SDSS-IV commitment to inclusivity

The below statement was shared with the SDSS-IV collaboration on 13th November. Following a request we now post it publicly here.


 

We write to affirm our commitment to treat every member of our collaboration with respect and dignity, regardless of their race, ethnicity, age, color, disability, faith, national origin, gender identity, gender expression, sexual orientation, social class, or political beliefs.

This week’s U.S. election results followed a long and divisive 2016 campaign. Our SDSS-IV collaboration is broad and international, and has a significant fraction of members based in the U.S. Our community comes from a range of backgrounds and experiences that may influence how they are impacted by current events.  We urge all members of the collaboration to be mindful of how we treat other members of our community during this challenging time.

We write particularly to express our solidarity with colleagues who have legitimate fears for their safety in the coming months and years. In the days following the election, some of us at U.S. institutions
have heard first-hand reports of harassment and intimidation of our colleagues and students, in some cases based on their race, of a sort that has previously been rare, and by perpetrators who expressed
political motivations.  Whatever one’s philosophy of government or beliefs about what economic, social, and foreign policies are best for the U.S., it is important that we reject such behavior; we hope that all of the U.S. national leaders will do so.

In this environment, we feel the need now to emphasize that in SDSS-IV we are committed to fostering an astronomy community that is safe, welcoming, and inclusive of all people, including those in historically marginalized groups.
SDSS-IV is currently in the process of drafting our Code of Conduct. Collaboration members are invited to comment on the current draft (link is internal website)  by emailing Jennifer Johnson (the Chair of the Code of Conduct Committee). You are also welcome to send comments to the Committee on Inclusiveness in SDSS (coins@sdss.org).

In the meantime please bring any concerns you have about collaboration climate to the collaboration management, or to our Ombudspeople, Jill Knapp and David Weinberg who can be contacted directly and confidentially via ombuds@sdss.org.

A Winter Night at APO

It’s almost March, and spring is in the air in much of the Northern Hemisphere, but here’s a beautiful Haiku written by SDSS Observer Patrick Gaulme as part of his SDSS 2.5m Observing Log for the night of Monday January 4th 2016 [Observed 1.5 h – Lost 9.9 for weather].

– A Winter night at APO –

No water in the faucets
Few photons in the bucket
Silent snow in the dead of night

AWinterNightatAPO

A winter night at APO, Image Credit: Patrick Gaulme, SDSS.

We all agree this lovely poem really captures the essence of observing in a snowy night, and we also think it demonstrates the huge range of talent found amongst the dedicated crew of SDSS observers working at Apache Point Observatory.

How SDSS Talked about Light for #IYL2015

This is a re-posting of the wrap-up article which appeared on the IYL2015 main blog.


 

2015 has been the International Year of Light.

As astronomers, here at the Sloan Digital Sky Survey everything we do is based on collecting light from cosmic objects. So we have been pleased to celebrate the International Year of Light, and especially the Cosmic Light Theme, supported by the IAU.cosmiclight_color_whitebgAs a small contribution to this celebration, every month in 2015 SDSS had a special blog post talking about the different ways we use light. Here’s a roundup of what we talked about through out the year.

In January we talked about How SDSS Uses Light to Study the Darkest Objects in the Universe. This blog post, by Coleman Krawcyzk and Karen Masters (both from the University of Portsmouth in the UK) with help from Nic Ross (Royal Observatory, Edinburgh) was about finding black holes by looking at the light from distant galaxies. Finding objects which are famous for not emitting any light, using light seems contradictory, but this article explains how the light created by the hot material falling onto a black hole can make these objects outshine the entire galaxy they live in.

Quasar

An artist’s rendition of a quasar created by Coleman Krawczyk (ICG Portsmouth). The image is drawn on a radial log scale with the central black hole 1 AU in size.

In February we wrote about How SDSS Uses Light to Measure the Distances to Galaxies. This of course was about the technique of measuring galaxy redshifts (ie. the shift of their light to longer wavelengths caused by the expansion of the Universe) by looking at absorption and emission lines in galaxy spectra and comparing their wavelength to the laboratory measurement. Edwin Hubble, and others, realised over 80 years ago, that this can be used to give distances to galaxies, as the amount of redshift increases with the galaxy’s distance. The original motivation for SDSS (back in the 1990s) was to used this technique to measure distances to a million galaxies, and in SDSS-IV we are continuing to use this in the eBOSS part of the survey, to map distances to ever more distant galaxies.

A map of the Universe from SDSS where the distance to galaxies is given in terms of their redshift. Credit: SDSS

A map of the Universe from SDSS where the distance to galaxies is given in terms of their redshift. Credit: SDSS

In March, we came back to the most local Universe, with a post by SDSS-IV Spokesperson, Jennifer Johnson (Ohio State University) on How SDSS Uses Light to Understand Stars Inside and Out in the Kepler Field. This was about part of the APOGEE survey, which is measuring spectra from stars which have light curves measured by the Kepler Satellite. This is a valuable experiment, as the combination of spectra and light curves allows us to measure the masses, ages and compositions of these stars.

The Kepler Field. Credit: NASA

The Kepler Field. Credit: NASA

In April, we moved back outside our own Galaxy, to measuring the invisible mass in other galaxies, with a post on How SDSS Uses Light to Explore the Invisible, by the MaNGA Lead Observer, and SDSS-IV Data Release Co-ordinator, Anne-Marie Weijmans from St Andrew University. This post talked about how MaNGA is measuring spectra across the face of nearby galaxies in order to get measurements of the internal motions (again using the redshift/blueshift of the spectra). These measurements give a way to measure the total mass of galaxies, which we find in all cases is much much more than the mass in stars.

MaNGAlogo5small

For May we went back in the history of SDSS, and talked about How SDSS Used Light to Make the Largest Ever Digital Image of the Night Sky. This post was about the the SDSS camera and the SDSS imaging survey, which ran from 2000-2008, and created a image of over 30% of the sky, containing over a trillion pixels (an image which dwarfs others that have also been claimed as the largest).

The SDSS Camera, now in storage in the Smithsonian Museum. Credit: SDSS, Xavier Poultney

The SDSS Camera, now in storage in the Smithsonian Museum. Credit: SDSS, Xavier Poultney

June also saw a post about SDSS imaging, and about an unexpected use for them, finding asteroids, in How SDSS Uses Light to Find Rocks in Space. This has been beautiful visualized in the below video, by Alex Parker.

