September 2009 - Utah-Astronomy - mailman.xmission.com

FORA.tv - Leonard Susskind - The Black Hole War
by RON VANDERHULE 26 Sep '09

26 Sep '09

Hear the man in his own words. Great web site for astro topics. Ron http://fora.tv/2008/07/23/Leonard_Susskind_-_The_Black_Hole_War<http://fora.tv/2008/07/23/Leonard_Susskind_-_The_Black_Hole_War>

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Re: [Utah-astronomy] Perhaps Black Holes Do Not Exist
by Wayne Sumner 26 Sep '09

26 Sep '09

This past summer I read the book "The Black Hole Wars - My battle with Stephen Hawking to make the world safe for Quantum Mechanics". The author relates how the loss of information in black holes is incompatible with the ideas of Quantum Mechanics along with many other fascinating ideas. I highly recommend it! Wayne A. Sumner Math/Physics/Astronomy/Engineering Boy's Tennis Coach Northridge High School Davis School District (801) 402-8610 >>> <erikhansen(a)TheBlueZone.net> 09/24/09 5:25 PM >>> >I liked the cartoon with a Physicist writing long equations on the blackboard.As the solution he wrote "then a miracle happens". My first contact with singularities was the idea that the Universe arose from a singularity, which seems to be something different than a Black Hole. I have gotten the impression that material being sucked into a black hole has been observed. I thought that was proof that Black Holes existed. The October Scientific American argues that black stars more dense than > neutron stars may form instead of black holes. Black holes are predicted > by > classical general relativity but do not take properly take into account > quantum mechanics. A quantum effect called vacuum polarization may grow > large enough to stop a hole forming and create a "black star" instead. > Such > a star would not have an event horizon but any energy emitted would be > shifted far to the red and not show as visible light. > > A major problem with black holes is the loss of information that would > occur > violating a fundamental feature of quantum mechanics called unitarity. > > I have always been skeptical of singularities since in every other area of > physics singularities mean a failure of the math or theory or both. When > the > theory predicts such things as infinite energy (the ultraviolet > catastrophe) > or singularities it usually means the theory needs to be modified. > > > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > Visit the Photo Gallery: http://www.slas.us/gallery2/main.php > Visit the Wiki: http://www.utahastronomy.com > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com

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Re: [Utah-astronomy] India's lunar mission finds evidence of water on the Moon
by Canopus56 25 Sep '09

25 Sep '09

The Chandrayann-1 NASA Press briefing of 9-24-2009 is available on NASA-YouTube: http://www.youtube.com/profile?v=je0FviGlBz8&user=NASAtelevision Clear Skies - Kurt

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(no subject)
by Tyler Allred 24 Sep '09

24 Sep '09

Hi all. I have been very busy lately imaging lots of fun and interesting objects. I have posted many new items to my personal astrophotography website, including dark nebulae in Cygnus, the newly discovered "soap bubble" and Crescent nebula with its OIII shell, the wild duck cluster, the Elephants Trunk, SH2-190, a new M13, the Cocoon, and more. I picked up an AP130 and have been using it recently for my imaging. I am very happy with the scope, although I will need a flattener to get the most out of it. Take a look if you get a chance. Clear Skies to you all, Tyler Here is a link to the "Latest Images" page on my website. Click the images a couple of times to see the full versions. http://71.18.228.62/gpage8.html Cheers. _____________________________________________

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India's lunar mission finds evidence of water on the Moon
by Dale Hooper 23 Sep '09

23 Sep '09

http://www.timesonline.co.uk/tol/news/science/space/article6846639.ece

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Re: [Utah-astronomy] LCROSS: Impact Crater Finders
by Canopus56 21 Sep '09

21 Sep '09

Joe wrote the link was bad. Joe, I retested it. Appears to be working. http://members.csolutions.net/fisherka/astronote/observed/LCROSS/20090916LC… - Kurt

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Re: [Utah-astronomy] LCROSS: Impact Crater Finders
by Canopus56 21 Sep '09

