Index charts to the 50 plates of Barnard's dark cloud atlas

This is to announce a preliminary release of index charts to aid in
using Plates and Charts 1-50 (omitting Plates 27 and 51) in Edward
Emerson Barnard's "A Photographic Atlas of Selected Regions of the
Milky Way" (1927) ("Barnard's Atlas"). Barnard's Atlas features
pictures taken with the 1910's state-of-the-art 10" Bruce Telescope.
The Atlas was intended to introduce the public to beauty of the Milky
Way and to provide a post-humus final version of Barnard's catalogue of
dark clouds.

These index charts plot the epoch J2000 boundaries of the epoch B1875
photographs in Volume I and in the annotated charts in Volume II of
Barnard's Atlas. For example, the reader can use the following index
chart for the Aquila area -

http://members.csolutions.net/fisher...dcc_aql7_1.gif

- to orient Plates 34 through 42 to the night sky.

These index charts are intended to be used in conjunction with a recent
internet distribution of Barnard's Atlas by the Georgia Institute of
Technology ("GIA").
http://www.library.gatech.edu/about_...ard/index.html

The GIA distribution of Barnard's Atlas offers PDF downloads that
compile in one file for each plate:
1) Barnard's photograph from Volume I of the Atlas.
2) Barnard's narrative on the plate.
3) Mary R. Calvert's annotated line-drawing chart showing the
outlines of the objects in Barnard's catalogue from Volume II of the
Atlas.
4) A digital overlay of Calvert's annotated chart over Barnard's
photograph.

Calvert's line drawings represent the definitive statement of the
boundaries that Barnard intended for each dark cloud in his catalogue.
Calvert's line drawings annotate the boundaries of distinct (solid
line) and indistinct (dotted line) dark nebulae and reflective regions
("nebulosity" in Barnard's Atlas). The following excerpt from Chart 42
illustrates the three types of plotted lines -

http://members.csolutions.net/fisher...t44gamCygExce=
rpt.jpg

Calvert's line charts give much more descriptive information on the
catalogue object than Barnard's catalogue. A typical note to Barnard's
catalogue provides little useful content, as illustrated by the note to
Barnard Object No. 3: "Irregular, dark space in nebula; curved, bright
strip of nebulosity in SW." Other chart alternatives, like Sky 2000
and Uranometria 2000, chart the Barnard objects, but often combine
outlines of several objects into one boundary.

The index charts to the plates in Barnard's Atlas can be downloaded as
follows. The numbers in parentheses list the Barnard Atlas plates
plotted on the index chart:

East Sgr (28-31) and East Sco (19-22) Groups to mag 7.1 and 7.6

http://members.csolutions.net/fisher..._sgre_scoe7_1=
..gif


http://members.csolutions.net/fisher..._sgre_scoe7_6=
..gif


West Sgr (23-26) and West Sco (11-18) Groups to mag 7.1 and 7.6

http://members.csolutions.net/fisher..._sgrs_scow7_1=
..gif


http://members.csolutions.net/fisher..._sgrs_scow7_6=
..gif


Aql-Sct (34-41) Group to mag 7.1 and 7.6

http://members.csolutions.net/fisher...dcc_aql7_1.gif


http://members.csolutions.net/fisher...dcc_aql7_6.gif


Cyg-Cep (43-50) Group to mag 7.1 and 7.6

http://members.csolutions.net/fisher..._cygcep7_1.gif


http://members.csolutions.net/fisher..._cygcep7_6.gif


Per-Cas (1-2) Group to mag 7.6

http://members.csolutions.net/fisher..._Per_dblclust=
er.gif


Per-Aur-Ori (3-9) Group to mag 7.1 and 7.6

http://members.csolutions.net/fisher..._oriper7_1.gif


http://members.csolutions.net/fisher..._oriper7_6.gif


CMa (10) Group to mag 8.5

http://members.csolutions.net/fisher..._CMa8_5_FOV13=
..gif


The J2000 Barnard plate boundaries are also distributed here in three
parts as Cartes du Ciel external nebula catalogues.
http://members.csolutions.net/fisher.../bdcc/bdcc.zip


