Lab 1: Constellations


Credit/Permission: For text, © David Jeffery. For figures etc., as specified with the figure etc. / Only for reading and use by the instructors and students of the UNLV astronomy laboratory course.

This is a lab exercise with naked-eye observations which are essential.

See Sky map: Las Vegas, current time and weather.

Sections

  1. Objectives (AKA Purpose)
  2. Preparation
  3. Tasks and Criteria for Success
  4. Task Master
  5. Constellations, Bright Stars, Observations
  6. The North Celestial Pole (NCP)
  7. Bright Stars
  8. The Rotating Sky
  9. Horizon Contour Line (IPI only and optional at the discretion of the instructor)
  10. Finale
  11. Post Mortem
  12. Lab Exercise
  13. Report Form: RMI Qualification: If you do NOT have a printer or do NOT want to waste paper, you will have to hand print the Report Form in sufficient detail for your own use.
  14. General Instructor Prep
  15. Instructor Notes: Access to lab instructors only.
  16. Lab Key: Access to lab instructors only.
  17. Prep Task: None.
  18. Quiz Preparation: General Instructions
  19. Prep Quizzes and Prep Quiz Keys
  20. Quiz Keys: Access to lab instructors only.


  1. Objectives (AKA Purpose)

  2. We will learn how to find some constellations and bright stars both on sky maps and in observations of the night sky, and thus begin to get the basic structure of the night sky in our minds.

    We touch on the following topics:

    1. Bayer designation.
    2. bright stars.
    3. constellations.
    4. the horizon.
    5. naked-eye astronomy.
    6. the planisphere.
    7. the sky.
    8. sky maps.


  3. Preparation

  4. Do the preparation required by your lab instructor.

    1. Prep Items:

      1. Read this lab exercise itself: Lab 1: Constellations.

        Some of the Tasks can be completed ahead of the lab period. Doing some of them ahead of lab period would be helpful.

      2. It is probably best to print out a copy of Report Form on the lab room printer when you get to the lab room since updates to the report forms are ongoing.

        However, you can print a copy ahead of time if you like especially if want to do some parts ahead of time. You might have to compensate for updates in this case.

        The Lab Exercise itself is NOT printed in the lab ever. That would be killing forests and the Lab Exercise is designed to be an active web document.

      3. Do the prep for quiz (if there is one) suggested by your instructor.

        General remarks about quiz prep are given at Quiz Preparation: General Instructions.

        For DavidJ's lab sections, the quiz prep is doing all the items listed here and self-testing with the Prep Quizzes and Prep Quiz Keys if they exist.

      4. This lab exercies does naked-eye astronomy. So we will be observing, but we will NOT be using telescopes (see information for our C8 telescopes).

        You should review the Observation Safety Rules.

      5. There are are many keywords that you need to know for this lab. Many of these you will learn sufficiently well by reading over the Lab Exercise itself.

        However to complement and/or supplement the reading, you should at least read the intro of a sample of the articles linked to the following keywords etc. so that you can define and/or understand some keywords etc. at the level of our class.

    2. Prep Items for Instructors:

      1. From the General Instructor Prep, review as needed:
        1. Basic Prep.
        2. Usual Startup Procedure.
        3. Usual Shutdown Procedure.

      2. If we have left-over unlabeled sky maps, you should put out one set for each group. There is no need to print new ones since the students can print them from the lab itself.

      3. Put out one planisphere per group so that the students will see them and just in case there is enough time to do Task 13: Contouring the Horizon.

      4. Since this is an observing lab, you should check the NWS weather well in advance of the lab night.

        Patchy cloud cover may be OK for this lab exercise. You will have to make a judgment call based on visual inspection of the sky.

        If the sky is going to be heavily clouded, then choose an alternative lab exercise without observations (or for which observations are NOT essential) from the Introductory Astronomy Laboratory Exercises.

      5. Since Lab 1: Constellations is the ordinary first lab, really the only alternative if you are clouded out is the ordinary second lab, Lab 2: The Sky.

        Unfortunately, Lab 2: The Sky is a bit of a long and tedious lab, but the students do need to cover the topics in it early in the course.

      6. To accommodate multiple sections, some sections at least will have to complete some Tasks earlier for early observations.

        The Tasks recommended for early completion are labeled as such in the Task Master.


