[Lvas] FW: Crab Nebula Observing Report
Rob
scopegeek at gmail.com
Sun Mar 1 21:23:12 PST 2009
Project Contributors:
At Roger's request, I'm adding my latest Mallincam image of the Crab
Nebula to this observation project. This image was captured during the
early morning (12:25am) of 21 February 2009 while on an LVAS outing to
Death Valley. This is my first real attempt at describing an
observation with the intent for others to read it.
In the picture below, I believe the nebula is oriented southeast to the
left extending to the northwest on the right. The notch that many
observers indicate being on the east side is located on the bottom of
this view. If I'm turned around on the orientation, I would appreciate
anyone's correction, as I still have a difficult time determining which
way is up in my telescopes. As observed here, the nebula is almost
twice as long as it is wide.
<cid:part1.00020109.04010901 at gmail.com>
I see a mottled nebula having uneven distribution of matter and a very
irregular edge with some portions being fairly distinct while other
sections of the edge thin out and just fade into the background. Some
observers describe the nebula as having three distinct sections running
southeast to northwest. I can somewhat agree with that observation. I
see two smaller ends separated by what almost appears to be a larger
midsection containing an irregular eliptical filament ring having
several knots of material around the ring. This ring is interior to the
nebula. The northwest section (right) of the nebula appears to be
thinner (less dense) than the other two brighter sections and may hold
the "S" pattern that other observers have detected. There is also a
much thinner hazy area to the left of the brighter southeast (left)
section which lies outside the brighter part of the nebula. In this
photo, I'm able to discern some green color in the midsection adjacent
to the dark notch on the east side. There are two brighter stars near
the east and west (top and bottom) boundaries of the nebula. There also
appears to be some other stars behind or embedded in the nebula and
shining through it. The larger of these stars is just south (left) of
the center section of the nebula. Two other stars almost form a
straight line extending from this star toward the right edge of the nebula.
I hope my image contributes to confirming your observation notes.
Roger - I hope the above is what you were looking for. I'm not sure how
you want to include my image and observation notes in the overall
project, but please use it as you see fit.
Looking forward to the next project object.
Rob Lambert
LVAS
roger ivester wrote:
>
> */LVAS,
>
> We have had quite a few communications over the past few weeks
> concerning the Crab Nebula. The intent of this report is to promote a
> desire to become a more skilled observer and record what you see.
>
> It is my sincere hope that all who read this observing analysis will
> find it both educational and rewarding.
>
> We will begin with quotes from some selected reference book sources. I
> will not list all of the information given, but only the most
> applicable portions related to the observational study of this object.
>
> Observing The Constellations by John Sanford: The filaments which are
> so prominent in red light photographs are dim but detectable with a
> large telescope such as one with a 22-inch aperture.
>
> The Universe From Your Backyard by David J. Eicher: A sketch by Eicher
> using a 17.5-inch f/4.5 reflector @ 71x does not show any stars within
> the nebula.
>
> The Messier Album by John H. Mallas and Evered Kreimer: Observations
> were made between 1958 and 1962 using a 4-inch f/15 Unitron refractor.
> It is easily seen in the 10 x 40 finder. Visually, a haze seems to
> surround the brighter middle, and the color appears slightly greenish.
> An experienced observer may notice some streaks throughout the inner
> portion of the nebula, but they are extremely difficult to see. Mallas
> did an excellent sketch which resembled an elongated teardrop with a
> slightly curving tail.
>
> Observing Handbook and Catalogue of Deep-Sky Objects by Brian Skiff
> and Christian Luginbuhl: This is only a very small amount of the
> information given for this object.
>
> 6 cm, broadly concentrated to the center elongated SE-NW. With a 15 cm
> the nebula is a moderately concentrated lenticular form extending to a
> 5' x 3' in pa 135°. With scrutiny the brighter portions give an "S"
> shape: the NE edge of the NW half and the SW edge of the SE half are
> brighter. In the 30 cm the "S" shape is quite distinct, and the whole
> nebula is very unevenly bright. A mag. 13.5 star is on the NE edge of
> the core; another of the same brightness is on the W edge. Two mag.