The Cartes du Ciel compatible nebula catalogues divide the 50 plates
into three groups:
1) All plates outside of the Sagittarius-Scorpius region (files
bdc1.hdr, *.dat and *.txt).
2) The west groups of the Sagittarius-Scorpius region (files
bdc2.hdr, *.dat and *.txt). See
http://members.csolutions.net/fisher..._sgre_scoe7_1=
..gif

3) The east groups of the Sagittarius-Scorpius region (files
bdc3.hdr, *.dat and *.txt). See
http://members.csolutions.net/fisher..._sgre_scow7_1=
..gif


The reason for dividing the Sagittarius-Scorpius region into two parts
is there are so many overlapping plates covering this region. Including
them in one plot catalogue generates a confusing, difficult to
interpret display. E.g. -

http://members.csolutions.net/fisher...c_confused.gif

The Sagittarius-Scorpio region includes the Milky Way galactic core and
local Sagittarius-Ophiuchus dark clouds.

Using an existing Barnard Dark Object catalogue for Cartes du Ciel
http://www.stargazing.net/astropc/external.html , it is now
possible to plot Barnard object locations and the Barnard Atlas plate
boundaries that surround those objects. Together with Cavert's charts
in Volume II of the Atlas, the amount of effort that amateur observers
need to expend to confirm the location and shape of Barnard dark cloud
can be greatly reduced.

Another useful featured provided by these index charts is the
identification of the location of bright stars in Calvert's line charts
and Barnard's star catalogue tables for each plate by Bayer and
Flamsteed numbers. Calvert's annotated charts in Volume II of the
Atlas only list stars by a three digit catalogue number. Common stars
like Deneb might be identified by only a number like "832". The Aquila
area index chart presented above also plots, using Cartes du Ciel, the
boundaries of the Barnard plates with Bayer and Flamsteed numbers for
bright stars. These index charts aid in rapidly locating the
corresponding bright stars in Calvert's line charts and in Barnard's
charts and tables.

The following objects in Barnard's catalogue of 349 dark clouds do not
appear on plates 1-50 of Barnard's Atlas: 6, 7, 8, 9, 12, 13, 16, 17,
18, 19, 25, 26, 27, 28, 29, 33, 37, 39, 140, 155, 158, 159, 162, 168,
175, 222, 230, 315. In Cartes du Ciel, these objects plot outside the
boundaries of any plate in Barnard's Atlas. Two Barnard Atlas plates,
nos. 2 and 42, contain no Barnard objects.

The epoch J2000 boundaries of the Barnard Atlas plates were generated
by making a table of crude, low precision B1875 coordinate take-offs
from Barnard's Atlas.

http://members.csolutions.net/fisher...ersB1875TakeO=
ffs.htm

As noted in the introduction to Volume II of the Atlas, prepared after
Barnard's death: "A high degree of accuracy is not claimed for these
charts, but they are sufficiently precise to locate and object closely
enough for identification in a catalogue." Using Meuss's low-precision
precession formula, the B1875 coordinates were translated to J2000
coordinates.

http://members.csolutions.net/fisher...rnersJ2000.htm

Nutation has not been applied. The resulting coordinates were ported
to Cartes du Ciel compatible nebula outline files.

Once plotted in Ciel, each of the 49 plates (1-50, omitting Plate 27)
in Ciel were inspected and compared for orientation and boundaries to
the plates in the Atlas and Barnard's star catalogue of each plate in
Volume II of the Atlas. It was felt that Ciel plots represented the
boundaries of the Barnard Atlas plates sufficiently for their intended
purpose: 1) to rapidly orient an Atlas plate to the night sky and 2) to
rapidly locate three bright stars and/or Messier objects located on
Calvert's line charts and Barnard's star catalogue table for that
plate.

