Last edit: 2011 May
Introduction
2010 Hardness is a Standardizable Candle for GRBs
2009 Post a Book-Free "Extraordinary Concepts in Physics" Course to the Web
2008 The Transparent Sun has Focal Point in Outer Solar System
2008 A New Type of Energy: Ultralight
2008 Friedmann Cosmology Equation Can be Written as a Sum over all Energy Types
2006 Post a Book-Free Introductory Astronomy Course to the Web
2005 A New Test of Gravity: Lensing of Gravity Itself
2004 Dark Energy Might be Higgs Fields
2004 The Asterisk*: An Online Astronomy Portal
2004 A Unique Way to Compress Astronomy Images
2002 Best Cadence Rates for Sky Monitoring are Variability Time Scales
2001 CONtinuous CAMeras Deployed to Monitor the Night Sky
2000 GRB Pulses Start at the Same Time at Every Energy
2000 GRB Pulses are Scale Invariant over Energy
1999 Continuous Monitoring of the Entire Night Sky is Now Possible
1999 The Astrophysics Source Code Library
1995 A Modern Curtis - Shapley Debate: The Distance Scale to GRBs
1995 Astronomy Picture of the Day
1994 Most Microlensing Occurs on Background Stars
1994 Microlensing Can Resolve the Surface of Stars
1994 Time dilation Discovery in GRBs
1994 Dim GRBs are Redder than Bright GRBs
1994 Digits of Irrational Numbers
1993 The Brightness Distribution of GRBs is Consistent with a Cosmological Distribution
1993 The View Near a Black Hole
1993 Ultracompact Neutron Stars
1992 Micro Black Holes Might Explain Everything
1989 How to Compute the Detection Probability of Gravitational Lensing
1985 Microlensing is not observable
Over the course of my career, I have had a few ideas of which I am particularly proud. Since it is hard to see what these ideas are from my resume and even my publication list, I have decided to explicitly describe some of the more notable ones here, as immodest as that may be. One idea behind this is to demonstrate to whomever might be interested, in particular aspiring graduate students, that I am not simply "Mr. APOD", but that in fact I am a practicing and publishing astrophysicist. Another testimony to my being an actual scientist is the list of people who have been awarded a Ph D. under my scientific supervision, which can be found here.
Now some the below ideas may not have been all mine, as some were created in collaboration with others, while for others I did not know of previous precedents at the time when I was working on them. I do realize that even given this list, I will likely be primarily remembered for my role in creating, writing, and editing the Astronomy Picture of the Day (APOD).
Oddly, my favorite ideas have not, in my opinion, led to my most cited papers. At the time of this writing, I have been an author on over 65 refereed science papers as part of over 200 science contributions that have been cited over 1500 times. Now not all of these have been my most exciting ideas -- many times papers resulted from ideas created by others or from more straightforward extensions of existing ideas or paradigms. The paragraphs below have turned out to have quite a few interesting stories, many of an autobiographical nature.
Last, I know that my career is not particularly distinguished. I would guess that most professors could produce a list of ideas and stories at least as interesting as what follows.
2010 Hardness is a Standardizable Candle for GRBs
If attributes of gamma ray burst (GRB) spectra can act as a standardizable candle, then the ratio of the number of high to low energy photons, a much easier quantity to measure, might correlate with it, and also be a standardizable candle. And it does. And hardness is particularly easy to compute for GRBs. This idea was developed in coordination with graduate student Amir Shahmoradi, and the published paper on it is: Sharmoradi, A & Nemiroff, R. J. 2010, Monthy Notices of the Royal Astronomical Society, 407, 2075.
2009 Post a Book-Free "Extraordinary Concepts in Physics" Course to the Web
Students study physics partly because the most strange and interesting parts, like black holes and quantum entanglement, intrigue them. Counter-intuitively, however, I could not find a single university that taught an undergraduate course discussing many of these ideas. And I looked. Almost all university physics courses involve balls rolling down inclined planes, or the potential surrounding a charged rod. So I created the course "Physics X: Extraordinary Concepts in Physics" that focused only on these "cool" and "extraordinary" physics concepts. I have made the lectures in this course book-free and freely available over the web here here. I thank the Physics Department Chair at Michigan Tech, Prof. Ravi Pandey, for allowing me to do. I am not sure that many other physics department chairs would allow one of their professors such leeway. My hope, though, is that other physics departments will take this lead -- and even the lectures themselves -- and provide cool courses for students interested in the truly extraordinary concepts in physics.
