OF THE ROGER N. CLARK

5
Making drawings and keeping
records
INTRODUCTION
Anyone who observes the sky should keep a
logbook. Even the most casual celestial sightseeing
becomes more meaningful if a few
notes are jotted down in a permanent record.
For more serious observing, complete notes
are essential. They document the viewing
conditions, provide a record of what was
actually seen, and create a baseline for comparing
future observations and gaining experience.
And, of course, they will form a rich
personal diary of starry nights.
Good records sometimes serve purposes
unanticipated at the time. Finding a supernova
in a galaxy, or an unexpected asteroid
or comet, are examples that come to mind.
Amateur observers often just list the objects
they see during a night. This has little
value unless you just like to compile lists and
figure out such things as how many galaxies
you have seen. The next level of sophistication
is to note the date, time, magnification
and telescope used. This still has little value
except to list-compilers.
At the next level, the observer might write
a few comments such as:
Time Object Power Comments
11:05 M63 36X easy
1l:l0 M51 75X maybe some spiral
structure
1l:l5 MI4 50 X partially resolved
1l: 25 MI3 75X mottled, spectacular
11:40 M57 100 X ring easily seen
12:10 Veil 36X barely seen
Such a list has only a little more value. What
is "easy" Spiral structure means
things to different people. "Barely seen"
not tell what it actually looked liJte.
elongated Were stars visible through
Which parts of it were seen
The list above is typical of some of
early records. In preparing this book, I
very disappointed to discover their lack
usefulness. Back then I also made
drawings a half inch to two inches wide,
rarely included field stars. Thus there is
way to tell the scale of a drawing or the
what was seen. Is that fuzzy patch the
extent of a galaxy including its spiral
only the bright central region A
field stars would have allowed
with photographs to find out.
Even longer descriptions can seem
aoequate on future reading. In some of
more exciting moments under superbly
country skies, I wrote 'Just like a
graph", and "so spectacular and
that a true drawing cannot be made."
comments recall fond memories but serve
tle other purpose.
To document the view fully, records
include the sizes of objects, the shapes
relative brightnesses of all their parts,
their placement with respect to stars.
chapter outlines ways to do so - either
writing or by one of three methods for
drawings.
WRITTEN DESCRIPTIONS
Any record of a sighting should include
tain basic data: the observer, date, start
state the kind of time and date, such as
versal Time or Mountain Standard
the observing site, the eyepieces and
magnifications, a sky quality note such as
ending times of the observation (be sure
--
MAKING DRAWINGS AND KEEPING RECORDS
. 'ble whether a clock drive was
. t star VIS I , . .
famtes and the approximate altlt de or aIr
used, f h biect. (See AppendIx C for a
0
rnass t e o .
J
. ssion of aIr mass.) . .
d" d
rna
dISCO . description should mclude estl-
A wntten
f h Obiect's size the IrectlOns an
tes 0 t e J ' .
f its details from reference pomts,
distances 0 . ' A
h d tails' relatIve bnghtnesses. n exand
t e e
_
arnple :
NGC 4565 Edge-on galaxy in Coma Berenices 51111
83 Start: 10:00 UT
8-inch,/lll.5 Cassegrain
Location: Wa ianae Ranch,
Hawaii
E 'h ' . 20mm Erfle (117x) 12.4mm Erfle (iBBX)
' }e y teces,
Faintest star at zenith: about magnitude 14.3 at IBBX.
Observer: R. Clark.
This object was hard to find, being in a star-poor
area. Once jo und, the view was amazing! I had se n
the galaxy in poorer skies in the .
early ! 970s bu dId
not think the dark lane was viSIble WIth an 8-znch.
Now the dark lane could be seen at 117x and 188X
by several observers easily (no a erted vision) .
The galaxy is about 11 arc-mznutes long, extending
northwest to southeast. The boundaries oj the
arms are ja irly sharp, except at the tips where they
fade slowly into the sky background. The central hub
is oval (about 2 by 1.5 arc-minutes); the long axis is
aligned with the arms. The edges of the hub fa de
first slowly, then quickly into the sky background.
Best view is with the 12.4 mm Erfle at 188X, in
which the galaxy extends over the whole field.
The dark lane is about 4 to 5 arc-minutes long and
about 0.3 arc-minute wide. The inner nuclear region
(the central 0.25 arc-minute) is much brighter and
lies southwest oj the dark lane.
On each side oj the nucleus in the long direction is
a bright spot about 0.25 arc-minute in diameter.
Another bright spot was glimpsed occasionally about
4 arc-minutes jrom the nucleus along the galaxy's
long axis.
A star lies 1.5 or 2 arc-minutes northeast of the
nucleus. It is ja inter than the nuclear region, probably
12th or 13th magnitude. A second star, a little
fainter, i.i about 4 arc-minutes south of the nucleus
and slightly west. A brighter one (mag. 10 or 11) is
8 arc-minutes west and 3 arc-minutes south of the
nucleus.
= End of observation: 10:42 UT.
DRAWINGS
It's often said that a picture is worth a
thousand words. Composing a thousand
words takes much time and thought and still
may leave the reader with the wrong mental
image. So when it comes to accurate recording
of scientific data, there's often no substitute
for a picture.
In past centuries a scientist was necessarily
a draftsman. Nowadays scientists in almost
all fields rely on photography to record images,
and the pencil and sketchpad no longer
rank as essential scientific tools. Visual astronomy,
however, remains an exception.
You'll need white paper, either plain or
with light graph lines for judging distances, a
soft pencil such as number 1 or 2, and a clean
eraser. Some observers draw with chalk on
black paper, but others find chalk hard to
control. Drawings of deep-sky objects made
at the telescope are generally done with scribbled
pencil shading. Better-looking finished
versions, made immediately afterward indoors,
use what is called the finger-smudging
technique. Using a dull pencil, lightly scribble
a somewhat smaller area than the desired
shading. Then use a clean, dry finger to
smear the marks until they blend together
into a uniform texture. If the patch is too
faint, scribble and smear some more until the
desired effect is produced. If the smear becomes
too dark, the eraser is used in the same
way as the pencil, followed by more smearing.
But lightening a smudge is harder than
darkening it, so sometimes it's necessary to
start again.
Pencil drawings on white paper are negatives:
the brighter a star or nebulous patch,
the darker the pencil mark or smudge. Some
people find it hard to get used to a negative
image, but most quickly learn to mentally
reverse dark areas on the paper to correspond
to bright areas in the sky.
Doing anything at the telescope other than
looking through it requires light. Any extra
light reduces the eye's sensitivity to faint objects.
But if the working light is too dim,
drawings become less accurate. I recommend
that a very dim flashlight be used. Red light
is traditionally preferred, but the rod cells are
more sensitive to all colors than cone cells so
there is no advantage to using red light. Figure
2.3c (page 9) shows this. In fact many
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