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We introduce a new, open-source, Python module for the acquisition and processing of archival data from many X-ray telescopes - Democratising Archival X-ray Astronomy (hereafter referred to as DAXA). Our software is built to increase access to, and use of, large archives of X-ray astronomy data; providing a unified, easy-to-use, Python interface to the disparate archives and processing tools. We provide this interface for the majority of X-ray telescopes launched within the last 30 years. This module enables much greater access to X-ray data for non-specialists, while preserving low-level control of processing for X-ray experts. It is useful for identifying relevant observations of a single object of interest but it excels at creating multi-mission datasets for serendipitous or targeted studies of large samples of X-ray emitting objects. The management and organization of datasets is also made easier; DAXA archives can be version controlled and updated if new data become available. Once relevant observations are identified, the raw data can be downloaded (and optionally processed) through DAXA, or pre-processed event lists, images, and exposure maps can be downloaded if they are available. X-ray observations are perfectly suited to serendipitous discoveries and archival analyses, and with a decade-long `X-ray desert' potentially on the horizon archival data will take on even greater importance; enhanced access to those archives will be vital to the continuation of X-ray astronomy., Comment: 5 pages, 1 figure, submitted to JOSS; GitHub repository - https://github.com/DavidT3/DAXA; Documentation - https://daxa.readthedocs.io/

The classical Cepheid KQ Sco is a valuable anchor for the distance scale because of its long pulsation period ($28^{\rm d}.7$) and evidence implying membership in the open cluster UBC 1558. Analyses tied to Gaia DR3 astrometry, photometry, spectroscopy, radial velocities, and 2MASS-VVV photometry indicate a common distance of $2.15\pm0.15$ kpc (\citealt{lin21} DR3 corrections applied). Additional cluster Cepheid candidates requiring follow-up are identified, and it's suggested that a team of international researchers could maintain a cluster Cepheid database to guide the broader community to cases where consensus exists., Comment: Accepted for publication (PASP). Modifications include corrected survey IDs in Table 2

The classical Cepheids CE Cas A, CE Cas B, CF Cas, and CG Cas are likely members of the binary open cluster comprising NGC 7790 and Berkeley 58. The clusters are of comparable age and in close proximity, as deduced from differentially dereddened $UuB_PBVGR_P$ photometry, and Cepheid period-age relations. Gaia DR3 astrometric and spectroscopic solutions for the clusters are likewise consistent. Conversely, the seemingly adjacent open cluster NGC 7788 is substantially younger and less distant., Comment: To be accepted for publication

The Local Volume Complete Cluster Survey (LoVoCCS) is an on-going program to observe nearly a hundred low-redshift X-ray-luminous galaxy clusters (redshifts $0.0310^{44}$ erg/s) with the Dark Energy Camera (DECam), capturing data in $u,g,r,i,z$ bands with a $5\sigma$ point source depth of approximately 25-26th AB magnitudes. Here, we map the aperture masses in 58 galaxy cluster fields using weak gravitational lensing. These clusters span a variety of dynamical states, from nearly relaxed to merging systems, and approximately half of them have not been subject to detailed weak lensing analysis before. In each cluster field, we analyze the alignment between the 2D mass distribution described by the aperture mass map, the 2D red-sequence (RS) galaxy distribution, and the brightest cluster galaxy (BCG). We find that the orientations of the BCG and the RS distribution are strongly aligned throughout the interiors of the clusters: the median misalignment angle is 19 deg within 2 Mpc. We also observe the alignment between the orientations of the RS distribution and the overall cluster mass distribution (by a median difference of 32 deg within 1 Mpc), although this is constrained by galaxy shape noise and the limitations of our cluster sample size. These types of alignment suggest long-term dynamical evolution within the clusters over cosmic timescales., Comment: 40 pages, 16 figures, 5 tables; revised and accepted for publication in ApJ

In this work, the thermal transport properties of thorium dioxide (ThO$_2$, thoria) with low levels of substitutional uranium (U) doping are explored. We observe strong indications of resonant phonon scattering, an interaction between phonons and electronic degrees of freedom, induced by this doping in addition to common ``impurity'' scattering due to mass and interatomic force constant differences. Uranium doping levels of 6\%, 9\%, and 16\% were studied in a single hydrothermally synthesized U-doped thoria crystal with spatially-varying U doping levels. Within this crystal, isoconcentration regions with relatively uniform doping were located for local thermal conductivity measurements using a thermoreflectance technique. The measured thermal conductivity profiles in the temperature range of 77--300~K are compared to predictions of an analytical Klemens-Callaway thermal conductivity model to identify impacts from different phonon scattering mechanisms. Highly suppressed thermal conductivity at cryogenic temperatures at these doping levels suggests that phonon resonant scattering plays an important role in thermal conductivity reduction in U-doped thoria., Comment: 7 pages, 4 figures

More often than not a lunch time conversation will veer off into bizarre and uncharted territories. In rare instances these frontiers of conversation can lead to deep insights about the Universe we inhabit. This paper details the fruits of one such conversation. In this paper we will answer the question: How many cows do you need to form a planetoid entirely comprised of cows, which will support a methane atmoosphere produced by the planetary herd? We will not only present the necessary assumptions and theory underpinning the cow-culations, but also present a thorough (and rather robust) discussion of the viability of, and implications for accomplishing, such a feat.

In our study, we show a multiwavelength view of ACT-CL J0019.6+0336 (which hosts a radio halo), to investigate the cluster dynamics, morphology, and ICM. We use a combination of XMM-Newton images, Dark Energy Survey (DES) imaging and photometry, SDSS spectroscopic information, and 1.16 GHz MeerKAT data to study the cluster properties. Various X-ray and optical morphology parameters are calculated to investigate the level of disturbance. We find disturbances in two X-ray parameters and the optical density map shows elongated and axisymmetric structures with the main cluster component southeast of the cluster centre and another component northwest of the cluster centre. We also find a BCG offset of $\sim$950 km/s from the mean velocity of the cluster, and a discrepancy between the SZ mass, X-ray mass, and dynamical mass ($M_{X,500}$ and $M_{SZ,500}$ lies >3 $\sigma$ away from $M_{\rm{dyn},500}$), showing that J0019 is a merging cluster and probably in a post-merging phase., Comment: 15 pages, 5 figures, Accepted for publication in special issue of Galaxies, from the conference "A New Window on the Radio Emission from Galaxies, Galaxy Clusters and Cosmic Web: Current Status and Perspectives"