> 13.5-14 stars are embedded in the N arm, one of which is at the
> tip; two others are embedded fairly symmetrically in the S arm.
> Several other faint stars are involved.
>
> Celestial Harvest by James Mullaney: As the preceeding book, this is
> only a very small amount of the information given for this object.
>
> Intricate irregularites...begin to appear in 10-inch and larger
> instruments (which) increase the mottled look. Lord Rosse regarded the
> filaments (which he said resembled the legs of a crab). Adding to the
> interest of this object is a tiny, neat close DS Struve 742 (7.2, 7.8,
> 4" sep.) lying just 1/2° West of M1.
>
> Fred Rayworth; Observer from Nevada: Fred supplied 29 observations
> from December 1984 through November 2007. As he sent an entire page on
> an excel spreadsheet I attempted to summarize the best I could. Fred,
> thank you for your interest in the project and your participation.
>
> 8-inch f/9.4 using an Erfle eyepiece with four entries: Very faint,
> and circular.
>
> 16-inch f/6.4 reflector; entries from March 1987 through November
> 2007: The "S" shape was evident. Very faint, but couldn't see the "S"
> shape on this night. Fairly bright and diffuse, and could see mottling
> in the nebula. Just a very soft glow tonight.
>
> Roger Ivester; Observer from North Carolina: Using my 10-inch f/4.5
> equatorial reflector this object appears large and bright. It has an
> irregular shape shape, a soft grey color, and is brighter in the NW
> region. Elongated NE-SW, it is situated almost equally between two
> somewhat faint stars in alignment with the orientation of the nebula.
> It shows uneven texture with a dark streak crossing the SE part. The
> edges of the nebula are irregular and uneven, fading gradually
> outwards from the brighter middle. The NW side fades more abruptly
> than the SE part. The crab is best viewed at 100-125x as higher
> magnification does not improve the view or increase fine detail. I
> cannot see the "S" shape described by Skiff & Luginbuhl and Fred
> Rayworth of Nevada using a 16-inch. On an extraordinary night, January
> 20th 1996 while observing with Bob Eskridge in a dark location in the
> South Mountains approxiamately 35 minutes north of Boiling Springs
> NC. While observing through Bob's 14.5-inch reflector I saw a
> beautiful "shimmering" of faint stars with the nebula. I could see at
> least (4) faint stars embedded within the nebula...a first for me. I
> have been unable to see the stars since, as I have tried many times
> before and since with my 10-inch. With the 14.5-inch I could also see
> a curving tail.
>
> Rob Lambert Observer from Nevada: Rob uses a Mallincam system and
> hopefully will provide an image of his most recent imaging session.
> Thank you Rob...
>
> Dr. Don Olive; Observer and Astronomy and Physics at Gardner-Webb
> University and Director of the Williams Observatory in Boiling
> Springs, NC. Don provided an excellent image taken from New Mexico. I
> will forward this image with all relative details again. Thank you Don
> for participating in our observing project.
>
> Tom English: Observer and Astronomy and Physics at GTCC in Greensboro
> North Carolina - Tom has been unable to see the stars within the
> nebula from his relatively light polluted observatory site. I would
> like to thank Tom for all of his support and training that he gave me
> almost 20 years ago. I have become a better observer and amateur for
> your efforts. Thanks again and also thank you for participating in our
> observing project.
> /*
> */Best regard to all...Roger Ivester
>
> /*
>
>
>
>
>
> /* I* can see how it might be possible for a man to look down upon
> the earth and be an atheist, but I cannot conceive how he could look
> up into the heavens and say there is no God. Abraham Lincoln/
>
>
>
>
>
>
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