1. Initial Problem Statement

Attempting to identify and observe the celestial bodies on your own is not an easy task. There are numerous resources to look at, but they often do not adapt to the user’s current location, environment, time of day, particular goals, et cetera.

Our idea is to create an easy-to-use astronomical sky guide that will allow people with some familiarity of astronomy to gain easier access to the sky. The device will aid users in locating celestial objects and phenomena according to user-specified goals.

2. User Identification

2.1 Model User

In order to identify users of our new device, we interviewed members of the Atlanta Astronomy Club (AAC). The AAC consists mainly of members whose experience levels vary from intermediate to advanced, with very few members who have little or no knowledge and experience. The majority of club members are intermediate and advanced amateur observers who are at least 30 years of age. The model user of the device we chose will be an adult intermediate amateur.

Several characteristics can be used to describe our users:

• Experience level: The users of this device will have some experience with outdoor observation, probably having observed the nighttime sky an average of between 3 and 30 times over the course of 1-4 years. Users often observe in groups and treat observation as a social event.
• Interest level: Our users have a high interest level in astronomy. This interest has been cultivated over several years of their lives, despite limited experience with actual observation. One user may be a NASA buff that likes to know about the scientific significance of objects in the sky, while someone else may just be intrigued by its mystery. Our users' interest in astronomy is manifested in their collection of astronomy related informational materials and paraphernalia.
• Current knowledge: Our users have a basic understanding of astronomy. This includes an understanding of orbits, phases, distances measured in degrees and constellations.
• Age: Our users are not limited to a minimum age, but should have a minimum maturity level or otherwise should be supervised by an adult while using the device.
• Physical Constraints: This device is centered on visual and physical mobility, so the user must be able to see, they must be able to adapt their physical positions (head, neck, sometimes full body movement) and they must be able to endure the outdoors. Hearing might also be necessary for enhanced features, such as making audio records or chatting between users.
• Degree of techno phobia: Users of this device must be somewhat comfortable with technology, and have a willingness to try new technology.
• Geographic distribution: Individual users may be located anywhere on the globe when using the device. Group users can be separated geographically, as the device will allow for communication among separated users.
• Culture: The device will be developed initially for English-speaking cultures of the industrialized, Western society.

2.2 Sample Scenario

Comments

• Interest level:Should it be for any interest level? Do we want to design a device that gets users excited about astronomy, or do we want to design one that is solely to aid people who are already interested in it?
• Current knowledge:The first thought was it should be designed for any knowledge level, but then what about people who have no idea what stars are, or who don't know anything about the solar system? Designing for this group would be more like designing a teaching system than a guide, so it was decided that users should have a basic understanding of astronomy. We will define later what this knowledge set should include.
• Age:It was first thought that the device should be for observers of any age, but this would prove difficult in using certain terms that youngsters might not understand – or we would have to design several views of the same information for different ages, so it was decided users should have a minimum maturity level or should be supervised.
• Physical constraints:This device is centered on visual and physical mobility, so the user must be able to see (designing for blind users would be a completely different project) and they must be able to be outside. There are other physical aspects we should pay attention to, averted vision (sometimes it is easier to see a star if you look next to it instead of directly at it), dark-adapted eye, color sensitivity, how environment affects the user physically, neck problems. Will the user have to be in a certain position to use the device and see the sky? We decided that hearing would be necessary for enhanced features, such as conversing between users.
• Degree of techno phobia:Users will have to be fairly comfortable with technology, it will be device that they will depend on to enhance their experience, especially if it is a device that has to be put on. At least a willingness to try new technology must be present.
• Geographic distribution:We want to allow users to be separated geographically, and have the device enable communication among users since observation is often a group activity. But we also want a user who is alone in one part of the world to be able to communicate with other users in different locations.
• Culture:We wondered if the device should be only for industrialized, Western society. We decided to limit this to English-speaking people because we need to leverage the body of knowledge created by Western society to create the device.
• Experience with observation outside:We initially thought the device would be designed for the full range of experience levels. We later decided to focus on intermediate observers who had some experience with outdoor observing. It was decided after the interviews that complete novices would have the most trouble with simply getting started, whereas we want our device to focus on the task of observing. At the other end of the spectrum, we did not want to design a device for an expert, because their tasks are also beyond that of simple observation. It is still believed, however, that the device will offer some utility to anyone involved in an outdoor observing trip regardless of knowledge or experience.