If our posts in February, March and April confused you because you didn’t understand what astronomers mean by measuring spectra, then the July post was for you: “How SDSS Splits Light into a Rainbow for Science”.  This post explained all about what spectra are, how to create them with gratings, and contained a with bonus activity to make your own spectroscope created by the SDSS Education and Public Outreach group.

Comparison of the spectra obtained from a diffraction grating by diffraction (1), and a prism by refraction (2). Longer wavelengths (red) are diffracted more, but refracted less than shorter wavelengths (violet).Credit: Wikimedia

Comparison of the spectra obtained from a diffraction grating by diffraction (1), and a prism by refraction (2).Credit: Wikimedia

Our August post, by the APOGEE survey Public Engagement officer, David Whelan (from Austin College, Texas)  was about the basic physics of the most abundant element in the Universe (hydrogen): “How SDSS Uses Light to Study the Most Abundant Element in the Universe.”

For September, we visited an IYL2015 Exhibit in Dresden with Zach Pace, Graduate Student at the University of Wisconsin, Madison. Zach reported on SDSS plates on display in the exhibit, linking back to an earlier post in which we explain why we need all these big aluminium plates to do our spectroscopic survey. IYL2015 – SDSS Plates (in Retirement).

Technische_Sammlungen3

SDSS Plate on Exhibit in Dresden.

We went back to the APOGEE survey in October, with a post by Gail Zasowski (from John’s Hopkins University) on How SDSS uses mysterious “missing” light to map the interstellar medium. In this post we learned about how SDSS has helped shed light on the the mystery of missing light caused by absorption in the material which is found between stars in our own Galaxy.

Finally last month, we talked about How SDSS Uses Light to Measure the Mass of Stars in Galaxies. Looking back to the post in February, we claimed that the total mass of galaxies is always much much more than the mass we can count in their stars. But how do we know how much mass is in the stars in a galaxy? This post explains how that can be done using measurements of the light from galaxies.

So that wraps up a year of the celebration of light in the SDSS. We certainly haven’t covered all the ways in which SDSS astronomers are using light to learn about the Universe around us, from asteroids in the solar system, to stars in our own Galaxy and galaxies are the furthest edges of the Universe. But we hope it gives you a flavour for the kinds of things the light collected by SDSS (both images and spectra) can be used for.

If you’re looking for a guided entry into SDSS science (especially suitable for educational use), please visit our Voyages.sdss.org site to discover guided journeys through the Universe. As always all SDSS data (through our 12th public data release, DR12) is available free to download, and look out for DR13 (including the first data from SDSS-IV) coming up in mid 2016.

 

Tweep of the Week: Anne-Marie Weijmans

The MaNGA Lead Observer, and our Data Release Co-ordinator, Anne-Marie Weijmans will be spending some time at Apache Point Observatory Dec 8-17th and has agreed to take over the @sdssurveys Twitter account for the trip. We’re hoping for some tweets about pie (as well as observing).

MaNGA Lead Observer (Anne-Marie Weijmans) plugging IFUs into an SDSS plate. Credit: SDSS.

MaNGA Lead Observer (Anne-Marie Weijmans) plugging IFUs into an SDSS plate. Credit: SDSS.

 

Dr. Weijmans is a Lecturer (Assistant Prof. for our US readers) and Leverhulme Early Career Fellow based at the University of St Andrews in Scotland. Her research interests concentrate on the structure and evolution of early-type (i.e. visually smooth) galaxies using Integral Field Spectroscopy. Before joining MaNGA she was a member of the ATLAS-3D survey, which was one of the first surveys to use this technique on a sample of galaxies.

How SDSS Uses Light to Measure the Mass of Stars in Galaxies

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Galaxy NGC 3338 imaged by SDSS (the red stars to the right is in our own galaxy). Credit: SDSS

It might sound relatively simple – astronomers look at a galaxy, count the stars in it, and work out how much mass they contain, but in reality interpreting the total light from a galaxy as a mass of stars is fairly complex.

If all stars were the same mass and brightness, it would be easy, but stars come in all different brightnesses, colours and masses, with the lowest mass stars over 600 times smaller than the most massive.

Hertzsprung-Russel Diagram identifying many well known stars in the Milky Way galaxy. Credit: ESO

Hertzsprung-Russell (HR) Diagram, which shows the mass, colour, brightness and lifetimes of different types of stars. This version identifies many well known stars in the Milky Way galaxy. Credit: ESO

And it turns out that most of the light from a galaxy will come from just a small fraction of these stars (those in the upper left of the HR diagram). The most massive stars are so much brighter ounce for ounce than dimmer stars this makes estimating the total mass much more of a guessing game than astronomers would like (while they are 600 times more massive, they are over a million times brighter). So astronomers have to make assumptions about how many stars of low mass are hiding behind the light of their brighter siblings to make the total count.

One of the first astronomers to suggest trying to decode the light from galaxies in this way was Beatrice Tinsley. British born, raised in New Zealand, and working at Yale University in the USA, Dr. Tinsley had a much larger impact on extragalactic astronomy than her sadly shortened career would suggest (she died of cancer in 1981 aged just 40).

Stars of different masses have distinctive spectra (and colours), as first famously classified by Astronomer Annie Jump Cannon in the late 1890s into the OBAFGKM stellar sequence. O stars (at the top left of the HR diagram) are massive, hot, blue and with very strong emission lines, while M stars (at the lower right) are low mass, red and show absorption features from metallic lines in their atmospheres. With a best guess as to the relative abundance of different stars (something we call the “initial mass function“) a stellar population model can be constructed from individual stellar spectra or colours and fit to the total light from the galaxy. Example optical spectra of different types of stars are shown below (or see the APOGEE View of the IR Stellar Sequence)

Example optical spectra of different stellar types. Credit: NOAO/AURA/NSF

Example optical spectra of different stellar types. Credit: NOAO/AURA/NSF.

Using data from SDSS (and other surveys) astronomers use this methods to decode the galaxy light – in fact we can use either the total light observed through different filters in the SDSS imaging, to match the colours of the stars, or if we measure the spectrum of the galaxy we can fit a population of stars to this instead. While in principle the spectrum should give more information, in SDSS (at least before the MaNGA survey) we take spectra through a small fibre aperture (just 2-3″ across), so for nearby galaxies this misses most of the light (e.g. see below), and most galaxies have colour gradients (being redder in the middle than the outskirts), so the extrapolation can add quite a lot of error to the inferred mass.

