The Arecibo Galactic Environments Survey (AGES) http://www.naic.edu/~ages/

Report to the skeptical review panel August 1st 2008

Introduction The Arecibo Galactic Environments Survey (AGES) is a proposal to use the Arecibo telescope with its multi-beam instrument ALFA to survey nearby galactic environments and the volumes behind them. The intention of the survey is to reach lower noise levels than ALFALFA and therefore to search for lower mass and lower column density HI objects. We drift scan across the sky with a goal of completing 25 scans across each point, equivalent to a 300s integration. For direct comparison with the ALFALFA survey we have smoothed our data to their spatial and velocity resolution and this gives typically a rms noise level of 0.75 mJy for AGES, compared to the ALFALFA published value of 2.2 mJy. ALFALFA, although covering a larger area is no deeper than previous ‘blind’ Arecibo extra-galactic surveys, while AGES pushes beyond the sensitivity of the previous deepest blind HI surveys. The proposed total sky coverage is 200 sq deg. The original proposal was for 2000 hours with targets spread across the RA range. The proposal was submitted in February 2005 but the start was delayed until late December 2005. It is important to recognize that the E-ALFA collaboration agreed at their meetings that a coordinated strategy was needed to explore the extragalactic Universe at 21cm. That strategy called for three different survey depths, following the classic ‘wedding cake’ design. ALFALFA is the large area shallow survey that will improve on the small number statistics of previous surveys. AGES is the middle level sensitivity survey, which will explore new parameter space at greater sensitivity than previous surveys, but will cover less area. Finally, AUDS will explore much greater depths over a very small area. To date AGES has been allocated about 500 hours of observing time in total; about one quarter of that originally requested. In the period covered by this review, 1st August 2007 to 1st August 2008, AGES was scheduled for 226 hours of telescope time most of which has been quite recent (since January) due to telescope painting. We request a minimum of 500 hours over the next year so that the survey can be completed over a reasonable period of time (hopefully within the next 3 years).

Technical issues We now routinely observe remotely from Cardiff, Socorro, Green Bank and University of Massachusetts. We have spent a considerable amount of time developing our data reduction pipeline, assessing data quality (Fig 1), testing source detection methods and quantifying completeness and reliability. During the precursor run (described in a previous report) we showed that we could successfully reduce noise levels by the expected factor of t1/2 by keeping the array at fixed azimuth and elevation while the sky drifts overhead. In order to account for the change in parallactic angle, and thus achieve uniform sky coverage, ALFA is rotated before every scan - all of this is now fully automated in software and is very easy for the observer to use (see http://www.naic.edu/~ages/a2048/AGES_guide.html). In order to attain fully sampled sky coverage each scan is staggered by half the beam separation. With this observing set up every beam covers the same patch of sky averaging out gain variations between beams and reducing the impact of side-lobe contamination. We have adapted the HIPASS software (LIVEDATA and GRIDZILLA) so that it operates on the Arecibo CIMAFITS file format. LIVEDATA performs bandpass estimation (using various user specified algorithms) and removal, Doppler tracking and calibrates and smooths (if required) the residual spectrum. GRIDZILLA is a gridding package that co-adds all the spectra letting the user have full control over beam selection, polarizations, frequency range and image and pixel size. For the AGES datacubes we chose 1 arc min pixels and 5 km/s channels and ALL of the reduced data cubes are publicly available in this format at http://www.naic.edu/~ages/public_data.html. We are currently experimenting with other ways of fitting the bandpass and combining scans to try and extract more extended features (Minchin et al., 2008, Taylor et al. 2008 – NGC7332 and Virgo cluster data) , in the future we intend to make available cubes reduced in different, but well documented ways.

Analysis of continuum sources in the NGC 7332 data (Minchin et al. 2007) has shown that the post-processing AGES beam is very close to circular with sidelobes at around the 5% level in the expected position. Deconvolving the beam will be necessary for science objective 8 (below) – investigating the low column-density extent of large . However this is not necessary for the other objectives of AGES and, with only two large galaxies in the currently completed datasets (NGC 1156 and NGC 7339), the scientific return does not currently justify devoting a large amount of team-members time to this problem at the moment.

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Fig. 1 Comparison (A1367 field) of the HI fluxes (left) and velocity widths (right) measured by AGES, L- wide and past literature. Filled circles indicate the 22 sources confirmed during L-wide follow-up observations, empty circles show the 18 galaxies already known from the literature. The dotted lines indicate the one to one correlation.

One of the challenges facing the extragalactic HI surveys is developing a method for detecting galaxies that is both well defined and complete. To achieve this goal we have been experimenting with different detection methods. Currently we search each data cube by eye (independently by two people) and also use two automated finders (POLYFIND) developed by Davies and Minchin and DUCHAMP developed by Matthew Whiting in Australia. We have also obtained follow up observations of low signal to noise detections to check on the reliability of our methods. In Fig. 2, as an example, we show the peak signal to noise of sources plotted against their W20 velocity width. In Auld (2007) we show that this is the best plane to carry out the selection cut (dashed line Fig. 2) giving us 75% reliability to 4σ.

Fig 2: Reliability selection criteria for 265 detections from the NGC 1156, Abell 1367 and NGC 628 regions. Black represents detections that have either been followed up or strong signals confirmed by 3 independent methods. Red represents sources that were not confirmed by follow up observations. represent sources that were detected by all three methods, circles by two methods and triangles by one method. Marked on the plot are reliability contours empirically derived from the data.

2 Current status The originally proposed survey fields are shown in Fig. 3.

Fig. 3. The originally proposed survey fields are marked in blue. Those that have been completed have been circled in red.

Current field status is:

Field Status NGC7332 5 sq deg requested and completed Virgo2 5 sq deg requested and completed A1367 20 sq deg requested 5 sq deg completed NGC1156 5 sq deg requested and completed NGC628 Precursor field completed Voids Not started NGC7448 20 sq deg requested 5 sq deg completed Virgo1 20 sq deg requested 5 sq deg completed and 5 sq deg to two thirds depth Leo1 Not started NGC3193 20 sq deg requested, one complete scan completed NGC2577 Not started M33 Not started UGC2082 Not started

Our total observed area to full depth amounts to 30 sq deg or just 15% of the total area request in the original proposal and only 10 sq deg more than at this time last year.1

Survey Science The scientific goals of the survey as given in the original proposal are listed below: 1. The HI mass function in different environments - around large galaxies, in groups, clusters and beyond the Local Supercluster - comparison with evolution models. 2. Given the excellent correlation between -formation-rate and 20cm continuum emission, we will use the continuum emission to measure the star formation rates of a large number of galaxies selected by their gaseous rather than their optical or far infrared properties. 3. The contribution of neutral gas to the baryonic mass density - the 'missing' baryonic matter problem. 4. The nature of and possible link between HVCs and dwarf galaxies - a possible solution of the CDM sub-structure problem ? 5. The identification of gaseous tidal features as signatures of galaxy interactions and mergers - the importance of mergers as a mechanism for the assembly of galaxies, gas removal mechanisms in clusters and groups. 6. The velocity dispersions of galaxies in groups and clusters - dark matter. 7. The dynamical masses of galaxies - galaxy rotation curves - dark matter. 8. The low-column-density extent of large galaxies - ionisation by the metagalactic radiation field. 9. The identification of isolated neutral gas clouds - remnants or precursors of the galaxy formation process ? 10. A comparison of the atomic hydrogen detected by QSO-absorption-line and 21cm observations - consistency between different observations that measure the same thing. 11. The spatial distribution of HI selected galaxies. 12. A comparison with numerical models of galaxy formation - providing input and tests of the simulations.

1 Note both Virgo1 and NGC193 have incomplete scan data. 3 13. Serendipitous findings - with a survey like this, covering large areas to low mass-limits and column-densities, we might hope to make new and unexpected discoveries.

In the rest of this section we will discuss science results not yet published. These are somewhat limited compared to last year as by far the majority of the observations have been obtained since January (due to telescope painting), a number of scans are incomplete and the Virgo fields are part of Rhys Taylor’s PHD project.