3. Task Analysis

3.1 Gathering Information

3.2 Identifying Involved Artifacts

Starmap          : identify constellations, find constellations
Detailed Starmap : identify objects, find objects
Sky Atlas        : identify objects, find objects, get data on
                   objects
Almanac          : get information on uppcoming events and
                   visible objects, get data on obecjts, use
		   maps of almanac, use tables of almanac
Tables           : Obtain coordinates of objects, obtain data
                   on objects
Astronomy program: identify constellations, find constellations,
                   find objects, get data on objects, get
		   information on uppcoming events
Web Service      : obtain data on objects
Telescope        : Focus object, observe object, make sketch
                   of object, make picture of object
Binocular        : observe object, make sketch of object
Clothing         : Keep gazer warm
Food             : support gazer (food, hot tea ...)
Pen              : make notes
Paper            : make notes
Tape Recorder    : make notes
Camera           : make notes, grab object
Flashlight       : illuminate items with red light

Objects          : sun, moon, planets, moons of the planets,
                   stars, deep-sky-objects
Planets          : Mercury, Venus, Earth, Mars, Jupiter, Saturn,
                   Uranus, Neptune, Pluto
Stars            : single stars, double stars, triple stars,
                   multi stars
Deep-Sky-Objects : planetary nebulae, emmission nebulae,
                   dark nebulae, open star clusters, globular
		   star clusters, galaxies
object data      : distance, magnitude, diameter, size in
                   arcseconds, type of object, object specific
		   information

3.3 Performing The Analysis

information source AND
    form XOR
        book
            sky atlas, almanac
	other printed
            starmap, detailed starmap, table
	computerbased
	    computer program, web service, CAT-System
    purpose OR
	find constellation
	    starmap, almanac, computer program
	identify constellation
	    starmap, almanac, computer program
	find object
	    detailed starmap, sky atlas, almanac, table,
	    astronomy program, web service, CAT-System
	identify object
	    detailed starmap, sky atlas, almanac, table,
	    astronomy program, web service, CAT-System
	get data on object
	    sky atlas, almanac, table, computer program,
	    web service, CAT-System
	get information on upcoming events
	    almanac, astronomy program
    scope XOR
        broad
	    almanac, starmap, sky atlas, computer program
	narrow
	    table, detailed starmap, web service, CAT-System
    level XOR
        basic
	    starmap, almanac
	advanced
	    sky atlas, table, detailed starmap,
	    computer program, web service, CAT-System
    availability XOR
        common
	    starmap, almanac, sky atlas, detailed starmap,
	    web service
	special
	    table, computer program, CAT-System

observing tool OR
    purpose XOR
        view
	    telescope, binoculars
	convenience
	    red illuminating flashlight, (hot) drinks, food
        recording
	    pen and paper, tape recorder, camera
    task OR
        focus object
	    telescope
	view object
	    telescope, binoculars
	grab object
	    pen and paper, camera
	do logging
	    pen and paper, tape recorder, camera
    complexity XOR
        low
	    binoculars, red illimunating flashlight,
	    pen and paper, tape recorder
	high
	    telescope, camera
    automation XOR
        low
            telescope, binoculars, pen and paper
	high
	    telescope, tape recorder, camera

3.4 Revealing Task Complexity by Task Decomposition

0. Find a constellation
    1. Identify sky directions
        1.1 Look for polar star
	1.2 Look on compass
    2. Look at starmap
    3. Match content of star map to sky

Plan 0: do 1 if desired
        while constellation not found do 2-3
Plan 1.1: do 1.1 or 1.2 if necessary

0. Focus object without CAT-system (Computer Aided Telescope)
    1. Obtain location of object and detailed map of area
        1.1 Use almanacs
	1.2 Use tables
	1.3 Use computer program
	1.4 Use star map
	1.5 Use detailled star map
	1.6 Use sky atlas
    2. Find constellation containing object
        2.1 Use plan 0 from upper decomposition
    3. Roughly point telescope
    4. Fine tune until object is focused
        4.1 Look at detailed map
        4.2 Finetune telescope by looking through view-finders
	4.3 Check Result

Plan 0: do 1-4
    Plan 1: do any of 1.1-1.6
    Plan 4: do 4.1-4.3 until object is focused

0. Focus object with CAT-system
    1. Callibrate CAT-system
        1.1 Follow instructions in manual
    2. Find out catalog number of object
        2.1 Use almanac
	2.2 Use sky atlas
    3. Type in number into CAT-system
    4. Wait for telescope to finish movement
    5. Check Result

