Astronoblog

Hello, I am Tonima Tasnim Ananna, a sophomore from Bryn Mawr College, a declared Physics major (at Bryn Mawr), undeclared Astronomy major (at Haverford), and one of the members of the recent ASTR341 Observational Astronomy group which went to Kitt Peak National Observatory (KPNO) at Arizona to find some RR Lyrae stars in faint satellite galaxies of the Milky Way. I’m so appreciative that the Louis Green Fund was available to support this trip to an observatory.

The satellites that we observed are galaxies Segue 2 and Segue 3, and Ursa Major 2 as control. The telescope that we used at KPNO is a 36’’ telescope called WIYN 0.9m.

Before we start, I will give a little bit of background on RR Lyrae star. These starts are special because they are a type of Pulsating Variable star – a kind of stars which periodically change their radius and luminosity, and reside in the “instability strip” of a HR-Diagram. The pulsating variables have a shell with temperature around 40,000K – a temperature at which Helium is ionize from He⁺ to He⁺⁺ – very close to its surface. This releases a lot of electrons into the shell, and as electrons scatter photons, this shell is very opaque to photons. The photons which random walk out of the hot core of the star cannot pass through this shell, and hence create a lot of pressure on the shell’s inner surface, forcing it to expand. As the hot gas expands, its temperature drops, and much like the surface of last scattering of the early Universe, the helium neutralizes and the shell’s opacity drops, and the photon flies free, suddenly increasing the luminosity of the star. But there is more to these stars than the cool Physics, these stars play a very useful part in gauging astronomical distances: their luminosity and period are related, so if we can find the period of such a star, we can find its absolute magnitude, and using the distance modulus, we can thus find its distance from us. This makes them excellent standard candles, and gives us the motivation to try to find them in faint galaxies like Segue 2 and 3, which have not yet been studied extensively for RR Lyrae.

To prepare for the observing run, at first we studied a handful of faint satellites of the Milky Way, prepared their hourly airmass table for the approximate time of our observation, and it turned out that the Segues make excellent objects for observation, with airmass smaller than 2 most of the time throughout the period of our observation. We approximated the expected background count based on lunar age at the time of our observation (around 7 days), and calculated exposure time that would give us a satisfactory signal to noise (100). The plan was to take images of the galaxies over a few hours (the RR Lyrae have periods of around half a day), and study the images for any changes in luminosity of stars over the period of observation. We used three different filters (B, V and I) to take the images.

The class split into three teams, and our team consisted of Assistant Professor Scott Engle, Andrew Sturner, and me. We were the earliest team there, and we observed the night of October 13^th, 2010. We arrived at Tucson on the night of 10^th, stayed at a Hyatt place for the night, went shopping for groceries the next day, had lunch at a restaurant called “Brushfire” which had excellent food and pictures of hell on its wall (to symbolize their food is spicy perhaps). Then we headed towards KPNO to observe. Tucson is surrounded by mountains, which was a treat for me because my native land, Bangladesh, is extremely two-dimensional. KPNO itself is on top of a mountain, elevated 7000ft above sea level, which, we found out, affords it exceptionally dark skies, far from city lights. We were inaugurated to our telescope’s system by another team working there on the night of the 12^th. During the training, we had time to wander outside at the sight, and take in the amazing night sky above the mountain. The disk of the Milky Way was visible as a dense, thick disk of stars across the sky. Once Orion nebula rose, we saw the super-red Betelgeuse and whiter Rigel. Andrew and I even spotted a shooting meteor, which Scott missed because at that instant he was unfortunately looking through a pair of binoculars.

Prior to the KPNO trip, most of our experience with telescopes was limited to the 12 and 16’’ Cassegrain telescopes at Haverford. This semester, we also started using CCD cameras to take pictures of our objects of interest. The telescope which we used at KPNO was 36’’, and with all due respect to our beloved 16’’ telescope, the WIYN 0.9m had a much more sophisticated system, complete with a liquid Nitrogen Dewar to keep the pixels of the CCD camera (called S2KB) cool to avoid thermal electron emission, and a system to take “dome flats”, or images of a flat field to correct our object images for biases in the camera’s pixels’ outputs. Another notable difference between the WIYN telescope and the 16’’ was the use of the Guide cameras – the WIYN telescope uses two special guide cameras to keep track of a star, and constantly outputs the degree to which the star’s image deviates from its centre, to verify that the telescope is keeping track of the our object of interest. But the best part of all has to be how little time we actually spent in the dome: we only needed to go to the dome to take a peek to verify everything looks as it should, and to fill the liquid Nitrogen Dewar. This was very comforting for me because last year when we were working for hours in the dome with the 12’’ telescope, no matter how much clothes I wore I always seemed to under dress by two jackets, and am sure was losing enough heat to be luminous myself. (But it was still fun when we got to look at the craters of the moon, and blue-green Neptune and Uranus).

