Friday, July 30, 2010

Final Post!

Wow, where have ten weeks gone? It seems like yesterday that I was just starting out, and didn't even know what a stealth galaxy was...

It's been incredible, learning so much so quickly. I feel extremely grateful for the opportunity to work for Beth and with the other people in lab. Research is cool! I know that sounds strange, but I may not have been able to say that at the beginning of the summer. It's been great working out problems without the structure of the school year, and getting to focus on the actual science.

Now, I also feel deeply invested in this project. I hope that I'm able to continue working with it, and I hope that others will be able to work with it as well. I tried to leave excessive documentation of my work so anyone can simply pick up where I left off...

For now, I'm off to Hawaii for the semester! Lot's of Astronomy out there, and I can't wait to see what it's like. (Be sure to check out updates on Astronoblog!)

Thanks, Summer. It's been great.

Thursday, July 29, 2010

One more day and much to do...

With one work day left, there's a ton to be done and tied up before I get out of here. Here's my to-do list as given by Beth this morning:

1. Run a BIG simulation of 4000 fake galaxies
2. Create a code that visualizes detectability as a function of galaxy size and total absolute magnitude
3. Run a few mini-tests to make sure that the results from my simulation match up with the results from Shane Walsh's simulation in "The Invisibles" paper.

I've made progress on the second two tremendously since morning, but they won't be done until I have more time to spend with them tomorrow. The big simulation will be run overnight-- It should take about 15 hours.

But there are updates, too! Beth found a bug in my old OLD code that generated the number of stars in a galaxy given a total absolute magnitude. It was only producing about half the number of stars it should have, thus making WAY too stealthy. Now, the detections are stronger. (Maybe too strong?) Beth says it will be necessary to go over every line of code before making any weighty conclusions from this, but if this many galaxies are truly being detected (~150/400), then we can say that Andromeda XIX - type galaxies do not exist around the Milky Way because they would have been detected by now...

All for now. Tomorrow's going to be a big day

Tuesday, July 27, 2010

Back on track... (?)

After a great deal of time, I realize that my concerns from yesterday were incredibly naive. I was concerned because my detections were no longer strong, and I thought there was an invisible bug that magically appeared in my code.

I realize now, though, that this was never the case, and my "working" code was not as strong as I thought. The detections are weak, which is why we were originally going to change the smoothing filter. The only reason I got a chunk of strong detections at the end of last week was because I ran a larger simulation. These galaxies, which are between 1-2 kpc in half-light radius, are incredibly stealthy, and thus hard to detect given the original search parameters. So, when I run small simulations with only 5-10 repetitions, hardly anything, (or nothing at all), pops out.

In other words:

CONCLUSION: In order to truly test the detectability of AndXIX-type galaxies around the Milky Way, the search parameters need to be changed. This needs to be done carefully, however, because when we tried this last week, nothing changed.

I will not detail the amount of stupid things I did this morning to come to this conclusion. Let's just say when you svn "revert", you loose a lot of stuff. However, I think it was good for this to happen, as frustrating as it was, because now I have a deeper understanding of the search algorithm and how it works.

Monday, July 26, 2010

It's like when your toys come to life when you leave the room...

For whatever reason, my simulation no longer works. On Friday, I made all kinds of cool and interesting adjustments to my Search code that allowed each galaxy to have a range of scale sizes and absolute magnitudes, not just the one specific to AndXIX. It worked out great, and I made some beautiful figures with the output files on the data that matched.

Today, I was tweaking the code SO slightly, and now the search code won't detect anything anymore. I tried going back to the original version from this morning, and no luck. It won't work. Something must have been changed, but where?? In order to proceed, I need to learn how to go back to previous versions on our version-controlled svn directory.

This is all too bad, too, because the small change I'm making is going to make the search and match process a lot more exact. Instead of having all of the detections compared to the inserted galaxies, only the detections from a given run will be compared to the galaxies of that same run. That way, we know the detections are really being matched to a single galaxy. I'm eager to do this, and would like to get past this other problem...

Tomorrow, I suppose... Only 4 days left!