We present a sample of 706, $z < 1.5$ active galactic nuclei (AGNs) selected from optical photometric variability in three of the Dark Energy Survey (DES) deep fields (E2, C3, and X3) over an area of 4.64 deg$^2$. We construct light curves using difference imaging aperture photometry for resolved sources and non-difference imaging PSF photometry for unresolved sources, respectively, and characterize the variability significance. Our DES light curves have a mean cadence of 7 days, a 6 year baseline, and a single-epoch imaging depth of up to $g \sim 24.5$. Using spectral energy distribution (SED) fitting, we find 26 out of total 706 variable galaxies are consistent with dwarf galaxies with a reliable stellar mass estimate ($M_{\ast}<10^{9.5}\ M_\odot$; median photometric redshift of 0.9). We were able to constrain rapid characteristic variability timescales ($\sim$ weeks) using the DES light curves in 15 dwarf AGN candidates (a subset of our variable AGN candidates) at a median photometric redshift of 0.4. This rapid variability is consistent with their low black hole masses. We confirm the low-mass AGN nature of one source with a high S/N optical spectrum. We publish our catalog, optical light curves, and supplementary data, such as X-ray properties and optical spectra, when available. We measure a variable AGN fraction versus stellar mass and compare to results from a forward model. This work demonstrates the feasibility of optical variability to identify AGNs with lower black hole masses in deep fields, which may be more "pristine" analogs of supermassive black hole seeds., Comment: 21 pages, 22 figures incl. 3 appendices; accepted for publication in MNRAS

This paper introduces a growth method---suboxide molecular-beam epitaxy (S-MBE)---which enables the growth of Ga2O3 and related materials at growth rates exceeding 1 micrometer per hours with excellent crystallinity in an adsorptioncontrolled regime. Using a Ga + Ga2O3 mixture with an oxygen mole fraction of x(O) = 0.4 as an MBE source, we overcome kinetic limits that had previously hampered the adsorption-controlled growth of Ga2O3 by MBE. We present growth rates up to 1.6 micrometer per hour for Ga2O3--Al2O3 heterostructures with unprecedented crystalline quality and also at unparalleled low growth temperature for this level of perfection. We combine thermodynamic knowledge of how to create molecular-beams of targeted suboxides with a kinetic model developed for the S-MBE of III-VI compounds to identify appropriate growth conditions. Using S-MBE we demonstrate the growth of phase-pure, smooth, and high-purity homoepitaxial Ga2O3 films that are thicker than 4 micrometer. With the high growth rate of S-MBE we anticipate a significant improvement to vertical Ga2O3-based devices. We describe and demonstrate how this growth method can be applied to a wide-range of oxides. S-MBE rivals leading synthesis methods currently used for the production of Ga2O3-based devices., Comment: 15 pages, 12 figures

The ability to learn new tasks and generalize performance to others is one of the most remarkable characteristics of the human brain and of recent AI systems. The ability to perform multiple tasks simultaneously is also a signature characteristic of large-scale parallel architectures, that is evident in the human brain, and has been exploited effectively more traditional, massively parallel computational architectures. Here, we show that these two characteristics are in tension, reflecting a fundamental tradeoff between interactive parallelism that supports learning and generalization, and independent parallelism that supports processing efficiency through concurrent multitasking. We formally show that, while the maximum number of tasks that can be performed simultaneously grows linearly with network size, under realistic scenarios (e.g. in an unpredictable environment), the expected number that can be performed concurrently grows radically sub-linearly with network size. Hence, even modest reliance on shared representation strictly constrains the number of tasks that can be performed simultaneously, implying profound consequences for the development of artificial intelligence that optimally manages the tradeoff between learning and processing, and for understanding the human brains remarkably puzzling mix of sequential and parallel capabilities., Comment: version 4. Added SIs, 33 pages total, 4 figures + 14 figures in SI, major edits to text

Photometric CCD {\it UBVI}$_C$ photometry obtained for 4860 stars surrounding the embedded southern cluster SAI~113 (Skiff~8) is used to examine the reddening in the field and derive the distance to the cluster and nearby van~Genderen~1. Spectroscopic color excesses for bright cluster stars, photometric reddenings for A3 dwarfs, and dereddening of cluster stars imply that the reddening and extinction laws match results derived for other young clusters in Carina: E$_{U-B}/$E$_{B-V} \simeq 0.64$ and $R_V \simeq 4$. SAI~113 displays features that may be linked to a history of dynamical interactions among member stars: possible circumstellar reddening and rapid rotation of late B-type members, ringlike features in star density, and a compact core with most stars distributed randomly across the field. The group van~Genderen~1 resembles a stellar asterism, with potential members distributed randomly across the field. Distances of $3.90 \pm0.19$ kpc and $2.49 \pm0.09$ kpc are derived for SAI~113 and van~Genderen~1, respectively, with variable reddenings E$_{B-V}$ ranging from 0.84 to 1.29 and 0.23 to 1.28. The SRC variables CK~Car and EV~Car may be outlying members of van~Genderen~1, thereby of use for calibrating the period-luminosity relation for pulsating M supergiants. More importantly, the anomalous reddening and extinction evident in Carina and nearby regions of the Galactic plane in the fourth quadrant impact the mapping of spiral structure from young open clusters. The distribution of spiral arms in the fourth quadrant may be significantly different from how it is often portrayed., Comment: 13 pages, 15 eps figure, in press in the Astronomical Journal

We present the 3.5-yr monitoring results of 225 GHz opacity at the summit of the Greenland ice sheet (Greenland Summit Camp) at an altitude of 3200 m using a tipping radiometer. We chose this site as our submillimeter telescope (Greenland Telescope; GLT) site, because its location offers favorable baselines to existing submillimeter telescopes for global-scale VLBI. The site shows a clear seasonal variation with the average opacity lower by a factor of two during winter. For the winter quartiles of 25% and 50%, the Greenland site is about 10%-30% worse than the ALMA or the South Pole sites. Estimated atmospheric transmission spectra in winter season are similar to the ALMA site at lower frequencies (<450 GHz), which are transparent enough to perform astronomical observations almost all of the winter time with opacities <0.5, but 10%-25% higher opacities at higher frequencies (>450 GHz) than those at the ALMA site. This is due to the lower altitude of the Greenland site. Nevertheless, half of the winter time at the Greenland site can be used for astronomical observations at frequencies between 450 GHz and 1000 GHz with opacities <1.2, and 10% of the time show >10% transmittance in the THz (1035 GHz, 1350 GHz, and 1500 GHz) windows. One major advantage of the Greenland site in winter is that there is no diurnal variation due to the polar night condition, and therefore the durations of low-opacity conditions are significantly longer than at the ALMA site. Opacities lower than 0.05 or 0.04 can continue for more than 100 hours. Such long stable opacity conditions do not occur as often even at the South Pole; it happens only for the opacity lower than 0.05. Since the opacity variation is directly related to the sky temperature (background) variation, the Greenland site is suitable for astronomical observations that need unusually stable sky background., Comment: 9 pages, 8 figures. Accepted in PASP

