Horsehead Nebula Website - new URL
AstroApp
We have just posted a new website called "The Horsehead Nebula", based
on some articles prepared in 1989/90 for ASTRONOMY Magazine but never
published until now.
See the following URL:
http://home.earthlink.net/~astro-app/horsehead/index.html
The topics discussed are:
- Wm. Herschel's "52 nebulous fields" in the sky, discovered with his
great speculum reflector telescope;
- The discovery of the Horsehead nebula on a photographic plate taken
by W. H. Pickering in 1888 at Harvard College Observatory: first
observed by Mrs. Williamina P. Fleming, and given credit by HCO's
Annal as "discoverer";
- The subsequent publication of the nebula, in Dreyer's Index
Catalogue, with a mistaken attribution to "Pickering", meaning the
Director of the Observatory: almost all subsequent references rely on
Dreyer, and NOT on the Harvard publication, and thereby err in
attributing the actual discoverer;
- The first pictures by Edward Barnard, at Lick Observatory, and Max
Wolf, at Heidelberg, in the 1890s;
- The fine 1900 plate by Dr. Isaac Roberts, a Welsh-born amateur
astronomer who set up his own observatory in Sussex;
- Subsequent arguments between Roberts -- and his wife, Dr. Dorothea
Klumpke-Roberts -- and Barnard about the nature of the nebula, and of
the actual existence of Herschel's 52 nebulous regions, not shown in
Roberts' images;
- The experience of Barnard in photographing the Horsehead in 1913 at
Yerkes Observatory, and then studying the nebula DIRECTLY at the
eyepiece of the great 40-inch refractor;
- The visual confirmation during WWI blackouts, at the Vatican
Observatory, of all 52 of the nebulous regions, by Fr. J. Hagen;
- The improved pictures obtained by Heber D. Curtis at Lick in 1918,
with the Crossley telescope;
- The superb photo taken by John C. Duncan with the 100-inch Hooker
Telescope at Mt. Wilson.
The images are included, by permission of various observatories and
archives, from historical publications.
In addition, we discuss modern astrophysical theories about the
constitution of the Horsehead nebula; and a comparison of "dark
interstellar matter" like the Horsehead, with "dark matter" on a
cosmological scale.
Two sections are provided to aid amateur telescope observers: an
account of a series of amateur viewing tests with small telescopes,
with suggestions about photographic techniques; and an article on
light pollution reduction and nebular filters.
Many professional astronomers at Lick Observatory, Harvard College
Observatory, and the Observatories of the Carnegie Institution
assisted the author by providing time for interviews, and by
suggesting resources for investigation. These include Dr. Don
Osterbrock (Lick), Dr. Martha Hazen (Harvard), Drs. Dale Cruikshank
and Alexander Tielens (NASA Ames), and Dr. Allan Sandage (Carnegie
Institution.)
October through the first couple of months of spring are the ideal
time of year for viewing and imaging the Horsehead nebula. We hope
the information in this new website will inspire you to take the
trouble to use the techniques required to see this object, one of the
supreme challenges of deep-sky visual observing.
Yours,
Astro-app
David Knisely
that even under dark "pristine" skies well away from city lights, the
H-Beta filter still provides a noticable increase in the contrast of the
object, as the faint natural "airglow" of the night sky (the airglow
lines and the faint glow from unresolved background starlight) is
filtered out by the H-Beta. I have even seen the UHC filter enhance the
view a bit, as it will often reveal at least a hint of the Horsehead
when it is invisible without a filter from a dark sky site. While I
have glimsed the faint band of IC 434 in some relatively small
apertures, the smallest aperture I have seen the Horsehead itself in is
a 4 inch refractor at about 20x to 25x (equipped with the H-Beta), so
you will probably get a lot of consternation from people who try it with
the smaller scopes and fail. It is probably one of the most difficult
objects which the amateur may try and go after. Clear skies to you.
--
David W. Knisely KA0...@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
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Marty
Marty