Thursday, July 22, 2010

Serious Simulations

Today was the day to up the ante on this simulation. Now, instead of generating, inserting, and searching for 40 stealth galaxies in a set of SDSS data, we're working with FOUR HUNDRED simulated galaxies!

VERY cool to run a big simulation like that, but it takes over an hour and a half... so, I've also been working on other things, like combining the code that generates, the code that inserts, and the code that searches into ONE GIANT code. I spent quite a while not only making that functional, but then also cleaning it up to make it as succinct as possible. I've also, y'know, been adding to my LaTeX document (... what else is new?)

So what are the results from this giant test? Well, while the code did a great job finding these stealths, the detections weren't good enough. All but one of the detections were classified as "weak," meaning that they would be indistinguishable from other overdensities in a given sky survey. So, the next step will be to tweak the search parameters to change the size of the smoothing filter and hopefully make these detections stronger. Mimi has been working on this aspect of the project, and it will be nice to collaborate with her more again...

Six days left! I can't believe it...

Wednesday, July 21, 2010

more detection tests

Not a ton of new stuff, unfortunately, considering it's been a week, but progress is being made.

Earlier this week, I finished up some RCS2 tests, and looked at the results when 100% of the background was placed with the input stealths. Depending on the detectability threshold used during SPHEREMATCH, the algorithm found anywhere between 23 and 31 out of the 40 stealths... not too shabby.

Yesterday, I worked to generalize all the code for SDSS and clean up the repository so that all SDSS and RCS2 code were in separate subdirectories. I was simultaneously working to run similar detectability tests with the SDSS data when Beth realized that the data we got was faulty. Instead of giving nice, clean, rectangular strips, it gave curved bits that were hard to analyze. So, when I ran the tests, nothing popped out.

Now, I have a tiny chunk of SDSS data to play with, but something's still wrong. I've run many tests this morning, and even when I shrink the "stealths" to a concentrated area (half-light radius of 100pc), and lighten the background to 1/100 of the full dataset, hardly any detections are found, and all detections are placed in the "weak" category. There must be a bug somewhere, but I've been reading and re-reading all my code, and can't seem to find the problem. Maybe this little SDSS dataset isnt' much better? It's not a prefect rectangle, but instead looks like a staircase within the box. I wonder if this is the issue...

Either way, there's a week and half left, and this project will soon be coming to a close! My goal for the end is to have the code be fully debugged and generalized so it can be used by anyone who picks up this project, (myself included?). It would also be nice to have some semi-concrete results from these detectability tests so we can know how to proceed. Finally, it's important for me to have a fully updated LaTeX document, so I can have an available summary of my work from this summer.

Thursday, July 15, 2010

Big Day

The day started out with an email from Beth with the above subject line, and a HUGE to-do list. Needless to say, it's been an incredibly productive day.

Here's what happened:

1. Running the debugged (!!!) Search Algorithm: Beth debugged that code like a total pro yesterday, and this morning, the Search Algorithm was working exactly as it should. I ran some tests to make sure this was SUPER true, which it was.

2. Matching detections to input galaxies: I added to an output analysis file that looks at the detections and how they match with the inserted fakes. Now, not only does this file tell us which fakes were detected, but it also outputs a data structure with information on those detections. Info includes: distance to detected galaxy, distance modulus filter used to detect galaxy, peak signal, area of detection [sq arcmin], and area of galaxy at half-light radius [sq arcmin].

3. Analyzing output data with figures: With this information, I began making plots that analyzed this data. As the fakes become stealthier and the data more robust, this code will easily adapt.

4. Making stealthier galaxies: We started out with galaxies with half-light radii of 200 pc, which isn't very stealthy at all, but was good while writing code and running tests. Now, we're using galaxies with half-light radii of 1683 pc -- the size of And XIX. Now detectability will no longer be as certain.

5. Odds and ends. I edited some code which output the average number of stars per degree during the search process. I cleaned up a few files. I made a directory for my SDSS files...

Up next: Making galaxies even stealthier. Or, rather, making the background more realistic. Right now, we're placing these stealths in only 10% of the RCS2 background data. With 100% of the data, these simulated galaxies will be MUCH harder to detect.

And that's all until next week! Tomorrow the gang goes rafting!