2008 The Transparent Sun has Focal Point in Outer Solar System
That the Sun's closest gravitational focus, were it transparent, is inside our Solar System, came up in discussion I had back in the graduate school with Prof. Christ Ftaclas, then at the University of Pennsylvania (now at U. Hawaii). At that time, in the 1980s,I was a standard-issue graduate student who enjoyed discussing hypothetical lensing effects. Ftaclas and I picked up on this again later and even presented a poster at the American Astronomical Society about it in 1997: Nemiroff, R. J. & Ftaclas, C. 1997, Our Sun as a Gravitational Lens, Bulletin of the American Astronomical Society, 190, 38.01 Nobody else seemed to know about it, nor, to be honest, really cared.
Later, when the Internet became prevalent, a more powerful literature search found that this idea was already had by others, as early as 1971 (see the reference list of the next paper). This seems to be an example where many people came up with the same idea independently. Still, the older papers did not have a modern model for the density profile of the Sun. I therefore deployed MTU graduate student Bijunath Patla (now a postdoc at Harvard) to looked into the transparent Sun as a gravitational lens more generally. It turns out that our Sun is a very interesting gravitational lens! Our paper about it is here: Patla, B. & Nemiroff, R. J. 2008, Gravitational Lensing Characteristics of the Transparent Sun, Astrophysical Journal, 685, 1297. Patla did a great job with this and it turned into his Ph D. thesis. By the way, the minimum focal length of the Sun, using modern density functions, is about 23.5 AU, just beyond the orbit of Uranus. There are several spacecraft out at least that far already, so the next step really is to equip a future spacecraft with a detector for radiations that go through the Sun, like gravitational waves and some types of neutrinos. Then the Sun would become a 700,000 km diameter focusing telescope.
2008 A New Type of Energy: Ultralight
When teaching an advanced undergraduate course in astrophysics that reviewed cosmology, I had to admit to myself that I not did I not understand why there were two Friedmann equations. Then, after more thought, I had to further admit to myself that I didn't really understand either of them. So I studied them. As I studied them and I came to understand them better, I soon realized that I didn't understand why normal matter, radiation, and (sometimes) a cosmological constant were represented by individual terms, but that other energy forms, like cosmic strings, were absent. I decided that they could have been included -- they were excluded only because an author didn't believe that they have a significant cosmological density. So, for clarity, I put them back in. Hah! The "explicit" Friedmann Equation(s) then appeared to be a sum over the cosmological constant energy (w=-1), domain walls (w=-2/3), cosmic strings (w=-1/3), normal matter (w=0), and radiation (w=1/3). Does anything seem missing to you? Where are the energy type of w=2/3? Or w=1? Or any energy type of w>1/3? I could not find reference to it anywhere. And I looked. I found that fields, including scalar fields, can have any w, and changing w to boot, but I am referring here to "stable" energy types, not fields. So I decided to include the w>1/3 terms "expanded" version of the Friedmann Equation(s). I called them ultralight energy. I didn't expect much ultralight in the present universe because it dilutes so fast as the universe expands. But it may have been important in times near the big bang. Or not.
I think ultralight is cool stuff and I am proud to have thought of it! Unfortunately, my paper on ultralight was rejected because the referee not because it was wrong, but because the referee deemed it "unmeasurable" and "cosmologically insignificant". So I uploaded my manuscript to the physics archive server, arXiv.org, as a preprint and left it at that. Here is the link: Nemiroff, R. J. 2007, The Opposite of Dark Energy, Limits on w=2/3 Ultralight in the Early Universe, astro-ph/0703737". The preprint is rarely cited. Perhaps defiant, I remain proud of it today: Viva ultralight!
2008 Friedmann Cosmology Equation Can be Written as a Sum over all Energy Types
Please see the above entry. With the help of graduate student Patla, I did publish a "teaching paper" about this here: Nemiroff, R. J. & Patla, B. 2008, Adventures in Friedmann Cosmology, A Detailed Expansion of the Cosmological Friedmann Equations, American Journal of Physics, 76, 265. Oddly, although cited only once, this paper is perhaps my "most downloaded paper", as it has been downloaded from ADS now over 2000 times. If you read closely, I do mention ultralight. (Viva ultralight!)
2006 Post a Book-Free Introductory Astronomy Course to the Web
My physics dept. chair, Prof. Pandey, told me that my university, Michigan Tech, would like to develop more online courses, and so encouraged me to put my pending 2006 Introductory Astronomy Course online. I politely declined, of course, because that would take more time teaching astronomy than I had planned, which meant less time for research. But Pandey was persistent, this time stressing that it would help the Physics Dept., and he also promised that I could get a percentage of the enrollment tuition placed into an open fund which could help fund my research. So then I agreed. Soon I even liked the idea.