On the 12^th, we woke up late because we have to stay awake throughout the coming night, had some food and went to meet Hillary, the sight supervisor, who gave us a second overview of the system. We filled the Dewar with liquid Nitrogen, and left to drive around the observatory. We were back a couple of hours later (around 4:30 pm) to take dome flats. We opened up the dome vents, turned on the exhaust fans and the dome flat lights (low intensity for our filters). We took 5 dome flats in each filter, 10 bias images (bias accounts for spontaneous reading by the camera for 0 second exposures), and by the time we were done with these, the sun has set, and it was time to start the Guider cameras to track a star. We looked through both guide cameras, and found an auspicious looking star (sorry about the bad pun) in the north camera. We started tracking it using a computer called MOSS, and entered the RA and DEC of Segue 3 in another computer called Olive. We moved the telescope to Segue 3, and using the focusing system of the computer Emerald, we analyzed a series of seven exposures of the galaxy for different focus values, and decided on the best focus value (in units particular to the system) for our images. The focus value changes with temperature, so we kept monitoring the temperature of the dome to see if we needed to make any adjustments. Luckily for us, temperature remained stable inside the dome and we only focused once per object. We started taking exposures (around 7 pm), and Professor Willman and her teams arrived. They were studying our activity the way we studied the other team the night before. We refilled the Dewar in the middle of observing Segue 3, because it needs refilling every 8 hours, and to show the other team how to do so. Then they left to rest, and we continued taking exposures of Segue 3, and completed 13 sets by midnight. Then we worked on a synoptic project which requested us to take pictures of M31 – Andromeda – in R band. We spent around one and a half hour taking flats, biases and images for this program, emailed them a notification, and moved to Segue 2. We refocused, took images of Segue 2 for a few hours – this time only in B and V band. We only managed to take 9 sets for Segue 2, and then had to move to Ursa Major 2. We took around 5 images of UM2 in V band, and then it was time for us to leave to catch an early flight back to Philly. We refilled the Dewar, and left pretty energized, even though we were up all night!

Now that we are back from the trip, we plan to analyze the images we took for a lab for ASTR341, and spot (fingers crossed) some standard stars that would help us estimate the distance to Segue 2 and 3. It is fun to solve problem sets, but it is much more satisfying to do something hands-on that produces a meaningful result, like this project. Even if we don’t get the result we are expecting, we still developed a better idea how real observers observe, and I personally got to observe the disk of Milky Way with naked eyes!

The five best things that happened to me and Emily Cunningham during our 12 am – 6 am shift at the 0.9m telescope at Kitt Peak National Observatory last night:

5. Mastering the art of filling the dewar with liquid nitrogen.

4. Overcoming a myriad of technical issues, including the fact that the telescope would not move at 6 am.

3. Not falling asleep.

2. Managing to obtain several good images of Segue II, a candidate dwarf galaxy, for science!

1. Taking exposures of the Trapezium Cluster in the Orion Nebula in four different filters. We hope to combine these to make a beautiful picture when we get back to Haverford!

Better than all of these things: not finding scorpions or snakes in our beds!

Greetings from the 0.9m telescope at Kitt Peak National Observatory! I’m here with Annie Preston, Emily Cunningham, Tim Douglas, and Erin Boettcher (Tonima Tasnim Ananna and Andrew Sturner were here, but already went home). The generosity of the Louis Green Fund supported all of the students to travel here to obtain observations of some Milky Way companions. The students will be posting here about their experiences, but limited internet access and long working hours are delaying our posts.

In the meantime, click for: a flavor of what we do all night long.