21 Sep '09

Joe wrote: > So it's probably not worthwhile setting up my 12". Joe, Here's my updated (9-21) observing guide. I feel this is doable. http://members.csolutions.net/fisherka/astronote/observed/LCROSS/20090916LC… (14 megs) Here's an info panel of relative size models of the ejecta curtain and Cabeus A1 at it brightest size and of the crater. They were done in Mathematica. http://members.csolutions.net/fisherka/astronote/observed/LCROSS/20090920Cr… My feeling is that where the plume is contrasted against a background of the sunlit lunar surface, it will not be visible. So, the relative sizes shown here should not be considered a useable guide. IMHO, essentially, a contrast effect will occur where the shadowed portion of Cabeus A1 as seen from Earth will disappear as the ejecta plume reaches an apparent brightness nearly equal to the surface brigthtness of the sunlit lunar regolith. The Feb. 28, 2008 LPOD reproduces a topographic color-coded NASA JPL south polar map. http://lpod.wikispaces.com/February+28,+2008 From this one can see that south polar mountains M1 and M3 rise about 6 kilometers from their surrounding terrain. When look at Tom Bash's high libration south polar image http://www.lpod.org/?m=20070106 - labeled at bottom), one can see how Cabeus A and Cabeus A1 sit near the foot of M1. Bash's image and the known height of M1 at about 6km gives me some sense of the vertical scale against which to imagine an LCROSS ejecta plume that is 5km high. The LCROSS lampshade model at its brightest is 5km tall, with 3km expected to appear above the target crater’s rim. At the extreme southwest lunar pole, length and width distances are distorted by foreshortening while the vertical dimension has almost no foreshortening. Gary wrote: > You may not be aware that areas of permanent shade on the lunar poles are colder than on the planet Pluto. Gary, see the LRO early science release press conference of 9-17. The LRO Team reconfirmed that the permanently shadowed regions of the lunar south pole are the coldest places with the (dwarf) planetary solar system. http://www.youtube.com/profile?v=59aaOW33aqs&user=NASAtelevision Clear Skies and Happy Impact Imaging - Kurt

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Today's Google logo
by Patrick Wiggins 21 Sep '09

21 Sep '09

As some here may know, Google modifies their logo every now and then to highlight various events. I rather like today's for H G Well's birthday: http://www.google.com patrick

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Re: [Utah-astronomy] LCROSS: Impact Crater Finders
by Gary Vardon 20 Sep '09

20 Sep '09

Fellow SLASers, You may not be aware that areas of permanent shade on the lunar poles are colder than on the planet Pluto Sincerely, Gary Vardon The book DO It Right will help you understand vital ideas leading to your geater success. GO to PublishAmerica. -----Original Message----- From: Canopus56 Sent: Friday, September 11, 2009 9:23 PM To: Utah Astronomy List Serv Subject: [Utah-astronomy] LCROSS: Impact Crater Finders The LCROSS Team announced its final target selection for a small crater on the rim of Cabeus A.ï¿½ I have prepared a finder page at the LCROSS Observation Google Group: http://groups.google.com/group/lcross_observation/web/finders Other sites with finders for the LCROSS impact crater are: Jim Mosher's Wiki LCROSS Impact Page http://ltvt.wikispaces.com/LCROSS+Impact New Mexico State Univ. Apache Point LCROSS Site Finders http://astronomy.nmsu.edu/rthamilt/LCROSS/media.shtml NASA LCROSS Team Observation Campaign page http://lcross.arc.nasa.gov/observation.htm and in the future: NASA LCROSS Citizen Science Page http://apps.nasa.gov/lcross/ _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com

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LCROSS - stops, masks and observing the LCROSS impact
by Canopus56 19 Sep '09

