Antonio Marin-Franch

The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters without Previous Hubble Space Telescope Photometry

We present the first results of a large Advanced Camera for Surveys (ACS) survey of Galactic globular clusters. This Hubble Space Telescope (HST) Treasury project is designed to obtain photometry with S/N (signal-to-noise ratio) 10 for main-sequence stars with masses 0.2 M⊙ in a sample of globulars using the ACS Wide Field Channel. Here we focus on clusters without previous HST imaging data. These include NGC 5466, NGC 6779, NGC 5053, NGC 6144, Palomar 2, E3, Lynga 7, Palomar 1, and NGC 6366. Our color-magnitude diagrams (CMDs) extend reliably from the horizontal branch to as much as 7 mag fainter than the main-sequence turnoff and represent the deepest CMDs published to date for these clusters. Using fiducial sequences for three standard clusters (M92, NGC 6752, and 47 Tuc) with well-known metallicities and distances, we perform main-sequence fitting on the target clusters in order to obtain estimates of their distances and reddenings. These comparisons, along with fitting the cluster main sequences to theoretical isochrones, yield ages for the target clusters. We find that the majority of the clusters have ages that are consistent with the standard clusters at their metallicities. The exceptions are E3, which appears ~2 Gyr younger than 47 Tuc, and Pal 1, which could be as much as 8 Gyr younger than 47 Tuc.

The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy

As part of the ACS Survey of Galactic Globular Clusters, we present new Hubble Space Telescope photometry of the massive globular cluster M54 (NGC 6715) and the superposed core of the tidally disrupted Sagittarius (Sgr) dSph galaxy. Our deep (F606W ~ 26.5), high-precision photometry yields an unprecedentedly detailed color-magnitude diagram showing the extended blue horizontal branch and multiple main sequences of the M54+Sgr system. The distance and reddening to M54 are revised using both isochrone and main-sequence fitting to (m - M)0 = 17.27 and E(B - V) = 0.15. Preliminary assessment finds the M54+Sgr field to be dominated by the old metal-poor populations of Sgr and the globular cluster. Multiple turnoffs indicate the presence of at least two intermediate-aged star formation epochs with 4 and 6 Gyr ages and [Fe/H] = -0.4 to -0.6. We also clearly show, for the first time, a prominent, ~2.3 Gyr old Sgr population of near-solar abundance. A trace population of even younger (~0.1-0.8 Gyr old), more metal-rich ([Fe/H] ~ 0.6) stars is also indicated. The Sgr age-metallicity relation is consistent with a closed-box model and multiple (4-5) star formation bursts over the entire life of the satellite, including the time since Sgr began disrupting.

JPCAM: A 1.2 GPIXEL CAMERA FOR THE J-PAS SURVEY

JPCam is a 14-CCD mosaic camera, using the new e2v 9k-by-9k 10microm-pixel 16-channel detectors, to be deployed on a dedicated 2.55m wide-field telescope at the OAJ (Observatorio Astrofisico de Javalambre) in Aragon, Spain. The camera is designed to perform a Baryon Acoustic Oscillations (BAO) survey of the northern sky. The J-PAS survey strategy will use 54 relatively narrow-band (~13.8nm) filters equi-spaced between 370 and 920nm plus 3 broad-band filters to achieve unprecedented photometric red-shift accuracies for faint galaxies over ~8000 square degrees of sky. The cryostat, detector mosaic and read electronics is being supplied by e2v under contract to J-PAS while the mechanical structure, housing the shutter and filter assembly, is being designed and constructed by a Brazilian consortium led by INPE (Instituto Nacional de Pesquisas Espaciais). Four sets of 14 filters are placed in the ambient environment, just above the dewar window but directly in line with the detectors, leading to a mosaic having ~10mm gaps between each CCD. The massive 500mm aperture shutter is expected to be supplied by the Argelander-Institut fur Astronomie, Bonn. We will present an overview of JPCam, from the filter configuration through to the CCD mosaic camera. A brief outline of the main J-PAS science projects will be included.

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini

Stephen Eikenberry, Reba Bandyopadhyay, J. Greg Bennett, Aaron Bessoff, Matt Branch, Miguel Charcos, Richard Corley, Curtis Dewitt, John-David Eriksen, Richard Elston, Skip Frommeyer, Anthony Gonzalez, Kevin Hanna, Michael Herlevich, David Hon, Jeff Julian, Roger Julian, Nestor Lasso, Antonio Marin-Franch, Jose Marti, Charlie Murphey, S. Nicholas Raines, William Rambold, David Rashkin, Craig Warner Department of Astronomy, University of Florida, Gainesville, FL 32611

Surface-brightness fluctuations in stellar populations IAC-star models for the optical and near-IR wavelengths

