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We present the first data release of the Survey on extragALactic magnetiSm with SOFIA (SALSA Legacy Program) with a set of 14 nearby ($, Comment: 43 pages, 28 figures. Accepted for publication to ApJ

We describe the data processing of the Survey on extragALactic magnetiSm with SOFIA (SALSA Legacy Program). This first data release presents 33% (51.34h out of 155.7h, including overheads) of the total awarded time taken from January 2020 to December 2021. Our observations were performed using the newly implemented on-the-fly mapping (OTFMAP) technique in the polarimetric mode. We present the pipeline steps to obtain homogeneously reduced high-level data products of polarimetric maps of galaxies for use in scientific analysis. Our approach has a general design and can be applied to sources smaller than the field-of-view of the HAWC+ array in any given band. We estimate that the OTFMAP polarimetric mode offers a reduction of observing overheads by a factor 2.34, and an improvement in sensitivity by a factor 1.80 when compared to previously obtained polarimetric observations using the chopping and nodding mode. The OTFMAP is a significant optimization of the polarimetric mode of HAWC+ as it ultimately reduces the cost of operations of SOFIA/HAWC+ by increasing the science collected per hour of observation up to an overall factor of 2.49. The OTFMAP polarimetric mode is the standard observing strategy of SALSA. The results and quantitative analysis of this first data release are presented in Papers IV and V of the series., Comment: 26 pages, 16 figures, 5 tables. Submitted to ApJ (Comments welcome)

We report on the neutral hydrogen gas content (21-cm emission) of eight extremely isolated early-type galaxies (IEGs) using the Green Bank Telescope. Emission is detected in seven of the eight objects. This paper is the third in a series that collectively present new HI observations for 20 IEGs. Among the 14 HI detections in our observations, eight exhibit a Gaussian-like HI line profile shape, four are double-peaked, one is triple-peaked, and another has a plateaued rectangular shape. Five additional IEGs observed in previous surveys were added to our analysis, bringing the total number of IEGs with HI observations to 25. Of these objects, emission is detected in 19 (76%). The 25 IEGs in our combined study have gas masses that are systematically larger than their luminosity-matched comparison galaxy counterparts. The isolated early-type galaxies presented here follow a trend of increasing gas-richness with bluer B-V colors. This correlation is also observed in a comparison sample drawn from the literature composed of loose group and field early-type galaxies. Two IEGs, KIG164 and KIG870, exhibit properties highly anomalous for spheroidal systems: luminous (M_B = -20.5, -20.1) and blue (B-V = 0.47, 0.48) respectively, with substantial neutral gas, M_HI = 4.1 & 5.5x10^9 M_(sun). Other IEG systems may represent early-type galaxies continuing to assemble via quiescent HI accretion from the cosmic web or relaxed merged systems., 11 pages; published in the Astronomical Journal

We have conducted a BVR imaging survey of nine early-type galaxies previously verified to exist in extremely isolated environments. Our goals are to establish a baseline of morphological and photometric properties for spheroidal systems evolving in extremely low-density environments and to compare these properties with signatures predicted for merged galaxy groups. We find that these isolated systems are underluminous by at least a magnitude compared with objects identified as merged group remnants in other studies. Image processing techniques sensitive to shell features produced no detections, a result in strong contrast to the high frequency of such structures found in other isolated elliptical galaxies. Two objects, KIG 164 and KIG 870, appear to be merger remnants, as indicated by their disturbed morphology, apparent tidal features, and blue colors. KIG 164 exhibits an asymmetric nuclear morphology and a low surface brightness "bridge" between it and a possible dwarf satellite. KIG 870 shows both fan-shaped emission at large radii and a possible double nucleus. Two other galaxies, KIG 412 and KIG 792, are also blue, but without any morphological peculiarities, suggesting that these systems are advanced mergers, older than KIG 164 and KIG 870. Two systems appear to be isolated lenticular galaxies with no evidence of a merger history. Based on their red colors, good fit to a R1/4-law light distribution, and the lack of morphological peculiarities, two other galaxies, KIG 557 and KIG 824, are found to be excellent candidates for passively evolving primordial elliptical galaxies formed early in cosmic time. Optical data were obtained with the 2.1 m Otto Struve telescope at McDonald Observatory, which is operated by the University of Texas at Austin.