Wednesday, July 14, 2010

A big update for little progress

I'm afraid I haven't updated in over a week because the process I've been going through has been extremely slow-going.

After the data was inserted into the RCS2 background last week, I've worked to run Beth's search algorithm on this data. But something's not working right. So, mostly I've been running tests, and debugging small things that I understand. Meanwhile, Beth has been working with me to try to figure out what the bigger problem is.

Here's how we know something's wrong: we run the search code, and when it detects something, it spits out information about that detection to an output file, (RA, Dec, distance modulus...). But the detections have been funky. Either they output nonsensical values, or output the same values over and over, or output values that do not relate to our generated fakes, (this is the latest problem). The code takes forever to run, and so its been a process of trying to debug, waiting a while, and seeing that it's still not right.

So, to maintain my sanity, I've been trying to do other things to keep busy. Yesterday I converted my code to use SDSS data as background, instead of RCS2. Today, I'm working on adding to my LaTeX document with updates from the past few weeks. It's pretty crazy to read about what I was doing 4 weeks ago, and realizing how far I've come...

Hopefully this search code debugging business will straighten itself out soon. Ultimately, we'd like to use it to test the detectability of Stealths, and figure out which galaxies we could be missing completely with current methods of detection.

Tuesday, July 6, 2010

Simulated Stealths Hidden!

Code written, and now the simulated stealths are "stuffed" into the RCS2 background! I even had some figures to bring to group meeting today, showing the CMD and positions for one "layer" of the simulation. The position graph pointed out a flaw in my coding, and I was able to correct it later this afternoon.

Hooray! SO, NEXT STEP: tweaking the code so it stuffs in 1 dwarf at a time, instead of 5. Figure out how long that takes. THEN: Run Beth's search algorithm, and compare output to input to see which stealths pop out, and which are too stealthy to be caught! (i.e., finding a possible detectability limit.) ALONG THE WAY: output data on distance, and central RAs and DECs of each galaxy into an ascii file.

This is quite great progress from one week ago. I'd like to think I'm getting better (good, even?) at complex code writing.

Monday, July 5, 2010

Dwarf Simulation Complete!

Hooray! Now I have the r and g magnitudes, magnitude errors, and positions of all stars in 50 simulated dwarfs with the same absolute magnitude and scale size as Andromeda XIX!

I was able to finish the code and debug by the time Beth came to lab this afternoon, which felt like a huge success, given how stuck I was this morning.

NEXT STEP: putting these fakes into RCS2 (and eventually SDSS) data! I've started the code for that, and hope to complete it tomorrow morning.

Still tugging away

Still working on complex coding. Right now, I'm concentrating on creating a file that simulates 50 fakes-- 10 each at 5 different distances. More FOR loops, and FOR loops inside FOR loops, and IF statements, and stuffing all of that into a data structure...

I will admit, I am feeling a little lost. This morning, I've been trying to debug old problems from Firday, as well as adding new layers onto the process. It's getting frustrating, because I'm losing sight of what I'm actually trying to do. (Maybe blogging all of this out will help.)

So, the steps for this process are as follows. My confusion comes when trying to think about the ORDER these steps need to fall in:

- using previously written code, simulate magnitudes (in both r and g band), magnitude errors, and x&y positions from the center of the fake (in units of arcmin) for each individual star in each simulated dwarf.

- For the above, simulate over 5 distance categories: 50, 100, 200, 300, and 500 kpc.

- For the above, simulate 10 times for each distance category

- Take data from all 50 simulated fake dwarf galaxies, and stuff into fits binary table. Every star should also have a reference number 1-50 that associates it with its galaxy.


Thursday, July 1, 2010

Feeling a little FOR Loop-y

Debugging is hard. Especially with FOR loops.

I have one file that creates the most beautiful simulated CMDs of a given absolute magnitude (the absolute magnitude of And XIX, to be exact), projected to five different distances. The issue is, the code was long and sloppy. I was hoping to condense the code using a FOR loop in a different file, but I've been banging my head against some error messages all morning. Every time I make progress and fix a problem, another one pops up. I'd really like to learn how to debug this more efficiently so I can have more efficient code!