Now MTU has some classroom studios all set up, and a savvy director to boot, so this actually turned out to be easier than I thought. I soon decided to make the lectures freely available to anyone with a web browser. I was surprised that I could not to find anyone else who put their video astronomy lectures on the web at that time. And I looked. To my delight, the class soon became one of the most downloaded iTunes courses of any university. I reprised the online class in 2008 using only APOD and Wikipedia because it seemed to me that both were now strong enough to carry an introductory class, and this would be cheaper and easier to access for students around the world. I half expected to be kidnapped by the powerful textbook cartels for undermining their business model, but so far they just ignore me (apparently, that's a national pastime). The free 2008 Astro 101 lectures are still online here.
2005 A New Test of Gravity: Lensing of Gravity Itself
No one knows if gravity can lens gravity itself. The earliest root of this idea that I can remember was a question I asked when taking particle physics as a graduate student at the University of Pennsylvania in about 1980. I asked if virtual particles were refracted by the dialectic indicated on the black board, as were real particles. Prof. Segre answered that no, they were not, but he did seem a bit troubled by this at the time and praised the question. The idea next surfaced when I was a postdoc in 1988 and I asked a mentoring professor (Prof. Tsvi Piran at the Hebrew University of Jerusalem) whether virtual particles were deflected by a black hole. As I recall, we were waiting for our bags to arrive in an airport carousel when I finally got up the nerve to ask him. He quickly answered "no." A few minutes later, however, as we dragged our bags through an airport toward a conference, he said it might be more complicated than he originally thought, and said he didn't really know. As before, while learning more and more physics (one typically learns the most physics only after one is already a professor), I have kept an eye on this question. I have never come across physics that gave me a full and satisfying answer. And I looked. So in 2005, after I was tenured, I published the idea. (Note to the reader: please don't publish such speculative ideas unless and until you have tenure -- you may be labelled a unemployable crackpot!) The paper is Nemiroff, R. J. 2005, Astrophysical Journal, 628, 1081.
To my surprise, the referee and editor had only minor quibbles with the manuscript -- I had little trouble getting it published. Some members of the gravitation community, however, seemed to find the idea uninteresting. I don't understand why -- perhaps they are right and the idea is uninteresting, but I haven't yet found anyone to tell me why, or perhaps the answer has more to do with sociology. Regardless, this idea is actually falsifiable. The paper actually takes this effect beyond idle speculation and into a realm where it can be tested and perhaps limited. This test appears to me well different than any yet existing way of testing gravity -- something one might consider exciting. Still, the paper is not highly cited.
2004 Dark Energy Might be Higgs Fields
Since coming to prominence in the late 1990s, I have been continually intrigued by the concept of "dark energy". Because I am a inherently a vain person, I thought that I myself could help humanity to better understand it. Unfortunately, I was handicapped by my knowledge of particle and string physics not being on a research level. Then again, however, if one bites off only a small piece of a puzzle, and analyzes only that in some detail, one still might make a contribution.
So when reading up on dark energy, I noticed two seemingly juxtaposed ideas. The first was that dark energy was some sort of field, say a simple scalar field, that had an unknown origin. The other was that the Higgs fields that create inertial mass might be visible in the universe, but seems not to be. So, being a simple person, I decided to see if the Higgs field could be the very field that creates dark energy. Even before this, I had the whim that perhaps a field that actually creates gravity was the dark energy, but this seemed to vague to pursue.
I intrigued graduate student Patla, who loved to discuss theoretical ideas, to look into this with me. We wrote down the key Higgs equations and found that it was mathematically possible that they could evolve into dark energy, but that "tooth fairies" were needed to force the equations to do unexpected things. Now one might expect that any mathematical framework that involves a "tooth fairy" would be discredited and unpublishable, but that would be wrong. It turns out there are many "tooth fairy"-heavy physics papers all over the literature. I am not making that up. Which fairies you tolerate appears to be partly a matter or taste. Unfortunately, the tooth fairies we invoked did not fit with the tastes of the referee, who rejected the paper, although not maliciously. If I had more interest and initiative, I might have persevered, argued longer, and possibly gotten it published. But I did not. Therefore, this too ended up as an arXiv preprint only manuscript, found here: Nemiroff, R. J. & Patla, B. 2004, Decaying Higgs Fields and Cosmological Dark Energy, astro-ph/0409649. The manuscript is only lightly cited. One day I do hope to return to this idea.
2004 The Asterisk*: An Online Astronomy Portal
After the Night Sky Live (NSL) sky monitoring network (described below) went online with its associated web pages, I thought it would be useful if people viewing the network images could communicate. I envisioned that people would exchange software updates, science results and software, future sky camera hardware ideas, and consult each other about unusual things being seen in the images. I was helped greatly in this endeavor by Lior Shamir, a graduate student who is excellent with computers. After a short while I realized that few people really cared about discussing the images, rather they just wanted to see the most recent ones near their location.