19 Sep '09

Stops, masks and observing the LCROSS impact A prior version of the NASA Citizen Scientist About page recommended an occulting disk in SCTs to reduce stray light. Such a disk effectively increases the size of the central obstruction. "The plume, if observable, will be very faint compared to the illuminated waning gibbous Moon, so any technique that can reduce stray light in your optical system should be used. On Schmidt-Cassegrain type telescopes, one trick is to make a circle of black paper about 30 percent larger than the secondary mirror mount that is temporarily taped to the mirror mount, preventing stray light from entering the baffle tube inside the tube assembly. Newtonian reflectors telescopes are a bit more difficult to shield from stray light, so the best approach is to just have clean, well collimated optics." I understand that this recommendation may be dropped, but wanted to explore further what role aperture stops and apodizing masks might play as useful observing accessories for the LCROSS impact. The general conclusion and recommendation of this note is that apodizing masks will increase resolution with acceptable brightness losses for SCTs and Newts in the 14 inch class. Apodozing masks and aperture stops may not be a good option for 10 inch Newts and SCTs. Apodizing masks probably confer no benefit for Newts or for refractors smaller than 10 inches in aperture. Occulting disks should not be used. These conclusions are based on a web-based page and amateur literature review. They are not based on experience, since I only rarely use a aperture stop and have not constructed an apodizing mask. However, my quick look has inspired to try and build an apodizing mask for lunar observing with my 10 inch Newt. The following is a discussion focusing on the use of apodizing masks and off-axis aperture stops with respect to the LCROSS impact. I have not personally built an apodizing mask and their effectiveness and use is the subject of much conflicting information on the internet. Here, I focus on the comments and opinions of three noted members of the amateur and professional community: John Westfall, Harold Suiter and Thierry Legault with some historical refernece to Sidgwick's Amateur Astronomy Handbook. The purpose of masks and stops for Newtonians and SCTs above 200mm in aperture relate to seeing found at the time of observation. Larger apertures are relatively more susceptible to distortion from atmospheric distortion than smaller refractors of 130mm or less because the larger scope's apertures subtend a greater angular dimension of the sky. Conversely, smaller apertures have larger larger Airy disks and inherently less resolution than a larger aperature Newtonian or SCT, i.e. a larger Dawes limit. Average or below average atmospheric turbulence robs larger Newtonians and SCTs of their superior performance relative to smaller refractors because there large apertures gather light from a relatively larger angular diameter. However, in skies with excellent seeing, the larger aperture Newt and SCT can access their inherently superior optical resolution - if for brief moments of still air - and out-perform their smaller refractor cousins. Application of these principles can be seen in the modern DSO imagers preference for smaller 135mm or less short fl refractors for imaging. Because they exposure for long periods in average seeing air, the seeing disk stays around 1-3 arcsecs in diameter, their digital cameras can accumulate light over long periods of time, and large aperture scopes are harder to make track accurately. These performance characteristics weigh in favor of a small aperture refractor for hobby DSO imaging. In such average or less than average seeing, smaller refractors give the visual illusion of having a better image. This is because their resolution is lower and because of this lower resolution, the smaller scope is not capable of transmitting the details of "boiling air" that one sees at higher magnification in the larger Newt or SCT. Because of poor seeing's effect on larger aperture Newts and SCTs, amateur owners of such scopes apply the rule-of-thumb that "stopping down, when seeing is poor, gives a better image." Sidgwick at 473. Aperture stops and/or apodizing masks convert the 10 inch Newtonian into a smaller aperture scope that is less susceptible to the effects of atmospheric distortion. The stop-down does not increase the inherent resolution performance of the larger aperture Newt scope. Counterintuitively, it creates the illusion of a higher resolution image by creating an inherently lower-resolution image that is less able to reproduce the effects of atmospheric disturbance. This benefit of stopping down is not, however, without a trade-off. First, Dawes limit still applies and the now smaller apertured stopped-down large light bucket scope has larger Airy disks and a lower resolution. Blocking the larger Newtonian scope also reduces the light collected of the mirror (light grasp) and the image is relatively dim as the large Newt's smaller refractor cousin. But as Westfall notes discussing apodizing rings this "creates some light loss, but with the Moon this is scarely a problem." Newtonians and SCTs are typically stopped down using an off-axis mask. Construction of a typical mask can be found on the web. An example can be found at: http://www.geocities.com/AlyaSerpens/OffAxisApertureStop.html . The aperture off-axis stop-down mask is a common-sense tool for the owner's of large Newts and SCTs. If you set up and seeing is so poor it cannot support your larger aperture, you can pull out a light-weight mask and convert your large aperture 10 inch scope into a 5 inch scope. An equivalent, but somewhat heavy gear option that I use is two own (and sometimes haul) a second 5 1/4" refractor. If I arrive at the site and seeing is bad, I can set up the smaller refractor instead