Aims. A new theoretical calibration of surface-brightness fluctuations (SBF) for single age, single metallicity stellar populations is presented for the optical and near-IR broad-band filters, as well as for the HST WFPC2 and ACS filters. Methods. The IAC-star code is used. Two Padua and the Teramo stellar evolution libraries have been considered. A set of single-burst stellar populations (SSP) with a wide range of ages (3 Gy−15 Gy) and metallicities (Z = 0.0001−0.03) have been computed using each one of the three considered stellar evolution libraries. For each SSP, color indexes and SBF magnitudes are given for the filters U, B, V, R, I, J, H, K, F218W, F336W, F439W, F450W, F555W and F814W, and for the first time, an uncertainty has been estimated for the SBF theoretical calibration. Results. Although some differences might be addressed, the Padua and Teramo stellar evolution libraries provide comparable SBF results. A detailed comparison of the present SBF calibrations with both previous calibrations and observational data is also presented. Comparing the different models with observational data, Padua based models reproduce fairly well the optical data for globular clusters, while Teramo based models fits both optical galaxies and globular clusters data, as well. In the near-IR wavelengths, the Teramo based models provide the only SBF theoretical calibration to date able to properly reproduce the observational data for superclusters, with intermediate-to-low metallicity. As a conclusion, Teramo based models work better than any other calibration reproducing observational data for the near-IR wavelengths. Furthermore, the age-metallicity degeneracy is broken for low metallicity (Z ≤ 0.0037) stellar populations. Finally, a clear relation between the B SBF absolute magnitude of a stellar population and its metallicity is found for intermediate to old populations, so the B-band fluctuation magnitude is proposed as a metallicity tracer. The present theoretical calibration shows that the analysis of SBF provides a very powerful tool in the study and characterization of unresolved stellar populations.

Extracting Hα flux from photometric data in the J-PLUS survey

Aims. We present the main steps that will be taken to extract H emission flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric data. Methods. For galaxies with z . 0:015, the H +[Nii] emission is covered by the J-PLUS narrow-band filter F660. We explore three di erent methods to extract the H + [Nii] flux from J-PLUS photometric data: a combination of a broad-band and a narrow-band filter (r 0 and F660), two broad-band and a narrow-band one (r 0 , i 0 and F660), and a SED-fitting based method using 8 photometric points. To test these methodologies, we simulated J-PLUS data from a sample of 7511 SDSS spectra with measured H flux. Based on the same sample, we derive two empirical relations to correct the derived H +[Nii] flux from dust extinction and [Nii] contamination. Results. We find that the only unbiased method is the SED fitting based one. The combination of two filters underestimates the measurements of the H + [Nii] flux by a 28%, while the three filters method by a 9%. We study the error budget of the SED-fitting based method and find that, in addition to the photometric error, our measurements have a systematic uncertainty of a 4.3%. Several sources contribute to this uncertainty: di erences between our measurement procedure and the one used to derive the spectroscopic values, the use of simple stellar populations as templates, and the intrinsic errors of the spectra, which were not taken into account. Apart from that, the empirical corrections for dust extinction and [Nii] contamination add an extra uncertainty of 14%. Conclusions. Given the J-PLUS photometric system, the best methodology to extract H + [Nii] flux is the SED-fitting based one. Using this method, we are able to recover reliable H fluxes for thousands of nearby galaxies in a robust and homogeneous way. Moreover, each stage of the process (emission line flux, dust extinction correction, and [Nii] decontamination) can be decoupled and improved in the future. This method ensures reliable H measurements for many studies of galaxy evolution, from the local star formation rate density, to 2D studies in spatially well resolved galaxies or the study of environmental e ects, up to mr0 = 21:8 (AB; 3 detection of H +[Nii] emission).

The Canarias Infrared Camera Experiment (CIRCE): optical and opto-mechanical design and manufacture

We report on the design status of the Canarias InfraRed Camera Experiment (CIRCE), a near-infrared visitor instrument for the 10.4 meter Gran Telescopio Canarias (GTC). In addition to functioning as a 1-2.5 micron imager, CIRCE will have the capacity for narrow-band imaging, low-and moderate- resolution grism spectroscopy, and imaging polarimetry. CIRCEs all-reflective aspheric optical design offers excellent throughput and image quality. We present an analysis of the optical layout and the progress of the opto-mechanical design and manufacture.

An accurate cluster selection function for the J-PAS narrow-band wide-field survey

The impending Javalambre Physics of the accelerating Universe Astrophysical Survey (J-PAS) will be the first wide-field survey of ≳ 8500 deg^2 to reach the ‘stage IV’ category. Because of the redshift resolution afforded by 54 narrow-band filters, J-PAS is particularly suitable for cluster detection in the range z 80 per cent completeness and purity is M_h ∼ 5 × 10^(13) M_⊙ up to z ∼ 0.7. We also model the optical observable, M^∗_(CL)–halo mass relation, finding a non-evolution with redshift and main scatter of σM^∗_(CL)|M_h∼0.14dex down to a factor 2 lower in mass than other planned broad-band stage IV surveys, at least. For the M_h ∼ 1 × 10^(14) M_⊙ Planck mass limit, J-PAS will arrive up to z ∼ 0.85 with a σM^∗_(CL)|M_h∼0.12dex. Therefore, J-PAS will provide the largest sample of clusters and groups up to z ∼ 0.8 with a mass calibration accuracy comparable to X-ray data.

THE ACS survey of globular clusters. Xiii. Photometric calibration in comparison with stetson standards

In this study we compare the photometric data of 34 Milky Way globular clusters, observed within the Advanced Camera for Surveys (ACS) Treasury Program (PI: A. Sarajedini) with the corresponding ground-based data, provided by the Photometric Standard Field Catalogs of Stetson. We focus on the transformation between the Hubble Space Telescope/ACS F606W to V-band and F814W to I-band only. The goal is to assess the validity of the filter transformation equations by Sirianni et al. with respect to their dependence on metallicity, horizontal branch morphology, mass, and integrated (V – I) color of the various globular clusters. The transformation equations as recommended by Sirianni et al. are based on synthetic photometry, were mostly tested on NGC 2419, and may introduce additional uncertainties when applied to different stellar populations. Such a dependence is expected due to the fact that the transformation equations are based on the observations of only one globular cluster, i.e., NGC 2419. Surprisingly, the correlation between offset and metallicity is found to be weak, with a low level significance. The correlation between offset and horizontal branch structure, as well as total cluster mass is still weaker. Based on the available data we do not find the photometric offset to be linked to multiple stellar populations, e.g., as found in NGC 0288, NGC 1851, and NGC 5139. The results of this study show that there are small systematic offsets between the transformed ACS- and observed ground-based photometry, and that these are only weakly correlated, if at all, with various cluster parameters and their underlying stellar populations. As a result, investigators wishing to transform globular cluster photometry from the Sirianni et al. ground-based V, I system onto the Stetson system simply need to add –0.040 (±0.012) to the V magnitudes and –0.047 (±0.011) to the I magnitudes. This in turn means that the transformed ACS V – I colors match the ground-based values from Stetson to within ~0.01 mag.

The Observatorio Astrofísico de Javalambre: current status, developments, operations and strategies

The Observatorio Astrofísico de Javalambre (OAJ) is a new Spanish astronomical facility particularly designed for carrying out large sky surveys. The OAJ is mainly motivated by the development of J-PAS, the Javalambre- PAU Astrophysical Survey, an unprecedented astronomical survey that aims to observe 8500 deg2 of the sky with a set of 54 optical contiguous narrow-band filters (FWHM ~14 nm) and 5 mid and broad-band ones. J-PAS will provide a low resolution spectrum (R ~ 50) for every pixel of the Northern sky down to AB~22:5 - 23:5 per square arcsecond (at 5 σ level), depending on the narrow-band filter, and ~ 2 magnitudes deeper for the redder broad-band filters. The main telescope at the OAJ is the Javalambre Survey Telescope (JST/T250), an innovative Ritchey-Chrétien, alt-azimuthal, large-etendue telescope with a primary mirror diameter of 2.55m and 3 deg (diameter) FoV. The JST/T250 is the telescope devoted to conduct J-PAS with JPCam, a panoramic camera of 4.7 deg2 FoV and a mosaic of 14 large format CCDs that, overall, amounts to 1.2 Gpix. The second largest telescope at the OAJ is the Javalambre Auxiliary Survey Telescope (JAST/T80), a Ritchey-Chrétien, German-equatorial telescope of 82 cm primary mirror and 2 deg FoV, whose main goal is to perform J-PLUS, the Javalambre Photometric Local Universe Survey. J-PLUS will cover the same sky area of J-PAS using the panoramic camera T80Cam with 12 filters in the optical range, which are specifically defined to perform the photometric calibration of J-PAS. The OAJ project officially started in mid 2010. Four years later, the OAJ is mostly completed and the first OAJ operations have already started. The civil work and engineering installations are finished, including the telescope buildings and the domes. JAST/T80 is at the OAJ undertaking commissioning tasks, and JST/T250 is in AIV phase at the OAJ. Related astronomical subsystems like the seeing and atmospheric extinction monitors and the all-sky camera are fully operative. This paper aims to present a brief description and status of the OAJ main installations, telescopes and cameras. The current development and operation plan of the OAJ in terms of staffing organization, resources, observation scheduling, and data archiving, is also described.