Live from the Hubble Space Telescope
UPDATE # 1
PART 1: Welcome to the project
PART 2: Scheduled web chats
PART 3: Arranging to see the television programming
PART 4: Student writing project: Happy Birthday Dr.
Tombaugh!
PART 5: A detailed plan for observing Pluto
Welcome to "LIVE FROM THE HUBBLE SPACE TELESCOPE",
a project developed by the Passport to Knowledge team.
Over the next three months, you will receive a unique perspective on
the Hubble Space Telescope (HST). Through this maillist, you will receive
regular Field Journals from the men and women who operate this unique
facility. You will hear from the astronomers and space researchers who
use the extraordinary power delivered by the HST to make exciting discoveries.
These behind-the-scenes reports will provide insights in the day-to-day
work required to make this NASA facility a success, including the broad
diversity of skills needed.
But this time, you won't just be watching....you'll be participating
in the mission. For the first time ever, the Space Telescope Science Institute
has dedicated three full orbits (~4.5 hours) of telescope time towards
the K-12 community. In December, students and educators debated what objects
to observe with our precious HST time. Together we reached a consensus
that Pluto and Neptune would be our targets. We will make the observations
in early March. When the data comes down, it will belong to K-12 classrooms
and Passport to Knowledge. Presently, the Hubble Space Telescope crew
is busily preparing for these observations.
LIVE FROM THE HUBBLE SPACE TELESCOPE (LHST) includes two live television
programs scheduled for March 14 and April 23 (each runs page Teacher's
Guide which will be available shortly. This document details a variety
of hands-on science activities designed to integrate with the online and
television resources.
A dedicated online archive is rapidly coming together. It includes the
complete collection of Field Journals, biographies of HST's people, an
image gallery, a collection of classroom projects and much more. This
"continuous construction" Web site is found at http://quest.arc.nasa.gov/livefrom/hst.html
As LHST evolves, special activities will be scheduled. For example,
in March we will provide students and educators an opportunity to email
questions to the HST team where each question will receive a personal
answer. A series of special Web Chat and CU-SeeMe sessions with HST folks
will be scheduled. As details emerge they will be announced on this updates-hst
mailing list.
Presently, we plan to publish these email updates about once per week.
The frequency will increase as we get closer to making our own observations
with the HST in March.
Throughout the LIVE FROM THE HUBBLE SPACE TELESCOPE project, our team
will be interested in receiving your ideas and feedback. Send any comments
to Jan Wee or to Marc
Siegel
If at any time you wish to stop receiving these electronic mailings,
send an email to listmanager
In the message body, write these words: unsubscribe updates-hst
We hope that LIVE FROM THE HUBBLE SPACE TELESCOPE will prove to be an
exciting learning resource for you and your students.
Thanks for your interest,
Marc
We are starting a regularly scheduled chat time online. Our goal is
to gather some feedback from folks about this project or to address some
of your concerns. We are particularly interested in chatting with teachers
who are planning to use this LHST material with their classes, but everybody
is invited.
For now, several project members (Jan and Marc) will be loitering online
each Tuesday from 3:00-4:00 PM (Pacific time). Please try to join us if
you can. If the time is bad, please send email to Marc
and suggest an alternate time.
ARRANGING TO SEE THE TELEVISION PROGRAMMING
If you plan on viewing the television programs live or on tape, now
is a good time to begin planning how you will do this. In the past, this
has been a significant obstacle for many participants, so we suggest that
you should actively explore options as soon as possible.
Your first action should be a call to the local PBS station. Find out
if they will be carrying the programming live or delayed. They can tell
you their schedule. If they are not planning to air the shows, consider
organizing a teacher phone campaign to inform your local station of your
educational wishes. Now is the timeframe that many stations are planning
their March/April schedules and it often doesn't take many calls to capture
their attention.
If that does not work, you will have to get creative. The LHST programming
will also be broadcast over NASA Television. Many cable companies normally
carry this station (its the one with live Shuttle mission coverage). Some
may be willing to carry NASA-TV just for these special events. Other avenues
to try include instructional television systems, community colleges or
anyone with access to a satellite dish. During an earlier project, one
excited teacher convinced a local satellite retailer to temporarily install
a free dish at the school. Also, NASA-TV is normally sent via digitized
video over the Internet using CU-SeeMe and MBONE technology. This option
preserves the live aspect of the programming, but Internet video suffers
from reduced video and audio quality.
Finally, if you cannot obtain the programming live, consider asking
any of the resources above to tape the programs for you and provide them
shortly after the broadcasts. NASA will also provide the programs on videotape
for a modest fee. More information will be announced about this option
in the future.
Good luck.