NGC 3338 with the approximate SDSS fibre size overlaid (note this is an example of a very large galaxy imaged by SDSS). Credit: SDSS, KLM

NGC 3338 with the approximate SDSS fibre size (ie. the part of the galaxy for which we measured spectra) overlaid (note this is an example of a very large galaxy imaged by SDSS, and not representative of most galaxies). Credit: KLM, SDSS

 

Many astronomers prefer to use models based on the total light through different filters (at least for nearby galaxies). The five filters of the SDSS imaging are an excellent start for this, but extending into the UV with the GALEX survey, and IR with a survey like 2MASS or WISE adds even more information to make sure no stars are being missed. However, these fits are still a “best guess” and will still have error –  there is often more than one way to fit the galaxy light (e.g. model galaxies with certain combinations of ages and metallicities can have the same integrated colours), so there’s still typically up to 50% error in the inferred mass.

The SDSS camera filter throughput curves (from left to right ugriz). Credit: SDSS

The SDSS camera filter throughput curves (from left to right ugriz). Credit: SDSS

 

But with galaxies spanning more than 3 orders of magnitude in total mass (ie. the biggest galaxies have more than a 1000 times the stellar mass of the smallest) this is still good enough for many purposes. It gives us an idea of the total mass in stars in a galaxy, which (as you know from earlier post for IYL2015) is almost always way less than the total mass we estimate from looking at the dynamics (ie. the “gravitating mass”). And the properties of galaxies correlate extremely well with their stellar masses, so it’s a really useful thing to have even an estimate of.


This post by Karen Masters is part of the SDSS Celebration of the International Year of Light 2015, in which we aim to post an article a month in support of the celebration of light. 

How SDSS Uses Mysterious “Missing Light” to Map the Interstellar Medium

This post by Gail Zasowski is part of the SDSS Celebration of the International Year of Light 2015, in which we aim to post an article a month in support of the celebration of light. 


 

It is increasingly rare for modern astronomers to work on “old” puzzles — that is, older than they are, or especially older than their advisors are. The last several decades have seen a huge advancement in our understanding of the Universe — we learned that stars evolve over time in predictable ways, that the Milky Way is one distinct galaxy among many, and that the Universe itself is expanding and even accelerating in size “outwards”. Very often, the questions that astronomers work on now are new questions that arise as other problems are answered, or as we build new telescopes and discover things that we didn’t even know we didn’t know about.

But there is one outstanding puzzle that has famously resisted an answer for nearly a century now. This mystery concerns a peculiar pattern of missing light arising from interstellar material — that is, from the giant clouds of dust and gas that lie in the vast distances between stars. These clouds contain atoms and molecules of all the elements that make up the stars and the planets and us — hydrogen, carbon, oxygen, and so on. They are 10^19 (that’s 10 000 000 000 000 000 000) times less dense than the air we breathe, but they are so huge that they contain enough atoms to add up to nearly 15% of the mass of the Galaxy! (Baryonic mass, of course — dark matter is a different story.) And now the SDSS has made some unique contributions to understanding the mystery in these clouds’ missing light.

Figure 1: The inner part of the Milky Way Galaxy, with numerous stars intermixed with giant clouds of interstellar gas and dust.  Image credit: Serge Brunier.

Figure 1: The inner part of the Milky Way Galaxy, with numerous stars intermixed with giant clouds of interstellar gas and dust. Image credit: Serge Brunier.

 

Some of the atoms and molecules in interstellar clouds emit light, like visible light or radio waves, that we can see with telescopes. But others don’t emit much light, and the only way we know they’re there is when they absorb some of the light of stars when the light passes through one of these interstellar clouds. Helpfully, each kind of atom or molecule absorbs only specific wavelengths of light, and we can measure these wavelengths in a laboratory to learn what the pattern is for each element or molecule. So when we look at the spectrum of one of these stars seen through a cloud, and we notice that some of the star’s light is missing, we can use the patterns of absorbed wavelengths to figure out what kind of atoms or molecules are in the cloud. For example, this is how we know that the clouds have elements like calcium and potassium in them1.

Okay, on to SDSS and the mysterious missing light! Way back in the late 1910s, astronomers started noticing some absorption patterns in their spectra that were very puzzling. They didn’t act like the patterns from atoms in the stars themselves, so they had to come from interstellar material. And they appeared in the spectra of stars all over the sky, so the material had to be something that was common. But they couldn’t figure out what the particles were! The patterns didn’t match those of anything we knew existed in interstellar clouds, or even anything we had measured in a laboratory.

Fast-forward nine decades, and the situation has progressed a bit, but not as much as one might expect. We now know of almost 500 separate absorption “features” (that is, wavelengths at which light is being absorbed by something), up from the original 2 discovered in the 1910s (Figure 2). We call all of these features “DIBs”, which stands for “Diffuse Interstellar Bands”2. We have determined that the DIBs are more consistent with being caused by molecules than by single atoms, and many people have theories as to which molecules those are. But it was just this year, in 2015, that scientists were first able to show conclusively that a particular molecule — the fullerene ion C60+ — is responsible for a particular DIB (actually, for four of them). The rest remain up for grabs!

Figure 2: The 400 strongest known DIBs.  The y-axis shows the typical fraction of background light absorbed when there is enough interstellar dust to absorb almost 60% of the total visible light.

Figure 2: The 400 strongest known DIBs. The y-axis shows the typical fraction of background light absorbed when there is enough interstellar dust to absorb almost 60% of the total visible light.

So where does SDSS come in? Well, proving that certain molecules produce certain DIBs requires a lot of equipment and a molecular spectroscopy laboratory, and that’s not really something SDSS is set up to do. But there’s another related puzzle — how are the molecules that produce the DIBs (whatever they are) distributed throughout the Milky Way? This is an important question, because the big molecules that are most likely to cause the DIBs are the kinds of molecules that contain a lot of the Galaxy’s carbon, which has an impact on things like the chemistry of newly formed planets. But because DIBs are generally only studied in small samples of stars very close to the Sun3, we didn’t have a good understanding of what the molecules were doing elsewhere in the Galaxy.