We present the results of single-dish atomic hydrogen (H I) observations of six highly isolated early-type galaxies. These objects are a representative subset of galaxies previously studied at optical wavelengths and selected to be separated by at least 2.5Mpc from companions brighter than M(sub V) =−16.5 mag. Each galaxy was observed with a single pointing using the NRAO Green Bank Telescope L-band receiver. Five of these systems were strongly detected in H I. These five galaxies exhibit H I profiles with a range of properties: single Gaussian-like peaks, separate double peaks, and double horn-like profiles. The four bluest galaxies (B−V

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is the world’s largest airborne observatory, featuring a 2.5 meter effective aperture telescope housed in the aft section of a Boeing 747SP aircraft. SOFIA’s current instrument suite includes: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), a 5-40 μm dual band imager/grism spectrometer developed at Cornell University; HIPO (High-speed Imaging Photometer for Occultations), a 0.3-1.1μm imager built by Lowell Observatory; GREAT (German Receiver for Astronomy at Terahertz Frequencies), a multichannel heterodyne spectrometer from 60-240 μm, developed by a consortium led by the Max Planck Institute for Radio Astronomy; FLITECAM (First Light Infrared Test Experiment CAMera), a 1-5 μm wide-field imager/grism spectrometer developed at UCLA; FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), a 42-200 μm IFU grating spectrograph completed by University Stuttgart; and EXES (Echelon-Cross-Echelle Spectrograph), a 5-28 μm highresolution spectrometer designed at the University of Texas and being completed by UC Davis and NASA Ames Research Center. HAWC+ (High-resolution Airborne Wideband Camera) is a 50-240 μm imager that was originally developed at the University of Chicago as a first-generation instrument (HAWC), and is being upgraded at JPL to add polarimetry and new detectors developed at Goddard Space Flight Center (GSFC). SOFIA will continually update its instrument suite with new instrumentation, technology demonstration experiments and upgrades to the existing instrument suite. This paper details the current instrument capabilities and status, as well as the plans for future instrumentation.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities are viewed as a first comprehensive assessment of the Observatory's performance and are used to guide future development activities, as well as to identify additional Observatory upgrades. Pointing stability was evaluated, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an active mass damper system installed on the telescope. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have also been performed. Additional tests targeted basic Observatory capabilities and requirements, including pointing accuracy, chopper evaluation and imager sensitivity. This paper reports on the data collected during these flights and presents current SOFIA Observatory performance and characterization., Comment: 13 pages, 13 figure, and 2 tables; accepted by ApJS

Using V-band imagery, we present results from a comparative density analysis of the local environments surrounding nine elliptical galaxies, with the objective of validating that these objects reside in extremely isolated environments. We have developed a technique that compares galaxy number density enhancements within well-studied clusters and loose groups with apparent clusterings of faint, predominantly uncataloged galaxies that are present in the fields of the isolated elliptical galaxy (IEG) candidates. The unique feature of this technique is the ability to combine size information of density peaks with number density values in order to place upper or lower limits on the distances of an apparent clustered structure in an IEG field. The utility of this technique is that probable physical association between an IEG and a clustered structure can be refuted without need of redshift information for the faint field sources. Of the nine IEG candidates studied, we conclude that one of the galaxies has possible membership with a loose group of Local Group density. Four other IEG candidates have environments that show density enhancements in the field that are possible loose groups with densities similar to the Leo or Dorado groups, but physical association with the IEGs is unlikely. The remaining four galaxies have environments that are confirmed to be isolated down to the detection limits that are detailed in the paper.