STUDENT WRITING PROJECT: HAPPY BIRTHDAY DR. TOMBAUGH!
Dr. Clyde Tombaugh, who discovered Pluto in 1930, celebrates his 90th
birthday on February 4th. Around February 23, we've arranged to meet with
Dr. Tombaugh and present him with some special birthday cards. Please
consider joining us in the activity below.
DESCRIPTION:
ALL.....
Have your students research Clyde Tombaugh's
background and the discovery of Pluto. Use your library
resources and online resources. You will find a
commentary entitled Clyde Tombaugh's Blinking
Persistence here
(that is vol one-a)
Also you'll find other related info on the discovery of Pluto
here
THEN.....Chose to do one or more of the following:
- Make a group birthday card which highlights Clyde's achievments or
contains poetic verse in celebration of his discovery of Pluto or have
students simply write a special personal message to Clyde! Use your
creativity!
- Have individual cards created using a paint program (like KidsPix
or Paint Shop Pro, etc.) showing Clyde on the night of his discovery
in 1930.
Print your student work and have students sign cards with special
birthday greeting.
Also PLEASE save your graphics files as jpeg or gif format
- Students can create an acrostic birthday card using PLUTO as the key
word (or use a related word/phrase). Decorate the card with images,
drawings, special greetings! For example: P--perseverance and persistence
in believing in yourself L--late nights scanning the heavens U--underworld
-- Pluto is named after this mythical god T--telescope.... "know your
telescope" your slogan! O--observatory at Lowell where Pluto was discovered
These acrostics can be generated on computer through paint program
or word processing program. Please print out your student's work and
have them sign with a special greeting to Clyde. Also save your student
work to diskette!
- Have students write an imaginative 1 page short story about their
own imaginary planetary discoveries and what happened the night they
became "junior Clyde Tombaugh's". .... what did they name their planet?
what does it look like? what struggles did they encounter as they searched
the heavens?
- Print out stories and create birthday card. Have students include
their short story within their self-designed birthday card.
- Have your students compose email greetings to Dr. Tombaugh and send
these to wee_j@mail.uwlax.edu Jan will print out the messages on special
paper and include them in our presentation package.
*Please attach files rather than send many short messages when possible.
We would like to have all student work sent to:
Jan Wee
431 North Youlon Street
West Salem, Wisconsin 54669
USA
by ****Friday, February 9****.
The Passport team will see to it that all items are delivered to Dr.
Tombaugh during a special presentation. We, in fact, are hoping to arrange
video clips that will be incorporated into one of the live telecasts.
If you would like to include a group photo of your class and note about
your school, etc. please do so. If you use a digital camera, please print
out the photo and also include it on the diskette containing student work
as described below.
Please send both **print copies** and diskettes with student work. If
possible we would like to share your student work online at our web site.
If you use computer based applications to produce student work, please
save to diskette, and label appropriate filename/application/etc. information
or send separate note detailing format information. (Note: We will not
include individual student names or their email addresses as per concern
about this type of information accessible on the net.)
Marc Buie
January 3, 1996
The BIG DECISION has been made for the "Live From HST" project. There
will be two orbits going to Neptune, and one to Pluto. Our goal for the
Pluto observations will be to take a picture that closely duplicates one
of the pictures taken earlier with HST. The next step in this process
will be to provide a precise plan of observation to STScI (Space Telescope
Science Institute).
The first step in planning this observation is to decide on the instrument
and its configuration. There are two imaging cameras on HST that we could
use, WFPC2 (Wide-Field Planetary Camera 2) and FOC (Faint Object Camera).
You might think that from the name we would pick WFPC2 but that's not
the case. There is one fundamental tradeoff between the two cameras that
makes the decision easy. The pixels that make up an image with each camera
are of very different sizes between WFPC2 and FOC. The FOC has smaller
pixels than WFPC2 and will capture the maximum resolution image possible
with HST. The WFPC2 was built to take picture over a wider area of "sky"
and had to sacrifice resolution to get more area.
Having decided to use the FOC, the next step is to decide on which filters
must be used. These filters select a limited range of color somewhere
between the ultraviolet and visible parts of the spectrum. We have time
in a single orbit to take a picture in two colors. There is a long list
of possibilities that I won't list here but I've decided on F410M and
F278M. These "codes" indicate the type and color of filter. M stands for
medium and refers to the width of the filter in wavelength (other possibilities
are N for narrow and W for wide). The number refers to the wavelength
of light near the center of the filter. 410 means 410 nanometers or 4100
Angstroms and corresponds to what we'd call blue light. 278 nm or 2780
Angstroms is ultraviolet light that we can't see with our eyes.
