Graduate Students: Use either IRAF, IDL, AIPS or any professional image processing package.
Undergraduate Students: Use any of these packages, MIRA on the IR Lab PC or your own wierd choice.
Links to a series of CCD images are listed below. These are images of a cluster containing standard stars (NGC 4147) and a piece of sky (P221) with several stars with unknown photometry. Download these images into your own directory.
1. Subtract the Bias frame from each sky flat and image frame.
2. Compute a flat field frame from the bias subtracted sky flats in each filter.
3. Flat field each of the image frames.
4. Determine the pixel to pixel standard deviation (pixel rms) for the sky in the P221 V and R frames.
5. Using a spherical or square aperture, determine the net brightness in counts of the stars A and B in P221. Compute the raw instrumental signal-to-noise for each of your measurements of each star in each filter.
6. Using the standard stars and mean airmass coefficients (0.2 mag/Amass in V, 0.15 mag/Amass in R), determine the V and R magnitudes of the two program stars. Compute the errors on these values assuming no error in the airmass corrections.
Graduate Students: Use the sky rms to determine the gain of the CCD. Use the additional bias frame to determine the CCD readout noise. Use this information to determine the precision of the flat fielding.
Standard Stars are in NGC 4147, see: Odewahn, S.C., Bryja, C.O. and Humphreys, R.M., 1992, PASP, 104, 553.
19, 29, 34, 53, 55, 71, 73, 82