Stuff to do

• Learn about the ALFALFA survey and, especially, take a look at the Using ALFALFA for science page. What does ALFALFA detect? How can we use ALFALFA to learn about galaxies?

• Read about the Sloan Digital Sky Survey in order to answer these questions. Some useful links are given here:
  Main SDSS site         DR6 site        Imaging camera parameters and description
  
  a. What is the operational status of the SDSS?
  b. What are the central wavelengths of the filters used to produce SDSS images?
  c. Why is it useful to obtain images in 5 filters simultaneously?
  d. Over what portion of the galaxy is the spectrum obtained? Why might that be important?

• Make a web page for yourself to keep track of what you are doing; you should put it in the directory called /home/hatillo/katieh/spr08 (actually we will need to get you a computer account for this...). See my hints on how to get started.

• Get started with IDL
  See especially the Intro to IDL for ALFALFA page

• The EGGGEN utilities:    
  1. Learn how to start up IDL accessing the Arecibo and ALFALFA utilities. For this, you'll have to ask one of the local experts.
  2. "plotalfa"
     "plotalfa" allows you to explore how ALFA scans accross a region of the sky using the ALFALFA observing mode. In IDL, it is developed as a widget which allows for more flexibility in specifying the region plotted. You can elect to see the galaxies and ALFA beams/tracks in a square box of variable size from 30 arcmin (0.5 degrees) to 10 degrees with allowed values of 0.5, 1.0, 2.0, 3.0 ...10.0 . The bigger the region, the more galaxies that are plotted.
     • Investigate the 10h13m45s,+03d24'00" field. Here, enter the coordinates ("AGC style") and specify the box size to be 0.5 degrees; this is the same as "plot30".
     • How many galaxies do you find?
     • As you increase the box size, see how the number and distribution of galaxies change. What do you notice about the distribution of galaxies? How might this be explained?
     • Set the box size to 5 degrees. How many objects do you find?

• The NGC 3165/6/9 group: This is the group we will be investigating. So, read some papers, starting with:    
  1. Haynes 1981 Astro. J. 86, 1126.

• The Arecibo General Catalog (AGC) is our private database containing basic data on several hundred thousand galaxies. It is not intended to be used by or distributed to people outside the ALFALFA collaboration.
  1. What are the conditions of use?     Look here for the answer and follow the link to answer the next questions.
  2. What is the "UGC"?
  3. When is the AGC entry number equal to the UGC entry number?
  4. What is the "position angle"?
  5. What is the "TELCODE" for Arecibo+ALFA?
  6. Some galaxies have two velocity measurements: "VOPT" and "V21". In that case, what should you adopt as the recessional velocity for the galaxy?

• Numerical integration of an HI profile
  1. Use our links to find the ALFALFA data entry for AGC/UGC 7192. Put the link on your webpage.
  2. On your webpage, record for yourself the ALFALFA catalog information for this object. Do you understand what the parameters mean? Add notes for your own reference, as needed. If possible, enter the data as a table on your webpage; if you don't know how to do it, ask for a hint.
  3. Make a link on your web page to the journal article containing the ALFALFA publication of this spectrum.
  4. Download the spectrum (ASCII file format) to your disk area on hatillo.
  5. Write an IDL routine to calculate the integral under the profile. If you run into "issues", ask! This will probably take you some time as you need to know how to read in a file, among other things.

• Reading ALFALFA catalogs:     ALFALFA produces catalogs containing a source name, the AGC number (where there is one), the HI centroid and the position of the optical counterpart, and then various parameters measured from the HI line.
  1. Learn what measurements are contained in an ALFALFA catalog.
  2. Write yourself a short IDL routine to read this test catalog, and try to calculate the HI mass from the parameter SintP

• Collaborative assignment for March 10th:     I won't be here next week, so Katie and Hong should work together to investigate some questions about how we should calculate distances to the NGC 3166/69 group. I'll expect a progress report on March 10th.
  1. Figure out how to calculate the supergalactic coordinates of the NGC 3166/9 group. Obviously, you also need to know what that coordinate system is, what its origin is, etc.
  2. Research distance estimates to members of the NGC 3166/9 group. Can you find any primary distances? Secondary distances? Make sure to note the errors on the distances as well as the distances themselves, and of course, keep track of references.
  3. Check out the brand-new Extragalactic Distance Database. Write a (web page) summary of how it might be useful to us. Plan to contribute your summary to other EGG documentation (i.e. subject to critique by the senior grad EGGS).

• There may be a SNeIa distane to NGC 3169. It is associated with SN2003cg, but I am having trouble finding if anyone has actually derived a distance. Look here for some info.

• Here is a catalog to experiment with for your cone diagram.

• A first look at the ALFALFA grid around NGC3169!
  While Katie was off in potato-land, Martha was chained in her office, flagging data. It is amazing how much data can be flagged during a telecon (as long as one is not chairing the discussion, of course). Anyway, Martha, with help from some of the extra-Cornell EGGs, finished Level I processing of all the ALFALFA drifts needed to make a grid around NGC 3169. Then she used RG's new version of grid_prep to generat the grid. This is not a standard grid; it is 3 deg X 3 deg centered on RA = 10,24hr, +03.5deg, withy 500 channels, starting from the channel with v=300 km/s and going up.
  • How many km/s is one channel? So what's the upper limit in velocity in km/s?
  • Make an RA,Dec plot of the locations of galaxies in that velocity window.
  • Here is the sky coverage of the grid, as generate by grid_prep. Understand what that figure tells us.

  • Victory: I made your grid and have flatfielded it. It didn't actually need to be baselined (it was flat enough; I ran only grid_flatfield, not grid_base). Copy the grid from /home/rutados/data/idl/work/grids/n3169/flat_n3169.sav to your own IDL directory. Then, in IDL:
    • restore,'flat_n3169.sav'
    • help,grid2,/st
    • gridview,grid2
    Now you have to learn about grids, gridview, ex3d, galcat, galflux. Enough to keep you out of trouble for a very long time..........
    See: LOVEDATA grid docs and all LOVEDATA IDL docs
  • So, for starters, make a plot of just the galaxies in the AGC which are contained with the 3 deg X 3 deg box centered on RA = 10,24hr, +03.5deg and within the velocities 300 < V < Vmax km/s, where you calculated Vmax above. (You can check your answer for Vmax by looking at the grid itself).