One group of SDSSers (led by Ting-Wen Lan, a graduate student at Johns Hopkins) tackled this issue by looking for the DIBs’ absorption signatures in optical SDSS spectra of other galaxies and quasars, seen through the Milky Way’s interstellar material. They had to be careful, because the galaxies’ and quasars’ spectra have absorption lines from their own stars and gas clouds, so identifying the weak features from the foreground Milky Way gas can be tricky. But the SDSS provides the biggest dataset available to look for DIBs: the team had so many spectra from SDSS-I, -II, and -III (almost 500,000 of them) that they could add many spectra together to boost the signal, and then map the DIB absorption strength on the sky (see the left side of Figure 3). Because they detected about 20 DIB features in each signal-boosted spectrum, they could also measure how each DIB behaves a little differently with respect to other interstellar gases, like hydrogen or carbon monoxide (Lan et al. 2015). This tells us that there isn’t one single molecule that can explain all of the DIBs!

However, the SDSS optical dataset doesn’t include any sources in the disk or inner parts of the Milky Way. This is because the interstellar material, which is concentrated in these parts of the Milky Way, is made up of not only gas particles but also dust grains (think of tiny soot particles). These dust grains block starlight, and block it much more than the DIB molecules do, especially at optical wavelengths. (Look back at the picture of the inner Milky Way in Figure 1.) So it is very hard to see any stars, galaxies, or quasars to use as “background” sources in which to look for DIBs.

Figure 3: Left: The strength of DIB absorption seen in optical wavelengths from SDSS background galaxies and quasars (Lan et al. 2015) and in infrared wavelengths with APOGEE (Zasowski et al. 2015).  Click HERE for an interactive version of this map!  Right: The motion of the APOGEE DIB molecules with respect to the Sun.  Image credit: T. W. Lan and G. Zasowski.  (HERE=http://www.pha.jhu.edu/~tlan/dibs-map.html)

Figure 3: Left: The strength of DIB absorption seen in optical wavelengths from SDSS background galaxies and quasars (Lan et al. 2015) and in infrared wavelengths with APOGEE (Zasowski et al. 2015). Click HERE for an interactive version of this map! Right: The motion of the APOGEE DIB molecules with respect to the Sun. Image credit: T. W. Lan and G. Zasowski.

And this is where APOGEE steps in. APOGEE is unique in the SDSS set of instruments because it measures light at infrared wavelengths. This kind of light is invisible to the human eye (we can perceive some infrared wavelengths ourselves, though we call it “heat”!), but it is very efficient at passing through some materials, including the interstellar dust that blocks visible light (Figure 4). This means that APOGEE is a great tool for measuring starlight — and the bits of it that get absorbed by the DIBs — very far from the Sun in the disk and bulge, where most of the stars and interstellar material are!

Figure 4: Looking at things with optical and with infrared light can lead to very different results!  On top, a plastic bag is opaque to visible light, but it is translucent to infrared light from the man's hand.  On the bottom, a similar effect occurs in an interstellar cloud, seen with visible light (left), like our eyes, and infrared light (right), like APOGEE.  Image credits: NASA/IPAC and ESO.  See more optical/IR comparisons HERE.  (HERE=http://coolcosmos.ipac.caltech.edu/cosmic_kids/learn_ir/)

Figure 4: Looking at things with optical and with infrared light can lead to very different results! On top, a plastic bag is opaque to visible light, but it is translucent to infrared light from the man’s hand. On the bottom, a similar effect occurs in an interstellar cloud, seen with visible light (left), like our eyes, and infrared light (right), like APOGEE. Image credits: NASA/IPAC and ESO. See more optical/IR comparisons HERE.

So I (Gail Zasowski, a postdoc at Johns Hopkins) led a second group of SDSSers who focused on a single, particularly strong DIB feature that APOGEE could detect. My team measured this feature in front of about 70,000 stars in the APOGEE dataset (Zasowski et al. 2015a). Because most of these stars lie in the dustiest parts of the Milky Way, we were able to fill in the parts of the DIB absorption map that Ting-Wen’s group couldn’t reach with optical data (left panel of Figure 3). We also found that, unlike many of the DIB features at visible wavelengths, this infrared DIB does not disappear in cold, dense interstellar clouds. This behavior means that the APOGEE DIB can be used to measure the approximate amount of interstellar material between us and a background star, including the amount of interstellar dust that blocks so much of the starlight.

Even more excitingly, my team is able to use the DIB features we detect to measure the speed at which the clouds of DIB molecules are moving with respect to the Sun. We can tell that the molecules are generally rotating with the Galactic disk in the same way that hydrogen and other major interstellar components do (right panel of Figure 3).  Since most DIB studies in the past have looked at stars relatively close to the Sun, this is the first time this dynamical behavior has been observed in any sort of large scale way.

My group even found evidence for DIB molecules flowing in the gas surrounding the beautiful Red Square Nebula (Figure 5). This detection may help us identify likely candidates for the molecule itself (Zasowski et al. 2015b).

Figure 5:  The Red Square Nebula.  Image Credit: P. Tuthill.

Figure 5: The Red Square Nebula. Image Credit: P. Tuthill.

Over the last hundred years, astronomers have learned that there is a large reservoir of unidentified, complex organic molecules in the interstellar medium, seen only in the mysterious signatures they leave in the light of stars shining through them. The SDSS has given us the ability to use these DIB features — even without knowing exactly what causes them! — to map the distribution and velocities of these molecules in the big spaces between the stars.


 

1 Some elements are also traced through their light emission, instead of light absorption. This has to do with the more complicated physics that happens in clouds with different densities and temperatures. For more information, check out http://www.ipac.caltech.edu/outreach/Edu/Spectra/spec.html, or search for “astronomical spectroscopy” online.

2This term refers to three facts about these features. Many of the features at optical wavelengths appear strongest in “diffuse” interstellar clouds, as opposed to very cold dense clouds with atoms packed more closely together (still very far apart by Earth standards, though). The “interstellar” part distinguishes them from absorption features coming from the atmospheres of stars. “Band” is used to indicate that the majority of the features appear broad in the spectrum of a background star — much broader than the narrow absorption lines coming from the star itself.

3This is because bright stars that are close to the Sun tend to have very few absorption lines coming from their own atmospheres, so it’s much easier to detect interstellar absorption lines.


This post by Gail Zasowski is part of the SDSS Celebration of the International Year of Light 2015, in which we aim to post an article a month in support of the celebration of light. 

SDSS Survey Operations Software Developer

The below is the text of a job advert looking for a software developer to work on the software we use to run our surveys.

For full details please visit the Job Advert.