Last week, I took my Astronomical Ideas class to Haverford’s Special Collections wing in Magill Library to discuss and interact with our first edition of Copernicus’s 1543 de Revolutionibus (On the Revolution [of the Heavenly Spheres]) and our first edition of Newton’s 1687 Principia. Ann Upton of our Special Collections department generously arranged a session with these books for my class. She also brought Owen Gingerich’s amazing book describing his census and study of all first and second editions of the Copernicus book, and a transfer of debt that had been signed by Newton. Fewer than 500 copies of the Copernicus book were produced in the first edition, and only 300-400 copies of the Principia were produced in its first edition. So these are two rare commodities.

Here, you can see Ann showing students the Gingerich book, in which he presents i) the results of his study of the marginalia of the hundreds of Copernicus books he inspected, in an effort to learn about the impact of Copernicus’s work on the evolution of astronomical thought and ii) the present locations of all books he inspected, their individual histories, and individual interesting facts:

Gingerich’s census revealed many juicy tidbits about the influence of Copernicus. Gingerich’s census was inspired by a richly annotated version of the book he viewed in the Royal Observatory in Edinburgh (if my memory serves me correctly) that had been owned by one of the leading astronomers of the 16th century. The detailed annotations made no mention of the heliocentric model that Copernicus is famous for today. I was particularly fascinated by the marginalia that Gingerich found in the copy that has been owned by Kepler, but previously owned by someone else. Gingerich found that two passages in particular had been annotated prior to Kepler acquiring the volume: One notation was of a passage where Copernicus raised the question of whether the center of the Sun or the center of the Earth’s orbit was the center of the Universe. Another notation was the word “ellipse”(!) written next to a passage where Copernicus was discussing the shapes of planetary orbits that included epicycles.

In this shot, you can appreciate the beautiful table with a wood base and glass top that the books were presented on. The Principia is on the left and De Revolutionibus is on the right, with Newton’s picture in the middle. Its amazing that any student can thumb through these works:

Finally, here is a cool candid of students using a flashlight on the Principia to detect the presence of the chain lines going crosswise through the pages. Chain lines – light lines hidden in the paper – are an artifact of the way paper was made back in the times of Copernicus and Newton. The crosswise orientation of the chain lies here reveals that this book’s pages were printed as “quartos”:

Hello Astronoblog enthusiasts! Maya Barlev here, Astrophysics major and Haverford class of 2012! This semester I’m in beautiful Honolulu, HI on a program called “A Semester ALMOST Abroad.” It has been WONDERFUL so far– hiking, going to the beach, taking classes at the University of Hawaii’s Institute for Astronomy…

AND, two weeks ago, I had the amazing opportunity to observe here:

… at the Keck Telescope on the peak of Mauna Kea on the island of Hawai’i! Keck has the largest optical and infrared telescopes in the world! As stated by the Keck Website: “Each telescope stands eight stories tall, weighs 300 tons and operates with nanometer precision. The telescopes’ primary mirrors are 10 meters in diameter and are each composed of 36 hexagonal segments that work in concert as a single piece of reflective glass.” Pretty cool, huh? I actually didn’t have time to make it up to the summit to see these incredible telescopes in person, but instead, I observed from here:

This is at Keck Headquarters, several thousand feet closer to sea level. And, this is where all the observing magic happens. All of the computers behind me control the telescope remotely, determining exposure times, focusing the mirrors, adjusting the positioning and so on.

But before I get ahead of myself, let me explain why I was here in the first place. Since this summer, I’ve worked with Prof. Beth Willman exploring the detectability of ultra-faint dwarf galaxies around the Milky Way and Andromeda. I’ve learned a lot about this field of Astronomy and the many challenges Astronomers face when trying to find and then analyze the properties of these elusive satellite galaxies. Beth’s colleague, James Bullock, is exploring similar issues, and had telescope time on Mauna Kea for two nights in September. Knowing that I would be in Hawai’i for the semester, Beth asked James if it would be alright for me to act as an observing assistant on this run.

So, thanks to Beth, James, and the Haverford KINSC Travel Stipend, I was able to go from O’ahu to the Big Island and observe the spectroscopic properties of several Andromeda satellite dwarf galaxies! I observed with Erik Tollerud, James’ graduate student at University of California Irvine. The goals of this run were to look specifically at a few of M31’s (Andromeda’s) faintest dwarfs and examine their stellar populations and ultimately their dark matter components. This research is highly related to the work I do with Beth, but instead of working theoretically from computer simulations, I was able to see this field of research from an observational standpoint.

