Height of Tycho's crater rim  Tycho is the crater with the central peak in the middle of this photo (I apologize that it's slightly out of focus).1  It is about 90 km across.  Determine the height of its eastern (on the right) crater rim.

¹ For a better photo of the same region see Piermario Gualdoni's Celestial Wonders .

 Objective: Find your way across the sky with your starfinder .

 Note that CONSTELLATIONS are in capital letters while Stars are not.
 

• Determine where North is
• Start with the very bright stars of the (huge) summer triangle (Altair, Deneb, Vega)
• Find these stars' respective constellations (AQUILA, CYGNUS, LYRA)
• find the Big Dipper (part of URSA MAJOR), use its "pointer stars" (Dubhe & Mirak) at the end of the pan, take their distance 5 times and you get to the North star Polaris
• Polaris is at the end of the Little Dipper (part of URSA MINOR)'s handle, stars are fainter than the Big Dipper's and it's as if the handle touches the other's pan
• find CASSIOPEIA's W and the great square of PEGASUS
• find CEPHEUS (between CASSIOPEIA and Polaris/Little Dipper), looks like a house
• find ANDROMEDA (fourth line of CASSIOPEIA's W points towards Almach [bright µ And star next to M 31])
• find DELPHINUS

 Objective: Find your way across the sky with your starfinder .

 Note that CONSTELLATIONS are in capital letters while Stars are not.
 

• Determine where North is
• Start with ORION
• Find the very bright stars around Orion (Castor and Pollux, Sirius, Capella, Aldebaran)
• find the Big Dipper (part of URSA MAJOR), use its "pointer stars" (Dubhe & Mirak) at the end of the pan, take their distance 5 times and you get to the North star Polaris
• Polaris is at the end of the Little Dipper (part of URSA MINOR)'s handle, stars are fainter than the Big Dipper's and it's as if the handle touches the other's pan
• find CASSIOPEIA's W and the great square of PEGASUS
• find CEPHEUS (between CASSIOPEIA and Polaris/Little Dipper), looks like a house
• find ANDROMEDA (fourth line of CASSIOPEIA's W points towards Almach [bright µ And star next to M 31])
• find TRIANGULUM

1. Observe these object with the unaided eye.
2. For each object or star, find another name in literature or from your star finder (hint: this name has to do with the brightness of the star, e.g. a or b for a very bright star, and the constellation you find the star in) .
3. Give its approximate position in the sky (e.g. North, 30 degrees), and comment on it (e.g. color, double star, clouds, galaxy etc.).
4. Number them according to their apparent brightness.

These are tougher:
M 31
M 13
M 45

1. Observe these object with the unaided eye.
2. For each object or star, find another name in literature or from your star finder (hint: this name has to do with the brightness of the star, e.g. a or b for a very bright star, and the constellation you find the star in) .
3. Give its approximate position in the sky (e.g. North, 30 degrees).
4. Number them according to their apparent brightness.

These are tougher:
M 45
M 31
M 42
 
 
 

Objective: Observe the following bright stars and determine their color, first with your unaided eye, then with the telescope.

Procedure:

1. Find these stars on your star finder (you may have to ask the instructor for some of them).
2. Memorize where they are (so you don't have to rely on the star finder too much, once you're outside in the darkness).
3. Find their spectral classification (see the image of spectral classes ), what color they should have (see your textbook Appendix or my stellar evolution appendix ) and what apparent magnitude they have.
4. Observe them with the unaided eye and determine their color.

Objective: Observe the following bright stars and determine their color, first with your unaided eye, then with the telescope.

Procedure:

1. Find these stars on your star finder (you may have to ask the instructor for some of them).
2. Memorize where they are (so you don't have to rely on the star finder too much, once you're outside in the darkness).
3. Find their spectral classification (see the image of spectral classes ), what color they should have (see your textbook Appendix or my stellar evolution appendix ) and what apparent magnitude they have.
4. Observe them with the unaided eye and determine their color.

Objective:  Observe the variable star Algol.

Possible dates for Algol observations in the evening in North America (see the monthly Astronomy or Sky & Telescope ; possibly our WebCT "Calendar"; table below, data are from the annual "Observer's Handbook" published by The Royal Astronomical Society of Canada):
date and time of (expected) minimum, but you need to subtract 6 or 7 hours from UT ! 
(Since the times are in UT and you need to subtract hours, the correct date for North America is usually the day before the posted one.  Also, although eclipses happen every 2 days and 21 hours, I only list the dates and times for convenient evening/late-night time observations in North America.)

