Search found 26 matches

by claw
Mon Jun 02, 2014 1:00 am
Forum: Galactic Working Group
Topic: Galactic counter proposal
Replies: 17
Views: 4915

Re: Galactic counter proposal

And one more refinement to the calculation above...
Including the scaling at high and low Declination, plus integrating over the whole sky down to Dec=-40, the enhancement needed to get uniform sensitivity is 14%. 12% of that is at low Dec, 2% is at high Dec (starting around +80 deg).

casey
by claw
Sun Jun 01, 2014 8:48 pm
Forum: Galactic Working Group
Topic: Galactic counter proposal
Replies: 17
Views: 4915

Re: Galactic counter proposal

Hey Everyone, I finished my estimate of the extra time needed to get uniform sensitivity at negative declinations. The principle effect I consider here is larger Tsys from spillover at low elevations. This does not consider confusion or sky Tsys effects, which are generally small except in the inner...
by claw
Fri May 30, 2014 5:42 pm
Forum: Galactic Working Group
Topic: Galactic counter proposal
Replies: 17
Views: 4915

Re: Galactic counter proposal

Hi Everyone, Thanks for putting your thoughts down again. I wanted to update you on the track the discussion has headed lately. This coming Monday, we are expected to come together on a consensus and start doling out writing assignments. The plan now is for a pure S-band survey (in something close t...
by claw
Tue May 20, 2014 6:03 pm
Forum: Galactic Working Group
Topic: Galactic counter proposal
Replies: 17
Views: 4915

Galactic counter proposal

Hi All, The current process of defining the VLASS has a baseline plan of a S-band, B-config all-sky survey. We are currently waiting for proposals to modify that baseline, while still fitting in the same ~8000 hour survey duration. I've found myself wondering if there are relatively small modificati...
by claw
Mon May 05, 2014 1:29 pm
Forum: Technical Working Group
Topic: Signal-to-noise as a function of spectral index
Replies: 3
Views: 3065

Re: Signal-to-noise as a function of spectral index

After a quick look, one of the best is from Kimball & Ivezic (2008): http://iopscience.iop.org/1538-3881/136/2/684/pdf/aj_136_2_684.pdf. They construct a master catalog of FIRST, NVSS, GB6, WENSS, and SDSS. They include a number of tests and discriminations of morphology, etc. The most relevant ...
by claw
Sun May 04, 2014 4:34 pm
Forum: Technical Working Group
Topic: Signal-to-noise as a function of spectral index
Replies: 3
Views: 3065

Re: Signal-to-noise as a function of spectral index

Great stuff again, Rick.
For context, it would be nice to overplot a histogram of the spectral index of all FIRST/NVSS sources. Do you know the best reference for such a data product?

casey
by claw
Wed Apr 30, 2014 1:52 pm
Forum: Technical Working Group
Topic: Accuracy of positions in low resolution surveys
Replies: 1
Views: 1851

Re: Accuracy of positions in low resolution surveys

Thanks for posting this, Rick. Great analysis and a good way to highlight the uniqueness of the VLA. One follow up question... You note that the radius of association may change with different survey depths (populations). Can you test your conclusion for a Galactic population? As far as I know, the ...
by claw
Fri Apr 18, 2014 5:56 pm
Forum: Galactic Working Group
Topic: where we stand
Replies: 16
Views: 4169

Re: where we stand

The reference to A config was in the context of the consensus survey, which is at S band. The consensus was drawn up last week by the science WG chairs. It is by no means final, but it is starting to sound like a plan that most people can get behind. If you think a revised GUTS white paper would hel...
by claw
Fri Apr 18, 2014 4:59 pm
Forum: Galactic Working Group
Topic: where we stand
Replies: 16
Views: 4169

Re: where we stand

Fair enough. Using the calculator, a depth of 90 mJy at band center will require ~3000 to observe the Galactic plane defined in GUTS. (Going to 80 microJy bumps it up to 3600 hours, so I thought it better to round the time down and keep a nice round depth value.) So, going back to Rachel's question:...
by claw
Thu Apr 17, 2014 8:43 pm
Forum: Galactic Working Group
Topic: where we stand
Replies: 16
Views: 4169

Re: where we stand

Hi Lorant, I think Steve explained the way we calculate the survey speed most completely in the topic I started on the VLASS calculator. Take a look in the middle of the discussion: https://science.nrao.edu/forums/viewtopic.php?f=62&t=143&start=10 As we've discussed, you are free to target a...

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