of the light-bucket Newt. (With age, the light-weight mask looks more attractive.) Another variant of a stopping mask is the apodizing diaphram mask. The apodizing diaphram mask differs in basic construction from the off-axis small-holed stop-down mask. Web examples of amateur construction of an apodizing diaphgram mask include urls - http://home.pcisys.net/~astrogirl/tips1.php http://www.csastro.org/gallery/article4.htm The apodizing mask consists of a series of mesh screens that are concentric and on-axis. Ancedontal web opinions on how well these masks work either (a) to inherently improve resolution in good seeing, or (b) to work as a stop-down mask in average or less-than average seeing, or (c) to work on refractors as opposed to Newts and SCTs widely differ. Harold Suiter, author of the widely respected _Star Testing Your Telescope_, feels that apodizing masks do not offer a benefit to SCTs that have a large central obstruction, while they will improve the image of a lower central obsructed Newtonian. Suiter, H. 2001. Apodization for Obstructed Amateurs. url: http://home.digitalexp.com/~suiterhr/TM/ApodDes.pdf Suiter, H. 2003. Apodization. (Webpage). url: http://home.digitalexp.com/~suiterhr/TM/apodize.htm Suiter also notes that such rings _must be engineered_ based on the telescope - they cannot be constructed from rules-of-thumb. Construction of the screen is a simple matter for amateurs and involves simple measuring, cutting cardboard or masonite and window screen material. On his Apodization website, Suiter provides an Excel spreadsheet by which an amateur can determine the proper measurements for an apodizing ring. The spreadsheet is not easy to follow and requires study. http://home.digitalexp.com/~suiterhr/TM/ApodizeTut.xls Suiter notes that _informally engineered_ apodizing masks that he obtained from local amateurs and that he tested usually did not confer benefit assumed by the owner. This was because the masks were not formally engineered and were created using rules-of-thumb. The second view by John Westfall, a widely respected professional lunar observer who has been active with the amateur community, is that apodizing masks will help both SCTs and Newtonians in their inherent resolution performance on lunar targets and during periods of average or less than average seeing. Westfall discusses apodizing rings in Westfall's _Atlas of the Lunar Terminator_ (2000) at 13. Westfall discusses the reasoning behind his use of an "apodizing ring" on obstructed telescopes. The circular slot in Westfall's ring for a 280mm SCT was at 72 and 86 percent of aperature. Westfall concluded that the ring inherently improves resolution for telescopes with large obstructions (SCTs or Newts) when lunar observing, but not for unobstructed telescopes. Westfall performed ray tracing analysis of unobstructed and obstructed telescope types. He computed that the performance of highly obstructed scopes (32%) changed when an apodizing ring was used: Ring? 50% Airy Disc arcsecs 80% Airy Disc arcsecs Transmission No 0.39 0.59 90% Yes 0.17 0.55 68% There was less of a performance increase for unobstructed scopes. Westfall's conclusion for unobstructed refractors is similar to Suiter, who concluded that the improvement confered on unobstructed scopes by apodizing masks "was subtle." Westfall concludes: "In summary, central obstruction removes light from the central Airy disk and places it in the diffraction rings, while an apodizing ring has the opposite effect. An apodizing ring can also improve the performance of an unobstructed system. Using an apodizing ring creates some light loss, but with the Moon this is scarely a problem." _Atlas of the Lunar Terminator_. With respect to the LCROSS experiment, there is uncertainty regarding plume brightness and a basic observing strategy assumes that observing the plume is _brightness limited._ As such, smaller aperture scopes of 10 inches or smaller probably should not use an apodizing mask - even if one could construct a properly engineered one within the remaining time before impact. Losing 68% of light-grasp to an apodizing ring would reduce the probability that the plume could be observed if it is less bright than the LCROSS Team model predicts. Observers may want to maintain a margin of safety with respect to light grasp should the plume not reach the modeled apparent brightness of 4 mpsas. Owners of larger 14 inch class Newtonians and SCTs might benefit from an apodizing mask while at the same time preserving margin of light grasp safety equal to a 10 inch telescope. If Westfall's reasoning is correct, an improved resolution resolution benefit will be confered in both good seeing or if seeing is less than average. With respect to occulting disks - which are simply larger artificial central obstructions - Thierry Legault's "Obstruction" web page analyzes the effect of central obstruction on lunar-planetary images. url: http://legault.perso.sfr.fr/obstruction.html Legault concludes that up to the larger 33% central obstruction of SCTs, "[T]he resolution power is not modified on high contrast structures: Moon, double stars, Cassini division, shadow of a ring or a satellite, edge of a planet,.... [T]he resolution power may be lowered on low contrast objects: surfaces of Mars, Jupiter and Saturn. . . ." Placing a larger than 33% occulting disk at the center of a larger Newtonian or SCT will probably both reduce resolution - dispropotionately more than would occur with an apodizing mask - and image brightness. In summary, a literature review indicates that apodizing masks for larger 14 inch class Newts and SCTs may improve observation of the LCROSS impact plume without causing unacceptable light losses. The improvement may be inherent and work in both excellent seeing skies or when seeing is less than average. Clear Skies - Kurt

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