Today:
Axes fixed
Contour RA-Dec plots are now beautiful.
Random position generator
Given the code to get me going. Set up a randomu and manipulated the arrays to have values within the RA's and Dec's of the GOODS-N field. Spherematched these with actual data positions to accommodate the odd shape of the footprint. Plotted 500 of the random sample of stars (and oplotted the GOODS survey), so check that they overlapped properly. Oddly, the Dec's range was fine, but the outer endges of the RA's got chopped off. Wasn't obvious to me how this happened by looking at the code, so this will be addressed tomorrow.
Tomorrow:
Random position cont...
-check out why edges got cut off
-make for southern field
-emperical comparison to observed stars' positions
Wednesday, July 15, 2009
Tuesday, July 14, 2009
Contoured Density Plots
Started off the day going over isochrone images with Beth
The Besancon Model still seems puzzling, showing a lot of faint red stars. The Trilegal looks better, and the isochrone fitted at 20kpc nearly follows the line of stars (great by my standards, since in my limited experience few things have lined up nearly this well, but Beth mentioned some discrepancies). We determined that the disk/halo stars cut-off should be at a v-i of 1.5.
I haven't yet started working the separated stars yet, as I got distracted today...
Distribution, smoothing, significance
Brainstorming ensues. Beth explained how the smoothing worked a little bit, which brought up some minor pixel issues. To get out the edges and contrasts we wanted, I used SEARCH2D to make a pixel map of just 1's and 0's to separate the outer area with no data. The significance ((image-mean)/stddev) was taken of the data, and plotted with the "nodata" area set to 0.0 on the grey-scale. I also made an accompanying histogram of n-sigma; it wasn't Gaussian but it had the right tailing-off-shape.
Went to talk on BLAST-thought it was cool
Contour lines
Adding to the distribution density plot are now contour lines. It took me pretty much all afternoon figuring out and working on the code from Beth to make these show up properly. In the end, with a little typo-spotting help from Gail, I got it to work. I even patted myself on the back a little for going back making the contour lines shift from black to white so that you could still distinguish them on the lighter and darker areas. Only problems are the axes... even more so when I tried to make another plot of the northern field (as I'd been working primarily with the southern one all day, and didn't want the poor guy to feel neglected).
Tomorrow:
(in no particular order)
Fixing axes
-Go through code again and see if I can't find the problem
-If not, talk to Beth about it
Implement color-cut
Random distribution generator
The Besancon Model still seems puzzling, showing a lot of faint red stars. The Trilegal looks better, and the isochrone fitted at 20kpc nearly follows the line of stars (great by my standards, since in my limited experience few things have lined up nearly this well, but Beth mentioned some discrepancies). We determined that the disk/halo stars cut-off should be at a v-i of 1.5.
I haven't yet started working the separated stars yet, as I got distracted today...
Distribution, smoothing, significance
Brainstorming ensues. Beth explained how the smoothing worked a little bit, which brought up some minor pixel issues. To get out the edges and contrasts we wanted, I used SEARCH2D to make a pixel map of just 1's and 0's to separate the outer area with no data. The significance ((image-mean)/stddev) was taken of the data, and plotted with the "nodata" area set to 0.0 on the grey-scale. I also made an accompanying histogram of n-sigma; it wasn't Gaussian but it had the right tailing-off-shape.
Went to talk on BLAST-thought it was cool
Contour lines
Adding to the distribution density plot are now contour lines. It took me pretty much all afternoon figuring out and working on the code from Beth to make these show up properly. In the end, with a little typo-spotting help from Gail, I got it to work. I even patted myself on the back a little for going back making the contour lines shift from black to white so that you could still distinguish them on the lighter and darker areas. Only problems are the axes... even more so when I tried to make another plot of the northern field (as I'd been working primarily with the southern one all day, and didn't want the poor guy to feel neglected).
Tomorrow:
(in no particular order)
Fixing axes
-Go through code again and see if I can't find the problem
-If not, talk to Beth about it
Implement color-cut
Random distribution generator
Monday, July 13, 2009
Isochrones
Finishing up from last week, I made gray-scale RA-Dec density plots, hess-style. Also considering going back to cutting out some of the faintest blue objects.