SDSS Survey Operations Software Developer

The Department of Astronomy at the University of Virginia (UVa) invites applications for a Survey Operations Software Developer to work directly with the Sloan Digital Sky Survey (SDSS-IV).  The SDSS-IV Survey, operating over the 2014-2020 period, consists of three, distinct astrophysical projects: eBOSS, which obtains precision measurements of key cosmological parameters; APOGEE, which performs a high-resolution, near-infrared spectroscopic survey of the Milky Way Galaxy; and MaNGA, which generates spatially resolved spectroscopic maps of individual galaxies.  SDSS-IV conducts observations from both a Northern Hemisphere Site at Apache Point Observatory (APO) in New Mexico and a Southern Hemisphere Site at Las Campanas Observatory (LCO) in Chile.  UVa is a full institutional participant in SDSS-IV as well as a member of the Astrophysical Research Consortium (ARC, which owns and manages APO).

The SDSS operations software contains the high-level data commands that execute survey observations, including telescope and instrument control, telescope guiding, back end frameworks, data storage and flow, observer GUIs and web applications. In the main, the Survey Operations Software Developer will maintain, document and improve the suite of SDSS operations software.  The successful applicant will interact with a variety of SDSS personnel (e.g., observers and other site staff, project scientists) and will coordinate the efforts of project software developers.  The specific responsibilities of the Survey Operations Software Developer include:

  • Ensuring that the SDSS observing system meets performance and reliability requirements.
  • Improving SDSS observing software and procedures and document the various improvements accordingly.
  • Testing, installing, and debugging newly developed software.
  • Tracking and resolving issues reported by the trouble-ticket system.
  • Responding to problems that occur during nightly observing.
  • Anticipating and planning for future survey operational needs.
  • Contributing to the LCO/APOGEE-2 operations software development.

A Master’s degree in Physics, Astronomy or a related field is required; a Ph.D. is preferred.  Applicants should possess proficiency in Python as well as knowledge of Unix Operating Systems.  The applicant should be substantially familiar with IDL and other programing languages in order to support SDSS legacy code. The initial appointment will be for one year.  Note, however, it is expected that the position should continue through the duration of SDSS-IV (mid-2020; contingent upon performance and available funding).  The hire will be done at the Research Associate level or higher, commensurate with experience.  Personal research time may also be available for the successful applicant.  Though the position will be based in Charlottesville, Virginia, travel to the APO and LCO sites will be expected.

For details on how to apply please see the full Job Advert.  Review of applications is planned to commence 1st December 2015.

The University of Virginia is an equal opportunity/affirmative action employer. Women and members of underrepresented groups are strongly encouraged to apply.  SDSS is also committed to work to increase the diversity of collaboration members.

What is MaNGA (in one sentence)?

MaNGAlogo5small

 

Some months ago, members of the MaNGA (Mapping Nearby Galaxies at Apache point observatory) survey (part of SDSS-IV) were asked to suggest ideas for a suitable taglines/catchphrase which would describe the survey in one sentence. This idea was that this would go on promotional materials SDSS-IV would take to the American Astronomical Society Meeting, and also the main SDSS website.

The working favourite to that point had been “the galaxy survey for people who love galaxies”, but we wanted something which described the scientific goals of the survey more precisely.

In the word of MaNGA PI, Kevin Bundy this request resulted in an “outpouring of creative, collective genius” (a phrase which Kevin suggested might itself be the appropriate one to describe the MaNGA team).

Here are some of the ideas the team came up with, catagorised by Kevin:

Ideas which reference The 3rd Dimension

  1. .. Now in 3D!
  2. Sloan goes 3D
  3. Sloan Galaxies in three dimensions
  4. Galaxies in 3D
  5. A new dimension in galaxy surveys
10 000 (nearby) galaxies mapped in 3D
  6. A multi-dimensional view of galaxies
  7. Galaxies in 3D by the thousands
  8. Thousands of local galaxies in 3D
  9. Ten thousand Galaxies. Three dimensions

Inspirational ideas

  1. To boldly go where no other Galaxy survey has gone before.
  2. Unravelling the galaxy avatar
  3. Ten thousand mysteries unfold

Direct (or descriptive) ideas:

  1. Census of local galaxies
  2. MaNGA: Deciphering galaxies pixel-by-pixel
  3. Observing the dynamical structures and composition of galaxies to unravel their evolutionary histories
  4. Galaxy birth, assembly, growth and ‘death’
  5. Galaxies Beyond the Central Fiber
  6. Spatially resolved spectroscopy of 10,000 nearby galaxies

Ideas Inspired by Biological Analogies

  1. Galaxy dissection
  2. Galaxies under the microscope
  3. Exploring the life cycle of galaxies
  4. Anatomising galaxies dead and alive
  5. Dissecting galaxies in their dark matter haloes

Humorous suggestions

  1. Galaxies do the full monty
  2. Everything you wanted to know about galaxies, and in 3D
  3. Experience galaxies in 3D, without the glasses

Clever/cultural references

  1. Taking spectra of the spectrum of galaxies
  2. Galaxies in 3D! It’s over 9000!!
  3. 10K3D
  4. How galaxies tick

The final decision was made to go with “Mapping the inner workings of thousands of nearby galaxies” for our website, and we have a banner which says “The 3D Lives of Galaxies”, although we also really like the creative idea of making an API to return all of these randomly.

MaNGA - Mapping the inner workings of thousands of nearby galaxies

 

Many thanks to: Jeff Newman, Bob Nichol, Kyle Westfall, Surhud More, Karen Masters, Aaron Dutton, Claire Lackner, Mike Merrifield, Daniel Thomas, Eric Emsellem, Carles Badenes, Anne-Marie Weijmans, Brian Cherinka, Demitri Muna, Brett Andrews, Christy Tremonti and Kevin Bundy for contributing ideas.

 

SDSS at the 29th General Assembly of the International Astronomical Union

The 29th General Assembly of the International Astronomical Union is due to start on Monday 3rd August 2015 in Honululu, Hawaii. These meetings happen every 3 years and are the biggest single conference in astronomy. This is your guide to all things SDSS related at IAU2015.

Thanks to generous support from the central project office, SDSS Education will be particularly well represented at IAU2015. SDSS Educational Consultant (Kate Meredith) and Director of EPO (Karen Masters) will be attending to run workshops on how to use SDSS data for education.

