ASTRONOMY 535 - PROBLEM SET #1 - DUE 01/22/03

  1. From looking at the specified Web sites, answer the following:

    1. APO web site (www.apo.nmsu.edu)
      1. List the detectors (number, type, and size) used in each of the following instruments: DIS, SPICAM, GRIM
      2. Who will be observing during the night of January 29, 2003? What instrument(s) will they be using?

    2. STScI web site (www.stsci.edu)
      1. What is the ACS?
      2. When are Cycle 12 HST proposals due? For what period of time are people applying for? What instruments are available?

    3. NOAO web site (www.noao.edu)
      1. What is GEMINI?
      2. When are the next set of proposals due for NOAO telescopes? What observing period do they cover?

  2. With your naked eye, the faintest star you can see on a dark site is about mag 6. What would the faintest magnitude be that you could see with your eye if you were looking through the eye-piece of a 5-m telescope? Explain your various assumptions.

  3. A Jansky is a unit used to measure flux density, most often in the radio; one Jansky is $10^{-26} W m^{-2} Hz^{-1}$. How bright is Vega at 5500 Å in Janskys?

  4. In the UBVRI system, the star Vega is essentially defined to have a magnitude of 0 in all bandpasses. What is the magnitude of Vega in the I band (effective wavelength 8000 Å) in the STMAG system? in the ABNU system? You can find the spectrum of vega in the computer file: /home/catalogs/spec/vega/vegaobs.dat on the Linux machines, or /home/charon1/holtz/vegaobs.dat on the Sun machines.

    From the file, $F_\lambda (8000) = 1.1237\times 10^{-9}$. In the STMAG system,

    \begin{displaymath}m_\lambda = -2.5 log F_\lambda - 21.1 = 1.273\end{displaymath}

    In the ABNU system,

    \begin{displaymath}m_\nu = -2.5 log F_\nu - 48.6 = -2.5 log \left(F_\lambda {\lambda^2\over c}\right) - 48.6 = 0.45\end{displaymath}

  5. Using the ETC exposure time estimator available on our Linux cluster, determine the faintest star (V band magnitude) you can observe (at S/N=10) with:
    1. ACS camera/ F555W filter
    2. ACS camera/ F606W filter
    3. WFPC2 camera/ F555W filter
    4. STIS camera/ clear filter (50ccd)


Rene Walterbos 2003-02-25