M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging Telescope (FUV-band), Hubble Space Telescope (NUV-band), Kitt Peak 0.9-m telescope (H-alpha, R, and I bands), and Palomar 5-m telescope (B-band), along with spectra from the International Ultraviolet Explorer and Lick 1-m telescopes. The wide-field UIT image shows FUV emission from (a) an elongated nucleus, (b) a diffuse inner disk, where H-alpha is observed in absorption, (c) a bright inner ring of H II regions at the perimeter of the inner disk (R = 48 arcsec. = 1.1 kpc), and (d) two 500-pc size knots of hot stars exterior to the ring on diametrically opposite sides of the nucleus (R= 130 arcsec. = 2.9 kpc). The HST/FOC image resolves the NUV emission from the nuclear region into a bright core and a faint 20 arcsec. long ``mini-bar'' at a position angle of 30 deg. Optical and IUE spectroscopy of the nucleus and diffuse inner disk indicates an approximately 10^7 or 10^8 yr-old stellar population from low-level starbirth activity blended with some LINER activity. Analysis of the H-alpha, FUV, NUV, B, R, and I-band emission along with other observed tracers of stars and gas in M94 indicates that most of the star formation is being orchestrated via ring-bar dynamics involving the nuclear mini-bar, inner ring, oval disk, and outer ring. The inner starburst ring and bi-symmetric knots at intermediate radius, in particular, argue for bar-mediated resonances as the primary drivers of evolution in M94 at the present epoch. Similar processes may be governing the evolution of the ``core-dominated'' galaxies that have been observed at high redshift. The gravitationally-lensed ``Pretzel Galaxy'' (0024+1654) at a redshift of approximately 1.5 provides an important precedent in this regard., revised figure 1 (corrected coordinate labels on declination axis); 19 pages of text + 19 figures (jpg files); accepted for publication in AJ