A single object test of the precession formula on Barnard 43 confirms
the low-precision accuracy of the precession formula used here to
transform epoch B1875 coordinates to J2000:

Barnard 43 in B1875 per VizieR catalogue VII/220A/barnard
B1875 16h 23m 00s -19.5d

CDS Simbad FK5/J2000 coordinates for B43:
16h 29.9m -19d 36m

Georgia Institute of Technology J2000 coordinates for B43:
16h 29m 7s -18d 50m

J2000 Precession formula used he
16h 30m 44.50s -19d 46m 14.5s

It is hoped that these index charts to the plates and charts in
Barnard's Atlas will increase the enjoyment of amateurs discovering
this overlooked class of difficult objects. A common problem
encountered when first observing dark nebulae is "Are you looking at
the right object?" For dark objects, this questions is more vexing
than when looking at typical light-emitting objects. Dark objects have
even less contrast than against the background night sky than dim
stars. Barnard (1919) cautioned that "It would be unwise to assume
that the dark places shown on photographs of the sky are due to
intervening opaque masses between us and the stars." I have always had
difficulty in understanding exactly what each Barnard objects consists,
given only commonly available coordinates and Barnard's tabular notes
by object number.

Calvert's line drawing charts (now distributed over the internet by the
Georgia Technical Institute) present the definitive statement on what
Barnard intended the boundaries of each object to be. But even
Calvert's charts can be difficult to use. It is hoped that the index
charts and Cartes du Ciel compatible external nebula databases will
remove some of these barriers to identifying the Barnard clouds and
will allow more amateurs to enjoy this interesting class of night sky
objects.

Future enhancements will expand Barnard's catalogue with the
corresponding opacity and positions of objects in Lynds' "Catalogue of
Dark Nebula" (1962) and the known distances to selected Lynd-Barnard
dark clouds in Hilton's "Distance measurements of Lynds galactic dark
nebulae" (1995).

Send comments and corrections to .

- Enjoy - Canopus56

Acknowledgements: These index charts and Cartes du Ciel compatible
catalogues make use of catalogues and data from the VizieR service of
the Centre de Donn=E9es astronomiques de Strasbourg, France.

Charts distributed here were generated using Cartes du Ciel.
http://www.stargazing.net/astropc/ .

This amateur-observer-author is not affiliated with the Georgia
Institute of Technology or Cartes du Ciel.

References:

Barnard, E.E. 1919. On the dark markings of the sky, with a catalogue
of 182 such objects. Astrophys. J., 49:1-24 (1919) NASA ADS link:
http://cdsads.u-strasbg.fr/cgi-bin/n...pJ....49....1B

Barnard, E.E. 1927. A Photographic Atlas of Selected Regions of the
Milky Way. Carnegie Institution of Washington.
http://www.library.gatech.edu/about_...ard/index.html ;
also available in hardcopy from ProQuest UMI Books on Demand.
http://wwwlib.umi.com/bod (BOD catalogue nos. WB1-2050305-060 and
WB1-2050305-061)

Barnard, E.E. 1927. Barnard's Catalogue of 349 Dark Objects in the
Sky. CDS VizieR catalogue VII/220A/barnard and VII/220A/notes.
http://vizier.u-strasbg.fr/viz-bin/Cat?VII/220A . The catalogues can
be queried through the CDS VizieR gateway at
http://vizier.u-strasbg.fr/viz-bin/V...rce=3DVII/220A ; Cartes
du Ciel compatible build
http://www.stargazing.net/astropc/external.html

Hilton J., Lahulla J.F. 1995. Distance measurements of Lynds galactic
dark nebulae. CDS VizieR catalogue J/A+AS/113/325/table1a and table1b.
http://vizier.cfa.harvard.edu/viz-bi...A%2bAS/113/325

Lynds, Beverly T. 1962. Catalogue of Dark Nebulae. Astrophys. J.,
Supp. 7, 1 NASA ADS Link:
http://cdsads.u-strasbg.fr/cgi-bin/n...pJS....7....1L

Meeus, Jan. 1999. (2d) Astronomical Algorithms. Willman-Bell.
http://www.willbell.com/math/mc1.htm

Great work! Do you plan a home page that will give this information and
the links?

Mike Simmons

Thanks, Mike. Yes, but it may be a few weeks so I wanted get things
out there to test the waters and get some first draft feedback. I
promise not to clog the newsgroup up with more lengthy posts on this
project. - Canopus56