Plan 0: do 1-5
    Plan 2: do 2.1 or 2.2

Comments

2. The second major decision concerned the type of task analysis to use. Initially we decided to use task decompisition but this later presented problems. The interviews revealed that observers use a multitude of resources and tools in different ways, different sequences and for different goals. They may consult the information sources before observing an object, or they may do this only after they observed something. Equally, a telescope may be used together with a recording device or for plain observing. Because of these peculiarities it seems unpratical to use a task decomposition for the very broad goal   Do Observation . Instead we decided it was best to use knowledge-based analysis in order to create taxonomies of activities and objects used during observation. In addition to the knowledge-based analysis, task decompositions for narrow goals, such as Find Constellation help reveal the difficulty and complexity of major activities during observation.

4. Task Environment

4.1 Environmental Constraints

• Transparency: This is a measure for how much light passes through the atmosphere. Even though the sky might look clear, the light of objects is still dimmed by steam or light clouds in the high atmosphere layers. A good measure for transparency is the faintest star visible with the naked eye. Transparency must be good to observe dim objects.
• Seeing: The air of the atmosphere is not totally calm. Turbulences in the atmosphere lead to flickering stars and un-sharp star images. This is the same phenomenon as the flickering seen above a hot road. Seeing determines the resolution with which the sky can be observed. In order to separate close multiple stars the seeing has to be good.

4.2 Physical Constraints

• Adaption: After leaving normal bright light conditions, it takes the eye at least 20 Minutes to fully adapt to the darkness and respond to as much light as possible.
• Averted Vision: The light-sensitive part of the eye, the retina, contains two types of receptors: cones and rods. Basically, cones are responsible for seeing colors. There are three types of cones, one type for each of the colors red, green and blue. Rods, on the other hand, are only sensitive to brightness and provide no color information. Rods do not work very well under poor lighting conditions, which is why humans are unable to properly distinguish colors by night. The fovea, a point at which the eye can see sharpest, contains more cones than rods. For the observation of a dim object by night this means that it is advantageous to not look directly into the object, but slightly past. By that, the little light of the object does not hit the fovea directly, but the regions around it, which are much more sensitive to small light portions than the fovea itself, thus revealing much more detail of the observed object. This technique is commonly used among stargazers and is referred to as averted vision.
• Color Sensitivity: For the dark-adapted eye it is most convenient to look at red illuminated devices to prevent the loss of the darkness adaptation. This can easily be seen when going to any astronomical observing site, where it becomes obvious that red light sources are dominating. Since the blue cones are smallest in number, the human eye is least sensitive to blue light. It is most sensitive to green light.
• Resolution: The resolution of the naked human eye is approximately one arc minute. That means a human can distinguish two separate points if their angular distance is one arc minute or larger. Using a telescope or binoculars improves the resolution for observing. Telescopes might reach resolutions far below one arc second from the physical point of view, however seeing conditions (see above) might drive the resolution up to only one to three arc seconds again.

5. Identifying the Larger System

The range of social groups in which stargazing takes place is rather large. Stargazers can go individually, in very small groups (1 or 2 other people), in small parties (around 10-20 people), or on occasion go in large groups (as many as 200 people). (Note: the goals of the stargazers may very well be different in different social environments.) There are many astronomy organizations that exist in order to bring together primarily amateur astronomers both for lectures and to organize stargazing events.

Stargazers usually make their observations at night, but depending on the phenomenon being observed, this can also occur in the morning before sunrise, or even during the day for solar phenomena. A stargazing session may last several hours, but may occur during the course of a longer expedition such as a camping trip, or even a week-long stargazing party. The preparation time can be significant, making the time from beginning preparations to the returning home for a single session take around 12 hours total.

Stargazers often travel to a relatively remote location, which can provide the highest possible quality of visibility of the night sky. This means that they will try to find a location far away from city lights. For some, their home environment is sufficient.

The expected weather conditions for stargazers will depend on the geographic location and time of the observations. Any kind of weather which allows for clear skies can be expected, indicating that it can be quite hot, quite cold or anything in between.

Information about events to observe may come from a variety of sources such as the WWW, fax, email, observers handbooks, and astronomical software. The primary periodicals for amateur astronomers are Sky and Telescope and Astronomy.

