Posts by John Vickers

21) Message boards : MilkyWay@home Science : 2012 (Message 24572) Posted 8 Jun 2009 by John Vickers Post: Hello MW@Home, Personally I find the 2012 scenario to be a bunch of malarky, about the equivalent of the Y2K scare. A couple of things to think about: Firstly, planet X was a theoretical creation to explain discrepencies in the gas giant planets'orbits. Turns out our estimates of the masses of these planets were off and the most recent estimates negate the need for another mass to make the model make sense. Secondly, even if we assume that the Mayan calendar ends at 2012 for an astronomical reason (unlikely since the calendar is made to be "rolled over" each time it is completed, 2012 is the time for the 13th roll, meaning the Mayan calendar has ended 12 times already...) a galactic alignment is going to have about as much of an affect as the sign you were born under. Mathematically the doctor performing the delivery has more of an effect gravitationally than even the closest stars. Something to look at in these websites are phrases like "recent data collected BY IHC ASTRONOMERS, astrophysicists, ..." in other words these are not peer reviewed scientific papers or generally accepted hypotheses, otherwise there would be referenced works from other scientists and institutions. This ( http://adsabs.harvard.edu/preprint_service.html ) website is a reliable source of peer reviewed papers that both are referenced by other astronomers and reference other works. If you search that database for "2012 doomsday" you will find that the most scientifically accepted doomsday scenario revolves around dark energy and is estimated to happen no sooner than 10 billion years in the future. Hope this eases your mind, John Vickers
22) Message boards : Number crunching : Compute Errors (Message 24563) Posted 8 Jun 2009 by John Vickers Post: Hello MW@Home, Can you please tell me if these _2s_2 runs that were returning errors are all "ps_sgr_208_2s_2", all "ps_sgr_235_2s_1" or a mix of both? Thank You, John Vickers Edit: typo: "ps_sgr_235_2s_2" - > "ps_sgr_235_2s_1"
23) Message boards : Number crunching : Compute Errors (Message 24263) Posted 5 Jun 2009 by John Vickers Post: Hello MW@Home, These _3s_ runs are 3 stream runs that I started. I will tell Travis that there is a problem with them on the GPUs but not the CPUs and abort said run asap. Sorry for the inconvenience, John Vickers
24) Message boards : Number crunching : ScreenSaver? (Message 24109) Posted 3 Jun 2009 by John Vickers Post: Hello MilkyWay@Home, As you may or may not know, I am a new scientist working with BOINC. I don't really have the knowledge or expertise to put together a fancy screensaver, the best I could do is a basic slideshow. However, I do have access to a large number of images that were used in Nate's Thesis. Things like circular cross sections of the sky (how we visualize each individual stripe of data), the same circular cross sections with just the stream stars or just the field stars, arrow-plots of the stream direction in space etc. Check out this paper by Nate for an example of some of the pictures I can make. ( pg 44 onward http://arxiv.org/PS_cache/arxiv/pdf/0805/0805.2121v2.pdf ) If anyone has experience making screen savers and would like some images to work with, feel free to PM me. I would be happy to talk it over with you and supply a package of images. Cheers, John Vickers
25) Message boards : Number crunching : ps_sgr_test_* and ps_sgr_10_1s_1 (Message 24103) Posted 3 Jun 2009 by John Vickers Post: Hello MilkyWay@Home, As you may or may not know, I am a new scientist working with BOINC. In the past half hour I have started a number of runs attempting to verify that I can in fact do it. I've been having some weird issues for the past week but I think I've figured everything out. these ps_sgr_test_* files are from that. ps_sgr_10_1s_1 is an actual scientific run, but I accidentally set the integral size to be too small so when you get workunits from that you will probably run into the frustration mentioned in this thread ( http://milkyway.cs.rpi.edu/milkyway/forum_thread.php?id=878#24047 ). I apologize for that and will try to get that run ended as soon as possible. Thanks for your patience, John Vickers
26) Message boards : Number crunching : Sgr_Coordinates: 1 (Message 23975) Posted 2 Jun 2009 by John Vickers Post: Hello Milkyway@Home, As you may or may not know I'm a new scientist working with BOINC. Basically what I'm doing is picking up where Nate left off. Nate sucessfully used this Maximum Likelihood algorithm to plot out the location and characteristics of the Sagittarius Dwarf Tidal Stream as it flows through the Milky Way. The maximum likelihood code was built to run on SDSS (http://www.sdss.org/) data which is organized into 2.5 degree wide slices of sky. The orientation of the slices in 3D space is determined by the number of the stripe in the SDSS survey. As such-- the objects we study are positioned haphazardly inside the stripes, obliquely angled as it were. We are of the opinion that if we could transform these stripes so that they are permendicular to the stream we would enable the program to calculate more accurate results. So we looked to a paper by scientist Stephen Majewski (http://arxiv.org/abs/astro-ph/0304198) in which a coordinate system was described with the plane of the Sagittarius Dwarf debris being the equator. After transforming our standard spherical coordinates into the Sagittarian spherical coordinates, we took slices of the sky along longitudinal lines that are the same shape as SDSS stripes. Since the Sagittarius Stream is on the equator in these new coordinates, each longitudinal slice contains a perpendicular cross section of the stream by definition. <<Here is a picture of 2 slices in the same part of the sky.