Re: [APML] OT: M17 in near-IR

["joe" <jmize@svic.net>]

Wei-Hao;

     Thkx for posting this interesting image.  Waaay back in 1994 the old
defunct magazine "CCD Astronomy" got me interested in NIR CCD's with their
article in their Summer issue, 'The Many Hues of Astronomical Color
Imaging'.  They compared Hubble filters to amateur color RGB filters.  I
noticed how much more detail and stars, although highly shifted into the
green, were captured with the Hubble filters than common amateur RGB
filters.

     Recently either "S&T" or "Astronomy" published in their 'New Notes' a
much better balanced NIR image of the Flame nebula taken by the Hale
telescope.  The article states;  "The infrared colors, Ks, H and J are shown
here as red, green and blue."

     Using the Flame article's statement I went searching for information
and found the Ks filter at BARR Associates and the H and J filters at OCLI.
Although I did find the filters I haven't found much more information on
them.

Ks (red)  = 2.150um, (1900-2400nm, Band Pass)
H (green) =  1.635um, (1400-1800nm, Iron)
J (blue) =  1.250um, (1100-1400)

     Your M17 is almost unrecognizable, that's what I like about NIR.  The
information you provide about the 1.8um range picking up telescope thermal
emission is interesting.  Palomar was able to image with their WF IR camera,
(red = 2.12um, green = 2.270nm, blue = 2.166um), probably because they chill
their camera.

     Although I still haven't transitioned across to CCD from film I'm still
interested in NIR CCD.  One day soon, hopefully, I intend to take the
plunge.  Meanwhile I collect images and information about NIR CCD imagery.
I may, probably am, off base with my scraps and pieces of information I've
collected but one day I hope to experiment in NIR CCD imagery here on Earth
with my modest equipment.

     Thank you for your informative posts, keep them coming.  Thkx...joe  :)



"May You Go Among The Imperishable Stars"

Joe Mize:     jmize@svic.net
StarFields Observatory   http://www.cav-sfo.com
Chiefland, FL    29:24'33.4"N    82:51'37.7"W
Moon Phase:     http://tycho.usno.navy.mil/cgi-bin/phase.gif

> ----- Original Message ----- 
> From: "Wei-Hao Wang" <whwang@gmail.com>
> To: "APML" <astro-photo@seds.org>
> Sent: Saturday, September 04, 2004 7:45 PM
> Subject: [APML] OT: M17 in near-IR
>
>
> > Hi list,
> >
> > Just for fun.  This is a near-IR picture of M17 I took in June:
> > http://www.ifa.hawaii.edu/~wang/misc/M17_ULB_2MASS.jpg
> >
> > The image was made using LRGB mode.  L image is taken by our
> > 2m telescope and a near IR camera called ULBCAM.  ULBCAM is
> > a prototype of the camera that will be used in the 6m Next Generation
> > Space Telescope.  It has four 2k by 2k near-IR chips (16 Mega pixels
> > in total) that is more like CMOS but unlike CCDs.  It's also the
> > largest near-IR camera on large telescopes.  To advertise this camera,
> > I was asked to take some pretty images during my observation.
> >
> > The L image is taken through J filter, whose central wavelength is about
> > 1.2 um, twice longer than that of visible red light.  Because this
camera
> > is only a prototype and doesn't have a proper aperture stop, it will see
> > the thermal emission from itself and from the telescope.  For this
reason,
> > we don't operate it at wavelengths longer than 1.8 um where thermal
> > emission starts to be strong.  With only one image taken at 1.2 um,
> > I cannot make a color picture.  I downloaded 2MASS 1.2, 1.6, 1.9 um
> > images from the internet and use them as RGB channels.  The 2MASS
> > data don't have the resolution and depth that ULBCAM has but they
> > provide reasonable color information.
> >
> > The blue color in this picture comes from hydrogen, I believe.  It's
just
> > the IR version of H-alpha line.  The yellow and red color may come from
> > hot dust around young stars.
> >
> > Enjoy.
> >
> > Wei-Hao
> >
> > -- 
> > ________________________________________________________________
> > Wei-Hao Wang  :)
> >
> > Institute for Astronomy at University of Hawaii
> >
> > Address:
> > 2680 Woodlawn Drive         Personal Website:
> > Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
> > ________________________________________________________________
> > _______________________________________________
> > Astro-Photo mailing list
> > Astro-Photo@seds.org
> > http://seds.org/mailman/listinfo/astro-photo
>
> _______________________________________________
> Astro-Photo mailing list
> Astro-Photo@seds.org
> http://seds.org/mailman/listinfo/astro-photo
>

_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo