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Supernovae 2006aa, 2006ab, and 2006ac
IAUC 8669 available at Central Bureau for Astronomical Telegrams.
| Discovery of SNF20060208-004 (Type II), Classification of SN 2006aa (Type IIn) and SN 2006ac (Premaximum Type Ia)
The Nearby Supernova Factory reports the discovery of SNF20060208-004(RA 09:07:43.11 Dec. +12:03:06.5 J2000.0) in images obtained February8.3 UT with an approximate magnitude of 18.9 (calibrated to R) using theQUEST II camera on the Palomar Oschin 48-inch telescope as a part of theJPL Near-Earth Asteroid Tracking component of the Palomar Consortium. Aspectrum (range 320-1000 nm) of this object obtained February 10.5 UTwith the Supernova Integral Field Spectrograph on the University ofHawaii 2.2-meter telescope, shows it to be a Type II supernova at anapproximate redshift of z = 0.03, as measured from the peak of itsH-alpha emission.
| Correlations among multiwavelength luminosities of star-forming galaxies
It has been known for two decades that a tight correlation existsbetween global far-infrared (FIR) and radio continuum (1.4 and 4.8 GHz)fluxes/luminosities from star-forming galaxies, which may be explainedby formation activities of massive stars in these galaxies. For thisvery reason, a correlation might also exist between X-ray and FIR/radioglobal luminosities of galaxies. We analyse data from the ROSAT All-SkySurvey and from IRAS to show that such correlation does indeed existbetween FIR (42.5-122.5μm) and soft X-ray (0.1-2.4 keV) luminositiesLX and LFIR in 17 normal star-forming galaxies(NSFGs), including 16 late-type galaxies and one host-dominant Seyfertgalaxy, as well as in 14 active star-forming galaxies (ASFGs) consistingof starburst-dominant Seyfert galaxies. The quantitative difference insuch correlations in NSFGs and in ASFGs may be interpreted in terms ofevolutionary variations from classic starburst galaxies tostarburst-dominant Seyfert galaxies. Meanwhile, some low-luminosityactive galactic nuclei (LLAGNs) tend to exhibit such a correlation thatwe infer for star-forming galaxies, implying that star-formingactivities might be more dominant in LLAGNs. In contrast, AGN-dominantSeyfert galaxies do not show such a LX versus LFIRcorrelation; this is most likely related to accretions towardssupermassive black holes (SMBHs) in galactic nuclei. In order toestablish a physical connection between theLX-LFIR correlation and global star formation rate(SFR) in galaxies, we empirically derive bothLX-LB and LFIR-LB relationswith the blue-band luminosity LB roughly representing themass of a galaxy. It appears that the more massive galaxies are, themore star formation regions exist in these galaxies. The global SFR isnot only associated with the mass of a galaxy but also closely relatedto the level of star-forming activities therein. We propose a relationbetween soft X-ray luminosity and SFR in star-forming galaxies. In orderto probe the LX-LFIR relation, we construct anempirical model in which both FIR and X-ray emissions consist of twocomponents with one being closely associated with star formation and theother one not. Based on this model, we infer a linear relation betweenFIR/soft X-ray in star formation regions and radio luminosities, and geta linear relation between LX and LFIR forstar-forming regions.
