Last week (Nov 3-5) 45 astronomers from the SDSS-III BOSS collaboration met at Princeton University to talk about the latest results from observing quasars. These extraordinarily luminous objects are powered by black holes feeding on gas in distant galaxies. Quasars are helping to tell us about the formation of galaxies in the early Universe and how the elements formed in stars are distributed in and around galaxies up to the present day.

The astronomers kindly paused in their contemplations to pose for the group picture above (photo credit: Keren Fedida).

Popular Science Magazine picks SDSS as one of the world’s ten “most amazing” databases:

http://www.popsci.com/technology/article/2011-10/amazing-databases-sloan-digital-sky-survey-database

and shows how much our view of the Universe has changed in the last 60 years due to the data from SDSS and other large-scale astronomical surveys:

http://www.popsci.com/content/visible-universe-then-and-now

The Discovery Channel’s Daily Planet followed the APOGEE team as they installed the APOGEE camera on the SDSS telescope and first used the system to detect light from stars in the Milky Way. The very first spectroscopic images clearly reveal the different elements that make up these stars and start telling the story of how generations of stars in our galaxy created the elements that make our Solar System and life itself possible.

http://watch.discoverychannel.ca/#clip525876

Michael Strauss (Princeton) just reported some really impressive statistics for SDSS. There are now over 4000 refereed papers with “SDSS” or “Sloan Survey” in their abstract or title.

To astronomical accuracy, that’s about one paper per day since the telescope saw first light in 1998 . These papers have been cited over 150,000 times (154,997, to be precise). The York et al. (2000) technical paper describing the SDSS has over 3000 citations itself.

The h-index of the survey is 159: that is, there are 159 papers with 159 or more citations (and 316 papers with more than 100 citations). The g-index is 288; i.e., the average number of citations of the 288 most cited papers is 288. Thus far in 2011, there are 486 papers published, and the year is not even complete.

To compare with some other major facilities:

* IRAS (launched in 1983) has 5822 papers, 187,377 citations, and h=158

* WMAP (launched in 2001) has 1855 papers, 93,097 citations, and h=123

* HST (launched in 1990) has 9460 papers, 329,920 citations, and h=190

Here is the ADS query that were used for the SDSS statistics

These queries are not exact; there are no doubt important papers that are missed, and some other papers that are included that are not really proper matches; for example, one of the most highly cited “SDSS” papers is the Becker et al. (1995) paper, describing the FIRST survey, which only makes reference to the SDSS footprint on the sky.

Daniel Eisenstein (SDSS-III Director) just reported that the SDSS-III collaboration has over 600 active scientists involved in accessing and analysing SDSS data (as counted by their wiki-page accounts). These scientists come from the 50 worldwide institutions now involved in SDSS-III, as well as approved external participants, collaborators and contractors. This proves that the SDSS-III is one of the largest collaborations in Astronomy.

A new movie created by David Kirkby (UC Irvine) shows the three-dimensional distribution of the Lyman-alpha “forest” (in blue) that appears in front of each of the 70,000 high-redshift quasars (yellow) in the preliminary BOSS DR9 sample. Only that portion of the forest where Lyman-alpha absorption is visible to the BOSS spectrograph is shown. Transparent spheres at redshifts of 2, 3 and 4 set the radial scale. Some of the gaps in the DR9 coverage will be filled in over the final years of the BOSS survey. The DR9 Lyman-alpha sample consists of about 32 million “pixels” of co-added spectral data, and almost 100 billion pixel pairs with 3D separations less than 200 Megaparsecs. The large volume sampled in DR9 offers an unprecedented map of the cosmological distribution of matter during an important earlier epoch in the interplay between dark matter and dark energy.

We show a frame of the movie here but you can get the movie at http://darkmatter.ps.uci.edu/lya-dr9/

SDSS-III scientists are working hard in Nashville. Eyal Kazin (NYU) grabs some rest during the banquet before starting work again. Photo by Stephen Bailey.