Field reddenings are summarized for 68 Cepheids from published studies and updated results presented here. The compilation forms the basis for a comparison with other published reddening scales of Cepheids, including those established from reddening-independent indices, photometry on the Lick six-color system, Str\"{o}mgren system, Walraven system, Washington system, Cape $BVI$ system, DDO system, and Geneva system, IRSB studies, and Cepheid spectroscopy, both old and new. Reddenings tied to period-color relations are the least reliable, as expected, while photometric color excesses vary in precision, their accuracy depending on the methodology and calibration sample. The tests provide insights into the accuracy and precision of published Cepheid reddening scales, and lead to a new system of standardized reddenings comprising a sample of 198 variables with an average uncertainty of $\pm0.028$ in E$_{B-V}$, the precision being less than $\pm0.01$ for many. The collected color excesses are used to map the dispersion in intrinsic colors as a function of pulsation period, the results contradicting current perceptions about the period dependence of dispersion in Cepheid effective temperatures., Comment: To appear in RevMexAA

Multi-color photometry of the stellar populations in five fields in the third Galactic quadrant centred on the clusters NGC 2215, NGC 2354, Haffner 22, Ruprecht 11, and ESO489SC01 is interpreted in terms of a warped and flared Galactic disk, without resort to an external entity such as the popular Monoceros or Canis Major overdensities. Except for NGC 2215, the clusters are poorly or unstudied previously. The data generate basic parameters for each cluster, including the distribution of stars along the line of sight. We use star counts and photometric analysis, without recourse to Galactic-model-based predictions or interpretations, and confirms earlier results for NGC 2215 and NGC 2354. ESO489SC01 is not a real cluster, while Haffner~22 is an overlooked cluster aged about 2.5 Gyr. Conclusions for Ruprecht~11 are preliminary, evidence for a cluster being marginal. Fields surrounding the clusters show signatures of young and intermediate-age stellar populations. The young population background to NGC~2354 and Ruprecht~11 lies 8-9 kpc from the Sun and $\sim$1 kpc below the formal Galactic plane, tracing a portion of the Norma-Cygnus arm, challenging Galactic models that adopt a sharp cut-off of the disk 12-14 kpc from the Galactic center. The old population is metal poor with an age of 2-3 Gyr, resembling star clusters like Tombaugh 2 or NGC 2158. It has a large color spread and is difficult to locate precisely. Young and old populations follow a pattern that depends critically on the vertical location of the thin and/or thick disk, and whether or not a particular line of sight intersects one, both, or none., Comment: 16 pages, 9 eps figures, in press in MNRAS

The nature of Galactic interstellar extinction is tested using reddening line parameters for several fields in conjunction with equivalent widths $W(\lambda4430)$ for the diffuse interstellar band at $4430$ \AA. The Cardelli et al.$\;$relations [29] at infrared, optical, and ultraviolet wavelengths are inconsistent with the newly-derived quadratic variation of $R_V({\rm observed})$ on reddening slope $X$. A minimum of $R_V=2.82\pm0.06$ exists for $X=0.83\pm0.10$, and is argued to represent true Galactic extinction described by $A(\lambda)\propto \lambda^{-1.375}$. It matches expectations for a new description of extinction in the infrared, optical, and ultraviolet by Zagury [32]. Additional consequences, reddened stars with no 2175 \AA$\;$feature and a correlation of normalized $\lambda4430$ absorption with $X$, are not predicted by the Cardelli et al.$\;$relation [29]. Known variations in $X$ from 0.62 to 0.83, and corresponding variations in $R_V({\rm observed})$ from 4.0 to 2.8, presumably result from forward-scattered starlight in the ultraviolet contaminating optical light of stars affected by dust extinction. A new understanding of the true nature of interstellar extinction is important for establishing an accurate picture of the extragalactic distance scale, which in turn is related to our understanding of the nature of the Universe., Comment: To appear in the CJP

A new compilation of UBV data for stars near the Cepheid S Vul incorporates BV observations from APASS and NOMAD to augment UBV observations published previously. A reddening analysis yields mean colour excesses and distance moduli for two main groups of stars in the field: the sparse cluster Turner 1 and an anonymous background group of BA stars. The former appears to be 1.07+-0.12 kpc distant and reddened by E(B-V)=0.45+-0.05, with an age of 10^9 yrs. The previously overlooked latter group is 3.48+-0.19 kpc distant and reddened by E(B-V)=0.78+-0.02, with an age of 1.3x10^7 yrs. Parameters inferred for S Vul under the assumption that it belongs to the distant group, as also argued by 2MASS data, are all consistent with similar results for other cluster Cepheids and Cepheid-like supergiants., Comment: Accepted for publication (Odessa Astronomical Publications)

The importance of strong school-university partnerships in bridging the so-called theory practice gap in pre-service teacher education has been well established in the literature. The experiences of pre-service teachers during practicum have in particular been shown to be enhanced where there are strong links between the two educational sectors. This paper draws from research conducted in two diverse Australian pre-service teacher education programs to evaluate factors that are perceived to profoundly impact on the professional experiences of pre-service teachers during practicum. The particular focus of this paper is the beliefs and experiences of school practitioners and university staff members regarding the efficacy of the practicum in enabling students to enact theory in practice. A mixed methods approach was adopted for both studies, one of which was located in an urban university in Tasmania, the other in a regional university in Queensland. Findings generated from the comparative study of both programs revealed some differences but predominantly a number of similarities between the perceptions of the two samples of school practitioners and university staff members towards practicum. Three key findings are presented and discussed in this paper. (Contains 2 tables and 1 footnote.)

Fundamental parameters characterizing the end-state of intermediate-mass stars may be constrained by discovering planetary nebulae (PNe) in open clusters (OCs). Cluster membership may be exploited to establish the distance, luminosity, age, and physical size for PNe, and the intrinsic luminosity and mass of its central star. Four potential PN-OC associations were investigated, to assess the cluster membership for the PNe. Radial velocities were measured from intermediate-resolution optical spectra, complemented with previous estimates in the literature. When the radial velocity study supported the PN/OC association, we analyzed if other parameters (e.g., age, distance, reddening, central star brightness) were consistent with this conclusion. Our measurements imply that the PNe VBe3 and HeFa1 are not members of the OCs NGC5999 and NGC6067, respectively, and likely belong to the background bulge population. Conversely, consistent radial velocities indicate that NGC2452/NGC2453 could be associated, but our results are not conclusive and additional observations are warranted. Finally, we demonstrate that all the available information point to He2-86 being a young, highly internally obscured PN member of NGC4463. New near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO public survey was used in tandem with existing UBV photometry to measure the distance, reddening, and age of NGC4463, finding d=1.55+-0.10 kpc, E(B-V)=0.41+-0.02, and tau=65+-10 Myr, respectively. The same values should be adopted for the PN if the proposed cluster membership will be confirmed., Comment: Accepted for publication in A&A

