ASTR 3510
Astronomical Observations and Instrumentation I: Imaging
Fall 2009
Lab #5:
The Semester Observing Project
Proposal Due: 27 October 2009 (Tuesday, in lab)
Data Due: 1 December 2009 (Tuesday, in lab)
Presentations Due: Last two weeks of class (in class)
Write-up Due: 10 Decemebrrrr 2009 (Last-day of classes)
****** DRAFT ******
Purpose:
Use the CCD to conduct a scientific project. As with serious research, you will be asked to submit
a project proposal by 27 October 2009. I will give you feedback on feasibility, after which you are
to conduct the needed observations and conduct any associated literature search. You will be
asked to hand-in a written report, ideally in the format of a short paper. I encourage you to use a
format similar to the scientific papers published in the Astrophysical Journal. In fact, you are
encouraged to use the LaTeX templates, or equivalent MS-Word templates, supplied by the
publishers of the ApJ. I will ask each of you to give a short, power-point presentation on your
project during the last two weeks of class. Each group will get about 20 to 30 minutes for their
presentations; each student is expected to present a part of the project him or herself.
Picking a Project Topic:
You are free to pick a topic of your own choosing.
Here, I make a few possible suggestions:
- The mass of Jupiter, and the photometric characteristics of its Galilean satellites. One group
could fully develop and analyze the observations obtained during the Jupiter imaging Lab.
Combine all the data taken by the class into a time-series of images. You can plot the orbital
motions of the 4 Galilean satellites. Using the known distance of Jupiter, compute the proper
motions of the satellites with respect to Jupiter’s disk, convert these to orbital velocities, and use
the orbital periods combined with the orbital semi-major axes to compute the mass of Jupiter. Use
the data from all 4 satellites, and compare the errors. How accurately can you get the mass? Use
the diameter of Jupiter’s disk to get its mean density. Can you measure the eccentricities of the
satellite orbits? How do the colors and color indices of the moons compare to the Sun’s colors?
- H-R diagram of an open or globular star cluster. Perform multi-filter photometry of a cluster in
at least 3 filters. Using a known distance, convert the observed apparent magnitudes into absolute
magnitudes, and plot the color-magnitude and color-color diagram for the clusters. Estimate the
spectral types of the stars in the clusters, and estimate the age of the cluster using the most massive
(or most luminous) star still on the main-sequence. Analyze the uncertainty in this age given your
photometric errors, and the limited number of stars on which you did photometry.
- Determine the luminosity function of HII regions in a spiral galaxy. Observed a nearly face-on
galaxy such as M33 or a portion of M31 in the H-alpha filter. Note, for these two objects, you will
need to build-up a mosaic since the galaxies are larger than our field-of-view. Calibrate the images
in magnitude and flux. Determine the H-alpha luminosities of HII regions in the Galaxy, plot the
“luminosity function” … the number of objects in some interval of luminosity as a function of
luminosity. For this project, you will want to use the SBIG ST1001E camera that has a 20 x 20
arcminute field of view.
- Morphological study of a Galactic HII region. Observe a nebula such as NGC 281 in Cassiopeia
in H-alpha, [OIII], H-beta, and at least two broad-band filters. Build a deep, color image. Study
and structure and morphology of the HII region. Estimate the electron density form the size and
surface brightness of the H-alpha emission. Estimate the extinction from the H-alpa / H-beta ratio,
which is about 3.0 for un-reddened emission by hydrogen. From the de-reddened emission,
calculate the luminosity of Lyman continuum ionizing photons given-off by the central massive
stars. Make a crude estimate of the age of the region from its size and distance.
- Identify variable stars in the outskirts of the Orion Nebula in at least 3 broad-band filters.
Measure the light variations and colors of young stars in the Orion Nebula. Plot their light curves.
- Photometric Monitoring of QSOs from the John Stocke list. Monitor `optically-violentlyvairable’ (OVV) quasars for bright flares. If a flare is found with mV brighter than 14-th
magnitude, it will be observe with the Hubble Space Telescope.
