The midterm exam is Tuesday, March 10. You will have 1.5 hours to complete it (a bit longer than the normal class period). If you will need to leave before 3:10 PM, feel free to come a little early to start the exam. If you don't come early, I ask that you enter the classroom quietly since others may be taking the exam already.
Topics of importance (not necessarily complete, but feel free to ask me about any specific topic excluded here):
Coordinate systems, angular distance. (I will not ask you to do spherical trig calculations on the exam.)
Time.
Precession, nutation, equinox, epoch.
Nomenclature.
Error analysis; propagation of errors, basic probabilities
Telescope design.
Aberrations
Focal plane scale, critical sampling, spatial resolution
CCDs: characteristics, basic functionality, major noise sources, calibration observations, and basic reductions.
Photometry: observational techniques, data processing, photometric systems.
The following questions do not give a comprehensive coverage of topics that may be on the exam. Rather, they are intended to give you practice on some concepts that were not well- covered in other homework problems. See your previous homeworks as a source of the type of questions on previously-discussed topics that may be on the exam. Solutions for these problems are available.
1. The parallax of the quadruple system HD 98800 is 21.43 +/- 2.86 milliarcseconds. The X-ray flux of the system is (3.3 +/- 0.5) x 10-12 erg/s/cm^2. What is the system's X-ray luminosity and its uncertainty? (1 pc = 3.086 x 10^18 cm).
2. After reducing your CCD data from a photometric observing run, you have the following numbers, measured in the Stromgren y filter:
Total
Star counts Sky ADU/ N(pix) Airmass
(ADU) pixel of aperture
Standard A 50,000 200 30 1
Target 1 3,000 200 10 1
Target 2 2,500 200 10 1.5
Standard B 30,000 200 30 2
You know from a standards list provided at the telescope that the
standards have Stromgren y magnitudes of y=6 for standard A and y=6.5
for standard B.All measurements were made with a gain of 2 e-/ADU on a
CCD with a read noise of 5 e-/pixel. All four stars have roughly the
same spectral type. The sky was clear and conditions seemed good, so
assume the night was photometric. (Usually, you'd want to check this
with your data, but take my word for it this time...)
a. Calculate the S/N ratio of the sky-subtracted flux for Target 1 and Standard B.
b. Give instrumental magnitudes for all four stars. Ignore aperture corrections.
c. What is the Stromgren y magnitude of Target 1?
d. What is the Stromgren y magnitude of Target 2?
(If you did not get an answer for b., you can make one up for use in parts c. and d.)
e. Why are color corrections less of a concern for these data than if you had used a Johnson V filter for the observations?
f. Assuming you made these observations from Tempe, what is the declination of Target 1?