  5. Task Master

    1. Task Master:

        EOF

      1. Task 1: Contouring Constellations: Complete early for observations later on.
      2. Task 2: Constellation Observations: Outside observing task to be done with a night sky.
      3. Task 3: Bright Star Labels: Complete early for observations later on..
      4. Task 4: Bright Star Observations: Outside observing task to be done with a night sky.
      5. Task 5: Ranking Star Brightness: Outside observing task to be done with a night sky. For IPI, optional at the discretion of the instructor. For RMI, required.
      6. Task 6: NCP Angle.
      7. Task 7: Circumpolar Circle Angular Radius for the NCP.
      8. Task 8: The Polaris Altitude.
      9. Task 9: Polaris Altitude from Hand Measurements.
      10. Task 10: Bright Star Data (IPI only).
      11. Task 11: The Rotating Sky.
      12. Task 12: Rotating Sky Explorer Questions: Omit update.
      13. Task 13: Contouring the Horizon (IPI only). Optional at the discretion of the instructor.

      End of Task


  6. Constellations, Bright Stars, Observations

  7. In this section, we find and label constellations and bright stars on sky maps.

    The sky maps aid in the observations of the constellations and bright stars which we also do in this section.

    The observation Tasks might have be delayed until after other Tasks are done depending the observing circumstances of the night.

    1. Introduction to the Celestial Sphere and Sky Maps:

      The celestial sphere is an imaginary sphere centered on the Earth and set at quasi-infinity beyond any actual astronomical objects.

      Taking the Earth as at rest, the celestial sphere rotates once per day (more precisely, once per sidereal day = 86164.0905 s = 1 day - 4 m + 4.0905 s (on average)) around the Earth turning on the celestial axis which is the extension of the Earth's axis to the celestial sphere.

      We locate astronomical objects on the sky in celestial coordinate systems (which just require angular positions) by projection onto the celestial sphere.

      Maps of celestial sphere or parts thereof are sky maps (AKA star charts).

      Note there is NO perfect way to project a curved surface on a flat one. So flat maps of the celestial sphere are always distorted in some way. Celestial globes depicting the celestial sphere have NO distortions, but like globes are mostly decorations.

      Historically, the celestial sphere in Aristotelian cosmology was a real physical sphere centered on the Earth on which the stars were fixed. This theory of the celestial sphere along with the rest of Aristotelian cosmology was discarded in the 17th century in the course of the Copernican Revolution (c.1543--c.1687).

    2. Introduction to TheSky (IPI Only):

      The instructor will give some intro to using TheSky software if necessary. Usually, we just do the orientation for TheSkyX.

      There is a self-orientation to TheSky at TheSky Orientation.

      The instructor may just direct you to do that orientation.

      There is also a a href="/~jeffery/course/c_astlab/000_thesky.html">List of Tricks for TheSky for reference.


    3. Task 1: Contouring Constellations:

      Sub Tasks:

      1. Print out the 3 Unlabeled Sky Maps in the figures below (local link / general link: Unlabeled Sky Maps)---unless your instructor has already printed the sky maps for you.

        You will only need one set of sky maps PER GROUP---unless your instructor directs otherwise

        The set of sky maps should be appended to the favorite report form---unless your instructor asks for each group member to make a set of sky maps.

        RMI Qualification: If you do NOT have a printer, just sketch the Unlabeled Sky Maps by hand with enough detail for your own use.

      2. Launch the TheSky which is on the desktop.

        RMI Qualification: Since the TheSky is NOT available, you will have to use Your Sky sky maps: the Jan01 sky map for the winter night sky and the Jul01 sky map for the summer night sky.

      3. Find the constellations listed below in Constellation Tables (general link: Constellation Tables) on the 3 sky maps you have printed out and label them with their abbreviated names. See Wikipedia: 88 modern constellations: Modern constellations for the abbreviated names.

        RMI Qualification: If you do NOT have a printer, you will have to write out the Constellation Tables by hand with enough detail for your own use. They are part of your Report Form.

      4. Surround the stick-figure representing each constellation with a tight-fitting contour line (or alternatively trace over the stick-figure with a colored pencil, etc.).

        The figure above (local link / general link: iau_scorpius_contour.html) illustrates a tight-fitting red contour line surrounding the stick-figure of a constellation labeled by its abbreviated name.

