|
The Observing Notes |
| |
Descriptive notes on these observations
should be interpreted in terms of the
seeing and transparency conditions under which they were made.
Best conditions
are sought, but few observations were made under ideal viewing
conditions.
Therefore, descriptions do not correspond to all details that can be
seen with
the equipment used. All notes are made at the telescope, without use
of
observing guides. Acquisitions are verified using the Observing
Handbook and
Catalogue of Deep Sky Objects (Cambridge 1998), the Burnham Handbook, or
the Webb
Society
Observer's Guides.In making these
observations, I have used three or more of the following points:
- Relative difficulty (given magnification and
seeing)
- Effect of averted vision (AV) and direct vision
(DV), (including "on-off" blinking effects)
- Relative size for object type
- Shape, elongation and directional alignment
- Brightness and density (of nucleus, core and
halo)
- Stellaring of nucleus (galaxies) or visibility
of central star (planetary nebulae)
- Ability to resolve into stellar points (globular and open clusters)
- Number of stars (open clusters)
- Effect of different eyepieces and filters on
appearance
|
| |
|
|
Star Charts |
| |
Prior to January 2004, all objects
were acquired with the
star hopping method, using the following charts:
SA: Star Atlas 2000.0, Wil Tirion,
Second Edition, Field Version (white stars on black)
SP: Skalnate Pleso Atlas of the Heavens - II, Deluxe Edition,
Antonin Becvar (Epoch 1950.0)
U: Uranometrica 2000.0 Deep Sky Atlas, Tirion, Rappaport,
Remaklus,
Second English Edition
After January 2004, most object acquisitions made
with the new Celestron 280mm SCT (CGE-1100) are device-aided,
verified using the Uranometria Star Atlas. |
| |
|
|
Observing Conditions |
| |
Seeing (atmospheric stability) and
transparency (atmospheric clarity or clearness)
are rated subjectively on 1-10 scales that are based on the
guidelines provided by
the American Association of Amateur Astronomers. I use 1-10 scales
because
their meaning is easier to intuit than 1-5 or 1-7 scales, and they
provide more
shades of difference. Seeing is primarily
influenced by
atmospheric
turbulence. The following scale
is used to rate conditions:
|
1 |
|
Chaotic: lowest
power stellar images unsteady |
|
2-3 |
|
Severely
disturbed: low power planetary/nebulae images unsteady |
|
4-5 |
|
Poor: medium
powers unsteady |
|
6-7 |
|
Good: only high
powers unsteady |
|
8-9 |
|
Excellent: only
highest powers soft |
|
10 |
|
Superb: all
powers steady |
Transparency is
influenced by cloud
cover, relative
humidity, and light conditions
which illuminate
airborne
particulates, including
light pollution, moonglow, and
residual sunlight. The following scale is used to rate conditions:
|
1 |
|
Mostly Cloudy |
|
2-3 |
|
Hazy; 1 or 2 Little Dipper stars
visible |
|
4 |
|
3-4 LD stars; Milky Way not
visible |
|
5 |
|
4 LD stars; Bright parts of MW
visible (Scutum starcloud) |
|
6 |
|
5 LD stars; Milky Way visible
with averted vision |
|
7 |
|
6-7 LD stars; Milky Way visible |
|
8-9 |
|
Excellent: 7 LD stars; M-31
visible |
|
10 |
|
Superb: M-33 and/or M-81 visible |
|
| |
|
 |
|
|
|
Observing Sites |
| Primary: |
Littleton, Colorado: Suburban site west of Denver with
50% tree blockage; dark Southern sky. At best transparency conditions
(5) Scutum star cloud
can be seen with naked eye, but not M-31. |
| |
Deer
Trail, Colorado: Ed Kline Dark Sky Site of the Denver
Astronomical Society. Clear horizon in all directions. Light domes
from Denver, 40 miles to the W; Colorado Springs 100 miles to the
SW; Limon, Colorado 20 miles to the SE. Best transparency: 9 |
| Others: |
DNM, Colorado
--
Dinosaur National Monument, NW Colorado
Fox Park, Wyoming -- in Medicine Bow National Forest (Best
transparency: 10)
Karchner Cavern State Park, AZ -- Campground 9 miles S of Benson,
Arizona
Lake City, Colorado -- 2 miles W of Lake San Cristobel
|
|
Object
Types |
|
OCl -- Open
(Galactic) Start Cluster
GC -- Globular Cluster
PN -- Planetary Nebula
DfN -- Diffuse Nebula
C/N -- Cluster with Nebulosity
Gal -- External Galaxy (Hubble Classification, for shape
only:) |
|
E - Elliptical (0 - 8: round to elliptical
shape)
S - Spiral
SB - Barred Spiral
I or Irr - Irregular
a - "Early" Type (bright nucleus; arms less developed)
b - Intermediate Type (lesser nucleus; arms more developed)
c - "Late" Type (weak nucleus; arms very conspicuous)
p or Pec - Peculiar
|
|
Images - NED/IPAC |
| |
Unless otherwise noted,
images in the Herschel 400 Observing List are positive-image
thumbnails created from negative images in the
NASA/IPAC
Extragalactic Database.
Comparison of the long-exposure
photographs with descriptions help to illustrate the large
differences between visual observations and photographs. |
|