Screen Shot 2015-07-31 at 14.44.32

This half day splinter session on Monday 10th August will give astronomers and educators (including, but very definitely not limited to members of the SDSS collaboration) a chance to participate in a hands on workshop exploring voyages.sdss.org, a new educator focused resource designed to enable the use of real data from the Sloan Digital Sky Surveys in the classroom. Participants will have the opportunity to contribute their own experiences using data in the classroom into new guided journeys through Voyages for specific educational levels and/or suggest new content based on exploration of SDSS data. The schedule of the workshop is as follows:

Workshop Schedule (Drop-in Welcome), Monday 10th August 2015 in Room 327, Hawaii Convention Center.

  • 8.30am: Welcome
  • 8.40am: Mapping the Universe with SDSS (Karen Masters)
  • 9.15am: Introduction to SDSS Voyages (Kate Meredith)
  • 10.00am: COFFEE BREAK
  • 10.30am: Matching content to a curriculum (Kate Meredith)
  • 10.50am: Hands on exploration of voyages.sdss.org
  • 12.00pm: Lunch/work time
  • 1.00pm: SDSS Plates and how to get one (Karen Masters)
  • 1.30pm: SDSS Plate resources online (Kate Meredith)
  • 2.00pm: END

The SDSS EPO group will run a similar workshop, but this time especially for High School Teachers as part of the Galileo Teacher Training Program, happening at the IfA, Honululu on 8th/9th August. One lucky Hawaii based teacher attending this training will be able to take an SDSS Plug Plate back to their school for use in lessons.

The SDSS EPO group will be active participants in Focus Meeting 19: Communicating Astronomy with the Public in the Big Data Era. As part of that, SDSS Director of EPO, Karen Masters will lead a discussion on what Researchers would like to Improve in Communication Initiatives. The outcome of this meeting is intended to be a Playbook on Communicating Astronomy with the Public in the Big Data Era.

There are also of course numerous science results from SDSS data being presented at the meeting. Thanks to the open data policy of SDSS many of these results are from scientists who have never been part of the SDSS Collaboration. Here is a summary of all the posters and talks at IA2015 which can obviously linked to SDSS data or projects.

Week 1 Posters:

FM16p.13. White dwarf+main sequence binaries identified from SDSS DR10, Lifang Li

FM19p.16. Galaxy Zoo: Science and Public Engagement Hand in Hand
Karen Masters; Chris Lintott; Julie Feldt; Bill Keel; Ramin Skibba

FM19p.17. SDSS Plate Packets – From Artifact to Teaching Tool
Kate K. Meredith; Karen Masters; Britt Lundgren; Oliver Fraser; Nick MacDonald

FM19p.18. SkyServer Voyages Website – Using Big Data to Explore Astronomy Concepts in Formal Education Settings
Kate K. Meredith; Karen Masters; Jordan Raddick; Britt Lundgren

S315p.193. High Resolution Molecular Gas and Star Formation in the Strongly Lensed z~2 Galaxy SDSS J0901+1814
Chelsea Sharon; Andrew Baker; Amitpal Tagore; Jesus Rivera; Charles Keeton; Dieter Lutz; Linda Tacconi; David Wilner; Alice Shapley

S315p.235. Detecting HII Regions in Z=0.1 Galaxies with Multi-Band SDSS Data
Chris Richardson; Anthony Crider; Benjamin Kaiser

Week 2 Posters:

DJp.2.15. Extreme Red Quasars in SDSS-BOSS
Fred Hamann; Nadia Zakamska; Isabelle Paris; Hanna Herbst; Carolin Villforth; Rachael Alexandroff; Nicholas Ross; Jenny Greene; Michael Strauss

DJp.2.19. Environmental dependence of AGN activity in the SDSS main galaxy sample
Minbae Kim; Youn-Young Choi; Sungsoo S. Kim

DJp.2.24. Exploring large-scale environment of SDSS DR7 quasars at 0.46Hyunmi Song; Changbom Park

FM14p.06. The link between galaxy mergers and single/double AGN: a statistical prospective from the SDSS
Xin Liu

P2.096. An efficient collaborative approach to quasars’ photometric redshift estimation based on SDSS and UKIDSS databases
Bo Han; Yanxia Zhang; Yongheng Zhao

S319p.01. SDSS J012247.34+121624, one of the most dramatic BALQSOs at redshift of 4.75 discovered by the Lijiang 2.4m Telescope
Weimin Yi

S320p.10. White dwarf + main sequence binaries identified from the data release of the Sloan Digital Sky Survey (SDSS)
Lifang Li
FM7p.06. Stellar mass of elliptical galaxies in the Sloan Digital Sky Survey
Chen-Hung Chen; Chung-Ming Ko

S319p.05. Variability of 188 broad absorption lines QSOs from the Sloan Digital Sky Survey
Weihao Bian

S319p.251. Redshift-Space Enhancement of Line-of-Sight Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Main-Galaxy Sample
Haijun Tian; Mark C. Neyrinck; Tamas Budavari; AlEXANDER SZALAY

Talks/Sessions:

 

Wed 5th
12.00pm: FM4.1.05 Hot evolved stars in massive galaxies
Claire Le Cras

Mon 10th
Voyage to Education with the Sloan Digital Sky Survey
Organizer(s): Karen Masters (University of Portsmouth), Kate Meredith (Yerkes)
8:30 AM – 2:00 PM; Room 327, Hawaii Convention Center

Thurs 13th
11.35am: FM7.5.05 Age derivation from UV absorption indices and the effect of the UV upturn.
Claire Le Cras

Mon 10th
Voyage to Education with the Sloan Digital Sky Survey
Organizer(s): Karen Masters (University of Portsmouth), Kate Meredith (Yerkes)
8:30 AM – 2:00 PM; Room 327, Hawaii Convention Center

2.30pm: S319.10.03. Extreme Red Quasars in SDSS-BOSS
Fred Hamann; Nadia Zakamska; Isabelle Paris; Hanna Herbst; Carolin Villforth; Rachael Alexandroff; Nicholas Ross; Jenny Greene; Michael Strauss

Fri 14th
10.55am FM17.7.02. Synergies of CoRoT asteroseismology and APOGEE spectroscopy — Applications to Galactic Archaeology
Friedrich Anders; Cristina Chiappini; Thaíse S. Rodrigues; Andrea Miglio; Josefina Montalbàn; Benoit Mosser; Leo Girardi; Marica Valentini; Matthias Steinmetz

12.00pm S319.12.06. Redshift evolution of massive galaxies from SDSS-III/BOSS
Daniel Thomas


 

If you are attending the IAU2015 we hope you have a great time, and we’ll see you on Social Media Karen Masters will be tweeting as @sdssurveys on #iau2015.

