The Outsider's Inside View post#014 - High and Dry


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Profile KevinDouglasPhD
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Message 551905 - Posted: 23 Apr 2007, 21:56:56 UTC

Things are rolling along. I have 118 SETHI datacubes finished, and for the GALFA data I made a bunch of low-resolution cubes to check the quality. Here's an image showing some low-velocity HI gas across a large span of the Arecibo sky:



Right now I'm trying to merge another data set with the lower half of this dataset. This will lead to better calibration of the data since the region has been observed more than once, and with a different observing technique. I think the program might be hung on the last step, however. It has to invert a huge matrix and I'm not sure it's going to work.

We had a short group meeting this afternoon. We mostly talked about improving our outreach activities (more news on the front page, etc.) and dealing with workunits and results that get "orphaned" at some stage of the database. I think Dave said something about having a 64-bit boinc client soon, so maybe we can have SETI@home for 64-bit machines in the near future. And earlier today we had a visit from a donor from Canada who helped bruno to come into existence.

So tonight is the last game of the first round of the NHL playoffs. If Vancouver wins, I'll have predicted 7 of the 8 first-round winners. It was tough to see Calgary lose last night but they gave Detroit a good run. That Hasek is still one of the best goalies around.

Profile Byron Leigh Hatch @ team Carl SaganProject donor
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Message 552012 - Posted: 24 Apr 2007, 0:53:13 UTC



WTG Kevin! Looks Good!


If Vancouver wins,

what ya mean if Vancouver wins ..... of course Vancouver will win! ... ;-)

heheheheheheh.... :-)))) ... LOL .....

Best Wishes
Byron

Wander Saito
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Message 552050 - Posted: 24 Apr 2007, 1:47:46 UTC

Hi Kevin,

I'm no astronomer but I'm a space buff and a long time trekker, so let me just say that those images you post are astonishing!! And you say this is low-res??
I hope you plan to post a complete picture once you get done processing all those datacubes you keep telling us about. Thanks!!

Regards,
Wander

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Message 552195 - Posted: 24 Apr 2007, 5:33:18 UTC

Hi Kevin

That's a real nice image. I was wondering, with all this processing of data, writing your own software to analyze it etc, how do you validate your results? I suppose it does not look anything like this in visible light?

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Message 552200 - Posted: 24 Apr 2007, 5:49:27 UTC

MOAR we say. Engulf us in science pls! I dunno as others, but i cant wait till i see this pic in full scale:)

Congratulations, btw!
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Message 552218 - Posted: 24 Apr 2007, 6:31:39 UTC - in response to Message 552050.

And you say this is low-res??

Consider the scale: the image is about 150° across, so represents a view of the sky that would stretch nearly from horizon to horizon.

For general orientation, here’s a star-chart (actually a screen-capture from xephem) of the area inside Kevin’s green box:



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Profile KevinDouglasPhD
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Message 552442 - Posted: 24 Apr 2007, 21:44:27 UTC - in response to Message 552012.



WTG Kevin! Looks Good!

If Vancouver wins,

what ya mean if Vancouver wins ..... of course Vancouver will win! ... ;-)

heheheheheheh.... :-)))) ... LOL .....

Best Wishes
Byron


Good call! Now I'm glad the Sharks and Canucks won't have to play each other until the third round...Detroit and Anaheim are going down!

I should have mentioned that the GALFA cubes I made were low-resolution in terms of velocity. In terms of angular resolution, they're pretty high-res. As for haba's question about how to validate the results, the best thing we can probably do is to compare it to previous HI surveys, such as the canonical Leiden-Dwingeloo Survey; even though its angular resolution is about 10 times worse than ours, if we smooth our maps to the LDS resolution they should agree. Both the SETHI and GALFA datasets are compared to LDS somewhere along their respective reduction pipelines. It seems to be working well.

I discovered yesterday (with some help) that there are a tiny number of seconds in my GALFA survey data that have bad spectra, such as the one on the left here:



Out of 192 days of data, I think I've found about 70 spectra, of one-second duration each, that look like this. The problem is, when you compare that spectrum to another one at the same coordinate in the sky (like the one on the right), your polynomial fit to find the relative scaling factor between them comes out very wrong, ie the evil NaN! I think this is what was hanging my matrix-inversion of yesterday's post. So I believe I've solved this problem. Also my 120th SETHI datacube finished, so I am 5/6 of the way to being done. It's been a good day.

Profile Byron Leigh Hatch @ team Carl SaganProject donor
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Message 552473 - Posted: 24 Apr 2007, 22:19:11 UTC - in response to Message 552442.






WTG Kevin! Looks Good!

If Vancouver wins,

what ya mean if Vancouver wins ..... of course Vancouver will win! ... ;-)

heheheheheheh.... :-)))) ... LOL .....

Best Wishes
Byron


Good call! Now I'm glad the Sharks and Canucks won't have to play each other until the third round...Detroit and Anaheim are going down!
...
<snip>
...
It's been a good day.
Kevin

Hi Kevin ,

I'm glad to hear you had a good day!
Keep up the good work!

Best Wishes
Byron

Profile KevinDouglasPhD
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Message 554256 - Posted: 26 Apr 2007, 18:45:32 UTC - in response to Message 552473.

Here's today's propaganda about how cool my job is. The first image is a region of the sky as imaged by the Leiden-Dwingeloo Survey, for low-velocity HI:



Now, here's what it looks like with my SETHI data (the images aren't exactly the same sky coverage, but close enough):



And finally, here's what I get from the GALFA survey (TOGS) when I combine it with another GALFA project:



Enjoy.

haba
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Message 554631 - Posted: 27 Apr 2007, 4:51:05 UTC

I'm impressed. Well done Kevin!

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Message 554791 - Posted: 27 Apr 2007, 12:27:08 UTC

I,m not sure where to take this, but being a seti user since 2000, i feel when the program changed to Bionic our old classic seti units should of been converted to bionic credits.
Rather than just stating OLD classic total :(, anyway im sure im talking to myself, i just keep losing interest in seti now, i wish they thought about it a bit more.......


Just an old user not happy........
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Profile Dr. C.E.T.I.
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Message 554820 - Posted: 27 Apr 2007, 14:32:23 UTC

Thank You Kevin - Beautiful Work there Sir! (for the *Science* A+)

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Profile Jim Baize
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Message 554882 - Posted: 27 Apr 2007, 18:31:40 UTC - in response to Message 554791.

I,m not sure where to take this, but being a seti user since 2000, i feel when the program changed to Bionic our old classic seti units should of been converted to bionic credits.
Rather than just stating OLD classic total :(, anyway im sure im talking to myself, i just keep losing interest in seti now, i wish they thought about it a bit more.......


Just an old user not happy........



this issue has been discussed ad nauseam. There are lots of reasons that seti classic could not be converted to seti boinc. If you feel so inclined, you can do a search of the message boards and find all the reading you can handle, and then some.

Good luck on finding the answer to that for which you seek.
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Message 554939 - Posted: 27 Apr 2007, 20:30:11 UTC - in response to Message 554791.

I,m not sure where to take this, but being a seti user since 2000, i feel when the program changed to Bionic our old classic seti units should of been converted to bionic credits.
Rather than just stating OLD classic total :(, anyway im sure im talking to myself, i just keep losing interest in seti now, i wish they thought about it a bit more.......


Just an old user not happy........

Here is the 'Berkeley, "Matt's" View'
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Message boards : SETI@home Staff Blog : The Outsider's Inside View post#014 - High and Dry

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