The 2011 SDSS-III collaboration meeting is being held at Vanderbilt University in Nashville. Over 3 days (Aug 12-15th), over 100 scientists are discussing their new results and achievements. Below is a group photograph.

A critical question for the SDSS-III BOSS is what kinds of galaxies are they observing. In a recent paper by Masters et al., SDSS-III scientists used additional, higher resolution data from the Hubble Space Telescope (HST) to answer this questions.

In SDSS images, BOSS galaxies, which are on average about 6 billion light years away, just looks like fuzzy red blobs. The goal of BOSS is to observe 1.5 million of them over 30% of the sky in order to map the large scale structure in great detail. For this study, they took a look at a tiny subset of 230 of them which have deeper HST images (which were taken as part of the COSMOS project – the largest area HST survey every yet done).

The study found that 75% of BOSS galaxies are massive ellipticals, but that a surprisingly high fraction (20%) of these are split into multiple components in the HST images. The remaining 25% of BOSS galaxies are massive spirals.

The image below shows an example of one of the spirals and one of the ellipticals shown in both the SDSS and HST image.

As well as the paper, you can look at a poster about this work which was presented both at the AAS in Boston in May, and also at the recent Galaxy Formation conference in Durham

Finally if you want to browse all the images yourself they are available at www.icg.port.ac.uk/~mastersk/BOSSmorphologies/

The commissioning of APOGEE is now in full swing as the team works out the capabilities of the new spectrograph. Quite remarkably, because APOGEE is an infra-red spectrograph, it can operate perfectly well in relatively bright observing conditions compared to the more traditional optical instruments used previously by SDSS. As shown below, APOGEE can take observations of the bulge component of our Galaxy in full moon and over the lights of nearby El Paso.

The APOGEE team below in the SDSS telescope control room during the first light observations in May 2011.

We would like to alert our users of large astrometry errors that we have identified in the SDSS Data Release 8 photometric catalog.  In particular, the regions not covered by UCAC2 (north of around 41 deg declination) the DR8 astrometry is offset 240 mas to the North and 50 mas to the West. The declination offset is nearly uniform in the affected area (at an rms level of about 60 mas).  Users trying to perform proper motion analysis, detailed astrometry, or performing spectroscopic observations should be aware of these shifts. A full description of our understanding of the errors and quality assessment plots can now be found in our  description of the DR8 astrometry.

These problems are currently being addressed and we plan to add supplemental tables with correct astrometry to the DR8 release. We will incorporate the new astrometry as the default for the DR9 data release.

An erratum has been prepared for submission to the Astrophysical Journal to correct the Data Release 8 paper’s statements on this issue.

In January, the SDSS collaboration released Data Release 8, including a much larger area of sky, with photometric data for nearly 500 million sky objects, and spectra for more than 1.5 million.

As always, data from all previous releases is still available also. New this week is the ability to cross-match sky objects between Data Release 7 and Data Release 8. If you have object IDs and parameters for a specific object from DR7, you can query for the same object in DR8.

The cross-matching is available three different ways:

SpecDR7: This is a unique match between a DR8 SpecObjAll and a DR7 photoprimary within 1 arcsec. DR7 PhotoTag columns and relevant DR7 ProperMotions are also included for convenience.

PhotoPrimaryDR7: This is a unique match between a DR8 photoprimary and a DR7 photoprimary, and matches between different run/camcol/field are allowed. The match radius is 1 arcsec. The table contains the DR8 and DR7 objids, the distance between them and the DR7 PhotoTag quantities.
PhotoObjDR7: This is a unique match between a DR8 photoobj and a DR7 photoobj, and matches are restricted to the same run/camcol/field are allowed. The match radius is 1 arcsec, and within this radius preference is given to a photoprimary match over a secondary. If no primary match exists, the nearestsecondary match is chosen. If more than one match of a given mode exists, the nearest one is chosen. The table contains the DR8 and DR7 objids and modes, the distance between them, and the DR7 phototag quantities.