How SDSS Splits Light into a Rainbow for Science

All of the Sloan Digital Sky Surveys currently active (APOGEE, eBOSS, MaNGA, Spider and TDSS) are spectroscopic surveys. A spectroscope is a scientific instrument, which splits light into a rainbow (or spectrum) in order to make precise measurements of the amount of light of different colours (or wavelengths). To date the SDSS collaborations have used three different spectroscopes (the SDSS, BOSS and APOGEE instruments) to measure the rainbow of light from millions of stars and galaxies in our mission to map the Universe. Below is an image of one of these spectrographs.

 

boss_spectrograph

The BOSS Spectrograph. In centre the instrument is shown with optical fibres plugged into it. The diagrams at the side show the path of the light through the instrument after it passes down the fibre. Different parts are labelled.This instrument you have made has many similarities to the BOSS spectroscope shown above.

It is possible to make your own spectroscope using simple household materials and use it to measure the spectra of common light sources.  Here are instructions to build an SDSS CD Spectropscope. This instrument you can make has many similarities to the BOSS spectroscope shown above. For example:

  1. You will construct a slit through which the light will pass. In the diagram of the BOSS spectroscope this is labeled “slit-head”, and the light from the optical fibres is collected, “collimated” (i.e. lined up) and passes though it.
  2. You will use an old CD to make a grating (the BOSS spectroscope has 4 gratings; 2 on each side, and sandwiched between prisms to make a “grism”). A typical CD is made with 625 lines per mm. The the BOSS spectrograph has 520 and 400 lines/mm for the blue and red sides respectively.

Your spectroscope will be sensitive to all visible light. In the BOSS spectroscope a “dichroic” is used to split the light into red and blue before passing it through the gratings. A dichroic has a special property that it is reflective to blue light, while red light passes through it. This means the light can be spread out more, and special cameras can be used to detect light from near ultraviolet, right across the visible rainbow to the near infrared.

Instead of a camera you will use your eye (or you could try using a camera lined up with the viewing window). In the BOSS spectroscope there are four cameras (two for blue and two for red light) each kept specially cold in a “dewer”.

When the light passes through the slit it gets spread out a little bit, and then when it passes through the CD, the very fine slits in it (the diffraction grating) spread it out more. Different colours are spread out (or “dispersed”) by different amounts. The angle of dispersion is set by both the wavelength (colour) of the light, and the line spacing on the diffraction grating. The below image illustrates this (compared to refraction which can also create spectra; this is the physics which creates natural rainbows from refraction in raindrops). The diffraction angle increases with wavelength (and decreases with the line spacing).

Comparison of the spectra obtained from a diffraction grating by diffraction (1), and a prism by refraction (2). Longer wavelengths (red) are diffracted more, but refracted less than shorter wavelengths (violet).Credit: Wikimedia

Comparison of the spectra obtained from a diffraction grating by diffraction (1), and a prism by refraction (2). Longer wavelengths (red) are diffracted more, but refracted less than shorter wavelengths (violet).Credit: Wikimedia

Here are some examples of the kind of spectra you should be able to take with your CD spectroscope.

Example spectra through a CD spectroscope. Credit: CoolStuff Newsletter

Example spectra through a CD spectroscope. Credit: CoolStuff Newsletter

To make precise measurements we don’t tend to look at a pretty image of a rainbow, but instead make a graph which shows the brightness as a function of the wavelength (colour). An example of this is shown below which is a typical spectrum of a galaxy shown at five different distances (or redshifts).

redshift

The spectrum of a galaxy shown at five different distances (or redshifts), z=(0.0, 0.05, 0.10, 0.15, 0.20) corresponding to distances of (6, 12, 18 and 21 hundred million light years). Credit: SDSS Skyserver

If you do make an SDSS CD Spectroscope please take a picture (either of it or through it) and share it with us on Twitter or Facebook.


 

This post is part of the SDSS Celebration of the International Year of Light 2015, in which we aim to post an article a month about how SDSS uses light in our mission to study the Universe. 

Undergraduates use SDSS Data to Discover the Densest Galaxies Known

Two undergraduates at San José State University have used public SDSS data to discover two galaxies that are the densest known. Similar to ordinary globular star clusters but a hundred to a thousand times brighter, the new systems have properties intermediate in size and luminosity between galaxies and star clusters.

The first system discovered by the investigators, M59-UCD3, has a width two hundred times smaller than our own Milky Way Galaxy and a stellar density 10,000 times larger than that in the neighborhood of the Sun. For an observer in the core of M59-UCD3, the night sky would be a dazzling display, lit up by a million stars. The stellar density of the second system, M85-HCC1, is higher still: about a million times that of the Solar neighborhood. Both systems belong to the new class of galaxies known as ultracompact dwarfs (UCDs).

The study, led by undergraduates Michael Sandoval and Richard Vo, used imaging data from the Sloan Digital Sky Survey, the Subaru Telescope, and Hubble Space Telescope, as well as spectroscopy from the Goodman Spectrograph on the Southern Astrophysical Research Telescope (SOAR), located on the Cerro Tololo Inter-American Observatory site. The National Optical Astronomy Observatory (NOAO) is a SOAR partner. The SOAR spectrum was used to show that M59-UCD3 is associated with a larger host galaxy, M59, and to measure the age and elemental abundances of the galaxy’s stars.

Two ultra-dense galaxies (insets) have been discovered orbiting larger host galaxies. The compact systems are thought to be the remnants of once normal galaxies that were swallowed by the host, a process that removed the fluffy outer parts of the systems, leaving the dense centers behind. Image credit: A. Romanowsky (SJSU), Subaru, Hubble Legacy Archive

Two ultra-dense galaxies (insets) have been discovered orbiting larger host galaxies. The compact systems are thought to be the remnants of once normal galaxies that were swallowed by the host, a process that removed the fluffy outer parts of the systems, leaving the dense centers behind. Image credit: A. Romanowsky (SJSU), Subaru, Hubble Legacy Archive

 

 

“Ultracompact stellar systems like these are easy to find once you know what to look for. However, they were overlooked for decades because no one imagined such objects existed: they were hiding in plain sight”, said Richard Vo. “When we discovered one UCD serendipitously, we realized there must be others, and we set out to find them.”