The itinerary for the weekend was as follows: Arrive Thursday, and try to stay up as late as humanly possible to get used to pulling all-nighters for the purposes of science. Friday, sleep in as late as possible for the same reason. Friday afternoon, prepare the equiptment for observing through many alignments, tests, and so on. After dinner Friday night, begin observing! Every hour or so, we’d need to adjust the coordinates, realign, and focus the telescope. Every minute of dark-sky is precious, and so we had to be efficient. One of the coolest things about observing was that not only were we in an extremely high-tech room with about a dozen computer moniters, but a handful of other scientists were actually also telecommed into the room. So, throughout the night, we were in communication with people in California, Australia, and, of course, Operational Assistants at the peak of Mauna Kea. It was pretty funny to meet a handful of scientists face-to-face who were also thousands of miles away. Saturday was the same in terms of scheduling, but was much easier since we had things set up and ready.

Overall it was an absolutely incredible experience. It was such a privilege to see professional astronomy at work from the modern, observational standpoint. I learned so much, and had a blast doing it! HUGE thank-yous go out to Erik for teaching me everything while at Keck, James for allowing me to be a part of his research, the KISNC for funding me, and, of course, Beth for making it all happen! ALOHA!

(I’m posting this on behalf of Ivan Meehan – pronounced Eee-von)

Hi this is Ivan Meehan, a rising junior, and I have had the most wonderful summer opportunity I could imagine!

I participated in a program that sent students to different universities around the world that were all collaborating on detecting gravitational waves. These waves have been described as ripples in the fabric of space-time and if detected, would open a whole new field of astronomy. Astronomers would be able to observe the universe using different gravitational wavelengths just like how they already do so with different electromagnetic wavelengths. Scientists believe this would especially give us more information about cataclysmic events like supernova explosions and neutron and black hole collisions.

I worked with the Optics group at Adelaide University in Adelaide, Australia. The current pair of gravitational wave detectors (they often work in pairs to help confirm the validity of a signal) in the U.S., the LIGO (Laser Interferometer Gravitational-wave Observatory) is expected to detect a signal approximately once every 50 years which is kind of lame. However, scientists are collaborating to build the Advanced LIGO which is expected to detect a signal approximately once a week. The Advanced LIGO requires technological developments like special mirror coatings and suspension techniques to make sure it works properly and the wavefront is not distorted. To be able to know how to correct for wavefront distortion the scientists will use a Hartmann Sensor, which measure wavefront distortion, or changes in the wavefront. At Adelaide University, I worked on characterizing the temperature sensitivity of the Hartmann sensor.
Basically I spent a lot of my summer taking pictures of spots and analyzing the spot displacements with MATLAB programs.

Aside from research, I also made time to meet many new people and explore the country. Adelaide is a small, picturesque city and a great place to spend the summer. I have to point out though, that in Australia it was actually winter time, and since Adelaide is on the southern coast, it was actually rather cold (32-60s degrees Fahrenheit, and usually in the 40s).

Some highlights include:

-going to Cleland National Park and getting to feed kangaroos and hold a koala!

-living in a residential college with graduate students from all over the world, and being the only American there!
-getting to spend a weekend in Sydney and see a symphony-orchestra concert in the Sydney Opera House!
-one of the astronomy professors invited me to the observatory one night and showed me some of the sights in the Southern hemisphere, like the Eta Carina nebula and the “Jewel Box”, an open cluster.

Lots of Haverford astronomy news to report, but I’m just going to focus on the Large Synoptic Survey Telescope (LSST) project and its role at Haverford for this post.  The LSST is a ~ $500 million optical survey telescope that is in its design, development, and construction phase.  It will be an 8m telescope that will have a camera with a 10 square degree field of view.  This telescope will live in Cerro Pachon, Chile and is expected to begin survey operations in 2018.  This survey of the sky will be groundbreaking in many ways; I will only highlight a couple.  With the ~1000 visits (combined over all filters, after 10 years) to all locations in the Southern sky, this survey will be the only one that can generate a deep map of a large fraction of sky in the time domain:  LSST will make a movie of the sky (I think that is a Tony Tyson quote, but I can’t remember).  With so many visits, LSST will also provide the deepest and most sensitive map of half of the celestial hemisphere reasonably possible from the ground at optical wavelengths. And…. (drumroll)… all of the data will be public immediately, enabling professional astronomers, enthusiasts, teachers and students anywhere to participate in ground breaking reasearch.