The nature of our Milky Way Galaxy is reexamined from an eclectic point of view. Evidence for a central bar, for example, is not reflected in the distribution of RR Lyrae variables in the central bulge [4,5], and it is not clear if either a 2-armed or 4-armed spiral pattern is appropriate for the spiral arms. Radial velocity mapping of the Galaxy using radio H I, H II, or CO observations is compromised by the assumptions adopted for simple Galactic rotation. The Sun's local standard of rest (LSR) velocity is $\sim 14$ km s$^{-1}$ rather than 20 km s$^{-1}$, the local circular velocity is $251 \pm 9$ km s$^{-1}$ rather than 220 km s$^{-1}$, and young groups of stars exhibit a 10--20 km s$^{-1}$ "kick" relative to what is expected from Galactic rotation. By implication, the same may be true for star-forming gas clouds affected by the Galaxy's spiral density wave, raising concerns about their use for mapping spiral arms. Proper motion data in conjunction with the newly-estimated velocity components for the Sun's motion imply a distance to the Galactic centre of $R_0=8.34\pm0.27$ kpc, consistent with recent estimates which average $8.24\pm0.09$ kpc. A cosinusoidal Galactic potential is not ruled out by observations of open star clusters. The planetary nebula cluster Bica 6, for example, has a near-escape orbit for a Newtonian potential, but a near-normal orbit in a cosinusoidal potential field. The nearby cluster Collinder 464 also displays unusually large tidal effects consistent with those expected for a cosinusoidal potential. A standard Newtonian version of the Virial Theorem for star clusters yields very reasonable masses ($\sim 3 \times 10^{11}M_{\odot}$ and $\sim 4 \times 10^{11}M_{\odot}$) for the Milky Way and M31 subgroups of the Local Group, respectively. A cosinusoidal relation should yield identical results., Comment: To appear in the CJP

A new X-ray, {\it UBVR}$I_c$, and {\it JHK$s$} study of the young cluster Westerlund 2 was undertaken to resolve discrepancies tied to the cluster's distance. Existing spectroscopic observations for bright cluster members and new multi-band photometry imply a reddening relation towards Westerlund~2 described by $E_{U-B}/E_{B-V}=0.63 + 0.02\;E_{B-V}$. Variable-extinction analyses for Westerlund~2 and nearby IC 2581 based upon spectroscopic distance moduli and ZAMS fitting yield values of $R_V=A_V/E_{B-V}=3.88\pm0.18$ and $3.77\pm0.19$, respectively, and confirm prior assertions that anomalous interstellar extinction is widespread throughout Carina (e.g., Turner 2012). The results were confirmed by applying the color difference method to {\it UBVR$I_c$JH$K_s$} data for 19 spectroscopically-observed cluster members, yielding $R_V=3.85\pm0.07$. The derived distance to Westerlund~2 of $d=2.85\pm0.43$ kpc places the cluster on the far side of the Carina spiral arm. The cluster's age is no more than $\tau \sim2\times10^6$ yr as inferred from the cluster's brightest stars and an X-ray (Chandra) cleaned analysis of its pre-main-sequence demographic. Four Wolf-Rayet stars in the cluster core and surrounding corona (WR20a, WR20b, WR20c, and WR20aa) are likely cluster members, and their inferred luminosities are consistent with those of other late-WN stars in open clusters. The color-magnitude diagram for Westerlund~2 also displays a gap at spectral type B0.5 V with associated color spread at higher and lower absolute magnitudes that might be linked to close binary mergers. Such features, in conjunction with the evidence for mass loss from the WR stars, may help to explain the high flux of $\gamma$ rays, cosmic rays, and X-rays from the direction towards Westerlund~2., Comment: 9 pages, 10 eps figures, in press in A&A

A previously-derived photometric parallax of 10.10+-0.20 mas, d=99+-2 pc, is confirmed for Polaris by a spectroscopic parallax derived using line ratios in high dispersion spectra for the Cepheid. The resulting estimates for the mean luminosity of =-3.07+-0.01 s.e., average effective temperature of =6025+-1 K s.e., and intrinsic color of (-)o=0.56+-0.01 s.e., which match values obtained previously from the photometric parallax for a space reddening of E(B-V)=0.02+-0.01, are consistent with fundamental mode pulsation for Polaris and a first crossing of the instability strip, as also argued by its rapid rate of period increase. The systematically smaller Hipparcos parallax for Polaris appears discrepant by comparison., Comment: To appear in ApJL

Classical Cepheids remain a cornerstone of the cosmic distance scale, and thus characterizing the dependence of their light amplitude on metallicity is important. Period-amplitude diagrams constructed for longer-period classical Cepheids in IC 1613, NGC 3109, SMC, NGC 6822, LMC, and the Milky Way imply that very metal-poor Cepheids typically exhibit smaller V-band amplitudes than their metal-rich counterparts. The results provide an alternate interpretation relative to arguments for a null and converse metallicity dependence. The empirical results can be employed to check predictions from theoretical models, to approximate mean abundances for target populations hosting numerous long-period Cepheids, and to facilitate the identification of potentially blended or peculiar objects., Comment: To appear in ApSS

A photometric UBV survey is presented for 610 stars in a region surrounding the Cepheid AQ Puppis and centered southwest of the variable, based upon photoelectric measures for 14 stars and calibrated iris photometry of photographic plates of the field for 596 stars. An analysis of reddening and distance for program stars indicates that the major dust complex in this direction is ~1.8 kpc distant, producing differential extinction described by a ratio of total-to-selective extinction of R=Av/E(B-V)=3.10+-0.20. Zero-age main-sequence fitting for the main group of B-type stars along the line of sight yields a distance of 3.21+-0.19 kpc (Vo-Mv=12.53+-0.13 s.e.). The 29.97d Cepheid AQ Pup, of field reddening E(B-V)=0.47+-0.07 (E(B-V)(B0)=0.51+-0.07), appears to be associated with B-type stars lying within 5' of it as well as with a sparse group of stars, designated Turner 14, centered south of it at J2000.0 = 07:58:37, -29:25:00, with a mean reddening of E(B-V)=0.81+-0.01. AQ Pup has an inferred luminosity as a cluster member of =-5.40+-0.25 and an evolutionary age of 3x10^7 yr. Its observed rate of period increase of 300.1+-1.2 s/yr is an order of magnitude larger than what is observed for Cepheids of comparable period in the third crossing of the instability strip, and may be indicative of a high rate of mass loss or a putative fifth crossing. Another sparse cluster, designated Turner 13, surrounds the newly-recognized 2.59d Cepheid V620 Pup, of space reddening E(B-V)=0.64+-0.02 (E(B-V)(B0)=0.68+-0.02), distance 2.88+-0.11 kpc (Vo-Mv=12.30+-0.08 s.e.), evolutionary age 10^8 yr, and an inferred luminosity as a likely cluster member of =-2.74+-0.11. V620 Pup is tentatively identified as a first crosser, pending additional observations., Comment: To appear in AJ