              
              Constellation Tables
              
              _________________________________________________________________________________________
              _________________________________________________________________________________________
              Table:  North Polar Sky Constellations
              _________________________________________________________________________________________
              Constellation               Observed Location in Sky     Why Not Observed?
                                          (Done in observations
                                           task below)
              _________________________________________________________________________________________
              Camelopardalis, CAM
              Cassiopeia, CAS
              Cepheus, CEP
              Draco, DRA
              Perseus, PER
              Ursa Major, UMA
              Ursa Minor, UMI
              _________________________________________________________________________________________
              

              _________________________________________________________________________________________
              Table:  Summer Sky Constellations
              _________________________________________________________________________________________
              Constellation               Observed Location in Sky     Why Not Observed?
                                          (Done in observations
                                           task below)
              _________________________________________________________________________________________
              Aquila, AQL
              Bootes, BOO
              Corona Borealis, CRB
              Cygnus, CYG
              Draco, DRA
              Hercules
              Lyra, LYR
              Ophiuchus, OPH
              Pegasus, PEG
              Sagittarius, SGR
              Scorpius, SCO
              Virgo, VIR
              _________________________________________________________________________________________
              

              _________________________________________________________________________________________
              Table:  Winter Sky Constellations
              _________________________________________________________________________________________
              Constellation               Observed Location in Sky     Why Not Observed?
                                          (Done in observations
                                           task below)
              _________________________________________________________________________________________
              Andromeda, AND
              Auriga, AUR
              Canis Major, CMA
              Canis Minor, CMI
              Gemini, GEM
              Leo, LEO
              Orion, ORI
              Perseus, PER
              Taurus, TAU
              Ursa Major, UMA
              _________________________________________________________________________________________
              

      End of Task

    4. Unlabeled Sky Maps:

      The 3 unlabeled sky maps printed out in Task 1: Contouring Constellations in are shown in the 3 figures below.




    5. Task 2: Constellation Observations:

      This task is to be done DURING observations and SIMULTANEOUSLY with Task 4: Bright Star Observations.

      So you have to wait until you go outside.

      Only the favorite report form requires filled-in tables---unless your instructor directs otherwise.

      Sub Tasks:

      1. Try to find all the constellations in the above Constellation Tables (general link: Constellation Tables) that are observable at this time of the year.

      2. When you have found a constellation, mark its location in the "Observed Location" column in the Constellation Tables.

        Example location specifications: near zenith, near nadir, northern sky, southern sky, eastern sky, western sky, some in-between sky, etc.

      3. If a constellation is NOT observed, in the Constellation Tables mark it as NOT observed in the observation column and report why NOT observed in the "Why Not Observed?" column: i.e., below or too near the horizon, lost in the city lights, clouded out, etc.

      4. Note that actually almost all the constellations can only be found by finding one or more bright stars in them.

        So this task has to be done SIMULTANEOUSLY with Task 4: Bright Star Observations specified below.

      End of Task

    6. Task 3: Bright Star Labels:

      Label the bright stars shown in Table: Bright Stars (general link: Table: Bright Stars) on the sky maps you printed out.

      Click on the name of the bright star to see a sky map locating it in its parent constellation.

      DO NOT fill in the Table: Bright Stars now.

        ____________________________________________________________________________________________________________
        Table:  Bright Stars
        ____________________________________________________________________________________________________________
        Bright Star    Bayer     RA       DEC       Transit  Above Horizon   Observed    Why Not Observed?
                       Desig-   (h m)     (deg       Time      at 9:00 pm     Today
                       tion               arcmin)               Today         (Y/N)
                                                                 (Y/N)
        ____________________________________________________________________________________________________________
        Aldebaran      α TAU    4h 36m    +16°31'
        Algol
        Altair
        Antares
        Arcturus
        Betelgeuse
        Capella
        Castor
        Deneb
        Polaris
        Pollux
        Procyon
        Regulus
        Rigel
        Sirius
        Spica
        Vega
        ____________________________________________________________________________________________________________
        

      End of Task

    7. Task 4: Bright Star Observations:

      This task is to be done DURING observations and SIMULTANEOUSLY with Task 2: Constellation Observations.

      So you have to wait until you go outside.

      Only the favorite report form requires filled-in tables---unless your instructor directs otherwise.

      Sub Tasks:

      1. Try to find all the bright stars in the above Table: Bright Stars (general link: Table: Bright Stars) that are observable at this time of the year.

      2. When you have found/not found a bright star mark it as "Y/N" in the observation column in Table: Bright Stars above. If the bright star is NOT observed, report why NOT observed the "Why Not Observed?" column: e.g., below or too near the horizon, lost in the city lights, clouded out, etc.

      End of Task

    8. Task 5: Ranking Star Brightness:

      If there is time DURING the observations, observe ONE or OTHER of the Big Dipper (which is an asterism in Ursa Major) or Cassiopeia and rank their brightest stars in order of apparent brightness (rank 1, 2, 3, etc.) in the tables below (local link / general link: Table: Big Dipper Stars; local link / general link: Table: Cassiopeia Stars). Any unobservable star, just rank as unobservable.

