Astrophysics Research Projects for NSF IRES May-July-August 2008 Shashi M. Kanbur (SUNY Oswego) Antonio Kanaan (UFSC)

Cepheid Variables  Linear relation between logP and M (in a number of different bands).  Is this relation non-linear: at least in the LMC optical wavebands, data suggests that it is.  Modeling, look at other wavelengths, apply/develop new statistical tests.  Look at data from other galaxies.  Reduce new set of IR data.  Use  Use

Application of new Statistical Methods  Kanbur, Ngeow, Nanthakumar and Stevens (2007) developed the testimator and Schwarz Information Criterion methods to LMC OGLE data.  Code this up and apply it to SMC OGLE data/DIRECT M31/M33 data plus any other Cepheid data sets that you can find.  Ngeow and Kanbur (2008) developed a mid-infrared PL relation. Nanthakumar and Kanbur (2009) developed an adaptation of the testimator to check for changing dispersion as a function of period – apply this to the Spitzer data plus at other wavelengths.  Develop the use of cubic splines to analyze variable star light curves – start of with an M31 RR Lyrae dataset.  Apply the methods of Koen Kanbur and Ngeow (2007) to other data sets eg the OGLE SMC data. This involves using the stats package “R” in a Linux environment.  The papers mentioned above are at

Cepheid IR data reduction  Become familiar with IR data reduction and photometry as outlined in documents generated by Frank Ripple/Travis Rooker/Dan Crain.  Try to automate this – in Python and see how these methods may change for the optical.  Construct CMD diagrams and look for the TRGB using a number of statistical methods – code this up – look at Makarov, D., et al 2006.

Cepheid IR PCA  Work on Cepheid IR PCA analysis.  Check work thoroughly.  Other datasets?  Can this be used to generate Cepheid light curve templates in the IR?  Fit polynomials to PCA progressions with period – compare with Tanvir et al Finish of this paper.

RR Lyraes  Look at M31 RR Lyraes – which is better Fourier/cubic splines/PCA?  Construct PC/AC relations as a function of phase for M31 RR Lyraes: fit lines/polynomials to observed progressions – compare with other data?  Relate metallicity to Galactic RR Lyraes using PCA: I have Galactic RR Lyrae data for which the metallicity and well observed light curves are available – relate light curve structure through PCA to metallicity using regression methods.  Look at M3/M15 paper – are there any other datasets that could be used? Analyze data given by Corwin. Any other interesting correlations from the models – finish this paper of. Look at Corwin et al (2008) for data on M15. I have this paper.

Modeling  Analysis of Marconi models – multiphase PL/PC relations – compare observed PC/AC relations as a function of phase with those from models.  Observed PC/AC relations can be found in my papers on I have the theoretical models.  D-R front transition in ionization fronts in Cepheids: a mixture of theory and numerical analysis.  LNA analysis for Elio Antonello – change existing code to solve up to 14 th or 15 th order. Current code goes up to 6 th order. Check. Then run models. Could possibly have a poster for a meeting in Liege, Belgium in July.  RR Lyrae models?  Why does our code produce lower amplitudes? This is a hard project.

Chimera  This is the name given to the Robotic Telescope Project.  Antonio Kanaan and Paulo Henrique at UFSC.  Also supported at LNA/OPD in Minas Gerais.  Software control system in Python.  Basics are working.

Web References  Python: and  Please go through this and try to refresh/become familiar with Python programming before you leave for Brazil. Pay particular attention to the concept of classes.      floripa?hl=en floripa?hl=en floripa?hl=en

Chimera  Follow instructions on chimera.sourceforge.net and try to install Chimera on machines (Ryann and Denis).  Download current source code at  Here there is also a directory with examples (docs/examples). Look at server.py, client.py. Try to run these files with python server.py and then python client.py.  Look at minimo.py which contains examples of all main structures that you can add to a Chimera instrument. Look at classes used – the main Chimera classes used.  Right now the source is the best documentation.  Join the googlegroups – can start discussions on this with PH and AK and myself.  “Look” at source and try to figure out how it works in conjunction with discussions with Paulo Henrique. Really need someone to dicument this!  Make sure you understand a bit about CCD imaging in Astronomy.

Data Reduction and Calibration  Data Reduction.  Read up about CCD’s.  Go through handout on data reduction and try to think how you might do this in Python. We will be doing this type of reduction for Chimera though its not exactly the same.  Write a routine to take a sky flat (point scope, take image, schedule this appropriately).  Calibration: find out about bias, darks, flats and how to process them – the above exercise should help you. Most of these frames can already be taken but need to integrate this into a smooth procedure.  Look up the Tyson and Gal 1986 paper or  Chromey and Hasselbacher 1996 (use and

Pointing Verification  Send the telescope to a given point. If you tell the scope to go to RA, DEC, EPOCH, how can you be sure that you are where you think you are? Mechanical imperfections etc. SO identify the field and get astrometric information from the image and make appropriate corrections and get map relating pixel coordinates to RA, DEC, EPOCH so that the center pixel goes to RA, DEC, EPOCH  Take an image, run sextractor - an open source program to identify the stellar sources.  Run wcstools to match the identified stars against a catalogue of stellar positions (UCAC II).  Find out about sextractor wcstools, UCAC II.  The above is a “poor man’s pointing model.

Graphical User Interface  Uses pyGTK.  Front end interface to the whole system.  Need to input, observer name, Object name, RA and Dec, Julian date, number of images in each filter – some other stuff regarding restrictions – discuss with PH.  Also need to integrate this with a GUI for the whole system eg. If a user wants to just adjust the focus and do nothing else.

Tasks  So the CS guys should concentrate on looking at the Chimera code and trying to understand it – then explain this to us perhaps? Perhaps after a while start working on the GUI interface and perhaps the pointing model?  Could be joined by the Physicists who are experienced in Python: work in pairs.  Physicists can also work on some of the Cepheid projects – would really like this to happen.  For the pure science projects, can work in pairs or individually – can work on these whilst in Brazil as well.  In Brazil there may be posssibilities to work on other projects related to white dwarfs plus instrumentation projects.

Machines  At Oswego: (rrlyrae) and (Cepheid) – this is a dual processor 64 bit AMD machine. Both run Debian Linux.  When off campus (perhaps on campus) can only get to these machines through moxie.cs.oswego.edu.  Once you get your campus address, you will have an account on moxie.cs.oswego.edu.  In Snygg, work in the moxie lab and ssh in. ssh –X for graphical output.

Oswego  Small college town.  Eating: College dining, Campus Center, Subway, Fajita Grill, Aztecas, Rudy’s.  Shopping: minor groceries (milk, bread, eggs) at the Gas Station. Otherwise Price Chopper etc. available at the other end of town.  I can take you for this major shopping to Price Chopper if you don’t have a car.