>> http://i698.photobucket.com/albums/vv346/vickej2/13ii.jpg?t=1243962157 http://i698.photobucket.com/albums/vv346/vickej2/35ii.jpg?t=1243962176 <<The first is an SDSS stripe, notice how the separated stream is very elongated. The second is in SGR geometry, notice how the stream is much more compact and circle shaped in the image-- it is still eliptical shaped in this plot because the distance is plotted in magnitudes, not real space>> After a little coding, viola, the program can calculate the exact same code using Sagittarius Geometry as well as SDSS geometry. The only difference is the algorithm for how the stripe number relates to actual position in 3D space. Last night with Travis' help, I started I believe 5 runs: ps_sgr_208_1 - ps_sgr_208_5. These 5 runs are of stripe 208 (any stripes above 200 denote sagittarius stripes, so stripe 200 is sagittarius stripe 8). You can easily tell if you are working on a Sagittarius stripe by looking in the parameter file and checking the "sgr_coordinates:" flag. 0 denotes SDSS geometry, 1 denotes SGR geometry. These runs are in a very controversial part of the experiment. Basically in this section of sky we are getting two different minima: one with the stream pointing toward the sun, and one with it pointing tangentially to the sun. This is a big topic of debate not only in our RPI research group, but in the astrophysics society as a whole. Hopefully with my new and improved cross sections some more light will be shed onto this area of the sky. <<Here is an overhead of the Sagittarian plane of debris with Nate's calculated vectors being plotted. I've circled the area of sky in question>> http://i698.photobucket.com/albums/vv346/vickej2/sky.jpg?t=1243962135 I look forward to working together, John Vickers P.S. I see a thread relating to the ps_sgr_208_test and the GPU application. I am fairly sure that Travis mentioned that the GPUs would have problems with the SGR geometry change when we were talking last night. The CPU applications seem to be running it correctly though. Apologies for the inconvenience.
27) Message boards : MilkyWay@home Science : Sloan Digital Sky Survey (Message 22855) Posted 21 May 2009 by John Vickers Post: We use the data gathered by the SDSS in our calculations for the MW@Home project. Surveys such as SDSS, SuperCOSMOS, 2MASS etc. each provide huge databases of star points used by astronomers, but do very little interpretation of the data. The interpretation is left to research astronomers. They provide the star points, we make sense of them. -John Vickers
28) Message boards : MilkyWay@home Science : Science progress with the new application? (Message 22716) Posted 19 May 2009 by John Vickers Post: Hello, By no means are we anywhere near out of work. We have plotted most of the Sagittarius Dwarf stream, yes. But we are looking into a new method of calculating that stream that will make our findings hopefully more accurate. We are also looking into modeling other streams. And after that we are going to try and model the Galactic Halo without any streams in it at all so we can understand it a bit better. After that... who knows? Cheers, John Vickers
29) Message boards : Number crunching : out of work? (Message 22715) Posted 19 May 2009 by John Vickers Post: Hello, Word on the Grapevine is.... "We're actually having a problem where our server is a bit overloaded so work can be rather scarce. Right now we're working on a fix to split our project into two separate ones (one specifically for GPU applications and the other for regular CPU applications) which should really cut down our server load so work can flow more smoothly. This should go live in the next week or so." Cheers, John Vickers
30) Message boards : MilkyWay@home Science : New scientists working with Milkyway@home (Message 22043) Posted 12 May 2009 by John Vickers Post: Hello, I'm also working with boinc over the summer-- I'm an undergraduate at RPI. I've actually been working with this program (the maximum likelihood calculator) since last summer. What I do is rearrange the star points we look at into a new spherical coordinate system with the object of interest (the Sagittarius Dwarf Stream) positioned on the equator. The reason behind this transformation has to do with the way the code analyzes the data: basically it takes 2.5 degree wide strips of data out of the sky and from there determines where the most dense areas of the sky are. Right now these strips of data are ordered in the manner in which the SDSS recorded them-- more based on the lgoistics of telescope running than data analysis. Thus when we look at these strips of data we see structures jumbled in at awkward orientations, sometimes perpendicular to the stripe, sometimes parallel. If we reorient these strips with respect to Sagittarius (from my coordinate transform) , so that the stream passes through them perpendicularly rather than at some oblique angle, we believe that the program will calculate more accurate information about the stream.

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