      Often only one of the two constellations will be in a good position: high in the sky and NOT lost in the city lights or clouds.

      The sky maps below (local link / general link: iau_ursa_major_ekrem.html; local link / general link: iau_cassiopeia.html) will allow you to identify the stars in the constellations. Print both sky maps. To print go right click on image/print preview/adjust size/print.

        RMI Qualification: If you do NOT have a printer, you will have to hand sketch the maps in sufficient detail for your own use.

      Of course, neither the Big Dipper nor Cassiopeia may be observable in which this task CANNOT be done.

      If the task CANNOT be done, say why NOT. Reason why NOT: _____________________________________________

              _______________________________________________________________________
              Table:  Big Dipper Stars
              _______________________________________________________________________
              Star                            Apparent Brightness Order
              _______________________________________________________________________
              Alioth (ε UMA)
              Alkaid (η UMA)
              Dubhe (α UMA)
              Megrez (δ UMA)
              Merak (β UMA)
              Mizar (Mizar-Alcor system)
              Phecda (γ UMA)
              _______________________________________________________________________
              

              _______________________________________________________________________
              Table:  Cassiopeia Stars
              _______________________________________________________________________
              Star                            Apparent Brightness Order
              _______________________________________________________________________
              α CAS (Schedar)
              β CAS (Caph)
              γ CAS (Tsih, Navi)
              δ CAS (Ksora, Ruchbah)
              ε CAS (Segin)
              η CAS (Achird)
              _______________________________________________________________________
              

      End of Task




  8. The North Celestial Pole (NCP)

  9. In this section, we do some tasks concerning the north celestial pole (NCP).

    The NCP is the location where the celestial axis intersects the celestial sphere---which is the imaginary, infinitely remote sphere on which we project astronomical objects in order to locate them on the sky.

    From the Earth's perspective, the celestial sphere rotates around once per day (more exactly once per sidereal day) on the celestial axis.

    It is best to do the tasks below before observations, but that may NOT be possible.

    1. Task 6: NCP Angle:

      Sub Tasks:

      1. Study the circumpolar figure below (local link / general link: declination_altitude_2.html). Note the north celestial pole (NCP), the equator, the right angle, and angles L, A, B.

      2. What is geographic quantity represented by angle L? (A number is NOT the answer.)     ________________________    

      3. What is the altitude (astro jargon for angle perpendicularly up from the horizon) above the due-north horizon of the north celestial pole (NCP) for a GENERAL location in the Northern Hemisphere? (A number is NOT the answer.) What is the altitude of the NCP for Las Vegas, Nevada? (A number is the answer.) Answer in sentence form.

        Hint: A regular sentence begins with a capital letter, ends with a period. It usually has a subject and a verb. NOT always.

        Answer:

      End of Task


    2. Task 7: Circumpolar Circle Angular Radius for the NCP:

      The circumpolar circle angular radius (CCAR) for the NCP for a given location in the Northern Hemisphere is the angle measured from the NCP within which astronomical objects are circumpolar for that location and above the horizon.

      Recall circumpolar astronomical objects are astronomical objects that NEVER rise or set---they are always above or below the horizon.

      Sub Tasks:

      1. Examine the animation in the figure below (local link / general link: sky_swirl_polaris_animation.html). Are all the stars circumpolar?     Y / N
      2. Which star is nearly at the NCP (i.e., which star is the pole star)?     ______________________    
      3. How far in angle can a star be from the NCP and still be circumpolar? A general answer is expected. Answer: An angle equal to the altitude of the NCP.
      4. What is the CCAR for the NCP for astronomical objects for a GENERAL location in the Northern Hemisphere (the answer is NOT a number) and from Las Vegas, Nevada (the answer is a number)? Answer in sentence form.

        Answer:

      End of Task


    3. Polaris: The Pole Star:

      Polaris is a particularly interesting bright star because it is within 1° of the NCP, and so to casual observation does NOT seem to move at all---it actually revolves in a very small small circle on the celestial sphere every day.

      Because it is so close to the NCP, Polaris is the Northern Hemisphere pole star of our historical period.

      Polaris makes the NCP easy to find---find Polaris and you've found the NCP to within 1°.

      See the figure below (local link / general link: sky_swirl_polaris_ehrenbuerg.html) illustrating the daily motion of stars around the NCP.