The students were motivated by the idea that all it takes to initiate a discovery is a good idea, archival data, and dedication. The last element was critical, because the students worked on the project on their own time. Aaron Romanowsky, the faculty mentor and coauthor on the study, explained, “The combination of these elements and the use of national facilities for follow up spectroscopy is a great way to engage undergraduates in frontline astronomical research, especially for teaching universities like San José State that lack large research budgets and their own astronomical facilities.”

The nature and origins of UCDs are mysterious – are they the remnant nuclei of tidally stripped dwarf galaxies, merged stellar super-clusters, or genuine compact dwarf galaxies formed in the smallest peaks of primordial dark matter fluctuations?

Michael Sandoval favors the tidally stripped hypothesis. “One of the best clues is that some UCDs host overweight supermassive black holes. This suggests that UCDs were originally much bigger galaxies with normal supermassive black holes, whose fluffy outer parts were stripped away, leaving their dense centers behind. This is plausible because the known UCDs are found near massive galaxies that could have done the stripping.”

An additional line of evidence is the high abundance of heavy elements such as iron in UCDs. Because large galaxies are more efficient factories to make these metals, a high metal content may indicate that the galaxy used to be much larger.

To test this hypothesis, the team will investigate the motions of stars in the center of M59-UCD3 to look for a supermassive black hole. They are also on the hunt for more UCDs, to understand how commonly they occur and how diverse they are.

Reference:

“Hiding in plain sight: record-breaking compact stellar systems in the Sloan Digital Sky Survey,” Michael A. Sandoval, Richard P. Vo, Aaron J. Romanowsky et al. 2015, Astrophysical Journal Letters, 808, L32. (Preprint: http://arxiv.org/abs/1506.08828)


 

This post is copied from a press release from the National Optical Astronomy Observatory.

NOAO is operated by Association of Universities for Research in Astronomy Inc. (AURA) under a cooperative agreement with the National Science Foundation.

The SDSS 2015 Collaboration Meeting

This past week was the 2015 SDSS Collaboration Meeting, held at the Instituto de Física Teórica IFT UAM-CSIC in Madrid, Spain (jointly organized by the Instituto de Física Teórica IFT UAM-CSIC and the Instituto de Astrofísica de Canarias).

Members of the SDSS Collaboration outside the IFT in Madrid earlier this week.

Members of the SDSS Collaboration outside the IFT in Madrid earlier this week.

You can read this news item (en Espanol) about the meeting: El “Sloan” continúa su exploración del Universo, or see this collection of Tweets by SDSS members during the meeting: Storify of #sdss15.

Social Media from the SDSS Collaborating Meeting in Madrid

This week many of us are at the Instituto de Física Teórica IFT UAM-CSIC in Madrid, Spain for our 2015 collaboration meeting (jointly organized by the Instituto de Física Teórica IFT UAM-CSIC and the Instituto de Astrofísica de Canarias).

The meeting hashtag is #sdss15.

Our twitter account @sdssurveys will be run by spokesperson, Jennifer Johnson this week. We’ll also be tweeting from survey accounts @mangasurvey (Karen Masters and Anne-Marie Weijmans), @APOGEEsurvey (by Jennifer Sobeck this week) and @eBOSSurvey (Britt Lundgren and Shirley Ho).

Join the conversation and find out what’s going on with the SDSSurveys right now.

Discovering Supernova in SDSS Galaxy Spectra

The post below was contributed by Dr. Or Graur, an assistant research scientist at New York University and research associate at the American Museum of Natural History. He recently led a paper based on supernovae detected in SDSS galaxy spectra (published in the Monthly Notices of the Royal Astronomical Society; the full text is available at: http://adsabs.harvard.edu/abs/2015MNRAS.450..905G).

 paper_header

One of the great things about the SDSS is that it can be used in ways that its creators may never have envisioned. The SDSS collected ~800,000 galaxy spectra. As luck would have it, some of those galaxies happened to host supernovae, the explosions of stars, inside the area covered by the SDSS spectral fiber during the exposure time. These supernovae would then “contaminate” the galaxy spectra. In Graur & Maoz (2013), we developed a computer code that allowed us to identify such contaminated spectra and tweeze out the supernovae from the data. In Graur et al. (2015), we used this code to detect 91 Type Ia and 16 Type II supernovae.

 

GM13_method

A galaxy+supernova model (blue) fits the SDSS spectrum (grey) much better than a galaxy-only model (green). The residual spectrum (lower panel, grey), after subtracting the galaxy component, is best-fit by a Type Ia supernova template (red).

With these samples, we measured the explosion rates of Type Ia and Type II supernovae as a function of various galaxy properties: stellar mass, star-formation rate, and specific star-formation rate. All of these properties were previously measured by the SDSS MPA-JHU Galspec pipeline.

 

In 2011, the Lick Observatory Supernova Search published a curious finding: the rates of all supernovae, normalized by the stellar mass of their host galaxies, declined with increasing stellar mass (instead of being independent of it; Li et al. 2011b). We confirmed this correlation, showed that the rates were also correlated with other galaxy properties, and demostrated that all these correlations could be explained by two simple models.

 

Type Ia supernovae, which are thought to be the explosions of carbon-oxygen white dwarfs, follow a delay-time distribution. Unlike massive stars, which explode rather quickly after they are born (millions of years, typically), Type Ia supernovae take their time – some explode soon after their white dwarfs are formed, while others blow up billions of years later. We showed that this delay-time distribution (best described as a declining power law with an index of -1), coupled with galaxy downsizing (i.e., older galaxies tend to be more massive than younger ones), explained not only the correlation between the rates and the galaxies’ stellar masses, but also their correlations with other galaxy properties.

sim_mass_fit

Type Ia supernova rates as a function of galaxy stellar mass

sim_sSFR_fit

Type Ia supernova rates as a function of specific star formation rate.

Simulated rates, based on a model combining galaxy downsizing and the delay-time distribution, are shown as a grey curve on both the above plots. This model is fit to the rates as a function of mass and then re-binned and plotted on the specific star formation rate plot, without further fitting.

For Type II supernovae, which explode promptly after star formation, the correlations are easier to explain; they are simply dependent on the current star-formation rates of the galaxies: the more efficient the galaxy is at producing stars, the more efficient it will be at producing Type II supernovae.

All of the supernova spectra from Graur & Maoz (2013) and Graur et al. (2015) are publicly available from the Weizmann Interactive Supernova data REPository (http://wiserep.weizmann.ac.il/). Please note that their continuua may be warped by our detection method (for details, see section 3 of Graur & Maoz 2013).