film result there
are large areas of the planetary that didn't record _at_ all_, but easily
are
recorded by CCD. Take a look at:
http://home.attbi.com/~jeboud/ccd_ngc6826.htm
This is a CCD image that Sean Walker and myself took last year. What may be
described as it's "pinched cheeks" are called "fliers" in planetary nebula
lingo. See: http://www.astro.washington.edu/balick/W_F_P_C_2/

While the fliers easily show up in both the film and CCD images, the regions
outboard of them are easily recorded by the CCD. The film image doesn't show
a trace of these regions. I hope to get a long film exposure to see if I
can record them, but these regions may be essentially all OIII. As good as
100F is, it certainly doesn't come close to the recording power of CCD at
the OIII lines.

Many of you are probably familiar with the greens and blues hues of OIII in
CCD images of these and other planetaries, especially since it was discussed
a few days ago here on APML. While 100F records *some* of these colors in
the most heavily OIII laden planetaries, the dominate color in these film
shots is from their H-alpha and NII emissions.


Processing on both of these shots was done with Photoshop and MaxIm DL.
Since the film's R channel is so fine-grained, a copy of the R channel was
successfully deconvoluted and unsharp masked and then used as a luminescence
channel to make an LRGB of M57. The luminescence channel for the NGC6826
LRGB image was actually made from both the R and G channels. Don't ask me
why...  I'm just still experimenting. <g>

Actually this work is done on a close crop of the object, as doing all this
on the entire image whould be a nightmare with the large files. At least on
my computer. The cropped result is then cloned back onto the unsharp masked
and minimum-filtered starfield.

Kinda sounds like I'm cheating, doesn't it?
:) :) :)


John Boudreau
jeboud@attbi.com
http://home.attbi.com/~jeboud/astro.htm


--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>