    4. Task 8: The Polaris Altitude:

      What is the altitude of Polaris for the Northern Hemisphere in general and for Las Vegas, Nevada in particular? Answer in sentence form.

      Answer:

      End of Task

    5. Finding Polaris:

      Finding Polaris is NOT so hard, but it takes a bit of know-how.

      It's a reasonably obvious naked-eye star, but there are many naked-eye stars as bright or brighter. So brightness alone won't find Polaris for you.

      It is the brightest star in Ursa Minor, and the end of the handle of the Little Dipper asterism in Ursa Minor. But the other Ursa Minor stars are much harder to find especially in bright sky conditions as in modern cities. So finding Ursa Minor is NOT the usual strategy for finding Polaris.

      There are two tricks for finding Polaris.

      One we leave for another day.

      The other is to look due north and use spread hands to measure out the angle of the NCP above the horizon (i.e., the altitude of the NCP from due north).

      The hand and angle diagram in the figure below (local link / general link: alien_angular.html) shows how to use your hand to make angular measurements.


    6. Task 9: Polaris Altitude from Hand Measurements:

      Sub Tasks:

      1. Read the subsection Finding Polaris above (local link / general link: Finding Polaris) and figure above (local link / general link: alien_angular.html). Have you read the caption?     Y / N    

      2. About how many spread hands is Polaris above the horizon in Las Vegas, Nevada? Answer in sentence form.

        Answer:

      End of Task


  10. Bright Stars

  11. In this section, we investigate bright stars as seen in the sky: i.e., stars of high apparent brightness.

    1. Meaning of Apparent in Astronomy:

      Note that in astronomy, "apparent" does NOT mean "false" or "seeming".

      It means "as seen from the Earth".

      So stars of high apparent brightness are bright as seen from Earth. They are NOT necessarily stars of high intrinsic brightness: i.e., high luminosity (energy output per unit time). They could just be very close to the Earth, and so have high apparent brightness.

    2. Bright Star Names:

      The stars of highest apparent brightness usually have traditional names mostly derived from Latin (e.g., Polaris which means of/near the North Pole: see Wikipedia: Polaris: Names) or Arabic (e.g., Algol which means the Ghoul: see Wikipedia: Algol: Names).

      The bright stars with traditional names are the named stars.

      For examples of named stars, see the sky map of Ursa Major below.


    3. Bayer Designation:

      Stars often have multiple names.

      The bright stars as well as often having traditional names (see Wikipedia: Named stars) also often have Bayer designations.

      Bayer designation is explicated as follows:

      For an example of a star with a Bayer designation consider Mizar in Ursa Major. It is also ζ UMA (as shown in the sky map above). The ζ (spelt out and vocalized zeta) means that Mizar (AKA ζ UMA) is about the 6th apparent brighest star in the constellation.

      In fact, the assignment of Greek letters is NOT always in the correct order of decreasing apparent brightness.

      Johann Bayer (1572--1625) who developed the Bayer designation had NO way of doing exact brightness measurements and, in fact, it was NOT part of his program to get the right order (see Wikipedia: Bayer designation: Is Alpha always the brightest star?).

      Nevertheless, in most constellation, the α star is the brightest and the β star the 2nd brightest.

      For reference, the Greek alphabet in order is given in the diagam below (local link / general link: greek_alphabet.html).


    4. Most Stars Have No Traditional Name or Bayer Designation:

      The named stars and the stars with a Bayer designation are only a tiny fraction of all stars even just in our local part of the Milky Way.

      And no one is giving any more such special names nowadays.

      To accommodate the millions of stars that are observed, other nomenclatures have been developed.

      Surveys of stars produce catalogs of stars and the stars are just named by their catalog number---it does NOT matter if a star has other names.

      For example, Algol (AKA β PER) is also HD 19356 (in the Henry Draper Catalog) and SAO 45864 (Smithsonian Astrophysical Observatory Star Catalog).

      The simplest way of naming a star is just to name it by its equatorial coordinates: i.e., its right ascension (RA) and declination (Dec or δ).

    5. The Meridian:

      The meridian in astro jargon is a great circle than passes through the NCP, SCP, and the zenith---the point directly overhead wherever you are.

      The meridian is illustrated in the figure below (local link / general link: horizontal_coordinates.html).


      Precise positional observations of
      astronomical objects transiting (i.e., crossing) the meridian are very easy to make.

      Hence, at least in NOT so long ago days, the local time for a transit (i.e., transit time) was a very important datum.

      It still is for a lot of purposes.