1. The isolated galaxy pair NGC7332 and NGC7339 AGES observations in July and August 2006 targeted the AGESGAL7332 region, with the NGC 7332/NGC 7339 galaxy pair in the foreground at a distance of 23 Mpc (Tonry et al. 2001). NGC 7332 is an S0 galaxy and NGC 7339 an Sa. Both of these galaxies have been previously observed at 21-cm. While NGC 7339 has been clearly observed, there is debate about whether there is HI in NGC 7332 with Knapp, Kerr and Williams (1978) claiming a detection and Haynes (1981) and others seeing nothing at its position. The AGES observations covered an area of 2.5 × 2 square degrees and reached a noise level of around 0.75 mJy after Hanning smoothing to a velocity width of 10 km/s. 56 HI sources were detected, of which 40 are entirely new detections, 10 are catalogued galaxies without previous , and only 6 are previously catalogued galaxies with redshifts in the literature (mostly from Springob et al. 2005). For most of the sources, possible optical counterparts have been identified on the Digitized Sky Survey, although for four sources only dubious associations have been possible and for one source no counterpart could be found. Follow-up is required to confirm 16 of the sources, which is currently ongoing (this could not be carried out in 2007 due to the painting project). Once this is completed, the catalogue will be published and made available via the VO.

Fig 4 The candidate AGES J2237+2253: DSS2 B band image (left) of a 6′ × 6′ region showing the HI position and the beam diameter. The HI spectrum is shown on the right.

The AGES observations find neutral hydrogen at the position of NGC 7332. However, this is clearly connected spatially and in velocity with the extended gas disc around NGC 7339 and is at a higher velocity (1300 km/s, in agreement with the Knapp et al. detection) than the optical velocity of NGC 7332 (1170 km/s; Simien & Prugniel 1997). This gas is almost certainly associated with NGC 7339 rather than NGC 7332.

The HI disc of NGC 7339 appears disturbed both morphologically and kinematically. This is almost certainly due to an interaction with NGC 7332 which is affecting the HI but not the optical disc. The total HI flux of NGC7339, measured off a cube optimised to give correct fluxes for extended sources, is ~ 11 Jy km/s. This is consistent with the Springob et al. (2005) result of 10.62 Jy km/s and gives (using the RC3 value of B_T(0) = 12.08) MHI/LB B = 0.12

M☉/L☉. This is unremarkable for an Sa galaxy.

In the immediate neighbourhood of NGC 7332 and NGC 7339, two new sources have been discovered. These are 7 7 AGES J2246+2342, with an HI mass of 6.7 × 10 M☉, and AGES J2238+2351, with an HI mass of 5.1 × 10 M☉. No HI connection can be seen between these galaxies and the galaxy pair. Karachentseva, et al., (1999) also identified two possible dwarf spheroidal galaxy, KKR 72 and KKR 73, as being potentially associated with the NGC 7332/NGC 7339 galaxy pair on the basis of their morphology. A re-examination of the plates by Karachentsev, carried out as part of the AGES study of this area, revealed a further possible dwarf spheroidal. We 7 place a limit on the HI mass of these objects of 10 MO, an order of magnitude lower than Huchtmeier et al. (2000), but still not reaching the levels likely to be necessary to detect a dSph galaxy. No other HI emission can be seen at

4 their locations within the AGES range (out to ~18,000 km/s).

The NGC7332 group now has 4 definite members, plus three possible dwarf spheroidals with unconfirmed 7 redshifts. Three of the galaxies contain >10 M☉ of HI and are thus detectable by our survey. The Renzo diagram of this group is shown in Fig 10. The two new HI-rich dwarfs and the disturbed disc of NGC7339 can be clearly seen.

Fig 5. Renzo diagram of the NGC7332 group overlaid on a DSS2 B band image. The colour contours represent the 5σ level in an individual channel, with the colour representing the velocity (red - lower, blue – upper). The two new sources lie to the west and east of NGC7339. It can also be seen that the contours around NGC 7339 are stretched to the north-east and cover the position of NGC 7332.

Beyond NGC 7332, the AGES survey gives clues to the large scale structure in this region. There appears to be a void beyond the group, with only 1 source being found between here and 7000 km/s (100 Mpc for H0 = 70). This is identified by Fairall as the Delphinus Void (2000 - 2999 km/s), Cygnus Void (3000 - 3999 km/s) and the Pegasus Void (4000 - 6999 km/s). At ~8,900 km/s (127 Mpc), there is an arc of 6 galaxies across 1.5 degrees of sky (3.5 Mpc), with a seventh slightly off the arc, all within 300 km/s. At ~16,800 km/s (240 Mpc), there are 3 galaxies, all within a radius from the centre of their triangle of 15 arc minutes (1 Mpc) over a velocity range of 400 km/s.

The volume beyond NGC 7332 also threw up the very high HI mass source AGES J2240+2441. This source, at a 10 velocity of 12800 km/s (183 Mpc) has an HI mass of 3.3 x 10 M☉ and a velocity width (at 20% of peak) of 485 km/s, this galaxy was not previously catalogued. Comparing the HI mass with the HICAT values from Zwaan et al. (2005), this is 5 times more massive than the an M*HI galaxy and is in the top 0.5% of galaxy masses found in HIPASS (23/4315 have log (MHI) > 10.5; log(M*HI) = 9.80). This galaxy does not have any photometric optical data, but measurements from 2MASS give H=12.44 giving an H-band luminosity (which is a good proxy for the 10 stellar mass) of 8.4 x 10 L☉ and MHI/LH = 0.4 M☉/L☉. From the DSS and 2MASS images, the galaxy appears to be close to edge-on and to be slightly disturbed. We have carried out VLA observations of this galaxy and are currently analysing the results.

2. The Virgo cluster – an update on thesis work The VC2 region

This region spans 5 square degrees, observed to full depth in Janurary-Februrary 2007. The region extends from the periphery of the cluster to its interior. 49 HI sources were detected though only 13 are cluster members (v < 3000 5 km/s). We have compared our source catalogue for this region with ALFALFA. While the greater depth of AGES means we have approximately twice as many detections overall, almost all of these detection are in the background. This perhaps indicates that very low mass HI objects do not exist in this region of the cluster. In all other respects (e.g. measured velocity widths, total HI flux etc.) measurements made by the two surveys are in very good agreement.

Despite this low detection rate we are able to discern some trends. For example, the HI population within the cluster appears spatially and in velocity disjoint from the optically selected sample indicating that the two populations are different, suggesting that sub-cluster A is not relaxed. Furthermore there seems to be some evidence that higher redshift galaxies (but still cluster members) are bluer than those at low red shift.

No early-type galaxies in Virgo are detected, with the arguable exception of the VCC2062/2066 pair which has a (previously known) HI tail. Stacking of 15 early-types with redshifts was attempted, but no detection was made. All detections are late-type and include all the late-types galaxies in this region (from the VCC). Many of the detections 10 are HI deficient with the total HI deficiency of galaxies in this region being ~10 Msolar. However no intra-cluster streams are detected. Stacking of the intracluster medium was used to reach column densities ~1017 atoms/cm3 but no detection was made. An automated algorithm has been developed to stack multiple areas to reduce the effects of a low filling factor, but no detections resulted.

There are no dark galaxies. Candidates (all in the background) have been found to be spurious with follow-up observations. One cluster member has MHI/LB B ratio of ~10. The MHI/LB B ratio varies as a function of MB B (fig. 6) and with this in mind the object appears extreme only because of its faint optical luminosity. It is also apparent that brighter objects have much lower MHI/LB B ratios.

Fig 6 . HI mass to light ratio against absolute magnitude for objects detected in the VC2 region

In the process of analysing the optical characteristics of the HI detections, we have made a serendipitous discovery of a cluster member elliptical galaxy with a stellar tail (VCC2000) with no HI detection, and a one tailed elliptical 10 in the background with an HI detection (VCC2041). Additionally we have detected an HI-massive (1.3x10 Msolar) galaxy in the background (v ~ 18000 km/s) showing signs of morphological disturbance in the optical and HI.

This data set has been searched by our usual source extraction procedures and we have also attempted to reduce the need for follow-up by gridding the two polarisations of ALFA separately. A spin-off from this is the development of a new automatic extractor that uses the combined cube and the separate polarisations. Tests so far indicate that this is more complete than both by eye and other automatic extractors and has a much lower rate of spurious sources compared to POLYFIND, and does not struggle in regions of a higher noise level as DUCHAMP does.

The VC1 region This is a preliminary analysis from the cube reduced earlier in the year with a little over 5 square degrees to approximately ALFALFA depth. The cube is currently being gridded to full depth over 5 square degrees and we 6 have another cube to 2/3 depth over an adjacent 5 square degrees. In total 76 objects are detected, of which 34 are Virgo cluster members. This is more than twice as many per square degree as in VC2 (consistent with the number of optically selected galaxies present) – this appears to be a much more HI rich area of the cluster.

Spatially and in velocity the HI detections follow the distribution of the optical galaxies, in contrast to VC2. Galaxies in this region appear to be distributed in 2 distinct populations when viewed in position-velocity space. There is also a suggestion of bimodality of HI deficiency.

Fig 7. A comparison of the HI deficiency of galaxies in the Virgo cluster regions.

