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Lab 1: Constellations / Lab Supplement

Sections

  1. Student Preparation which includes Quiz Preparation.
  2. Special Instructions For Instructors
  3. Startup Presentation
  4. Post Mortem

  1. Student Preparation

    2. Required Lab Preparation:

    1. Read Lab 1: Constellations. It is hard to understand software/hardware tools without first seeing and playing with them, but insofar as possible you should be prepared to use the tools. You could also fill out any parts of the lab that can be done ahead of time.
    2. Read the Startup Presentation.
    3. Read the IAL 2: The Sky sections 4,8,9,10.
    4. Read the Post Mortem. Better before than after actually.
    5. Read a sufficient amount of the articles linked to the following lab keywords so that you can define and/or understand the terms etc. at the level of our class: Bayer designation, bright stars, celestial globe, celestial meridian (AKA the meridian), celestial sphere, constellations, equatorial coordinate system (AKA celestial coordinates), declination (Dec), horizon, list of brightest stars, list of constellations, meridian, Milky Way, nadir, planisphere, Polaris, right ascension (RA), sky map, TheSky, transit, zenith.

    Supplementary Lab Preparation: The items are often alternatives to the required preparation and to each other.

    1. Bennett book p. 28--36 and p. A-28--34.
    2. Many other intro astro books give similar presentations on the appearance of the sky and the celestial sphere usually in the 1st or 2nd chapters.

    Examination in Australia Quiz Preparation:

  2. Special Instructions For Instructors

    1. Check as needed:
      1. Usual Startup
      2. Usual Shutdown

    2. Check the weather online at NWS 7-day forecast, Las Vegas, NV in advance and by personal visual inspection at/during the lab period. What if the weather does NOT permit the outside part? You can have the students do the observations on the TheSky or you can outside part a leftover part till next week. But note that the next lab is a long lab (Lab 2: Celestial Sphere), and so you will have to do the leftover part rapidly. You can have the students start Lab 2: Celestial Sphere to save time next week.
    3. As the lab time approaches you should also check Sky map: Las Vegas, current time.
    4. Set out on each table the Lab 1 sky maps for each student or for the group depending on your choice, a celestial globe, and a planisphere. For Lab 1 sky maps, you should help use up the prepared set in the storeroom. However, if they are used up, use the online Lab 1 sky maps. You can print them out and copy them ahead of time.
    5. You will need your flashlight for outside work. Yours truly uses a cap-light.
    6. An iPad with SkySafari can be used help find constellations and stars for the students when you go outside. You might need to practice with the iPad and recharge the battery. The iPad User Guide is a reference and/or you could get some instruction.
    7. Drawing in the horizon on the sky maps is tricky for the students. I just ask them to use the planisphere. The oval window edge approximately defines the horizon. All they need to do is to roughly plot the contour line across or between appropriate constellations on their sky maps.
    8. If there is a quiz, you will usually give it at the start of the lab period.
    9. As always, you will have to give a Startup Presentation which briefly outlines the lab, introduces lab keywords, and covers any special tools if necessary. Yours truly prefers the Startup Presentation to be no more than about 10 minutes. The astro labs are an active learning environment and students get restless and lose attention after more than about 10 minutes in my experience.
    10. You will need to give some introduction to the TheSky if you didn't do that during the orientation period. Even if you did give an intro then, you probably have to repeat a bit of it now. Point out the online List of Tricks for TheSky. Any suggestions to improve this list are welcome.

    red foxes

    Caption: "Red foxes (Vulpes vulpes) at the British Wildlife Centre, Horne, Surrey, England." (Slightly edited.)

    Credit/Permission: © Keven Law, Photo 2008 Aug17 / Creative Commons CC BY-SA 2.0.

    Image linked to Wikipedia.

  3. Startup Presentation

    4. This lab is designed to give students a general orientation in observing the sky.

    We can break that down a bit.

    1. You will get some practice finding constellations and bright stars.

    2. This practice will be with tools in the lab room and with naked-eye astronomy on the roof.

    3. The tools are sky maps, celestial globes, and planispheres on the tables, and TheSky (computer software),

    4. For reports, use pencil. It's easy to make changes and there will almost always be changes to make.

      Answer any questions requiring sentences with sentences.

      You can certainly peer review each other, but do not directly copy.

    5. A sky map is a 2-dimensional map of the sky.

      To make such maps we project all astronomical objects on an infinitely remote imagined sphere centered on the Earth's center.

      The sky maps show all or part of this sphere.

      The sphere is called the celestial sphere.

      The most usual angular coordinates for sky maps are the equatorial coordinates with the coordinates individually being right ascension (RA) and declination (Dec).

      The right ascension and declination are analogous to, respectively, longitude and latitude on the 2-dimensional spherical surface of the Earth.

      An example of an all-sky sky map is below.

      In later labs, we will do more with the celestial sphere, equatorial coordinates, and sky maps.

    6. Planispheres are explained with the image below.

    7. If we did not get the TheSky intro done in the lab Orientation, we will do that now.

      If needed during this lab, you can refer back to the TheSky intro and the List of Tricks for TheSky.

      The instructor can also help with problems with the TheSky.

      TheSky has an online help if all else fails.