I've chosen these to be the same as the filters used in the previous
observations. Why did we chose these originally? Well, we need to take
one picture at a wavelength that has been thoroughly studied in the past.
A great deal of work has been done on the appearance of Pluto in blue
light, some of which I've done myself. So, the choice of F410M was an
attempt to get a picture that can be directly compared to previous work.
The choice of F278M was a compromise. Going further and further to the
far UV becomes more interesting because Pluto might look dramatically
different. However, our sun doesn't actually put out that much light in
the ultraviolet so the amount reflected from Pluto drops dramatically
as we go to shorter and shorter wavelength. F278M is about as short in
wavelength as we can go and still get a decent picture in the time we
have.
So, are we done? Well, not quite. We've chosen the filter, now we need
to decide how long to integrate in each filter. The FOC is carefully designed
to take images of faint objects. You might think that Pluto is a faint
object but in fact it's quite bright. Before you can take a picture you
must first calculate exactly how bright Pluto will be as seen by the camera.
The FOC can see faint stuff but it takes pictures by literally counting
the photons as then come in. For an object like Pluto, we must ensure
that the camera doesn't have to count any faster than about 1 photon/second
in the brightest pixel on Pluto. That's pretty slow. Using the previous
observations, I know that the count rate will be about 8-10 counts/second.
To keep from damaging the instrument, we must put in a neutral density
filter (sort of like using sunglasses) to make Pluto appear dimmer.
With this slow count rate, we will need to integrate on Pluto as long
as we can. We have 1 orbit to do this. An orbit is nominally 94 minutes
long but during half of this the Earth is in the way and we can't see
Pluto. To make the observation the telescope is moved to point at Pluto.
As soon as the earth is out of the way it begins looking for guide stars
to lock onto and keep the telescope pointed at Pluto. This step takes
about 12 minutes. We now have about 40 minutes left before the earth blocks
our view again. It turns out that we can get two 15 minute exposures packed
into the viewing time and that's what I've put into the schedule.
There is one exciting thing about these pictures. We have the benefit
of seeing the previous pictures and using them to modify the experiment.
The first time we did this we had to compute the brightness of Pluto without
any example to follow. Since there are always some uncertainties involved
we had to choose a conservative amount of neutral density to ensure that
Pluto wouldn't appear too bright. Well, looking at the numbers yesterday
I found that we can use less neutral density than before. This means we
will collect 4 times as many photons in these pictures as was done before
and thus we should have pictures with less noise.
Now that we know how the observations will be done the next step is
to decide when to observe. We've been told by STScI that the observations
will be scheduled for the weeks of March 4th or March 11th. During that
two week interval, I've calculated when Pluto will show the same side
as seen during the other pictures. Those previous pictures were taken
at 15, 112, 203, and 289 degrees east longitude. This is a list of when
these geometries will repeat.
longitude UT date and time priority
-------------------------------------------
203 1996/03/04 06:11:23 #2
112 1996/03/05 20:56:22 #6
15 1996/03/07 14:14:40 #4
289 1996/03/09 02:51:56 #8
203 1996/03/10 15:29:13 #1
112 1996/03/12 06:14:15 #7
15 1996/03/13 23:32:36 #5
289 1996/03/15 12:09:55 #9
203 1996/03/17 00:47:15 #3
I've chosen longitude 203 as the highest priority because there is an
interesting bright spot in the south polar regions and because there are
some differences between the visible and UV images. This longitude shows
up three times during the two weeks and have been assigned the highest
priorities. I suspect that one of these three times can be scheduled but
just in case, I've ranked the other times as well. Why do we need a list
at all? Why can't we just say when we want the observation to be done?
Well, one of the worst problems plaguing precise scheduling of HST observations
is the South Atlantic Anomaly (SAA). This is an area over the South Atlantic
Ocean off the coast of South America where the Van Allen Radiation Belts
dip closer to the atmosphere due to the shape of the magnetic field of
the Earth. If HST is used to take pictures during the passage through
this area, the images become contaminated with radiation noise. For any
object in the sky, there is roughly 6-7 hours each day where you cannot
observe the object because you are in the SAA when the object is not blocked
by the earth. Thus there is a 30-40% chance for a random time to be impossible
to schedule because of the SAA passage. By providing a number of possible
times, we can be sure that at least one of these can be scheduled free
of the SAA.
So, now all this information has been distilled down and transmitted
to STScI where the observation plan will be further refined. If all goes
well, we just sit back and wait for our data. You might be interested
to know that doing all this work and planning took me about 2-3 hours
and slightly longer than that to write it all down. Of course, I've got
the advantage of having worked at STScI for 3 years learning all this
stuff. If you've never worked with HST before, developing an observational
plan could take weeks of work.
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