We present wide-field, imagery and photometry of 43 selected nearby galaxies of all morphology types at ultraviolet and optical wavelengths. The ultraviolet images, in two broad bands at 1500 Angstroms and 2500 Angstroms, were obtained by the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission. The UV images have approx. 3" resolution, and the comparison sets of ground-based, CCD images (in one or more of B, V, R, and H alpha ) have pixel scales and fields of view closely matching the UV frames. The atlas consists of multiband images together with plots of UV/optical radial surface brightnesses, colors and other associated photometric parameters such as half-light radii. In an appendix, we discuss the sensitivity of different wavebands to a galaxy's star formation history in the form of "history weighting functions" and the importance of UV observations as probes of evolution during the past 10-1000 Myr. We find that UV galaxy morphologies are usually significantly different from visible band morphologies as a consequence of spatially inhomogeneous stellar populations. Differences are quite pronounced for systems in the middle range of Hubble types, Sa through Sc, but less so for ellipticals or late-type disks. Normal ellipticals and large spiral bulges are fainter and more compact in the UV. They typically exhibit smooth and unresolved far-UV profiles with, however, far-UV/optical color gradients which are larger than any at optical/IR wavelengths. The far-UV light in these cases is probably produced by extreme horizontal branch stars and their descendants in the dominant, low-mass, metal-rich population.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne observatory, carrying a 2.5 m telescope onboard a heavily modified Boeing 747SP aircraft. SOFIA is optimized for operation at infrared wavelengths, much of which is obscured for ground-based observatories by atmospheric water vapor. The SOFIA science instrument complement consists of seven instruments: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), GREAT (German Receiver for Astronomy at Terahertz Frequencies), HIPO (High-speed Imaging Photometer for Occultations), FLITECAM (First Light Infrared Test Experiment CAMera), FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), EXES (Echelon-Cross-Echelle Spectrograph), and HAWC (High-resolution Airborne Wideband Camera). FORCAST is a 5–40 μm imager with grism spectroscopy, developed at Cornell University. GREAT is a heterodyne spectrometer providing high-resolution spectroscopy in several bands from 60–240 μm, developed at the Max Planck Institute for Radio Astronomy. HIPO is a 0.3–1.1 μm imager, developed at Lowell Observatory. FLITECAM is a 1–5 μm wide-field imager with grism spectroscopy, developed at UCLA. FIFI-LS is a 42–210 μm integral field imaging grating spectrometer, developed at the University of Stuttgart. EXES is a 5–28 μm high-resolution spectrograph, developed at UC Davis and NASA ARC. HAWC is a 50–240 μm imager, developed at the University of Chicago, and undergoing an upgrade at JPL to add polarimetry capability and substantially larger GSFC detectors. We describe the capabilities, performance, and status of each instrument, highlighting science results obtained using FORCAST, GREAT, and HIPO during SOFIA Early Science observations conducted in 2011.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities have been viewed as a first comprehensive assessment of the Observatory's performance and will be used to address the development activity that is planned for 2012, as well as to identify additional Observatory upgrades. A series of 8 SOFIA Characterization And Integration (SCAI) flights have been conducted from June to December 2011. The HIPO science instrument in conjunction with the DSI Super Fast Diagnostic Camera (SFDC) have been used to evaluate pointing stability, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an Active Mass Damper system installed on Telescope Assembly. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have been performed using the HIPO+FLITECAM Science Instrument configuration (FLIPO). A number of additional tests and measurements have targeted basic Observatory capabilities and requirements including, but not limited to, pointing accuracy, chopper evaluation and imager sensitivity. SCAI activities included in-flight partial Science Instrument commissioning prior to the use of the instruments as measuring engines. This paper reports on the data collected during the SCAI flights and presents current SOFIA Observatory performance and characterization.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, is an airborne observatory with a 2.7-m telescope that is under development by NASA and the German Aerospace Center DLR. From late 2010 and through the end of 2011, SOFIA conducted a series of science demonstration flights, Early Science, using FORCAST (the Faint Object InfraRed Camera for the SOFIA Telescope), HIPO (the High-speed Imaging Photometer for Occultations), and GREAT (the German REceiver for Astronomy at Terahertz frequencies). Flying at altitudes as high as 13.7 km (45,000 ft), SOFIA operates above more than 99.8% of the water vapor in the Earth’s atmosphere, opening up most of the far-infrared and sub-millimeter parts of the spectrum. During Early Science, 30 science missions were flown with results in solar system astronomy, star formation, the interstellar medium, the Galactic Center, and extragalactic studies. Many of these investigations were conducted by the first group of SOFIA General Investigators, demonstrating the operation of SOFIA as a facility for the astronomical community. This paper presents some recent highlights from Early Science.

The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint U.S./German project, is a 2.5-meter infrared airborne telescope carried by a Boeing 747-SP that flies in the stratosphere at altitudes as high as 45,000 feet (13.72 km). This facility is capable of observing from 0.3 {\mu}m to 1.6 mm with an average transmission greater than 80 percent. SOFIA will be staged out of the NASA Dryden Flight Research Center aircraft operations facility at Palmdale, CA. The SOFIA Science Mission Operations (SMO) will be located at NASA Ames Research Center, Moffett Field, CA. First science flights began in 2010 and a full operations schedule of up to one hundred 8 to 10 hour flights per year will be reached by 2014. The observatory is expected to operate until the mid 2030's. SOFIAs initial complement of seven focal plane instruments includes broadband imagers, moderate-resolution spectrographs that will resolve broad features due to dust and large molecules, and high-resolution spectrometers capable of studying the kinematics of atomic and molecular gas at sub-km/s resolution. We describe the SOFIA facility and outline the opportunities for observations by the general scientific community and for future instrumentation development. The operational characteristics of the SOFIA first-generation instruments are summarized. The status of the flight test program is discussed and we show First Light images obtained at wavelengths from 5.4 to 37 \"im with the FORCAST imaging camera. Additional information about SOFIA is available at http://www.sofia.usra.edu and http://www.sofia.usra.edu/Science/docs/SofiaScienceVision051809-1.pdf, Comment: 35 pages, 17 figures