Evidence is presented indicating that the young star cluster Westerlund~2 lies $d_{\odot}\sim3.0$ kpc in the direction of Carina. The distance is tied partly to new $UBVRI_c$ photometry and revised spectral classifications for cluster stars, which imply that dust in the direction of Carina is characterized by an anomalous extinction law ($R_V\sim3.8$). That result was determined from a multi-faceted approach relying on the variable-extinction and color excess methods., Comment: 4 pages, 4 eps figure, proceedings of IAU Symposium 289, Beijing, August 2012

Acquiring near-infrared K-band (2.2 um) photometry for RR Lyrae variables in globular clusters and nearby galaxies is advantageous since the resulting distances are less impacted by reddening and metallicity. However, K-band photometry for RR Lyrae variables in M5, Reticulum, M92, omega Cen, and M15 display clustercentric trends. HST ACS data imply that multiple stars in close proximity to RR Lyrae variables located near the cluster core, where the stellar density increases markedly, are generally unresolved in ground-based images. RR Lyrae variables near the cluster cores appear to suffer from photometric contamination, thereby yielding underestimated cluster distances and biased ages. The impact is particularly pernicious since the contamination propagates a systematic uncertainty into the distance scale, and hinders the quest for precision cosmology. The clustercentric trends are probably unassociated with variations in chemical composition since an empirical K-band period-magnitude relation inferred from Araucaria/VLT data for RR Lyrae variables in the Sculptor dSph exhibits a negligible metallicity dependence: (0.059+-0.095)[Fe/H], a finding that supports prior observational results. A future multi-epoch high-resolution near-infrared survey, analogous to the optical HST ACS Galactic Globular Cluster Survey, may be employed to establish K-band photometry for the contaminating stars discussed here., Comment: To appear in PASP

This paper corrects and completes a previous study of the shape of the extinction curve in the visible and the value of Rv. A continuous visible/infrared extinction law proportional to 1/{\lambda}^p with p close to 1 ({\pm}0.4) is indistinguishable from a perfectly linear law (p = 1) in the visible within observational precision, but the shape of the curve in the infrared can be substantially modified. Values of p slightly larger than 1 would account for the increase of extinction (compared to the p = 1 law) reported for {\lambda} > 1{\mu}m and deeply affect the value of Rv. In the absence of gray extinction Rv must be 4.04 if p = 1. It becomes 3.14 for p = 1.25, 3.00 for p = 1.30, and 2.76 for p = 1.40. Values of p near 1.3 are also attributed to extinction by atmospheric aerosols, which indicates that both phenomena may be governed by similar particle size distributions. A power extinction law may harmonize visible and infrared data into a single, continuous, and universal, interstellar extinction law., Comment: This article does not replace but completes arXiv:1109.2199 (A.N. 333, 160). Accepted for publication (Apr 26, 2012). To appear in Astron. Nachr. (July, 2012)

RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC2419, and NGC6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry., Comment: To appear in ApJL

New X-ray (XMM-Newton) and JHKs (OMM) observations for members of the star cluster Alessi 95, which Turner et al.(2012) discovered hosts the classical Cepheid SU Cas, were used in tandem with UCAC3 (proper motion) and 2MASS observations to determine precise cluster parameters: E(J-H)=0.08+-0.02 and d=405+-15 pc. The ensuing consensus among cluster, pulsation, IUE, and trigonometric distances (d=414+-5(se)+-10(sd) pc) places SU Cas in a select group of nearby fundamental Cepheid calibrators (Delta Cep, Zeta Gem). High-resolution X-ray observations may be employed to expand that sample as the data proved pertinent for identifying numerous stars associated with SU Cas. Acquiring X-ray observations of additional fields may foster efforts to refine Cepheid calibrations used to constrain H_0., Comment: To appear in ApJ

The parameters for the newly-discovered open cluster Alessi 95 are established on the basis of available photometric and spectroscopic data, in conjunction with new observations. Colour excesses for spectroscopically-observed B and A-type stars near SU Cas follow a reddening relation described by E(U-B)/E(B-V)=0.83+0.02*E(B-V), implying a value of R=Av/E(B-V)~2.8 for the associated dust. Alessi 95 has a mean reddening of E(B-V)_(B0)=0.35+-0.02 s.e., an intrinsic distance modulus of Vo-Mv=8.16+-0.04 s.e. (+-0.21 s.d.), d=429+-8 pc, and an estimated age of 10^8.2 yr from ZAMS fitting of available UBV, CCD BV, NOMAD, and 2MASS JHKs observations of cluster stars. SU Cas is a likely cluster member, with an inferred space reddening of E(B-V)=0.33+-0.02 and a luminosity of =-3.15+-0.07 s.e., consistent with overtone pulsation (P_FM=2.75 d), as also implied by the Cepheid's light curve parameters, rate of period increase, and Hipparcos parallaxes for cluster stars. There is excellent agreement of the distance estimates for SU Cas inferred from cluster ZAMS fitting, its pulsation parallax derived from the infrared surface brightness technique, and Hipparcos parallaxes, which all agree to within a few percent., Comment: Accepted for Publication (MNRAS)

New and existing CORAVEL, UBVJHKs, HST, HIP/Tycho, ARO, KPNO, and DAO observations imply that the fundamental Cepheid calibrator Zeta Gem is a cluster member. The following parameters were inferred for Zeta Gem from cluster membership and are tied to new spectral classifications (DAO) established for 26 nearby stars (e.g., HD53588/B7.5IV, HD54692/B9.5IV): E(B-V)=0.02+-0.02, log t=7.85+-0.15, and d=355+-15 pc. The mean distance to Zeta Gem from cluster membership and six recent estimates (e.g., IRSB) is d=363+-9(se)+-26(sd) pc. The results presented here support the color-excess and HST parallax derived for the Cepheid by Benedict et al. (2007). Forthcoming precise proper motions (DASCH) and Chandra/XMM-Newton observations of the broader field may be employed to identify cluster members, bolster the cluster's existence, and provide stronger constraints on the Cepheid's fundamental parameters., Comment: To appear in ApJ Letters

