NGC4473 as before, but with a larger image this time

Now our starting image looks like this:
[V2.fits]

(NGC4473 is the elliptical in the center, the Green Bar on it is 1 arcmin long)

To begin, we make a hand mask just like before. Here are the regions selected for hand-masking:


And the actual mask:
V2hand.pl on V2.fits

(I obliterated the left side  because it got really noisy, but it probably won't matter much anyway)

Let's be silly and run ellipse on this!

(it totally bombs out after ~200")


As before, we kick off our grand analysis with some smoothing. Since inner=3, outer=8 worked best last time, we use those parameters for the ring-median smoothing, and get this smoothed image:
[V2r38.fits]


While we have this smoothed image handy, we kill (send to 0) all the pixels included in our hand mask, and draw a contour around intensities of 200:
[V2r38k200.fits]


This central region of NGC4473 is now (using imexpr) made into a mask file, called V2cent1.pl that has values of 0 for the central region and 1 elsewhere (this will be multiplied by later on)
The UNmask has been created!


Back to the smoothed image...


The smoothed image is subtracted (with imarith) from the original V2.fits and we get:
[V2r38s.fits]


OBJmask this with hsigma of 2:
[V2r38sP1.pl overlaid on V2r38s.fits]



Now we multiple this by the UNmask and we get this:
[V2r38sP1un.pl overlaid on V2.fits]


We imcopy V2r38sP1un.pl to V2.pl, and run ellipse on this, making this fit:


The model of the fit looks like this:
[V2r38sP1unM.fits]


and subtracting that from V2.fits (with imarith), we get:
[V2r38sP1unMs.fits]



Well, so, now we run OBJmask on this, with the same V2hand.pl mask on it blocking bright stars and bright nearby galaxies:
[V2r38sP1unMsP1.pl on V2r38sP1unMs.fits]


And this same overlay on the original V.fits, to show what ellipse will see, Including the UNmask.
[V2r38sP1unMsP1un.pl on V2.fits]



ellipse has its way with it, and spits out:


the model looks like this:
[V2r38sP1unMsP1unM.fits]


And subtracting this from the original image, we get:
[V2r38sP1unMsP1unMs.fits]



running OBJmask on this (with V2hand.pl masking bright stars and galaxies), we get:
[V2r38sP1unMsP1unMsP1.pl on V2r38sP1unMsP1unMs.fits]


UNmasking and overlaying on the original image, we get:
[V2r38sP1unMsP1unMsP1un.pl on V2.fits]



Running ellipse on this, we get this fit:


Here's where we stop and collect all of these back together and make a big composite image of each iteration:


see the 1sigma and 2sigma versions on the smaller image compared with this one, too


back to Virgo main page