With some new direction on how to proceed in looking at the distributions of the GOODS stars, I set out with it in mind to select out the disk vs halo stars into two groups. Using our brains for this, I started with an isochrone generated online to check where on the Trilegal model it would fall. I had to convert it from Absolute to Apparent magnitude, using 20kpc as the distance. I was pleased to find that the curve fell along the stars in my hess diagram.
Next is to use magnitude and color limits to pick out the groups of stars and check out their distributions for any kind of structure or randomness.
With some new direction on how to proceed in looking at the distributions of the GOODS stars, I set out with it in mind to select out the disk vs halo stars into two groups. Using our brains for this, I started with an isochrone generated online to check where on the Trilegal model it would fall. I had to convert it from Absolute to Apparent magnitude, using 20kpc as the distance. I was pleased to find that the curve fell along the stars in my hess diagram.
Next is to use magnitude and color limits to pick out the groups of stars and check out their distributions for any kind of structure or randomness.
Friday, July 10, 2009
Enough of this stuff, It's Friday, I'm in love
Yep, it's Friday. And I like that song. ^_^
So, with my nice new star catalogs, as of this morning I have:
1) made RA-Dec plots
2) made CMDs
3) made a histogram of the distribution of apparent magnitudes
4) done the above for the Besancon Model catalog for comparison
The N and S catalogs have 1151 and 1175 stars in them, respectively. In the RA-Dec plots their distribution appears pretty homogeneous across the fields. About 35% of the stars are magnitude 26.5 or brighter, and these have overall the same kind of random distribution, but with some odd voids in areas. (In the future- may consider a random coordinates generator to see the probabilities of distributions, to see if these voids are significant.)
The magnitude distribution of the model is of a similar shape, but with more evenly increasing numbers the fainter the stars, rather than the leap in numbers from brighter to fainter in the GOODS stars.
This afternoon I did a lot:
I started using the Trilegal model as another comparison for a star catalog.
I also learned how to make a Hess diagram, and with a little help from code from Alex and some of Dylan's work, I got it to work by the end of the day.
Further project direction Monday.
So, with my nice new star catalogs, as of this morning I have:
1) made RA-Dec plots
2) made CMDs
3) made a histogram of the distribution of apparent magnitudes
4) done the above for the Besancon Model catalog for comparison
The N and S catalogs have 1151 and 1175 stars in them, respectively. In the RA-Dec plots their distribution appears pretty homogeneous across the fields. About 35% of the stars are magnitude 26.5 or brighter, and these have overall the same kind of random distribution, but with some odd voids in areas. (In the future- may consider a random coordinates generator to see the probabilities of distributions, to see if these voids are significant.)
The magnitude distribution of the model is of a similar shape, but with more evenly increasing numbers the fainter the stars, rather than the leap in numbers from brighter to fainter in the GOODS stars.
This afternoon I did a lot:
I started using the Trilegal model as another comparison for a star catalog.
I also learned how to make a Hess diagram, and with a little help from code from Alex and some of Dylan's work, I got it to work by the end of the day.
Further project direction Monday.
Wednesday, July 8, 2009
I'm Baaaaack!
I have returned from the British Isles and returned to work.
Since I had put together my research summary paper before leaving, it was easy to review and jump back in right where I left off. I spent the morning cleaning up a few things in my paper, and then spent most of the day working on polishing up and finalizing my flux-ratio cut-off. By group meeting after lunch I'd made a few plots trying to be more precise with my parameters and sort through the data, systematically eliminating fainter objects that clouded over the color-color plot and getting down to the good stars. By the end of the day I made the final call: up to 1.4 (best at magnitude 26.5 or brighter, but am including up to 28).
That being done, I now have my stars catalog and am going to look at their distributions.
Since I had put together my research summary paper before leaving, it was easy to review and jump back in right where I left off. I spent the morning cleaning up a few things in my paper, and then spent most of the day working on polishing up and finalizing my flux-ratio cut-off. By group meeting after lunch I'd made a few plots trying to be more precise with my parameters and sort through the data, systematically eliminating fainter objects that clouded over the color-color plot and getting down to the good stars. By the end of the day I made the final call: up to 1.4 (best at magnitude 26.5 or brighter, but am including up to 28).
That being done, I now have my stars catalog and am going to look at their distributions.