However, we have to think positiviely-- my coding is becoming pretty sophisticated, and that's definitely something to be proud of. This code utilizes three different functions written to simulate different aspects of these dwarfs. It's pretty great that I'm able to do that.

... Now I just have to get to the next step...

Monday, June 28, 2010

Unsuccessful and Unsatisfying

I usually post good, happy bits, but I'm not feeling too hot about today.

Goal: write some code to take a file with info on 4 million+ stars and create a function that relates apparent magnitude to magnitude and color errors. This will then be useful when generating more accurate CMDs.

I did start this, and eventually created another file that only used data of 500,000 stars so IDL would run faster. However, I spent quite a few hours working with the 4 million star fits binary table, so a lot of my time was spent waiting (and waiting, and waiting) for IDL to give me a different error message. Not a great feeling. Also, my for loop is irky, and I don't feel really experienced enough to debug it properly.

Tomorrow morning hopefully I'll figure this out. Especially because our group meeting tomorrow marks the halfway point for research and we will share our progress from the last 5 weeks, and goals for the next 5 weeks. I've been really good about bringing things (figures) to group meetings, but I'm afraid my rut will prevent me to bring my usual good news and progress...

Friday, June 25, 2010

Quick Friday Update

Today officially marks the halfway point of this summer research extravaganza!

I was not nearly as productive as I would have liked to be today, but I did get some things done. Mostly, I worked to write functions that create a fake CMD given a certain isochrone. I eventually got a product, but it took far too long, in my personal opinion. Gail and Mimi both headed out early, and so instead of persistently asking questions, as I typically do, I pushed through and figured it out more or less independently. That definitely got frustrating at times, but I feel like I have a deeper understanding now of how to write functions in general.

So, hooray for the weekend! In between lines of code for the past few weeks, I have been creating the greatest Summer Music Mix that has ever been put together. Today I finished it, so if any of my many millions of readers out there want a copy, just give a holler.

Thursday, June 24, 2010

Fake Progress

I mean, it's real progress, but my fake dwarfs are progressing quite nicely.

Yesterday, I did some more IDL learning, and wrote functions generating star positions in fake galaxies that fit an exponential, circularly symmetric model. Today, I wrote a function converting these positions into x and y coordinates in terms of exponential scale lengths. Beth then gave me a little bit of contour-plot bootcamp, and she helped me produce this little number:

... nice, huh?

This afternoon, I worked on creating a function to convert these x and y coordinates in units of exponential scale lengths to angular size in units of arcmin, as well as plotting an isochrone of an old, metal poor galaxy, as provided to me by Mimi. As I write these functions, I'm also trying to keep track of my work through headers that explain what the function does and how to use it.

I've really been enjoying these simulations. A week ago, this blog post would have seemed like a foreign language. But now, I'm excited to work more and more on this project of creating these fake galaxies, mostly because I know where this work is heading. Soon enough, these fakes will be put in simulated fake backgrounds, so we can determine their detectability. And, ultimately, we'll determine how detectable dwarfs like these fakes would be in our own sky...

As a side note-- a special blog Thank You goes to Beth, who has been putting up with me in her office for long periods of time these past few days. I know she has a ton to work on, so I'm feeling pretty grateful that she takes so much time out of her day to help me. THANKS BETH!

Tuesday, June 22, 2010

Making Fakes

It's happening! After closing loops on old data analysis projects, and writing about it LaTeX, I'm beginning the process of making fake dwarfs!

What this means, is that I take random star samples from the Ursa Major HST stellar data set, and make them into other "fake" dwarf galaxies. I did this many times, and had not 1, not 2, but 25
figures to bring to group meeting today. They were all of CMD's of these fakes, some of several fakes of the same sample size overplotted on one another. After group meeting, I calculated total magnitudes of these simulated dwarfs.

Next step: randomly distribute said stars spherically with an exponential fit. Beth will show me how to do this tomorrow.

Big goal: put these fakes at different distances and against different backgrounds, and LOOK FOR THEM!

We're approaching the halfway mark soon enough, so it would be great to get hopping on this!

Science is so cool.

Friday, June 18, 2010

Something to show for the past four weeks

I have the most beautiful LaTeX document that has ever been made. Or, at least I think so, (in a maternal way).