I have just returned from the four-day visit to the April meeting of the APS (American Physical Society) – a big meeting where physicists from many field come together, share the scientific news, take political stances and discuss the evolution of the profession. I was presenting our latest results on the three-dimensional Lyman-alpha forest and did so twice: on Sunday morning to the press and on Sunday afternoon to the scientists.

In the morning press conference me and two other hopefuls were showing our results to some fifteen journalists. It is an interesting exercise as you try to make your science appear as interesting and exciting as possible, while at the same time avoid making it neither too unintelligible nor overly dumbed down. Ultimately, the biggest problem is that what makes scientists tick is not what makes a good story. Although they looked suspiciously sleepy to me while I was waving my hands vigorously, we did a good job as you can read via Google News .

The afternoon talk was given to a bunch of physicists, which, however, were not astronomers. This was hard in a different way: I had to make a valid scientific argument about why what we did is interesting and important to an audience who understand physics, but are not experts in the cosmology. I had a good impression, but alas, one cannot browse the web to see what impact did I impress onto those guys and gals.

Words by Anže Slozar , lead author on the recent analysis of the lyman-alpha forest clustering seen in the quasar spectra from BOSS. Anže presented his results to both the press and fellow physicists, and the SDSS-III press release can be found on the main SDSS-III website

If you want to see more of Anže, then check out his youtube video

On April 25th, the APOGEE spectrograph arrived at Apache Point Observatory, ready for installation in the SDSS buildings and in preparation for first astronomical light. We provide below some photos of the arrival.

Above: Outside the 2.5m SDSS telescope being prepared for lowering into the SDSS-III spectrograph room.

Above: Don’t drop it!

Above: Finally inside!

Photos by Gretchen Van Doren

On Friday April 22nd 2012, the APOGEE spectrograph left its integration lab at the University of Virginia and was loaded onto a truck headed to Apache Point Observatory in New Mexico for installation and commissioning in the coming weeks. We provide here a photo blog of that process.

Below: The APOGEE team carefully guides the several ton instrument out of the integration lab. The cryostat is resting on a specially designed shipping palette including several means of shock absorption. On top of the cryostat are the reels holding the three hundred, 40-meter long fiber optic links that will eventually connect the spectrograph to the Sloan 2.5-m telescope. Team members pictured from left to right: Paul Maseman, Eric Walker, Steve Majewski, David Nidever and Fred Hearty.

Below: University of Virginia Dept. of Astronomy chair, John Hawley, looks over the proceedings. Visible is the optical fiber feedthrough end of the spectrograph.

Below: The APOGEE spectrograph positioned at the loading dock.

Below: Loading and lifting the APOGEE spectrograph with the frontloader. The fiber optic feedthrough and grating end of the spectrograph is that farthest away from the frontloader, while the collimator end is closest.

Below: Loading the APOGEE instrument onto the air-ride truck.

Below: Project manager Fred Hearty directs loading of the truck with the APOGEE spectrograph and other palettes of ancillary gear.

Below: Signing over responsibility of moving APOGEE to the “custom critical” shipping company, and wishing the drivers a safe trip!

Below: Mixed emotions after a long and exciting week…

Congratulations to the APOGEE instrument team for an amazing job! And thanks to all of SDSS-III for the incredible support.

Below: Some of the local APOGEE team members involved with APOGEE loading day activities standing in front of the instrument poised for shipping: (left to right) Ana Garcia-Perez, Eric Walker, Adam Burton, Matt Nelson, Fred Hearty, Charles Lam, Paul Maseman, Steve Majewski, David Nidever. At the time of all of this moving activity at UVa, APOGEE Instrument Scientist John WIlson was in Baltimore busily making last measurements and adjustments to several APOGEE optical elements with the Johns Hopkins University team (Robert Barkhouser and Stephen Smee); these last elements of the instrument were shipped out on Saturday. Also missing from the photo are Jim Barr, Janice Dean and Lihong Yao, as well as Mike Skrutskie, head of the UVa instrument lab, who, on top of providing experienced help loading up the APOGEE hardware for shipment, had also to duck out to teach a class!

(All photos by Guillermo Damke.)