We have undertaken an imaging survey of 34 nearby galaxies in far-ultraviolet (FUV, ~1500A) and optical (UBVRI) passbands to characterize galaxy morphology as a function of wavelength. This sample, which includes a range of classical Hubble types from elliptical to irregular with emphasis on spirals at low inclination angle, provides a valuable database for comparison with images of high-z galaxies whose FUV light is redshifted into the optical and near- infrared bands. Ultraviolet data are from the UIT Astro-2 mission. We present images and surface brightness profiles for each galaxy, and we discuss the wavelength-dependence of morphology for different Hubble types in the context of understanding high-z objects. In general, the dominance of young stars in the FUV produces the patchy appearance of a morphological type later than that inferred from optical images. Prominent rings and circumnuclear star formation regions are clearly evident in FUV images of spirals, while bulges, bars, and old, red stellar disks are faint to invisible at these short wavelengths. However, the magnitude of the change in apparent morphology ranges from dramatic in early--type spirals with prominent optical bulges to slight in late-type spirals and irregulars, in which young stars dominate both the UV and optical emission. Starburst galaxies with centrally concentrated, symmetric bursts display an apparent ``E/S0'' structure in the FUV, while starbursts associated with rings or mergers produce a peculiar morphology. We briefly discuss the inadequacy of the optically-defined Hubble sequence to describe FUV galaxy images and estimate morphological k-corrections, and we suggest some directions for future research with this dataset., Accepted for publication in the ApJS. 15 pages, 17 JPEG figures, 10 GIF figures. Paper and full resolution figures available at http://nedwww.ipac.caltech.edu/level5/Kuchinski/frames.html

The Ultraviolet Imaging Telescope (UIT) has returned the first significant sample of ultraviolet imagery of galaxies combining a large field-of-view and spatial resolution comparable to ground-based observatories. During the Astro Spacelab missions, UIT obtained spatially-resolved far-UV (λλ 1500 A) imagery of ∼35 disk galaxies. We have utilized the FUV light profiles and morphology to characterize the high-mass stellar populations in these systems. A variety of radial light profiles are found, including two systems, NGC 4214 and NGC 3310, which exhibit R1/4 profiles produced by their Population I stellar components.

During the Astro-1 Spacelab missions, the Ultraviolet Imaging Telescope (UIT) obtained spatially-resolved far (λ∼1500 A) and mid-UV (λ∼2500 A) imagery of ∼25 nearby galaxies. The sample spans the Hubble sequence including ellipticals, disk systems and irregular galaxies. These images have a resolution of ∼3 ′′ , a limiting surface brightness, μ 1500 ≈25 mags arcsec −2 , and cover the full angular extent of each system, many of which have angular diameters exceeding 5 ′ . The UIT data permit determination of both global FUV properties with improved photometric precision, and detailed investigation of galaxian morphology at intermediate (spiral arms, nuclear rings), and small (star-forming complexes) scales. We are constructing datasets which combine the UV imagery obtained by UIT with associated optical (UBVRI,Hα) and near-IR (JHK) images of comparable depth and spatial resolution obtained at ground-based telescopes. Our primary goal is to provide a morphological Atlas of Galaxies extending from the far-ultraviolet (λ∼1500 A) to near-infrared (λ∼2.2μ) wavelengths. The Astro-1/UIT Atlas contains registered and flux-calibrated images at FUV, NUV, R and Hα bandpasses for galaxies which are spatially resolved, surface brightness profiles, and integrated magnitudes (or upper limits) for the entire sample.