Most stargazers keep logs of their observations. Some also record their observations photographically.
 
 

Comments

3. The description of the larger system in which our device will be used is based both our own familiarity with stargazing, on our interviews of several individuals who currently participate in stargazing, and perusal of the websites of some astronomy clubs. In addition members of the AAC were observed "in action".

6. Usability Criteria

The three most crucial usability criteria for our device will be:

Familiarity: "The extent to which a user's knowledge and experience in other real-world or computer-based domains can be applied when interacting with a new system." Familiarity will be important in assessing the usability of our device for two reasons. First, the constraints of the users' task environment require that they are able to leverage previous experience with technology in order to quickly learn the system and use the device. Often, intermediate observers will fail to try new devices because they seem complicated and taking the time to learn them is rarely convenient. Second, it is important the design of the device upholds and reinforces the current astronomical knowledge and experience of its users, including techniques of location, identification and record-keeping. The device may streamline these activities but it will be important for users to understand how their previous experience fits in with the new system.

Dialogue Initiative: "Allowing the user freedom from artificial constraints on the input dialogue imposed by the system." Users must have full freedom to use the device in order to support their particular needs. Stargazers often have an agenda of objects they would like to observe and the device must be designed to fully support these goals without being restrictive. The device should not interfere with the users' goals.

Observability: "Ability of the user to evaluate the internal state of the system from its perceivable representation." Given that the location and identification of objects in the sky is an integral part of observation, users must understand what they are viewing at all times while using the device. As such, the design of the device must establish an explicit relationship between interface elements and the objects actually in the sky.
 
 

Comments

4. Deciding on which usability criteria to focus on was relatively easy. We based the criteria on the concerns expressed by our users. Some of these were based on statements made outside of the actual interview, such as "I don't use software because the programs are too complicated".

7. Evaluating Existing Systems

7.1 Printed Star-Maps

• Fixed maps: Fixed maps usually come as a set of several different maps, each of which is designed for a specific time. Since the sky changes as the Earth rotates, different maps have to be used at different times. This includes day of year as well as time of day. Maps can be reused, i.e. a map could be valid for May 1st, 11pm as well as for May 15th, 10pm. For reasonable work, a set of 12 maps should be sufficient.
  Printed maps can also be very detailed, as there are books which show separate maps for each constellation. This is particularly important for users who need detailed maps for finding a certain object. Usually these detailled maps are collected in a sky atlas which provides additional information for each map, including data on astronomical objects covered by the map.
  
   
   
   
   
   
   
   
   
   
   
  
• Turnable maps: By clever design these maps let the user adjust the day of the year and time of the day with a rotating transparent foil mounted on top of the map. By that, only one map is needed instead of a set of maps. However, in this form, the user must accept distortions on the map.
   
   
   
   
   
   
   
   
   
  

Printed maps are very cheap and give an expert user quick access to information about visible stars. However, transfering the information from the map to the sky requires some training, which is why fixed maps are rather unsuitable for the occasional user and novices. They need no power supply, but the user must illuminate the map once he or she is outside observing.
 

7.2 Tables and Almanacs

Almanacs, also called a Year-Book, provide the user with year specific information of astronomical events. Usually this includes descriptions of events each month, a listing of visible planets and their accompanying moons and of other interesting objects. Good Almanacs also include star maps and a table-section. Most sky observers use an Almanac, and depending on the writing style of the material presented, it might also be of some use to a novice users, who for example might find information about what bright light-point is visible right after sunset in the west.  [example]
 

7.3 CAT Devices

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

7.4 Computer Programs

As handheld devices become more popular, there have also been efforts to create sample astronomy programs for these devices based on the existing computer programs. Primarily, these programs struggle with small displays and slow response times. Despite, they reveal the same problems as normal computer programs.  [example]
 

7.5 Web-Based Systems

7.6 Planetariums

8. Conclusion

The analysis of this part of the project revealed many different activities involved in stargazing. The basic tasks to be performed have been identified. In essence, it is all about finding and identifying some object. As the task decompositions of these sub goals have shown, these tasks can be very tricky and time consuming. Thus, there is an ample scope for improving the convenience of these tasks. Also, there are many other tasks that might reveal difficulties. For example, several users complained about humidity being a problem during observation, and that this is a problem for books or paper, which soak full of water, thus making the consultation of books or recording on paper during observation more difficult. The global tasks of the device to be developed have been identified.

9. References