New and existing UBVJHKs, spectroscopic, NOMAD, HST, and revised HIP observations are employed to determine properties for delta Cep and its host star cluster. The multi-faceted approach ensured that uncertainties were mitigated (~2%). The following fundamental parameters were inferred for delta Cep: E(B-V)=0.073+-0.018, log(t)=7.9+-0.1, and d=272+-3(se)+-5(sd) pc. The cluster exhibits a turnoff near B6 (M*/Ms~5), and the brightest host cluster members are the supergiants zeta Cep (K1.5Ib) and delta Cep. To within the uncertainties, the two stars share common astrometric parameters (pi, mu_ra, mu_dec, RV\sim-17 km/s) and are tied to bluer members via the evolutionary track implied by the cluster's UBVJHKs color-color and color-magnitude diagrams. The cluster's existence is bolstered by the absence of an early-type sequence in color-magnitude diagrams for comparison fields. NOMAD data provided a means to identify potential cluster members (n~30) and double the existing sample. That number could increase with forthcoming precise proper motions (DASCH) for fainter main-sequence stars associated with classical Cepheids (e.g., delta Cep), which may invariably foster efforts to strengthen the Galactic Cepheid calibration and reduce uncertainties tied to H_0., Comment: Accepted for Publication (ApJ)

Existing photometry for NGC 2264 tied to the Johnson and Morgan (1953) UBV system is reexamined and, in the case of the original observations by Walker (1956), reanalyzed in order to generate a homogeneous data set for cluster stars. Color terms and a Balmer discontinuity effect in Walker's observations were detected and corrected, and the homogenized data were used in a new assessment of the cluster reddening, distance, and age. Average values of E(B-V)=0.075+-0.003 s.e. and Vo-Mv=9.45+-0.03 s.e. (d=777+-12 pc) are obtained, in conjunction with an inferred cluster age of ~5.5x10^6 yr from pre-main-sequence members and the location of the evolved, luminous, O7 V((f)) dwarf S Mon relative to the ZAMS. The cluster main sequence also contains gaps that may have a dynamical origin. The dust responsible for the initial reddening towards NGC 2264 is no more than 465 pc distant, and there are numerous, reddened and unreddened, late-type stars along the line of sight that are difficult to separate from cluster members by standard techniques, except for a small subset of stars on the far side of the cluster embedded in its gas and dust and background B-type ZAMS members of Mon OB2. A compilation of likely NGC 2264 members is presented. Only 3 of the 4 stars recently examined by asteroseismology appear to be likely cluster members. NGC 2264 is also noted to be a double cluster, which has not been mentioned previously in the literature., Comment: To appear in AN

Approximately 14% of known Galactic open clusters possess absolute errors 20% as evaluated from n>3 independent distance estimates, and the statistics for age estimates are markedly worse. That impedes such diverse efforts as calibrating standard candles and constraining masses for substellar companions. New data from the VVV survey may be employed to establish precise cluster distances with comparatively reduced uncertainties (<10%). This is illustrated by deriving parameters for Pismis 19 and NGC 4349, two pertinent open clusters which hitherto feature sizable uncertainties (60%). Fundamental parameters determined for Pismis 19 from new VVV JHKs photometry are d=2.40+-0.15 kpc, =0.34+-0.04, and log(t)=9.05+-0.10, whereas for NGC 4349 the analysis yielded d=1.63+-0.13 kpc, E(J-H)=0.09+-0.02, log(t)=8.55+-0.10. The results exhibit a significant (>5x) reduction in uncertainties, and indicate that: i) existing parameters for the substellar object NGC 4349 127b require revision, in part because the new cluster parameters imply that the host is 20% less-massive (M*/Ms~3.1); ii) R Cru is not a member of NGC 4349 and should be excluded from period-Wesenheit calibrations that anchor the distance scale; iii) and results for Pismis 19 underscore the advantages gleaned from employing deep VVV JHKs data to examine obscured (Av~4) and differentially reddened intermediate-age clusters., Comment: To appear in A&A Letters

Preliminary constraints are placed on a cluster of YSOs (J2000 02:54:31.4 +69:20:32.5) discovered in the field of the classical Cepheid SU Cas. WISE 3.4, 4.6, 12, and 22 um images reveal that the cluster deviates from spherical symmetry and exhibits an apparent diameter of 3x6'. SEDs constructed using 2MASS Ks (2.2 um) and WISE photometry indicate that 19 (36%) class I, 21 (40%) class f, and 13 (25%) class II objects lie r<3' from the cluster center. Conversely, 11 (18%) class I, 13 (21%) class f, and 37 (61%) class II objects were detected for r>3'. Approximately 50% of the class I sources within r<3' were classified solely using WISE photometry owing to the absence of detections by 2MASS., Comment: Accepted for Publication (MNRAS)

Evidence is presented which supports findings that the classical Cepheid VIc period-Wesenheit function is relatively insensitive to metallicity. The viability of a recently advocated strong metallicity dependence was evaluated by applying the proposed correction (gamma=-0.8 mag/dex) to distances established for the Magellanic Clouds via a Galactic VIc Wesenheit calibration, which is anchored to ten nearby classical Cepheids with measured HST parallaxes. The resulting gamma-corrected distances for the Magellanic Clouds (e.g., SMC, mu(0,gamma)~18.3) are in significant disagreement with that established from a mean of >300 published estimates (NED-D), and a universal Wesenheit template featuring eleven delta Scuti, SX Phe, RR Lyrae, and Type II Cepheid variables with HST/Hipparcos parallaxes. Conversely, adopting a null correction (i.e., gamma=0 mag/dex) consolidates the estimates. In tandem with existing evidence, the results imply that variations in chemical composition among Cepheids are a comparatively negligible source of uncertainty for W(VIc)-based extragalactic distances and determinations of H_0. A new approach is described which aims to provide additional Galactic Cepheid calibrators to facilitate subsequent assessments of the VIc Wesenheit function's relative (in)sensitivity to abundance changes. VVV/UKIDSS/2MASS JHKs photometry for clusters in spiral arms shall be employed to establish a precise galactic longitude-distance relation, which can be applied in certain cases to determine the absolute Wesenheit magnitudes for younger Cepheids., Comment: Accepted for Publication (ApJ Letters)

The putative association between the 10.8 d classical Cepheid TW Nor and the open cluster Lynga 6 has generated considerable debate in the literature. New JHKs photometry in tandem with existing radial velocities for Lynga 6 stars imply cluster membership for TW Nor, and establish the variable as a high-weight calibrator for classical Cepheid relations. Fundamental mean parameters determined for Lynga 6 are: d=1.91+-0.10 kpc, E(J-H)=0.38+-0.02, and log(t)=7.9+-0.1. The Benedict et al.(2007)/Turner (2010) Galactic VIc Wesenheit function was revised using TW Nor's new parameters: W_VI,0=(-3.37+-0.08)log(P_0)-2.48+-0.08. TW Nor/Lynga 6 lie beyond the Sagittarius-Carina spiral arm and occupy the Centaurus arm, along with innumerable young Cepheids and clusters (e.g., VW Cen & VVV CL070)., Comment: Accepted for Publication (ApJ Letters)