Let me tell you a little about it. First and foremost, it documents every piece of valuable work I have done over the past four weeks. It has every derivation, every error calculation, every figure, every investigation... I'm very proud.

Also, all the bits and pieces are in the places I want them to be! I know, I know-- I vowed yesterday not to consume my time with layouts, but I did it anyway. Although, it didn't really take too much of my time. There are apparently plenty of people out there who are frustrated with this flaw of LaTeX, and several of them wrote about how to fix those problems and published their findings on the wonderful World Wide Web.

Also, in addition to the sections I planned to write as I posted on Tuesday, I also wrote a section analyzing the depths of different stellar data sets in hopes of eventually simulating fake dwarf galaxies. By looking at data sets from 5 dwarfs, and a data set from one globular cluster, I was able to determine which would provide the best CMD to model our fake dwarf on. (Turned out to be Ursa Minor, but I'll let you read the document for the reasons why.)

Next week, I'll (hopefully) start writing the code to make these fake dwarfs, either with this data from Ursa Minor, or from simulations from a program called StarFISH.

Thursday, June 17, 2010

Wednesday and Thursday Updates

I've got to keep track of what I'm doing, so I feel like I'm making progress, right?! So, some lists of things I've done, am doing now, and will be doing later. Must be in list form, because at 11:57, my blood sugar is running a little low before the lunch-hour.

What I did yesterday:
- Wrote section (3) of the LaTeX document and inserted all figures. LaTeX sucks at putting figures where I want them. Gail says to just let it be. I've poked and prodded and made some progress, but it still doesn't look great.
- Finished Method 2 for Calculating Avg Surface Brightness at Half-Light Radius-- (That REALLY needs an abbreviation... AvSB@HLR?)-- and then compared it graphically to Method 1.
- Went to a talk by Peter Love about "the foundational questions in quantum mechanics". It was designed to be for anyone doing research this summer, not just a physics audience. It was a great talk. I sat next to my Enviornmental Biologist/Chemist roomate, and she enjoyed it fully, too.

What I've done this morning:
- Put the Methodology comparison figure into LaTeX. Proofread and edited the whole document. Played with page formatting a little more, not a lot of luck having figures go where I want them. (I'm deciding RIGHT NOW to no longer waste time dwelling on making this document look great. I have other stuff I need to be doing.)

What I'll do this afternoon:
-finally get to analyzing different dwarfs (and one Globular Cluster) to see how good they would be as sources to make fake dwarfs for our algorithm.
- put those conclusions into the LaTeX document

In the meanwhile-- Mimi is being AWESOME and decided to take on a calculation Beth requested from France-- something about changing the units of our RA and DEC data. I must admit, it didn't sound too fun, so I'm grateful Mimi volunteered...

As an exciting side note: Beth's using one of my figures in her talk tomorrow in Lyon!!

Tuesday, June 15, 2010

Not only am I an IDL graphing machine...

...I'm also a LaTeX machine!!!!

While Beth is away, I'm working to compile all the work I've done so far into a LaTeX document. I have never used LaTeX before, and I'm kind of enjoying it. I think, like graphing in IDL, I like figuring out the different commands to make my work look good. Here's the outline for my document:

1. Intro
2. Calculations for Average Surface Brightness at Half-Light Radius (both Methods)
3. Figures (Surface Brightness v distance, Size-Luminosity, ellipticity, Surface Brightness Methods comparison)

I was able to get through writing section 2 this afternoon, mostly because this morning, I calculated the Avg Surface Brightness at half-light radius using Method 2-- i.e. using an exponential model and applying it to the known central surface brightness.

Beth wanted me to do this by integrating in IDL, and calling a function I wrote for the exponential relation. However, that didn't work out. Hopefully she'll show me where I went wrong in that procedure when she gets back from France, but I for now I solved for all of the necessary integrals thanks to Now I'm just waiting to input the finished data for central surface brightness care of Mimi-- (who's back from home! hooray!)

Here's what's up for tomorrow:
- use Mimi's data and find Surface Brightness with Method 2
- make figures comparing Methods 1 & 2
- start writing section (3) in LaTeX document

Monday, June 14, 2010

Finished Graphs

... at least I hope they're finished. Still need the A-OK from Beth.