Monday, June 22, 2009
Latex, but not like the glove...
Been learning how to use LaTeX today to write up my work. Because I just started with a template made by Beth from Astro 333, it hasn't been hard to get going. I'm just plugging in my graphics and describing my process. (For the sake of good record keeping, and so that I can jump back in easily without losses when I get back from vacation.)
What was really exciting was that after I went back and looked at a color-color plot of my star catalogs (about 1000 stars in each field!) that made last Friday, it showed the sequence brilliantly. I color coded a few kinds of stars to look at, namely a "faint" vs "bright" parameter (25th mag cutoff), and a now a flux ratio cut off, where anything less than 1.3 was displayed in a group, and another group of 1.3-1.5. The sequence was made up almost entirely of the <1.3, with only a few bright stars from the other group along the stream. I plan on going back to this to see how far past the cut-off those good-looking stars are, after I finish my LaTeX-ing. Which may mean after I get back from my two weeks away.
I'm going to finish up my LaTeX-ing tomorrow morning, and then I'm off to the U.K.
Cheerio then!
What was really exciting was that after I went back and looked at a color-color plot of my star catalogs (about 1000 stars in each field!) that made last Friday, it showed the sequence brilliantly. I color coded a few kinds of stars to look at, namely a "faint" vs "bright" parameter (25th mag cutoff), and a now a flux ratio cut off, where anything less than 1.3 was displayed in a group, and another group of 1.3-1.5. The sequence was made up almost entirely of the <1.3, with only a few bright stars from the other group along the stream. I plan on going back to this to see how far past the cut-off those good-looking stars are, after I finish my LaTeX-ing. Which may mean after I get back from my two weeks away.
I'm going to finish up my LaTeX-ing tomorrow morning, and then I'm off to the U.K.
Cheerio then!
Thursday, June 18, 2009
Two down, plenty left to go...
About to finish up item 3 of the Plan.
The past few days I've just been going through and documenting my star-picking process and kind of taking inventory of my really good graphics and adjusting them for updated parameters. My official classification cut-off is now 0.75-1.0 for stars.
Today I have been working on the flux-ratios. My hope is that two peaks will appear on my histogram and help me pick a parameter to further weed out a few galaxies (which would correspond to the anomalous lines, that don't fit a star's profile, on my aperture magnitude vs aperture radius plots). When I went through, I was careful with my math in my code, making sure I had done my distance modulus algebra correctly and all, and made some good histograms.
THEN somewhere down the line I realized I'd in fact still managed to input my magnitudes backwards. I had the equations set up correctly, but instead of solving for flux(ap11)/flux(ap8) I had gotten flux(ap8)/flux(ap11). Not a huge deal, so I just flipped 'em around to see where that got me.
What's left to do is really look at their peaks (i.e. I've been looking at them, but am unsure what to do with what I see, and need to consult Beth in the morning, and compare "star" vs "galaxy" peaks, etc.), and pick a parameter, like flux ratios greater than 1 are in fact galaxies and discard those from my star catalog.
Then: vacation, and then moving on with the Plan.
The past few days I've just been going through and documenting my star-picking process and kind of taking inventory of my really good graphics and adjusting them for updated parameters. My official classification cut-off is now 0.75-1.0 for stars.
Today I have been working on the flux-ratios. My hope is that two peaks will appear on my histogram and help me pick a parameter to further weed out a few galaxies (which would correspond to the anomalous lines, that don't fit a star's profile, on my aperture magnitude vs aperture radius plots). When I went through, I was careful with my math in my code, making sure I had done my distance modulus algebra correctly and all, and made some good histograms.
THEN somewhere down the line I realized I'd in fact still managed to input my magnitudes backwards. I had the equations set up correctly, but instead of solving for flux(ap11)/flux(ap8) I had gotten flux(ap8)/flux(ap11). Not a huge deal, so I just flipped 'em around to see where that got me.
What's left to do is really look at their peaks (i.e. I've been looking at them, but am unsure what to do with what I see, and need to consult Beth in the morning, and compare "star" vs "galaxy" peaks, etc.), and pick a parameter, like flux ratios greater than 1 are in fact galaxies and discard those from my star catalog.
Then: vacation, and then moving on with the Plan.
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