Deep high-resolution imaging of galaxies at high-redshift has revealed a remarkable diversity of emission structures in the restframe ultraviolet. To better understand these remote and primeval realms, it is important to compare them with UV-emitting counterparts in the local universe. As part of two Spacelab/Astro missions, the Ultraviolet Imaging Telescope (UIT) has obtained wide-field (40-arcmin), well-resolved (3 arcsec) images of ∼50 nearby galaxies in the vacuum ultraviolet. Followup groundbased imaging at UBVRI and Hα bands has been completed for most of the well-resolved galaxies. Analysis of a small subset of these galaxies has revealed strong variations in the emission morphologies as a function of restframe wavelength. In the present study, we compare the UV morphologies of barred and unbarred spiral galaxies as a function of Hubble type and absolute luminosity. Radial extents are measured relative to their visible counterparts, and characteristic UV emission structures are identified (e.g. rin...

We describe the properties of a sample of extremely isolated early-type galaxies (IEGs) selected from the spectroscopic Sloan Digital Sky Survey. Sample galaxies are isolated from nearest neighbors more luminous than MV = ?16.5 by a minimum distance corresponding to 2.5?Mpc and 350?km?s?1 in redshift space. The candidate IEGs exhibit a number of unusual features as compared to bulge-dominated galaxies in cluster and group environments, including fainter luminosities, blue colors suggesting possible recent star formation, and smaller physical sizes. The paper is the first in a series analyzing this isolated galaxy sample.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne observatory consisting of a specially modified Boeing 747SP with a 2.7-m telescope, flying at altitudes as high as 13.7 km (45,000 ft). Designed to observe at wavelengths from 0.3 micron to 1.6 mm, SOFIA operates above 99.8 % of the water vapor that obscures much of the infrared and submillimeter. SOFIA has seven science instruments under development, including an occultation photometer, near-, mid-, and far-infrared cameras, infrared spectrometers, and heterodyne receivers. SOFIA, a joint project between NASA and the German Aerospace Center DLR, began initial science flights in 2010 December, and has conducted 30 science flights in the subsequent year. During this early science period three instruments have flown: the mid-infrared camera FORCAST, the heterodyne spectrometer GREAT, and the occultation photometer HIPO. This article provides an overview of the observatory and its early performance., Comment: 7 pages, 4 figures; Accepted for publication by the Astrophysical Journal Letters

A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case between the DB white dwarfs with nearly pure helium atmospheres and the helium-rich DQ white dwarfs which exhibit carbon bands. Corrected for an inferred pressure shift Vp = + 38 + or - 4 km/s for the C I 2479 line, a gravitational redshift of Vrs = + 26 + or - 13 km/s is deduced from which a most probable mass of 0.55 solar mass is derived.

We look for correlated changes in stellar mass and star formation rate along filaments in the cosmic web by examining the stellar masses and UV-derived star formation rates (SFR) of 1,799 ungrouped and unpaired spiral galaxies that reside in filaments. We devise multiple distance metrics to characterise the complex geometry of filaments, and find that galaxies closer to the cylindrical centre of a filament have higher stellar masses than their counterparts near the periphery of filaments, on the edges of voids. In addition, these peripheral spiral galaxies have higher specific star formation rates (SSFR) at a given mass. Complementing our sample of filament spiral galaxies with spiral galaxies in tendrils and voids, we find that the average SFR of these objects in different large scale environments are similar to each other with the primary discriminant in SFR being stellar mass, in line with previous works. However, the distributions of SFRs are found to vary with large-scale environment. Our results thus suggest a model in which in addition to stellar mass as the primary discriminant, the large-scale environment is imprinted in the SFR as a second order effect. Furthermore, our detailed results for filament galaxies suggest a model in which gas accretion from voids onto filaments is primarily in an orthogonal direction. Overall, we find our results to be in line with theoretical expectations of the thermodynamic properties of the intergalactic medium in different large-scale environments., 16 pages, 15 figures (including one 3D figure that can be interacted with when reading the PDF in Adobe Reader). Accepted for publication in MNRAS on January 13th, 2016