Look at 'em! They look so good! (Click to see better image.) The first graph plots Average Surface Brightness at the Half-Light Radius v. distance from the Milky Way. The second and third graphs are Size-Luminosity graphs. The second graph is more zoomed in, and labels the MW satellites. The third graph also plots Globular Clusters.

Thursday, June 10, 2010

Moving on to Phase Two

After almost three full weeks of working in IDL to organize and analyze the known data about previously discovered dwarfs around the MW and M31, I'm getting ready to move towards creating an algorithm to find undiscovered dwarf galaxies.

To kick-start this process, Beth had me read bits of a paper by Walsh, Willman, and Jerjen entitled "The Invisibles: A Detection Algorithm to Trace the Faintest Milky Way Satellites." Basically, the method is to take stars from known dwarfs, and combine them into "fake" dwarfs, that can then be placed behind different backgrounds of stars to create a program to look for similar objects in the real local neighborhood. Who knows! Maybe this could lead to the discovery of the Barlev-Fuchs 1...

In other news, I've more or less tied up all of my loose ends in terms of plots and data analysis on the known dwarfs, and Beth even showed the plot from Tuesday in her brief talk at AstroPhilly yesterday at Swarthmore! It was nice to see a figure of mine projected on a big screen at a talk for the first time! AstroPhilly was good, too. It was interesting to hear about the range of projects going on at neighboring institutions. Also, we got to look at Swat's new 24" telescope. I'm jealous, mostly because currently our dome needs manual pushing in order to rotate.

Looking ahead -- Beth will be in France at at conference next week, and so I'll need to figure out things to keep me productive in her absence. Hopefully that can be panned out tomorrow afternoon.

Tuesday, June 8, 2010

A Graph to be Proud of

Beth wants us to have nice figures to show at AstroPhilly at Swat tomorrow. Lucky for her, I happen to be a beast at graphing.

Here's what I'll be showing (sorry for the poor quality!):

Its the Size-Luminosity plot I've been working on, but with different symbols for MW dwarfs, M31 dwarfs, and Globular Clusters. Also, those dashed lines are lines of constant surface brightness.

Hooray for good graphs!

Monday, June 7, 2010

Loose Ends

Today and tomorrow, my goal is to tie up all of the things I've been working on for the past weeks.

After meeting with Beth this afternoon, we made a giant to-do list of things that need to happen before I can close up these projects. Here are the projects I have, and the things that need to be done to them before they're finito:

1. Calculating the average Surface Brightness within the half-light radius. Beth and I spent a long time discussing the effect of ellipticity on the half-light area, and thus the Surface Brightness within this area. I've since made a few pretty figures that shows this relationship, both in general, and with respect to our specific data. I'm still trying to figure out if I can make the assumption that the Elliptical half-light radii calculated in the Martin et al 2008 paper can be used for the major-axis radii of the half-light ellipses. (Gosh, that was a figurative "mouthful" that I hope I still understand tomorrow...)

2. Graphing distance from home galaxy vs. said Surface Brightness above. So far, I have this for Milky Way dwarfs, and the graph is labeled and pretty. However, some error bars are missing, so I need to account for those tomorrow.

3. Graphing size vs. Mv, with lines of constant Surface Brightness overplotted on top. Still need to do that last step. I think I have all the pieces to accomplish that tomorrow.

Great. So, hopefully, all of this can be finished tomorrow-- (unrealistic?)-- and then move on to bigger and better things. That way, I can struggle with those bigger and better things while Beth is away in France next week...

Friday, June 4, 2010

nothing FITS better!

An update from yesterday morning that I am only now writing about:

The FITS Binary table is complete! Or, if not "complete," at least up-to-date with all the data we've been working with. I successfully structured and stuffed, so now our data will be easier to manipulate. I think Mimi's already working with it to compute each satellite's distance to it's "home" galaxy.

So, Hooray! Successfully completed. And it was fun, too, surprisingly. I suppose part of this learning process is also learning how to enjoy the day-to-day tasks that I know will ultimately help the big-picture project.