Disappointed, rather than fold the online bulletin board, I reformatted it. I renamed it the Asterisk*, primarily so that people could comment on APODs. The name was meant to convey that each of these comments could be considered to be an asterisk (*) to those APODs. Also, the "aster" part of asterisk means "star". My hope was to leverage APOD's popularity and drive people to know about and contribute to discussions of the Night Sky Live project and images as well.
As usual, I was wrong again. Even with this wide on-ramp, few people seemed to care about commenting on any aspect of the Night Sky Live project. The APOD discussion board section, however, seemed to be going quite well, and some knowledgeable people began posting there and even answering questions about the posted APOD image and even astronomy.
Therefore, a few years later, as the NSL project was concluding, I had closed all NSL discussion and fully moved the Asterisk into a bulletin board that would bolster APOD in as many aspects as possible. In 2010, I renamed the bulletin board Starship Asterisk, trying to encourage new people to post by envisioning the online board as a space ship. My most recent thought is to keep all of this but also open up more sections, like ASCL, dedicated to more professional astronomers. One hope is that this may bolster amateur sky enthusiasts. The main page for the Asterisk is here.
2004 A Unique Way to Compress Astronomy Images
A graduate student of mine who specialized in computer science, Lior Shamir, once seemed insulted by the idea that astronomers might figure out a better way to compress images than computer scientists. Image compression was a mature field and competitive field, he related, driven by increased revenue to big corporations that could compress and uncompress information efficiently. Still, it seemed to me that astronomy images, in particular ones that had dark backgrounds and bright stars, might be unique enough to utilize their own compression algorithm(s). The background for this was our own sky monitoring project, Night Sky Live, which was generating hundreds of images every night that were being sent over to our main computer at MTU, and using lots of bandwidth in the process. After convincing him of the uniqueness of the approach, Shamir and I brainstormed and came up with an astronomy specific method to maximize image compression, in particular a photometry specific method.
A key part of the best idea we came up with was to do a preliminary pass on the digitized images and find the stars. Assuming these locations were only a small fraction of the image, the star image pixels could be recorded exactly as measured, whereas the dark background could be highly compressed. Since in many astronomy images stars make up only a small fraction of the total image area, this technique could yield very large compression rates while leaving the ability to detect changes in stellar brighness untouched. Shamir and I were unable to find anything like this published anywhere. And we looked. So we coded this up, tested it, implemented it in practice as part of our Night Sky Live sky monitoring project, and wrote up a paper. The paper is here: Shamir, L. & Nemiroff, R. J. 2005, PHOTZIP: A Lossy FITS Image Compression Algorithm That Protects User-defined Levels of Photometric Integrity, Astronomical Journal, 129, 539.
The knowledgeable but anonymous referee did inform us of a precedent paper in a conference proceedings many years ago (Press 1992), which is cited, but significant differences remained. This paper appears to be quite useful for the astronomy photometry community, but is rarely cited -- I'm not sure why. The routine, remains available through the Astrophysics Source Code Library (ASCL), described below.
2002 Best Cadence Rates for Sky Monitoring are Variability Time Scales
In the early days of sky monitoring, in particular when the Night Sky Live project that started in 2000, I decided to present a conference paper on the best cadence rates to detect things like GRB optical afterglows and microlensing. This seemed simple enough. I soon realized that I had little idea how this should work -- my preconceptions were wrong. Still, I kludged something together that seemed OK at the time (I mean, how hard could this be?), and presented the conference paper anyway. I don't think that conference proceedings were ever published. I later determined that was good, because I came to again realize that I still didn't know what I was talking about. Determining optimal cadence rates seemed trickier than I thought, at least for me.
Well after the conference, I tried again to revisit the idea with a new determination to understand myself what must be obvious to others. But I kept getting it wrong. I could find nothing written on the subject. And I looked. Finally, slowly, one glaring conceptual error after the next, I realized how to do it right. It was right because it just made so much sense. So I wrote up a paper. I was very proud of my work, and I worked very hard on this paper, trying to make it as general as possible, and even included examples from major sky monitoring projects that might soon exist. Surely my work would be met by warm hugs and gratitude. And who better to administer the first warm hugs and gratitude than my scientific mentor Paczynski, who identified himself as the referee of the paper.
So Paczynski rejected the manuscript. This was particularly unnerving since previously it was hard to find places where we had a sustained disagreement. Paczynski said that sky monitoring was too dependent on details of specific site details to make the generalizations that I made in my manuscript. Surprised, I tried to argue but he didn't want to hear it. He suggested that the only way the paper could get published is with a new referee. The next referee, Prof. Andrew Gould, who also identified himself, was also an acquaintance. He was also somewhat skeptical, but after a few pitched (but polite) exchanges, I was able to convince him that this was good stuff, or at least publishable stuff.