The MHI/LB B relation is very scattered, but bright objects do appear to have lower values compared to the background sample.

Fig 8. The environmental effect on the HI mass to light ratio.

In contrast to VC2, in VC1 some dwarf ellipticals are detected (these are new HI detections), but not every late-type VCC cluster member is detected (but we do need to look at the full depth cube). Several galaxies are detected that are definitely Virgo cluster members but do not appear in the VCC, despite being brighter than the completeness magnitude. Finally, there are also some candidate dark galaxies in the background, as well as high velocity clouds, but a more detailed analysis is required to determine if these really are HI detections without optical counterparts.

6. Inferences from the whole sample – We have put the current whole sample together to make some very ‘tentative’ first estimates of global parameters (Auld, 2007). In Fig. 9 we show the HI mass function derived for the sample compared to other recent determinations. The last data point is not included in the fit as we have only one object of this mass (lack of sufficient area coverage). The best fit gives the following parameters for the Schechter -3 9 function; α=-1.3, Φ=0.008 Mpc and M*=7.7x10 Mo. The current data agrees well with the HIPASS data and

7 eventually we should be able to extent the mass function to masses an order of magnitude lower than HIPASS to see if there is the sharp up turn controversially found by the Arecibo Slice Survey of Schneider et al., (1998). Splitting the sample into field and cluster (Abell 1367) there is a hint that the cluster HI mass function is less steep at the faint end than in the field, as might be expected due to the gas loss mechanisms that cluster galaxies may experience, this again needs to be confirmed when we have better statistics. Integrating the mass function gives an 7 -3 atomic hydrogen mass density of ≈8x10 Mo Mpc . This is consistent with other measures, but towards the high end. This value leads to ΩHI≈0.0004 which is about 2% of the cosmic baryon budget.

Fig 9. The HI mass function derived from the first three datacubes (NGC 628, NGC 1156 and Abell 1367). The solid line is that of the AGES data. The dashed line is that of the Arecibo Dual Beam Survey (Rosenberg & Schneider, 2002). The dotted line is from the HIPASS data (Zwaan et al. 2003). The dash-dot line is from the Arecibo HI Sky Survey (Zwaan et al. 1997). The last bin was not included in the derivation of the parameters since there is only one object in this mass bin.

Follow up observations Optical imaging for 6 out of the 14 AGES fields is available from the Sloan Digital Sky Survey (Data Release 6). For the other fields we are carrying out optical follow up of the HI sources detected using 2m class telescopes. 2MASS JHK imaging is available for all the fields and UKIDSS-LAS JHK imaging for the VC1 and VC2 fields. GALEX FUV and NUV imaging has been obtained for great part of VC1, N6555 and VC2. Hα follow up for part of the VC1, VC2 and A1367 fields is under way. 21cm follow up has been carried out at Arecibo and the GBT.

Availability through the Virtual Observatory (VO) As announced in our report last year, we had our first AGES public release on Novembeer 2007. This includes 124 HI sources, i.e. all the data so far published in refereed journals. The data archive is based on a MySQL database, following the basic requirements of the VO: i.e. the data products are available in VO-Table format and the database can be accessed through a Simple Cone Search Query using the VO tools. We also provide one dimensional spectra for all the sources detected in the AGES cubes. The database can be accessed easily from the web (http://www.astro.cf.ac.uk/pub/Luca.Cortese/ages/database/public/query_simple.html). In addition it is fully registered into the NVO registry and it can be automatically queried using the various NVO tools (e.g. Datascope, Aladin, etc...). Finally, we have activated a contact with the IPAC/NASA Extragalactic Database (NED) (Barry Madore & Olga Pevunova) in order to make all the AGES spectra available from NED.

Synergy with the Square Kilometer Array (SKA) Auld is both an AGES consortium member and employed as a PDRA to work on the science exploitation of the SKA. The AGES survey has approximately the same sensitivity that a ‘quick look’ SKA (a few seconds) all sky survey may have which could be one of the first projects to be carried out. We have been using AGES data as an input for an SKA simulator of the HI sky. Stated goals for SKA at 21cm are the evolution of atomic hydrogen and the delineation of the large scale structure of the Universe. The AGES is specifically designed to quantify how the evolution of atomic hydrogen is different in different environments in the local Universe and we are already seeing how large scale structure is described very differently for galaxies selected at 21cm compared to those selected 8 optically.