I’ve just returned from an All Hands Meeting for this project in my capacity as co-chair of the Milky Way and Local Volume Structure science collaboration.  The meeting was at a Ritz-Carlton resort outside of Tucson, AZ.  I now understand why Ritz-Carlton has such a good reputation: the hotel, service, food, and setting were all completely fantastic.  I couldn’t get over it the entire time.  Lucky for me, the science and professional company were also unbeatable.  Its been an amazing experience to participate in the development phase of LSST, an exciting project that I strongly believe in.  One reason that I am so excited about the LSST project is the impact it will have on the science that I work on – near-field cosmology using resolved stellar populations in the local universe.  The stellar density, proper motion, and photometric chemical abundance maps that LSST will enable will be transformative for this field.

A big topic of chatter during this meeting was the impending August 13 release of the results of the Decadal Survey of astronomy.  From the American Astronomical Society’s email to members this week: “It is difficult to overemphasize the importance to our discipline of the decadal survey recommendations. Congress, the White House, and the funding agencies applaud us for undertaking this effort, and they will use our community priorities to allocate federal resources to astronomy and astrophysics projects.”  I returned August 13 to Haverford on a redeye flight so had to miss out watching the live webcast of the survey results with my LSST colleagues … which is too bad because LSST was ranked as the top priority for large, ground-based astronomy projects for the next decade!

This brings me to the role my involvement with LSST has been playing at Haverford.  (This post is long already, so I won’t talk about research outside the classroom).  In all of the classes I teach, I bring my experience doing survey science (both Sloan Digital Sky Survey and LSST).  My first year and sophomore students use Galaxy Zoo, a citizen science project using SDSS data.  I write some LSST inspired calculations for my sophomore level, calc-based class for astro and astrophysics majors.  The biggest impact is in my Galactic Astronomy class for junior and senior majors.  A large portion of the credit for this class is in the form of a research project.  The first time I taught this class, I had all students either use SDSS data to study the Milky Way or develop a science case for LSST along the lines of the Science Book that the collaboration was writing at the time.  They wrote their results in a paper and presented their results in a workshop style format.  I used this opportunity to teach students how to do research while also teaching them about the process of developing a large scientific project.  This Spring, I will have all of my students do their research projects on LSST science.  The current plan is to have them all analyze different aspects of the growing simulated data that are available for LSST.  This will be an awesome way for them to be involved with this developing project, and I think the top ranking bestowed upon LSST will help to inspire the students even more.

I’ll post soon about Haverford’s new telescope resources, so stay tuned for that!

In addition to all of the off campus research that our students have posted about on Astronoblog, four Haverford astronomy students spent 10 weeks of summer research in the Willman lab.  [See cute picture of the team in the Astronomers at Play post.]  We had a great summer together – even more together than I anticipated.  Owing to a thunderstorm induced power failure, my iMac was in the hospital for most of the summer while I worked in my basement lab with the students.

Gail Gutowski (’10) spent the summer wrapping up her photometric analysis of the Willman 1 object, based on data obtained at Kitt Peak National Observatory in 2006.  We are hoping to submit the paper before the end of this year, but it may be delayed a bit because of the many technical problems encountered during artificial star testing.

Oliver Elbert (’11) embarked on an analysis of an N-body + SPH simulation of a Milky Way-massed galaxy formed in a cosmological context.  In particular, he studied the halo of this galaxy and “observed” it the way the LSST project will observe the actual Milky Way based on RR Lyrae stars.  This is a work in progress and will form the basis for Oliver’s thesis.  Maybe he will have a cool animation to post here in the Fall.

Maya Barlev (’12) and Miriam Fuchs (’13) both studied ultra-faint galaxies.  They began by learning the ropes of IDL programming and dwarf galaxy basics through compiling an extended version of Wolf’s/Kalirai’s recent Milky Way dwarf satellite catalogs.  They then studied the detectability of “stealth galaxies” – particularly low surface brightness galaxies – around the Milky Way, inspired by the detection of And XIX around M31 and by Bullock et al’s recent prediction that there may be very stealthy galaxies still hidden around the Milky Way.  Maya wrote a lot of software to simulate, and then to search for, fake stealth galaxies.  Miriam studied the statistics of randomly distributed fields of stars analyzed with different algorithms in an attempt to quantify “significant detection”.  Jen Campbell (’11) will join this project when she returns in the Fall, and bring some of these threads forward to completion for her thesis work.