Proposals:
Use the Apache Point Observatory telescope observing request form (I can provide you with a
sample template) to write a short (1 page) observing proposals. The proposal should have the
following elements:
Title and Investigators: Your title and group participants.
Camera and Filter requirements: Apogee or SBIG 1001E? Which filters do you need?
Give an estimate of the total amount of time you will need. Include times for flat-fields, darks, bias
frames, opening & closing, and overheads needs to acquire your target data and any calibration
frames.
Scientific Justification: In a short paragraph, explain what you propose to observe and why.
What is the goal of the project? What do you hope to learn from the observations?
Observing Plan: Describe how you plan on conducting your observations. Which filters will
you use? How long-will the exposure times be? What will be your limiting magnitude, given your
proposed total exposure time per filter? (Use a realistic estimate of read-noise, sky-noise, and other
sources of noise such as the photon noise form the object if it is bright.) Combine this with an
estimate of the photometric zero-point for the 24” to estimate the magnitude of the faintest star you
can detect, and the uncertainty in the magnitude and flux measurements of your target objects.
Describe your calibration plan and data reduction strategy. How accurately do you need to know
your magnitudes? What Landolt fields will you use for cabiration?
Observations:
Following approval or your project by Adam or me (we may suggest changes to your strategy),
Conduct your observations. Plan on getting your data collection phase completed by midNovember! Start reduction early. As you reduce your data, you may find problems, in which case
you may need to retake some exposures. DO NOT PROCRASTINATE .... analyze your data as
soon as you get it.
Write-Up:
Your write-up should be in the style of an ApJ Letter (short, to the point, and no more than 4 pages,
including figures when printed with the emulateapj package). The elements of a write up are:
Title
List of authors and co-authors, including affiliations (in your case ASTR 3150, class of 2009,
University of Colorado Boulder)
Abstract
A few sentence summary of the aims of your project, the methods used, and statement of main
results.
(Example: In this paper, we use multi-epoch imaging conducted over a 2 week period in October
and Novembrrrrrr 2009 to measure the orbits of the four bright Galilean moons on Jupiter. Using
observations obtained during 17 different times on 8 nights, we found that the orbital periods of the
4 Galilean satellites are a, b, c, and d. The orbit semi-major axes are, v, w, x, & y. These
measurements are combined with the distance of Jupiter, D = x AU on 14 November 2009, to
provide an estimate for the mass of Jupiter of xxx grams.)
Introduction
A PP or two describing your project and why it is important or interesting. A short history (…
Galileo discovered the 4 satellites of Jupiter in 1609. Kepler’s laws (Kepler, 16xx) can be used to
determine the mass of Jupiter from the orbital periods an semi-major axes of its moons …. In this
paper we present multi-epoch imaging of the Jovian system.)
Observations
Describe the observations. Tabulate relevant parameters, such as date, filter, seeing estimate,
exposure time, number of exposures, photometric reference fields and stars, etc. Describe how
the data were reduced and analyzed.
Results
Discuss your basic findings, including magnitudes, positions, etc. Show plots and images in
Figures. Provide an error analysis. Here is where you present the “facts” and measurements.
Discussion
Here is where you present the interpretation. (for the Jupiter example, write-down the formulae
used to fit the orbital motions of Jupiter’s moons. Present a table of orbit radii an periods in
measured (arc-sec or arc-minute offsets from the center of Jupiter’s disk along with estimates of
measurement errors) and derived quantities (orbit radii in cm, estimate mass of Jupiter using
Newton’s or Kepler’s laws).
Conclusions
A summary of what you found
References
An alphabetical table of citations in the text.
I will show you proper ApJ style text in class.
Oral Power-Point Presentations:
Finally, your group will generate a PowerPoint presentation to be given during the last two
weeks of class in December. Follow the standards of presentation you have seen in the APS
Colloquia. Adam and I may “grill” you at the end during a question and answer period. Make
sure you understand the background, relevant physics, and mathematics of your projects. You will
need to be able to do simple, back-of-the envelope computations on the white-board. Thus, you
should know your basic constants and formulae relevant to your project. Think of this exercise as
a final exam, or as a real “job interview” for a professional position.