Yes, In my biased opinion, this is good stuff. There are times when I think something over and over and over and eventually it becomes so simple I have a hard time explaining it to anyone because it has all become just so obvious. This was one of those cases.
Additionally, over the years I have come to realize at this is also important stuff partly because it is at the base of a classic conundrum common to many aspects of life and science: how often do you check for something? How often does a warthog check for nearby tigers? How often do you look out the window to see if your ride is here? Etc. Determining cadence rates is fundamental, and astronomical applications are not only similar but keys to telescope efficiency. The published paper is here: Nemiroff, R. J. 2003, Tile or Stare? Cadence and Sky-monitoring Observing Strategies That Maximize the Number of Discovered Transients, Astronomical Journal, 125, 2740. I don't remember who the editor was that accepted the paper even over Paczynski's objections, but (s)he deserves warm hugs and gratitude. To my delight, this paper does get cited a bit, and it is downloaded quite a bit more. Still, my endless vanity being what it is, I thought it would be cited more.
Epilogue: When I was an associate professor, a well-respected full professor here at MTU (Prof. Kostinski, atmospheric sciences) stopped by my office and said that he thought I might be ready to apply for full professor status, but first he wanted to see a good paper that I had written since becoming an associate professor. I showed him this paper. A few days later he returned to my office, said he thought this was good stuff, and encouraged me to apply for full professorship. I was indeed promoted. That was quite gratifying!
2001 CONtinuous CAMeras Deployed to Monitor the Night Sky
To actually monitor the entire night sky required real hardware. Almost all astronomy hardware at this time consisted of small field of view, high magnification devices. I wanted to do just the opposite -- I wanted to deploy wide field of view devices that monitored and recorded as much of the sky as possible, as often as possible. This, I felt was the best way to monitor variability on the night sky. And this variability could include the slight variability of stars to the great variability of novas, supernovas, and the optical transients to GRBs.
For this I was fortunate to pique the interest of (then) graduate student Wellesley Pereira and MTU colleague Prof. J. Bruce Rafert. Rafert and his own graduate student were putting much effort into developing the MTU 16" telescope into a classical research telescope. If you know me, though, you might realize that is a bit too normal for my tastes. Although perhaps Rafert thought my sky monitoring project as a bit strange, he continually provided much expertise, particulalry when it came to actual sky observations, because, well, I was nearly clueless. On request, Rafert would come to my office and lecture me on how real photometric measurements were actually made and computationally reduced.
At first Pereira and I designed and built a device designed to stare at Earth's northern spin axis -- near Polaris -- and keep recording the surrounding and changing sky in that direction. With this strategy, the camera mount would only need to spin and not move about and find locations all over the sky. Fortunately, my NSF CAREER grant was worded vaguely enough that it could be adapted to pay for the CCD. We set up our wide-field CONtinuous CAMera 1 (CONCAM1) on the edge of the roof of MTU's small college observatory. As planned, we took many pictures of the same part of the night sky. Still, there was too little data to do any real science at that point. Also, it also appeared that it would be too much money to order the parts for, and build, the multiple CONCAM1s needed to monitor the entire sky all at once. It was when contemplating the corner I had painted us into when I had what I thought was a better idea -- fisheye CONCAMs. Fisheye CONCAMs would see only the brighter stars, but they could monitor the entire sky on a much more limited budget.
To the best of my knowledge, nothing like this had ever been done. Moreover, it seemed counter to any observational astronomy approach of which I was aware. Still, as usual, I did an extensive search for previous similar projects, and during this search, I did find a precedent. In the US southwest, there was deployed one US Army fisheye digital camera that was being used to monitor clouds. I therefore emailed a person listed on that web page. From the web pages and the emailed response, from what I could tell, although this camera did record some stars, their setup was not equipped for astronomy and in particular, appeared to do no astronomical photometry. And their setup seemed to cost well over $100K. After some thought and investigation, I thought I could design and deploy a real astronomical camera for much less.
I soon found myself searching hardware sites for components and doing back of the envelope estimates trying to get the output from any commercial fisheye lens to fall onto the observing area of any commercial CCD. At first they seemed all to be mutually exclusive -- all fisheye lenses I could find only made image circles well wider than listed CCD dimensions. Also, the focal lengths of fisheye lenses all tended to be too short for practical use. Then I lucked onto a web site that advertised a defocusing lens, and I realized that putting one of these in the optical path could increase the focal length just enough to enable a practical device. And the costs were not excessive, particularly if I used a common commercial fisheye lens and other common commercially available parts. I ordered the parts and deployed Pereira to the lab to make sure this really worked. It did. So then we gave all the parts and a water proof case to the Physics Department's industrious machinist, Dave Cook, and asked him to make it all fit together. My mantra is that I wanted light to go in the top, power to go in the bottom and data to go out the bottom of the box. I also wanted no moving parts. Cook did a masterful job, and we had our first "observatory in a briefcase" done, which we then called CONCAM1 (again).