The likely membership of the planetary nebula Abell 8 (PN G167.0--00.9) in the open cluster Bica 6 is confirmed by CCD spectra, UBV(RI)c photometry, and radial velocities for luminous cluster stars. The reddening, estimated distance, and radial velocity of the planetary nebula agree with parameters derived for Bica 6 of E(B-V)=0.42, d=1.60+-0.11 kpc, and Vr=57+-1 km/s, with a cluster age of 1 Gyr, a diagnostic blue hook, and a few blue stragglers, including a peculiar B1 Vnn star (HDE 277593) that may be a post-AGB star. The results identify Bica 6 as a potential calibrator of the planetary nebula distance scale. The central star of the planetary nebula has a reddening of E(B-V)=0.49+-0.02, with a possible circumnebular excess, and an estimated luminosity of Mv=+7.44+-0.16. It is also an optical double in 2MASS images, with a likely progenitor according to evolutionary considerations being a late B-type dwarf of ~2.3 Msun., Comment: Accepted for Publication (PASP)

A reanalysis of the (seemingly very distant) open cluster Shorlin 1, the group of stars associated with WR 38 and WR 38a, is made on the basis of existing UBV and JHKs observations for cluster members. The 2MASS observations, in particular, imply a mean cluster reddening of E(B-V)=1.45+-0.07 and a distance of 2.94+-0.12 kpc. The reddening agrees with the UBV results provided that the local reddening slope is described by E(U-B)/E(B-V)=0.64+-0.01, but the distance estimates in the 2MASS and UBV systems agree only if the ratio of total-to-selective extinction for the associated dust is R=Av/E(B-V)=4.0+-0.1. Both results are similar to what has been obtained for adjacent clusters in the Eta Carinae region by similar analyses, which suggests that `anomalous' dust extinction is widespread through the region, particularly for groups reddened by relatively nearby dust. Dust associated with the Eta Carinae complex itself appears to exhibit more `normal' qualities. The results have direct implications for the interpretation of distances to optical spiral arm indicators for the Galaxy at l=287-291 degrees, in particular the Carina arm here is probably little more than ~2 kpc distant, rather than 2.5-3 kpc distant as implied in previous studies. Newly-derived intrinsic parameters for the two cluster Wolf-Rayet stars WR 38 (WC4) and WR 38a (WN5) are in good agreement with what is found for other WR stars in Galactic open clusters, which was not the case previously., Comment: Accepted for Publication (Ap&SS)

Space reddenings are derived for 15 Galactic Cepheids from dereddening CCD BVRIc data for AF-type stars in the immediate vicinities of the variables, in conjunction with 2MASS reddenings for BAF-type stars in the same fields. Potential reddening solutions were analyzed using the variable-extinction method to identify stars sharing potentially similar distances and reddenings to the Cepheids, several of which have large color excesses. The intrinsic BVRIc color relation for AF dwarfs was modified slightly in the analysis in order to describe better the colors observed for unreddened stars in the samples., Comment: manuscript submitted for peer review

SRC variables are M supergiants, precursors to Type II supernovae, that vary in brightness with moderately regular periods of order 100-1000 days. Although identified as pulsating stars that obey their own period-luminosity relation, few have been examined in enough detail to follow the temperature and spectral changes that they undergo during their long cycles. The present study examines such changes for several SRC variables revealed by CCD spectra obtained at the Dominion Astrophysical Observatory (DAO) during 2005-2009, as well as by archival spectra from the DAO (and elsewhere) for some stars from the 1960s to 1980s, and Cambridge radial velocity spectrometer measures for Betelgeuse. Described here is our classification procedure and information on the spectral type and radial velocity changes in three of the stars. The results provide insights into the pulsation mechanism in M supergiants., Comment: To appear in the Odessa Variable Stars 2010 conference proceedings (see http://uavso.org.ua/?page=vs2010), edited by I. Andronov and V. Kovtyukh

The Galactic calibration of the period-luminosity (PL) relation for classical Cepheids is examined using trigonometric, open cluster, and pulsation parallaxes, which help establish independent versions of the relationship. The calibration is important for the continued use of classical Cepheids in constraining cosmological models (by refining estimates for H_0), for defining zero-points for the SNe Ia and population II (Type II Cepheids/RR Lyrae variables) distance scales, for clarifying properties of the Milky Way's spiral structure, and for characterizing dust extinction affecting Cepheids in the Milky Way and other galaxies. Described is a program to extend and refine the Galactic Cepheid PL relation by obtaining UBVRIJHKs photometry and spectra for stars in open clusters suspected of hosting classical Cepheids, using the the facilities of the OAMM, DAO, AAVSO, and ARO., Comment: To appear in the Odessa variable stars 2010 conference proceedings (see http://uavso.org.ua/?page=vs2010), edited by I. Andronov and V. Kovtyukh

A collection of active photometric observations over the last half decade, archival data from the past 120 years, radial velocity observations from 1984, and recent monitoring through a pro-am collaboration reveal that the 9th magnitude F9 Ib supergiant HDE 344787 is a double-mode Cepheid variable of extremely small amplitude. It displays remarkably similar, but much more extreme, properties to the exotic Cepheid Polaris, including a rapidly-increasing period and sinusoidal light variations of decreasing amplitude suggesting that pulsational stability may occur as early as 2045. Unlike Polaris, HDE 344787 displays sinusoidal light variations at periods of both 5.4 and 3.8 days, corresponding to canonical fundamental mode and overtone pulsation. But it may be similar to Polaris in helping to define a small subgroup of Cepheids that display characteristics consistent with a first crossing of the instability strip. An update of 2010 observations of this remarkable star is presented., Comment: To appear in the Odessa variable stars 2010 conference proceedings (see http://uavso.org.ua/?page=vs2010), edited by I. Andronov and V. Kovtyukh

Random changes in pulsation period occur in cool pulsating Mira variables, Type A, B, and C semiregular variables, RV Tauri variables, and in most classical Cepheids. The physical processes responsible for such fluctuations are uncertain, but presumably originate in temporal modifications of the envelope convection in such stars. Such fluctuations are seemingly random over a few pulsation cycles of the stars, but are dominated by the regularity of the primary pulsation over the long term. The magnitude of stochasticity in pulsating stars appears to be linked directly to their dimensions, although not in simple fashion. It is relatively larger in M supergiants, for example, than in short-period Cepheids, but is common enough that it can be detected in visual observations for many types of pulsating stars. Although chaos was discovered in such stars 80 years ago, detection of its general presence in the group has only been possible in recent studies., Comment: To appear in the proceedings of the Odessa Variable Stars 2010 Conference (see http://uavso.org.ua/?page=vs2010&lang=en), edited by I. Andronov and V. Kovtyukh