      Astronomical objects move 15° west on the sky per sidereal hour (which is slightly shorter than a standard hour) along small circles of constant declination just due to the eastward rotation of the Earth---or from a geocentric perspective, the westward rotation of the celestial sphere.

      15° is 1 hour of right ascension.

      So if you know today's transit time for an astronomical object and its declination, you can estimate where it will be any observing time.

      The importance of transit times is the reason for including them in Table: Bright Stars above (local link / general link: Table: Bright Stars).

    6. Task 10: Bright Star Data (IPI only):

      Making use of TheSky, complete the data in Table: Bright Stars above (local link / general link: Table: Bright Stars) in the favorite report form only---unless directed otherwise by your instructor.

        You should have already set the date and time for TheSky6 if you are using TheSky6. If NOT, go Toolbar/Data/Time and set to today's date (see Date & Time if needed) and to time 9:00 pm (unless the instructor says use another time) using the buttons.

      The columns "Observed Today" and "Why Not Observed?" should be filled out in Task 4: Bright Star Observations during the observations.

      Note the column "Above Horizon at 9:00 Today" makes use of the "visibility" row in the TheSky6 information box which gives rise and set times on the 24-hour clock.

      If the rise time is after the set time, then the star set and then rose during today's date (see Date & Time if needed).

      End of Task


  12. The Rotating Sky

  13. The apparent rotation of the sky is NOT a big part of this lab since is hard to observe in our short period of observations.

    Still we can a little intro to the rotating sky.

    1. The Apparent Rotation of the Sky:

      The sky does an apparent rotation about the celestial axis every sidereal day = 86164.0905 s = 1 day - 4 m + 4.0905s (on average) (which is a little shorter than a metric day =24 h = 86400 s).

      The celestial axis is just an extension to the celestial sphere of the Earth's axis.

      The apparent rotation is caused by the physical rotation of the Earth relative to the fixed stars to very high accuracy/precision.

    2. Task 11: The Rotating Sky:

      During tonight's observations (which are described above in section Constellations, Bright Stars, Observations), did you notice the apparent rotation of the sky?

      1. Yes.
      2. Yessss! Awesome!
      3. No.
      4. The rotating sky is all a crock.

      End of Task

    3. Task 12: Rotating Sky Explorer Questions: Omit update:

      Complete this task using the Rotating Sky Explorer displayed in the figure below (local link / general link: naap_rotating_sky_explorer.html). EVERYONE in the group must do the task for themselves.

      Sub Tasks:

      1. Push all the buttons to see what they do. Did you do this?     Y / N    
      2. Is the Big Dipper/Orion/the Southern Cross (as marked out by the Rotating Sky Explorer) completely circumpolar from the latitude of Las Vegas, Nevada?     _____________________    
      3. Where on Earth are all stars circumpolar (i.e., they never rise or set)?     __________________________________________________    
      4. Where on Earth are NO stars circumpolar?     __________________________________________________    

      End of Task



  14. Horizon Contour Line (IPI only and optional at the discretion of the instructor)

  15. Since we love nothing more than a tedious, finicky task at the end of a long night.

    1. Task 13: Contouring the Horizon (IPI only):

      On the 3 Unlabeled Sky Maps given in section Constellations, Bright Stars, Observations (local link / general link: Unlabeled Sky Maps) mark approximately with a contour line the horizon for our location for today's date (see Date & Time if needed) for 9:00 pm.

      See the below subsection Finding the Horizon (local link / general link: Finding the Horizon) for help in finding the horizon.

      This task takes about 15 minutes or so which may be too much time at the end of the night. So it is omittable at the discretion of the instructor.

      End of Task

    2. Finding the Horizon:

      The TheSky6 should just show the horizon on its sky map. The horizon is the boundary between night (dark on the sky map) and day (green on the sky map).

      For TheSky6, List of Tricks for TheSky shows you how to get the horizon marked on TheSky6 sky map including the one in Mercator projection.

      Another way to find the approximate horizon is to make use of a planisphere (see the figure below: local link / general link: planisphere.html)

      Set a planisphere for today's date at 9:00 pm (see Date & Time as needed).

      The sky above our horizon is approximately seen in the oval window.

      The window border marks our horizon approximately.

      Locate the horizon by finding what constellations the window border crosses or goes between and then use that information to locate the horizon on sky maps.



  16. Finale

  17. Goodnight all.


  18. Post Mortem

  19. Post mortem comments that may often apply specifically to Lab 1: Constellations:

    1. Nothing yet.