This lab is one of a series of World Wide Web labs developed for the
large introductory astronomy classes at Northwestern University. The
intro courses are geared towards non-science majors, and have no
formal laboratory periods. The labs are intended to provide hands-on
laboratory experience despite the lack of a formal laboratory
facility. The Northwestern campus is wired for Ethernet, and students
are provided with free Ethernet software. Most students own their own
computers, and can perform the laboratory exercises in their dorm
rooms. We have created an astronomy tutorial room with seven Power
Macintoshes for those students who lack an appropriate computer, or
need help with a lab. The room is staffed by teaching assistants.
Funding was provided by National Science Foundation grant number
DUE-9354525, with Northwestern University principal investigators
Drs. David M. Meyer and David Taylor. Dave Meyer has been the primary
overseer of this project.
Data and Results
A very special thanks to Dr. Laura Ferrarese and co-authors for
permitting me to use their published data and figures. I hope
they are pleased with my use of them.
WFPC2 image processing
The Hubble Space Telescope WFPC2 images were processed using IRAF, the
Image Reduction and Analysis Facility, STSDAS, the Space Telescope Science
Data Analysis System, and SAOtng,
the next generation version of the Smithsonian Astrophysical
Observatory SAOimage display program. GIF images of M100 fields were
made within SAOtng.
IRAF is written and supported by the IRAF programming group at the
National Optical Astronomy Observatories (NOAO) in Tucson, Arizona.
STSDAS is written and supported by the STSDAS Group at the Space
Telescope Science Institute in Baltimore. SAOtng (SAOimage: The Next
Generation) is an astronomical display program being developed
cooperatively by Smithsonian Astrophysical Observatory (SAO) and the
National Optical Astronomy Observatories (NOAO).
I would like to give a personal note of thanks to Eric Mandel, the
architect for SAOtng, for his prompt, enthusiastic and friendly
support. Although SAOtng was still under development, Eric made the
time to quickly fix every major problem I encountered in the Dec Alpha
version. He also patiently explained details when necessary.
My job was a lot easier for his efforts. Making GIFs from WFPC2
exposures is a breeze in SAOtng.
Programs and GIFs
Animated GIFs were created using whirlGIF. WhirlGIF
was developed by Kevin Kadow, and is based on Mark Podlipec's txtmerge
Thomas Boutell's Mapedit program
was used to create some of the imagemaps.
Most of the non-astronomical GIFs were hand-drawn using Adobe Photoshop. Only the stylized
5-pointed star GIFs and the stylized Sun were downloaded from other
Web pages. I had to draw many of the GIFs freehand with a mouse,
which was no small task. I am most grateful to Northwestern
University's Learning Technologies Group, especially Dennis Glenn, Joe
Germuska, and Dimitrios Dimitroyannis, for their ever-friendly
technological support, and the loaner of a graphics tablet in recent
months. The tablet didn't make me a better artist, but it sure made
life a lot easier.
Some of the remaining GIFs were created with the aid of the gd library written by Thomas
Boutell; I used the Perl version GD.pm,
written by Lincoln Stein of MIT. Other GIFs were created with the aid
of Adobe Photoshop. Many were
created or revised with the aid of XV, the X windows image display
software by John Bradley.
Some of the Perl programs in this lab are based on or make use of
programs written by Thomas Boutell, from his book "CGI Programming in C & Perl." One
file of Perl subroutines was written by Robert Lentz, formerly of
Northwestern University. John Watson kindly extracted portions of a
Lentz program and inserted detailed comments to provide me with a
starter CGI program which uses form elements to obtain image
coordinates. The book "Teach Yourself CGI Programming with Perl in a
Week," by Eric Herrmann, was extremely helpful.
Most of the animated GIFs in the Cepheid hunt were created by
Northwestern graduate student Tom Renbarger. That was quite a job!
Tom was supported by a GAANN Fellowship from the Department of
As most browsers do not normally support the Greek alphabet, I thank
Karen Strom and helpers for making Greek
letters available to the community as GIFs.
When I began this project, I knew nothing about authoring Web pages.
How I ended up doing this is a long story. Creating this lab required
learning a vast amount of information about the Web, HTML, CGI
programming, servers, software packages, and computer platforms.
Robert Lentz, formerly a Web programmer and system administrator in
the Northwestern astronomy group, taught me many of the basics, and
pointed me to relevant sources of information. Although he is now
employed elsewhere, he continues to provide support on advanced
topics. He also taught me a lot about Macintoshes. Northwestern
graduate students Hyong Lee and John Watson cheerfully provided a
wealth of information on a variety of Web and computer topics.
Northwestern research faculty Drs. Bill Purcell and Steve Matz
enthusiastically offered their time, comments and suggestions when
repeatedly asked, "Can I see how these pages look on your
computer screens?" Last, but hardly least, working for Dave Meyer has
been a pleasure.
Diane Dutkevitch, Lecturer, Northwestern University
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