This research aims to secure precise distances for cluster delta Scutis in order to investigate their properties via a VI Wesenheit framework. Deep JHKs colour-colour and ZAMS relations derived from ~700 unreddened stars featuring 2MASS photometry and precise HIP parallaxes (d<~25 pc) are applied to establish distances to several benchmark open clusters that host delta Scutis: Hyades, Pleiades, Praesepe, alpha Per, and M67 (d=47+-2,138+-6,183+-8,171+-8,815+-40 pc). That analysis provided constraints on the delta Sct sample's absolute Wesenheit magnitudes (W_VI,0), evolutionary status, and pulsation modes (order, n). The reliability of JHKs established cluster parameters is demonstrated via a comparison with van Leeuwen 2009 revised HIP results. Distances for 7 of 9 nearby (d<250 pc) clusters agree, and the discrepant cases (Pleiades & Blanco 1) are unrelated to (insignificant) Te/J-Ks variations with cluster age or [Fe/H]. JHKs photometry is tabulated for ~3x10^3 probable cluster members on the basis of proper motions (NOMAD). The deep JHKs photometry extends into the low mass regime (~0.4 Msun) and ensures precise (<5%) ZAMS fits. Pulsation modes inferred for the cluster delta Scutis from VI Wesenheit and independent analyses are comparable (+-n), and the methods are consistent in identifying higher order pulsators. Most small-amplitude cluster delta Scutis lie on VI Wesenheit loci characterizing n>~1 pulsators. A distance established to NGC 1817 from delta Scutis (d~1.7 kpc) via a universal VI Wesenheit template agrees with estimates in the literature, assuming the variables delineate the n>~1 boundary. Small statistics in tandem with other factors presently encumber the use of mmag delta Scutis as viable distance indicators to intermediate-age open clusters, yet a VI Wesenheit approach is a pertinent means for studying delta Scutis in harmony with other methods., Comment: Accepted for Publication (JAAVSO)

2MASS JHKs data are used to infer the reddening and distance of open clusters for which limited optical data are available. Intrinsic ZAMS color-color and color-magnitude relations are derived with reference to existing calibrations, standard stars, three uniformly-reddened clusters: Stock 16, NGC 2362, and NGC 2281, and unreddened Hyades dwarfs. The method of inferring interstellar reddening and distance for sparsely-populated open clusters is applied to Berkeley 44, Turner 1, and Collinder 419, for which existing results conflict with those inferred from JHKs data. The last two clusters are of special interest: Turner 1 because it hosts the Galaxy's longest-period classical Cepheid, and Collinder 419 because it lies in the Cygnus X complex., Comment: Accepted for Publication (RMAA)

A VI Wesenheit diagram featuring SX Phoenicis, delta Scuti, RR Lyrae, type II and classical Cepheid variables is calibrated by means of geometric-based distances inferred from HST, Hipparcos, and VLBA observations (n=30). The distance to a target population follows from the offset between the observed Wesenheit magnitudes and the calibrated template. The method is evaluated by ascertaining the distance moduli for the LMC (mu_0=18.43+-0.03 se) and the globular clusters omega Cen, M54, M13, M3, and M15. The results agree with estimates cited in the literature, although a nearer distance to M13 is favoured (pending confirmation of the data's photometric zero-point) and observations of variables near the core of M15 suffer from photometric contamination. The calibrated LMC data is subsequently added to the Wesenheit template since that galaxy exhibits precise OGLE photometry for innumerable variables of differing classes, that includes recent observations for delta Scuti variables indicating the stars follow a steeper VI Wesenheit function than classical Cepheids pulsating in the fundamental mode. VI photometry for the calibrators is tabulated to facilitate further research, and includes new observations acquired via the AAVSO's robotic telescope network (e.g., VY Pyx: =7.25 and -=0.67). The approach outlined here supersedes the lead author's prior first-order effort to unify variables of the instability strip in order to establish reliable distances., Comment: Accepted for Publication (JAAVSO)

The rationale behind recent calibrations of the Cepheid PL relation using the Wesenheit formulation is reviewed and reanalyzed, and it is shown that recent conclusions regarding a possible change in slope of the PL relation for short-period and long-period Cepheids are tied to a pathological distribution of HST calibrators within the instability strip. A recalibration of the period-luminosity relation is obtained using Galactic Cepheids in open clusters and groups, the resulting relationship, described by log L/L_sun = 2.415(+-0.035) + 1.148(+-0.044)log P, exhibiting only the moderate scatter expected from color spread within the instability strip. The relationship is confirmed by Cepheids with HST parallaxes, although without the need for Lutz-Kelker corrections, and in general by Cepheids with revised Hipparcos parallaxes, albeit with concerns about the cited precisions of the latter. A Wesenheit formulation of Wv = -2.259(+-0.083) - 4.185(+-0.103)log P for Galactic Cepheids is tested successfully using Cepheids in the inner regions of the galaxy NGC 4258, confirming the independent geometrical distance established for the galaxy from OH masers. Differences between the extinction properties of interstellar and extragalactic dust may yet play an important role in the further calibration of the Cepheid PL relation and its application to the extragalactic distance scale., Comment: Accepted for Publication (Astrophysics & Space Science)

A campaign is described, open to participation by interested AAVSO members, of follow-up observations for newly-discovered Cepheid variables in undersampled and obscured regions of the Galaxy. A primary objective being to use these supergiants to clarify the Galaxy's spiral nature. Preliminary multiband photometric observations are presented for three Cepheids discovered beyond the obscuring dust between the Cygnus & Aquila Rifts (40 \le l \le 50 degrees), a region reputedly tied to a segment of the Sagittarius-Carina arm which appears to cease unexpectedly. The data confirm the existence of exceptional extinction along the line of sight at upwards of A_V~6 magnitudes (d~2 kpc, l~47 degrees), however, the noted paucity of optical spiral tracers in the region does not arise solely from incompleteness owing to extinction. A hybrid spiral map of the Galaxy comprised of classical Cepheids, young open clusters & H II regions, and molecular clouds, presents a consistent picture of the Milky Way and confirms that the three Cepheids do not populate the main portion of the Sagittarius-Carina arm, which does not emanate locally from this region. The Sagitarrius-Carina arm, along with other distinct spiral features, are found to deviate from the canonical logarithmic spiral pattern. Revised parameters are also issued for the Cepheid BY Cas, and it is identified on the spiral map as lying mainly in the foreground to young associations in Cassiopeia. A Fourier analysis of BY Cas' light-curve implies overtone pulsation, and the Cepheid is probably unassociated with the open cluster NGC 663 since the distances, ages, and radial velocities do not match., Comment: Accepted for Publication (JAAVSO)

Extragalactic Type II Cepheids are tentatively identified in photometric surveys of IC 1613, M33, M101, M106, M31, NGC 4603, and the SMC. Preliminary results suggest that Type II Cepheids may play an important role as standard candles, in constraining the effects of metallicity on Cepheid parameters, and in mapping extinction., Comment: Accepted for Publication (Acta A.)