I was quite proud of our new CONCAM1. It so happened that Pereira and I were soon on the road to a conference in Santa Barbara, California, so we decided not only to show off our CONCAM1 at this conference, but to go to the headquarters of the Santa Barbara Instrument Group (SBIG), and demonstrate how their ST7 CCD was being used in our novel device. SBIG president RIchard Holmes was quite accommodating, and he seemed to admire our novel concept and design. Sadly, he was not so impressed that he offered any substantial discount on future SBIG CCDs, though. In retrospect, I believe he saw this as an opportunity to sell even more of his SBIG CCDs. Holmes did come in useful on some occasions, though, when trying to troubleshoot our future CONCAM devices.
The following year had me spending significant time trying to control SBIG CCDs and data flow with Linux, as this gave us full control of shutter, dark frame, and image characteristics. Also, Pereira, Rafert, Cook, and I kept upgrading our CONCAMs to larger CCDs and fisheye lenses with greater throughput. The very next step was a device we called CONCAM2, which was ready to deploy somewhere in the world other than the cloudy winter skies near Houghton, Michigan. Thus started our next great adventure: trying to find a perch.
Social connections are important in any field, and in this case it was only through an acquaintance I had made in my previous life as a postdoc researching GRBs at NASA's Goddard Space Flight Center that made the key difference. This acquaintance, Dr. Scott Barthelmy, knew of a building that at Kitt Peak National Observatory that NASA could well make better use of. In a previous incarnation, the building housed something called the Explosive Transient Camera that used a bank of CCDs too look for transients on the night sky. So here was a case of another precedent that I had missed. Since this project had concluded, Barthelmy was looking for new projects that might make good use of their Kitt Peak Building. Putting our CONCAM on the roof of this building seemed like a natural. The site had dark skies, high bandwidth, power, and was in the US. After Barthelmy realized that I was incapable of bolting two screws together, he was the one who actually installed our CONCAM2 on the roof. That night, in April 2000, we took the first fisheye images of our all sky monitoring project.
As usual, I didn't understand the immediate result. The camera appeared to be recording bright stars, but oddly there were faint bands of light running across the images that looked a little like really long clouds that were mostly transparent. I reasoned there was something wrong with our instrument. Later, I found out we were seeing ripples in the atmosphere called gravity waves. Then something unexpected happened yet again that would change the course of the project, yet again.
At the Kitt Peak canteen, someone I didn't know came up to me, said that he heard that we were taking wide angle night sky images, and asked to see one. Apparently he wasn't interested in the stars in the field, he was interested to see the CLOUDS in the field. I guess he wanted to know how good his observations of the previous night would be. So CONCAM2 made an immediate splash not as a star monitor or a transience monitor, but as a cloud monitor. Interesting. The CONCAM project now had a better selling point.
Now hyped as a cloud monitor, we were soon able to get CONCAM2s -- and then CONCAM3s -- up on almost every major observatory in the free world. We charged $20K. a device. Locations included Mauna Kea (Hawaii), Wise Observatory (Israel), Canary Islands, Cerro Pachon (Chile), Siding Spring (Australia), South Africa. At its peak, the (now renamed) Night Sky Live (NSL) project had eleven (11) CONCAMs running simultaneously all over the world, reporting images back to NightSkyLive.net at MTU continuously. Notable collaborators included Prof. Noah Brosh at Tel Aviv University, and Dolores Perez-Ramirez who was a postdoc with us for a while. Pereira and Shamir also leveraged the project and data for their Ph D. theses.
What I didn't expect is that in order to keep the NSL project running efficiently, I would slowly have to shift from being a scientist to being a technical consultant. Fortunately, after Pereira graduated, graduate student Lior Shamir arrived and did most of the programming the ran the NSL network. Even so, and even with no moving parts, these CONCAMs kept running into a series of (usually minor) problems and the host observatories were counting on us to solve them. Just keeping the network up and running was becoming a full time job.
Sadly, this was a job I might have kept for at least a little while longer, but could not. Although many of the observatories housing CONCAMs indeed liked having a real time all-sky cloud monitor, more and more of them felt that they could create and deploy their own CONCAM-like device themselves, for less money than we were charging, and have more internal accountability to boot. Even so, I got enough observatory collaborators together to cobble together an ambitious grant proposal to the US National Science Foundation (NSF) for a new round of even better sky monitors, dubbed CONCAM4s. A proposal that was was turned down. Without new money, the NSL project was doomed. So we kept recording as much data as we could, handed off the existing CONCAMs to their host observatories, and gradually shut down the project.