    8. Make use of the tables 1.1--1.4 in the lab report as directed.

      In fact, we don't make use of the tables in order.

      1. First label the constellations that appear in the lab tables 1.2, 1.3, 1.4 on the sky maps.

        Then draw a contour line around the whole constellation.

          Note the observation column for Tables 1.2, 1.3, 1.4 is to be filled out when observing OUTSIDE later in the evening.

          Location can be described using words such as north, south, east, west, or combinations of these, as high or low, as near zenith or near the horizon.

          Just locate them reasonably.

          Actually, often we just locate a constellation by locating a bright star in it. Frequently, that's all one can find/recognize for sure.

        Three kinds of horizon
      2. Second draw in today's horizon for 9:00 pm.

        You will have to use TheSky to get the required data.

        Use 9:00 pm for today's date .

        Set this time and date on TheSky.

        TheSky does NOT automatically set the date.

        For the summer and winter sky maps, drawing the horizon is straightforward if you can make TheSky show the horizon in Mercator projection

        This can be done, but it takes a few steps that detailed in List of Tricks for TheSky.

        For the polar sky map a variety of approaches help.

        Identify the constellations the horizon crosses or skirts and use those constellations as your guide.

        Your done summer and winter sky maps, will help.

        TheSky in stereographic projection will show the horizon in the neighborhood of the celestial poles

        The difficulty in plotting the horizon is that the sky maps given by TheSky and your hardcopy sky maps have somewhat different projections.

        There is no uniquely good way of mapping (i.e., projecting) a spherical surface to a flat surface. There is always some distortion. When you are comparing to maps with different projections of the same thing, it takes some practice to compensate for the different distortions.

        The oval window's edge on the planisphere is approximately the horizon. This can be useful in guiding your drawing of the horizon.

        In fact, using the planisphere to find the horizon location may be good enough if your good at mentally adjusting for different projections.

      3. Third fill in Table 1.1 using data from the TheSky

        Add an extra column on the left-hand side of Table 1.1 with heading "Observed". Here you will indicate whether bright star was actually observed from the roof and if not, why not: e.g., cloud cover, building, etc. in the way, below the horizon, or just could not find.

          Add the Observed column right now.

        The "Visible" column in Table 1.1 is just for whether the bright star was above the horizon at 9:00 pm.

        In the "Time Observed" column just use 9:00 pm in all cases.

        The Table 1.1 is crude lesser cousin of ephemerides (singular ephemeris)---tables of predictions for positions of astronomical objects---see the figure below for a Medieval ephemeris page.

      4. Fourth label the bright stars that appear in the lab Table 1.1 on the sky maps.

        This part is actually best done simultaneously with part 3.

    9. The class should be ready to go to the roof between 9:00 pm and 9:30 pm for observations.

      This part of the Startup Presentation should usually be given then, NOT at the beginning of the lab.

      We CANNOT wait until later.

      Most students should be mostly done the inside work by then.

      You should check the Sky map: Las Vegas, current time.

      Outside directions and rules:

      1. We are going to the roof now to do our outside naked-eye astronomy.

      2. Don't worry if you are not finished the inside work, you can finish later.

      3. Take your sky maps, your Tables 1.2, 1.3, and 1.4, and the planispheres.

      4. I will lock the door, and so you can leave your stuff behind.

      5. If it is winter or otherwise cold, dress warmly.

      6. There two sets of telescope mounts: on the near side of the dome and on the far side of the dome.

        Go to the near ones if they are unoccupied and the far ones if not.

      7. Tonight the telescope mounts have no telescopes on them. They can be used as small tables.

      8. Each group will use a telescope mount as their station.

      9. You will need a flashlight or at least cell phone flashlight.

      10. No food or drink on the roof.

      11. Look out for obstacles. It's dark and there are the telescope mounts and their bases. There could be chairs and stools.

      12. Let your eyes adjust to the dark.

      13. No horsing around up there. There are ways to hurt yourself in the dark.

      14. Go out the door and to the east stairwell and up.

      15. I'll follow immediately as soon as I lock the door.

      16. Get started with your observations and filling in your tables.

    10. Look for the most obvious constellations and bright stars first: e.g., Orion in winter, Cygnus in summer, Ursa Major or Cassiopeia at any time of the year.

    11. We just want a rough location in the sky for the tables: north, south, east,west, or in between; nearer to zenith or nearer to the horizon or in between.

    Boris Karloff, The Mummy

  4. Post Mortem

    5. Below are some generic comments for Lab 1: Constellations that may often apply.

    Any that are semester-section-specific will have to added as needed.

    1. The grades are often very high on the first lab, but it is an easy lab. Other labs have more places to lose marks. However, generally lab grades are high and students differentiate on the quizzes.

    2. Try to be neater. Remember to use pencil since erasure and correction are often needed.

    3. Put the lab report pages in order with the sky maps last.

    4. Make sure you indicate clearly which report is yours. Your partners' names have to written down as partners.

    5. Staple the reports in the upper left-hand corner. If no staples are available, fold the left-hand corner to hold the sheets together.

    6. Make sure you indicate clearly which report from a group is to be marked in detail. The other group reports get the same mark if they are complete. People get docked marks for incompleteness.

    7. There were no sentence answers on this lab report, but there will be on later lab reports. Be sure that you answer those with sentences.