12.409 | Spring 2002 | Undergraduate

Hands-On Astronomy: Observing Stars and Planets


Course Meeting Times

Lectures: 1 session / week, 3+ hours / session


This seminar covers background for and techniques of visual observing and imaging with a small telescope. As the physics and math involved are elementary, 12.409 does not make the brain-bashing problem-set demands characteristic of many other MIT courses.

However, you will need to invest a fair amount of time and care in your work for the course, and the time investment tends to collide with some of your prime homework-time. Clear nights in Cambridge are rare enough that we must take full advantage of each one: sometimes we’re extremely fortunate, with a section getting 5 to 7 clear nights during the term. Sometimes we’re extremely UNfortunate, and a section gets only 2 or 1 (or less?) useful nights. As any given class night may be an ‘observing night’, you must be prepared to devote one entire evening each week to 12.409.

12.409 uses six 8-inch reflecting telescopes; you’ll be paired off and work two persons per scope. We set up the telescopes on campus until you’ve had enough experience to be able to take full advantage of a darker locale.


Your pass/fail grade will be determined using two criteria:


As 12.409 is a hands-on ’techniques and experience’-type course, we state the following for the record: in order to pass 12.409, you must attend your section each week. Actually, this will probably be the most challenging part of this seminar - arraying your other commitments to handle one night a week of observing.

It’s possible that, despite all your best efforts to pick a class night you can make every week, some unforeseen illness, personal emergency, or critical schedule conflict will crop up during the term on a class night and force an “excusable” absence. If this happens, contact your section instructor promptly, before the class if at all possible. We don’t hassle you for one excusable absence, although it’s virtually guaranteed to be on a clear night for your section. However, requests to excuse more than one absence are looked upon with extreme disfavor, and generally speaking are not granted except in extraordinary circumstances.

A student puts it succinctly: “two misses equals death.”

Normally to make-up a class we’ll give you a written lab exercise to complete. It’s difficult to arrange to make-up a class by attending another section, since sections of 12.409 are usually quite full and non-uniform weather causes them to diverge soon after the first week anyway.

Absences for reasons under your control are not excused, such as “punting”, “have to prepare for a quiz scheduled/paper due for the following morning”, or “unprepared for class” (too tired, didn’t bring warm clothes, etc.). In case of an unexcused absence you’ll be encouraged to drop the subject and try again in some future term as an alternative to the failing grade you otherwise would receive. We also reserve the option of counting repeated tardiness as an unexcused absence.


Observing Notebook

You’ll need to have some sort of laboratory notebook to use for recording observations and writing calculations. In 12.409, it will be inspected by your instructor as a major criterion for evaluating your performance in the course.

Please get yourself an observing notebook before your first 12.409 class. An 8.5- by 11-inch spiral-bound notebook of about 50 pages has always been more than enough for an entire term (even assuming piles of clear nights), so that’s what we recommend. Some observers prefer a notebook with lined or graph-paper pages (to help in reproducing angles and making sketches) though plain paper should be adequate for our purposes. You need a notebook in which the pages are bound together, since looseleaf notebooks tend to be clumsy if you’re out working on a windy rooftop. (Plus, fishing white looseleaf sheets out of a white snowdrift in the dark a few stories down is kind of a pain.) Spiral notebooks are particularly well-suited for 12.409 work: you can conveniently fold the cover all the way back, and can include your handouts using looseleaf rings. (Hint: avoid black covers; they’re impossible to locate in the dark.) Please arrange to have this notebook be exclusively for your 12.409 work, so that its being collected for inspection won’t deprive you of your notes for any other classes you may accidentally be taking. Please be certain also to bring your notebook to ALL class sessions (including the first one).


Most of the “material” (such as it is) for 12.409 is distributed as a set of handouts. However, if you don’t yet know the major constellations and bright stars you should also purchase: Rey, H.A. The Stars. Boston, MA: Houghton Mifflin, 1976. ISBN: 0395245087. Even if you already know your way around the sky, but learned to picture the constellations by a method other than Rey’s method of showing them, you might want to get yourself the book since we’ll many times describe locations of stars by where they fit into Rey’s pictures (e.g. “Perseus’ left armpit”).

Expected Student Preparation

Expected student preparation for an evening of observing includes coming to class on-time, awake, fed, and warmly dressed (see next paragraph).

A few words about “Evening Attire for the Sensible Observer”:

The reality of observing (or more properly, one reality, for there are several) is that you can get cold, all the way from late autumn through early spring. In particular, rooftops are almost always breezy (therefore cold) and Westford, MA is an “outlying area” (therefore cold). (Lest you think summer observing is completely trouble-free, forget not Mr. Mosquito.)

When observing you’ll want at least one EXTRA layer over whatever you usually find effective for a given air temperature; I recommend dressing as if the air temperature where you’ll be observing were an extra 15 to 20 degrees lower than what the thermometer reads. This extra is necessary because for the most part you’re NOT MOVING AROUND enough to generate any body heat that way. Here’s what I wear for wintertime observing (since it’s really un-cool for the instructor to get cold…):

  • Long underwear (recommend two sets if T below 25 degrees F)
  • Heavy trousers; heavy shirt (wise to bring wool sweater as well)
  • Wool socks
  • Hiking boots (mine aren’t specifically insulated but they’re made out of thick stuff; my wool socks do the insulating.) Insulated boots are good also; sneakers are usually inadequate and are NOT recommended.
  • Wool neckwarmer or scarf
  • Wool hat (Having some hat is CRUCIAL, since most of your body heat is lost through your head.)
  • Warm gloves

Like so many other things in life, observing is significantly less fun than it could be if you’re underdressed for the occasion. So, if you err, arrange to do so on the side of preparedness: if you bring too many warm clothes you can always decide you need not wear all of them, but if you bring too few, you lose, in a most uncomfortable way.