Although the Night Sky Live project did not survive, I find solace in that it created or bolstered precedents that are still important in astronomy today. For example, many major observatories now have their own fisheye cloud monitors, which make their own major telescopes more efficient. Also, the drive to continually monitor the entire night sky has only gotten stronger. So much so that, in retrospect, perhaps the fisheye approach to CONCAMs might not have been ambitious enough.
In terms of productivity, the project did produce several papers and several firsts, in my opinion. For example, Tte NSL project was the first project to monitor most of the night sky, most of the time. A conference paper announced this here: Nemiroff, R. J. et al. 2003, Expanding Fisheye Webcam Network Now Capable of Monitoring Most of the Night Sky, Bulletin of the American Astronomical Society, 202, 3.03 . The NSL project was the first to trigger on a (possible) rapid optical transient, lasting only minutes, in real time. This possible transient was seen by two different CONCAMs in different parts of the world at the same time, and resulted in this paper: Shamir, L. & Nemiroff, R. J. 2006, OT 060420: A Seemingly Optical Transient Recorded by All Sky Cameras, Publications of the Astronomical Society of the Pacific, 118, 1180. Years of CONCAM data analyzed later to create the best limits on naked eye optical transients yet made. That paper, where the statistics are trickier than they look, is here: Shamir, L. & Nemiroff, R. J. 2009, Frequency Limits on Naked-Eye Optical Transients Lasting from Minutes to Years, Astronomical Journal, 138, 956 .
2000 GRB Pulses Start at the Same Time at Every Energy
Some ideas appear so obvious that it is hard to believe that they aren't common knowledge. Conversely, if one looks at data in ways that aren't common, sometimes obvious things may just pop out. This is one of those cases.
Partly to check if gravitational lensing commonly occurs in gamma ray bursts (GRBs), my colleagues and I continually printed out prompt emission light curves. Since lensing is supposed to be achromatic -- the same at every color -- I developed a simple program that would just print out a time-aligned version of all four energy bands of recorded gamma-ray emission from the BATSE instrument on board NASA Great Observatory Compton. Given my luck, of course, I was not able to find any evidence of gravitational lensing. (Actually, I was able to find comedic solace in that this appeared to be a case where the entire universe WAS conspiring against me.)
Along the way, however, I stared at quite a few GRB light curve plots, all stacked in energy so that they their start time were all co-aligned. Hundreds of plots. Eventually, without running a single computer program or doing any analyses other than holding up the straight bottom of a stapler, it seemed quite evident to me that when a pulse in a GRB begins, it begins at all plotted energies at the same time. Now since GRB pulses tend to overlap each other, most cases were not so clear, but whenever a pulse seemed to begin in isolation, this seemed to hold up.
I asked people about this, assuming this was common knowledge, but nobody seemed to know about it. I could find nothing written about this. And I looked. So I found some relatively clear cases of this, branded this as the "Pulse Start Conjecture" and published it as part of a greater paper here: Nemiroff, R. J. 2000, The Pulse Scale Conjecture and the Case of BATSE 2193, Astrophysical Journal, 544, 805. The title of the paper refers to another GRB characteristic, potentially even more interesting, that is described below.
2000 GRB Pulses are Scale Invariant over Energy
Another facet of GRBs, as indicated above, appeared to be more subtle and hence surely more controversial. The same printouts of GRB pulse light curves as measured in different energies, when held up to a light and tilted just right, seemed consistent with the idea that GRB pulses really had the same shape at all energies. It other words it seemed, upon inspection, that the only real differences between GRB pulse light curves at any two energies was scale factors on the X and Y axes. Therefore, were a light curve at one energy somehow printed on rubber graph paper, it could be stretched in X and Y to fit right on top of the same GRB pulse measured at another energy. This seemed to me to be saying something about GRB pulse physics, although exactly what I didn't know. As usual, I could find nothing written about this. And I looked. So I first presented it at a meeting, and then wrote it up. The paper was the same paper that I announced the Pulse Start Conjecture (discussed above) and can be found here: Nemiroff, R. J. 2000, The Pulse Scale Conjecture and the Case of BATSE 2193, Astrophysical Journal, 544, 805. The paper gets a lot of reads but only a moderate amount of citations, although the pace appears to be picking up.
1999 Continuous Monitoring of the Entire Night Sky is Now Possible
I expect this entry to be a controversial one. This idea starts with a daydream: the Starship Enterpise from Star Trek (tm) is on a mission and needs to know the history of a common star on their main view screen. A bridge officer says that data on that star is only available back to ... some date. The daydream ended then because it occurred to me that this date had not yet occurred. At the time of this daydream, to the best of my knowledge, there was only data on specifically interesting stars, and single archived plates and prints of much of the sky taken about 50 years ago. There was, at that time, to the best of my knowledge, no sky monitoring program that would regularly record the brightness of a random nearby star. So I thought about what would be needed to start one.