• Find information on Algol, e.g. at Sky & Telescope .
• What is the mechanism that makes Algol vary in brightness?
• If the minimum is late at night, start four hours before and you may quit when Algol reaches that minimum.  If the minimum is early in the evening, start at the time of that minimum and go on for four hours.  In either case, you check every half hour for a total of four hours.
• Find Algol (see chart).
• Over the course of four hours, observe Algol’s change in brightness (every half hour).
• Compare Algol’s brightness to Mirfak, Almach, and other surrounding stars.  During mid eclipse, Algol is way fainter and in fact, appears of the same brightness as Gorgonea Tertia (r Persei) to its right.
• Keep a log of your observations.

Finding Algol.  First find the W - Cassiopeia, which is off this finder chart to the upper left.  Use binoculars to find the pretty double cluster (oval at left) between the W and Mirfak at lower left.  Algol (b Persei, lower right) forms a large right triangle with Mirfak ( a Persei, lower left) and Almach ( g Andromedae, upper right).  All three are usually of about the same brightness (see photo on the left below; or chart, which is the negative image of that photo) .  At the deepest eclipse, Algol becomes as faint as Gorgonea Tertia (r Persei) to its right (boxed on the chart; see also photo on the right below) . I admit that these photos aren't perfect reproductions, although I can clearly see a difference.  However, this is a lab and you have to see for yourself - and you will clearly see that Algol changes its brightness.

These are the actual photos while the above is a negative.
 
 

 During fall semester this lab is in October or later.

Close to the college (or your home/work place) or anywhere in town with all the street lights:
1. Observe the star cluster Pleiades with the unaided eye and figure out how many stars you can see.

 
2. Observe the Pleiades with binoculars or a telescope. Count again.

 

In an area without any bothering lights:

3. Observe the Pleiades (with and without binoculars) and figure out how many stars you can see.

1.  For the following M(essier) objects (at SEDS) , find their proper names, constellation, position, describe them, and make a drawing of how they look like on a photo (Messier images at SEDS) .
2. Observe them and make a drawing of what you see.
3. Explain the differences between the photos and your observations.

M 31

M 13

M 45

M 8

M7 / M6
 
 

Deep Sky Quiz at Catalunya (in Spanish).

1.  For the following M(essier) objects (at SEDS) , find their proper names, constellation, position, describe them, and make a drawing of how they look like on a photo (Messier images at SEDS) .
2. Observe them and make a drawing of what you see.
3. Explain the differences between the photos and your observations.
 

M 31

M 45

M 42

M 13
 
 

Deep Sky Quiz at Catalunya (in Spanish).

1. Objective: Identify individual sources of skyglow and light pollution. Make notes of what kind of lighting and shielding is used by these sources. Become an advocate for dark skies .  Check e.g. the IDA's page on good lighting fixtures .
2. Which constellations can you easily identify?
3. Count how many constellations you can see.
4. Repeat steps 2 and 3 in an area without light pollution.

Objective: Resolve the double stars Mizar and Alcor.

1. Find information on Mizar and Alcor.
2. Resolve them with the unaided eye, then with binoculars or a telescope.
3. Comment on your observations.

Objective: Find out which size the field of view both the finder and the telescope (with a certain eyepiece) have and how field of view and magnification are related.  For all practical purposes, the instructor will give easier to follow instructions.

Procedures:

1. What is the celestial equator?
2. Name at least three stars that are close to the celestial equator and are visible during our class time.
3. Aim the telescope at a star near the celestial equator (doesn't have to be a bright one) and center the star in the field of the telescope and finder.
4. Measure the time in minutes it takes for the star to drift out of the field.
5. Divide this time by two. The result is the angular diameter of the telescope/finder in degrees. Write this result into the table below.
6. Read the focal lengths of objective and eyepiece off the telescope.
7. Determine the magnification of the telescope:
8. Results

 objective's focal length fo = ...
 

Telescope	fe Eyepiece	Magnification	Field of view	resolving   power	light-gathering  power
.......
finder

9. a) For which purpose would you choose a high magnification?

b) When would you choose a large field of view?

To my WNCC Astronomy home page .