Wednesday, June 2, 2010

A Quick One

OK, just a quick post for mental organization.

Beth showed Mimi and me the wonderful ways of FITS binary tables today, and I'll be structuring the one we'll be working with. I left Beth's office thinking-- great. I completely understand what I need to do, and I'll do it ALL before I rush home to play Ultimate in Philly.

Of course, that never works, does it? There were a few alignment issues in the ascii data table I needed to read in, and so I spent the last hour editing and lining up columns of data. So, at least that nitty-gritty step is done.

Up next: structure the FITS binary table. I'm ready to come in tomorrow morning, pump some tunes, and knock it out. Hopefully, once we have that set up, it will be easier and neater manipulating our data.

Tuesday, June 1, 2010

I'm an IDL Graphing MACHINE!!!

...or something like that.

Over the past few days, I've been learning how to make detailed, attractive graphs of the huge dwarf data table we're working with. I now know how to make graphs in color, have error bars on data points, and even label the data points accordingly. I made a really nice graph today of Distance versus Surface Brightness for all of the known Milky Way dwarf companions. (I wish I could post it here! I'm extremely proud of it.) I spent a lot of time labeling each dwarf, so the graph was readable (dare I say, beautiful?!)

Also, graphing allowed me to catch a pretty important mistake, today. While plotting Size versus Mv, I noticed some of the Magnitudes were positive, when they were all supposed to be negative. After close inspection, I realized that the way I read the data table into IDL was incorrect. Every once in a while, it would cut off a character from the beginning of the string in a column. I then reformatted, and double checked that every data point was correct. It was necessary, but caused some frustration and eye-crossing. Glad it's fixed now...

Next up: Making that Size vs. Mv graph more sophisticated, with lines of constant surface brightness over-plotted onto the data. Don't know how I'm going to tackle that yet, but I will, possibly (probably) with the help of others in the lab.

Also, as per Beth's wishes, I'm going to post here more. I haven't felt like I've done anything huge or note-worthy lately, so I haven't posted. But I guess that's nonsense. If I'm in lab for eight hours a day, I must be doing enough stuff to write about. I think I've only liked posting in moments of success or excitement so far. So, New Goal: write even when feeling stuck or uninspired. Then, later, when I've worked through it, I'll be able to visibly see my progress.

As an inspirational closing note, I was sent this link last week, and have been looking at it whenever I need a pick-me-up. Enjoy:

Wednesday, May 26, 2010


...mostly. But I'm feeling great about today. And, I would have never imagined saying that only a few hours ago.

So, my morning was not-so-fun. Mostly struggling with this foreign language of IDL. My goal was to read the Kalirai data table in to IDL, and so I spent most of the morning aligning columns and then failing to understand what I was supposed to do next. By lunch, I was pretty frustrated, and wondering why I'd chosen to go into an academic field that required so much computer knowledge that I didn't know, and didn't really want to know.

But, thanks to Mimi, who told me to relax over lunch and sit in the sun, so I could return with a clear head and a relaxed mindset, I was able to tackle IDL this afternoon. I have now successfully read in the data table (!!) with the readfmt command passed on to me by Beth.

I also started calculating the average surface brightness at the half-light radius in IDL. Something's still a little off there, though. The final result I get is not quite what I get when I work it out by hand. I'll look at this again tomorrow...

The moral of today's story is a motivational one. I am capable of figuring this stuff out, (given some patience and time). And, when I do accomplish something that seems impossible, it feels pretty good.

(Too many feelings for a science blog? Not sure... Still new at this.)

Monday, May 24, 2010

My First Day!

5:18 pm, and my first day of research is over. Look out, stealth galaxies! We might just find you...

Today I worked on filling in some gaps on a table created by Kalirai et al. 2010 that lists the properties of known dwarf galaxies in the local group. Hopefully this is the first step to creating a complete "Census of Dwarfs," as called for by our very own Beth Willman in her 2009 paper.

Also, hopefully, my rusty computer skills will get polished up and be riding as good as new by the end of the week. All of those Unix commands are coming back slowly but surely...

(As a side note: This is the first blog I've ever made. A little nerve-wracking, but it's all for science, so I can play along.)