This search did turn up some history. For one, a conversation with Prof. Paczynski indicated that he had already been thinking along similar lines, and referred me to a conference proceedings he had written the previous year that I had not seen.
As an aside, this is not the first time that I presented Prof. Pacynzski with an idea I thought was original but that he had thought up previously. This time I remember relaying to him another daydream that seems to recur at the beginnings of some of our discussions. In this daydream, I tell him, I am slashing through the dense forests of some faraway place in the world, hot on the trail of some valuable treasure. Yes, it's a bit lit Indiana Jones. Anyway, following my tattered map, I feel that I am finally getting close to the treasure when I come across a clearing. In the clearing sits Prof. Paczynski. He is already searching for the same treasure, but he has a better map and actual hot food. "Oh there you are," Prof. Paczynski tells me. "I have been expecting you. It is good to see you. Have a seat -- there is much work to be done!"
Actually realizations that Paczynski (or someone) had previously similar ideas were not totally disheartening. Although my pride and vanity were dinged, I was happy to see that this idea was actually a good one. Sometimes, OK many times; OK most times speculative ideas I follow end up crashing spectacularly (I keep a folder of them, by the way). Sometimes the idea just does not work out at all, sometimes one of my premises is wrong (or way wrong), sometimes I rediscover what should have been obvious, sometimes my math is faulty, and sometimes I missed a key word that would have shown me that this subject has been thought about for years already.
Anyway, the search also turned up an existing sky survey that even Prof. Pacynski didn't know about. In turned out that the GROSCE project (PI: H. S. Park, a wonderful and thoughtful woman working at LANL) had been monitoring the sky as part of the GRB afterglow project since the mid 1990s. When not chasing GRB afterglows, the GROSCE wide angle cameras would tile the sky and record data. To the best of my understanding, this really was the first sustained sky monitoring project. The GROSCE data was then put on tapes and placed in a filing cabinet. I actually got to see many of the tapes piled up in the filing cabinet in LLNL. Park and I discussed ways of "liberating the data" so that scientific analyses could be done. I therefore joined Park's project and thought about trying to make their data more generally available. We continually rediscovered, however, that this would be an expensive and time consuming undertaking.
Nevertheless, I decided to write a paper on this and try to actually quantify how difficult it would be to monitor the sky down to almost any limiting magnitude. Paczynski's conference paper in Japan, which I finally located, turned out to be mostly qualitative and discussed what discoveries such a survey might make. I myself had taken for granted that many discoveries would be made because the universe was so variable and because so little time monitoring of the sky had ever been done. Therefore, what I wanted to explore was how many telescopes would be needed, how much data must be recorded, etc. to actually get a useful sky monitoring project to work. I could find nothing written on the subject. And I looked. I therefore worked with a Prof. Rafert who was in my department and had a better understanding of telescopes and practical observational astronomy than I had. The paper is here: Nemiroff, R. J. & Rafert, J. B. 1999, Toward a Continuous Record of the Sky, Publications of the Astronomical Society of the Pacific, 111, 886. I believe that Prof. Code was the referee, who made some good suggestions.
In retrospect, however, it now seems to me that this paper was not ambitious enough. Our analysis only went down to a visual limiting magnitude of 20. Sky monitoring has now become big business, with many efforts now attempting records of the sky down past visual magnitude 25. I did not think the community would put THAT much money into this type of effort. I was wrong. Oddly, even though this paper was published openly and even though I circulated the paper at an Aspen Conference on Sky Monitoring a few years later, the current sky monitoring community ignores it. I am not sure why. For example, I don't think the PanSTARRS or LSST community has ever cited this paper. To my delight, though, to the year he died, Prof. Pacyznski cited this paper almost every chance he got.
1999 The Astrophysics Source Code Library
Computers have quickly changed science, but some aspects of science publishing are slower to change. It used to be, before computers, that when you published a paper, you gave enough information to make your results reproducible. Now so much science is done with computers that creating a separate computer routine to reproduce the results in a paper is prohibitive. Therefore, to reproduce those results, the computer code(s) should be made available, in my opinion. People could then not only run the code, but inspect the source text to see what approximations were being used and how algorithms were being implemented.
Unfortunately, very few papers make available the computer codes that enabled them. Oddly, at this time, no real venue existed for presenting these codes to the public. And I looked. So I decided to create the Astrophysics Source Code Library (ASCL). I recruited a friend and fellow astrophysicist Prof. John Wallin to help, but as time went on he acted more as an advisor than an editor or contributor. The announcement of this library is here: Nemiroff, R. J. & Wallin, J. F. 1999, The Astrophysics Source Code Library: www.ascl.net/, Bulletin of the American Astronomical Society, 194, 44.08. Later, D