Publication resulting from the AGES survey Auld et al., 2006, MNRAS, 371, 161 – ‘The Arecibo Galaxies Environment Survey: precursor observations of the NGC628 Group’. Auld, PhD thesis University of Cardiff,, 2007, ‘A search for dark galaxies through the AGES’. Cortese et al., 2007, IAUS, 235, 196 – ‘AGES observations of Abell1367 and its outskirts’. Cortese, 2008, In the proceedings of IAU symposium 244 ‘Dark Galaxies and Lost Baryons’, pub Cambridge University press, p. 350 – ‘AGES observations of the Abell cluster 1367 and its outskirts’. Cortese et al., 2008, MNRAS, 383, 1519 - ‘AGES: II A HI view of the nearby cluster A1367 and its outskirts’ Cortese, 2008, In the proceedings of ‘The Evolution of Galaxies through the neutral hydrogen window’, AIP conf proc, (astroph://0803.4061) – ‘Neutral Hydrogen and Star-Formation in the Coma-A1367 Supercluster’. Minchin et al., 2006, AAS, 208, 5306 – ‘First Results from the Arecibo Galaxies Environment Survey’. Minchin et al. , 2006, AAS, 209, 95.03 – ‘A Neutral Hydrogen Survey of the NGC7332 Region with the Arecibo L-band Feed Array’. Minchin et al., 2007, AAS, 210, 81.02 – ‘Neutral Hydrogen in the the Arecibo Galaxy Environmet Survey Volume behind NGC7332’. Minchin et al., 2007, IAUS, 235, 227 – ‘Arecibo Galaxies Environment Survey – description of the survey and early results’. Minchin, 2008, In the proceedings of IAU symposium 244 ‘Dark Galaxies and Lost Baryons’, pub Cambridge University press, p. 112 – ‘Arecibo Galaxy Environments Survey – Potential for finding Dark Galaxies’. Minchin et al., 2008, in "Galaxy Evolution through the Neutral Hydrogen Window", AIP Conf. Ser. 1035, eds. R. Minchin & E. Momjian, publ. AIP, New York, p. 235, "Investigating the Effect of Environment on Neutral Hydrogen Content and Morphology: the Arecibo Galaxy Environment Survey." Minchin et al., 2007, in "The Modern Radio Universe 2007", publ. Proceedings of Science, Trieste, Italy, #027, "The Arecibo Galaxy Environment Survey: A sensitive survey for neutral hydrogen in the local Universe." Ojalvo et al., 2006, AAS, 209, 78.10 – ‘Arecibo Observatory and the national Virtual Observatory’. Taylor, 2008, In the proceedings of IAU symposium 244 ‘Dark Galaxies and Lost Baryons’, pub Cambridge University press – ‘Searching for Dark Galaxies: the AGES VC2 Region’..

The AGES Consortium Davies J. (Cardiff University, UK), Auld R. (Cardiff University, UK), Baes M. (University of Ghent, Belgium), Boselli A. (Lab. Astrophysique Marseille, France), Bothun G. (University of Oregon, USA), Brosch N. (Wise Observatory, Isreal), Brinks E. (University of Hertfordshire, UK), Catinella B. (MPA, Germany), Cortese L. (Cardiff University, UK), Disney M. (Cardiff University, UK), de Blok E. (University of Cape Town, South Africa), Gavazzi G. (University of Milan, Italy), Giovanelli R. (Cornell University, USA), Haynes M. (Cornell University, USA), Henning P. (University of New Mexico, USA), Hoffman L. (Lafayette, USA), Irwin J. (Queens University, Canada), Karachentsev I. (Moscow University, Russia), Kilborn V. (University of Melbourne, Australia), Koribalski B. (ATNF, Australia), Linder S. (Munich University, Germany), Minchin R. (NAIC Arecibo, USA), Momjian E. (NAIC Arecibo, USA), Muller E. (ATNF, Australia), O'Neil K. (NRAO Greenbank, USA), Putman M. (University of Michigan, USA), Rosenberg J. (George Mason University, USA), Sabatini S. (Rome Observatory, Italy), Schneider S. (University of Massachusetts, USA), Spekkens K. (Cornell University, USA), Taylor R. (Cardiff University, UK), van Driel W. (Meudon, France).

The consortium is a diverse group of astronomers from a wide range of institutions all over the world. These institutions include small colleges like Lafayette and mid-sized research departments like George Mason University as well as larger research institutions and observatories. More than one third of the astronomers involved are female.

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