Me?  I spent a lof ot time collaborating on these projects.  I also gave 3 different talks [at a particle physics workshop, a colloquium, and at a conference] and provided some support for a couple of papers (one computational, one observational) that were accepted/submitted during the summer.  I overcame tough technical setbacks (read: file server disaster) and finally submitted a paper that has been a long time coming – a spectroscopic study of the Willman 1 object.  At the end of the day, we argued that this thing is (or was) a dwarf galaxy based on the fact that two of its member stars have iron abundances that differ by an order of magnitude.  The total luminosity of the Wil 1 object is less than 1000 times that of the Sun (which is less than the luminosity of the individual stars that my Swarthmore colleague, David Cohen, studies!) but we believe that it is a galaxy, or the remnants thereof.  I’m eagerly awaiting the arrival of Ross Fadely, the postdoc who will be joining our group in a couple of weeks and eagerly awaiting moving away from studying my namesake object.

Now, I’m preparing to attend the All-Hands collaboration meeting for the Large Synoptic Survey Telescope (LSST) project next week in my capacity as (co-)chair of the Milky Way and Local Volume Structure science collaboration.  Fingers crossed for the role of LSST in the Decadal Survey report to be released a week from today

(Although posted by bwillman, this post was written by Miriam Fuchs)

My name is Miriam Fuchs, I’m a sophomore at Haverford, and working with Beth Willman this summer doing research on ultra-faint dwarf galaxies. Last Friday, our research team left INSC basement and headed to Jim Thorpe, PA, where we went whitewater rafting down the Lehigh River.

It was a beautiful day for rafting. First things first,: a necessary stop at Dunkin’ Donuts, where we fueled up for the day. After an initial “detour” (we may be good at finding dwarf galaxies, but finding the rafting site…..), we got to Pocono Whitewater, where we were given life vests, paddles, and safety instructions.

And then we were on our way! It was so relaxing just to be in the sun, soak up some rays, and battle some mini rapids along the way. Every so often, we were allowed to jump in the water and float around. One lesson learned that day: don’t mess with science folks when it comes to water splashing. Needless to say, everyone was drenched with water within the first 20 minutes. Midday, we stopped for a lunch of hot dogs, chips and lemonade. After that, the Willman group re-united for the last leg of the trip, and enjoyed a nice series of almost-rough rapids.
Before coming back to Haverford, we stopped off at Annie’s Ice Cream, where we indulged our sweet tooths and got milkshakes and sundaes. Yum yum. All in all, a great day!

Beth Willman, here.  Last Wednesday, I spent the day visiting Swarthmore College’s astronomers: David Cohen and Eric Jensen.  We had a great time talking about our own research, comparing notes on student research and teaching, and discussing the possibility of increasing the cross-pollination between Swarthmore’s and Haverford’s astronomy programs.  (side note: I learned that Professor Cohen also loves squids, although I professed neither my own interest in squids and other sea creatures nor that my cluster of computers has a sea creature naming scheme, with the lead computer being named Squid.)

Swarthmore has a great astronomy program that nicely complements our own.  Whereas Haverford’s expertise is in galaxies and cosmology, Swarthmore’s expertise lies in stars and planets.  This led us to discuss ways to take advantage of these strengths by coordinating when we teach classes on X topic and by encouraging students to take classes at the other campus.  We even very briefly mentioned the possibility that “trading” faculty for a class here or there could be more successful than trading students.  In the Fall, Cohen will be teaching what should be a great Interstellar Medium seminar that meets Wednesday afternoons for 2.5 hours.  (side note number two: the interstellar medium is a lot more exciting and fascinating than its name may initially lead one to believe).  I intend to advertise this to Haverford students.  One tricky bit about encouraging students to take courses at both campuses in astronomy is that it would be particularly difficult for athletes to take an afternoon class at the other campus, because they couldn’t get back by 4 pm for practice.

A final cool thing I learned about is a nifty gadget called a “SunSpotter”(tm).  I’d love to get a handful of these to use in our Astronomical Ideas and Introduction to Astrophysics I classes.