| Radio emission from AGN detected by the VLA FIRST survey
Using the most recent (April 2003) version of the VLA FIRST survey radiocatalog, we have searched for radio emission from >2800 AGN takenfrom the most recent (2001) version of the Veron-Cetty and Veron AGNcatalog. These AGN lie in the 9033 square degrees of sky alreadycovered by the VLA FIRST survey. Our work has resulted in positivedetection of radio emission from 775 AGN of which 214 are new detectionsat radio wavelengths.Tables 3 and 4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/35
| High-energy sources before INTEGRAL. INTEGRAL reference catalog
We describe the INTEGRAL reference catalog which classifies previouslyknown bright X-ray and gamma-ray sources before the launch of INTEGRAL.These sources are, or have been at least once, brighter than ~ 1 mCrababove 3 keV, and are expected to be detected by INTEGRAL. This catalogis being used in the INTEGRAL Quick Look Analysis to discover newsources or significantly variable sources. We compiled several publishedX-ray and gamma-ray catalogs, and surveyed recent publications for newsources. Consequently, there are 1122 sources in our INTEGRAL referencecatalog. In addition to the source positions, we show an approximatespectral model and expected flux for each source, based on which wederive expected INTEGRAL counting rates. Assuming the default instrumentperformances and at least ~ 105 s exposure time for anypart of the sky, we expect that INTEGRAL will detect at least ~ 700sources below 10 keV and ~ 400 sources above 20 keV over the missionlife.The Catalog is available in electronic form at the CDS via anonymous ftpto cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?/A+A/411/L59
| The Hamburg/RASS Catalogue of optical identifications. Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources
We present the Hamburg/RASS Catalogue (HRC) of optical identificationsof X-ray sources at high-galactic latitude. The HRC includes all X-raysources from the ROSAT Bright Source Catalogue (RASS-BSC) with galacticlatitude |b| >=30degr and declination delta >=0degr . In thispart of the sky covering ~ 10 000 deg2 the RASS-BSC contains5341 X-ray sources. For the optical identification we used blue Schmidtprism and direct plates taken for the northern hemisphere Hamburg QuasarSurvey (HQS) which are now available in digitized form. The limitingmagnitudes are 18.5 and 20, respectively. For 82% of the selectedRASS-BSC an identification could be given. For the rest either nocounterpart was visible in the error circle or a plausibleidentification was not possible. With ~ 42% AGN represent the largestgroup of X-ray emitters, ~ 31% have a stellar counterpart, whereasgalaxies and cluster of galaxies comprise only ~ 4% and ~ 5%,respectively. In ~ 3% of the RASS-BSC sources no object was visible onour blue direct plates within 40\arcsec around the X-ray sourceposition. The catalogue is used as a source for the selection of(nearly) complete samples of the various classes of X-ray emitters.
| The HRX-BL Lac sample - Evolution of BL Lac objects
The unification of X-ray and radio selected BL Lacs has been anoutstanding problem in the blazar research in the past years. Recentinvestigations have shown that the gap between the two classes can befilled with intermediate objects and that apparently all differences canbe explained by mutual shifts of the peak frequencies of the synchrotronand inverse Compton component of the emission. We study the consequencesof this scheme using a new sample of X-ray selected BL Lac objectscomprising 104 objects with z<0.9 and a mean redshift bar {z} = 0.34.77 BL Lacs, of which the redshift could be determined for 64 (83%)objects, form a complete sample. The new data could not confirm ourearlier result, drawn from a subsample, that the negative evolutionvanishes below a synchrotron peak frequency log nupeak =16.5. The complete sample shows negative evolution at the 2sigma level(< Ve/Va > = 0.42 +/- 0.04). We concludethat the observed properties of the HRX BL Lac sample show typicalbehaviour for X-ray selected BL Lacs. They support an evolutionarymodel, in which flat-spectrum radio quasars (FSRQ) with high energeticjets evolve towards low frequency peaked (mostly radio-selected) BL Lacobjects and later on to high frequency peaked (mostly X-ray selected) BLLacs.Appendix (Tables 8 and 9, Fig. 8) is only available in electronic format http://www.edpsciences.org
| Astrophysics in 2000
It was a year in which some topics selected themselves as importantthrough the sheer numbers of papers published. These include theconnection(s) between galaxies with active central engines and galaxieswith starbursts, the transition from asymptotic giant branch stars towhite dwarfs, gamma-ray bursters, solar data from three major satellitemissions, and the cosmological parameters, including dark matter andvery large scale structure. Several sections are oriented aroundprocesses-accretion, collimation, mergers, and disruptions-shared by anumber of kinds of stars and galaxies. And, of course, there are theusual frivolities of errors, omissions, exceptions, and inventories.
| Unveiling the AGN powering the ``Composite" Seyfert/Star-forming galaxy NGC 7679: BeppoSAX and ASCA results
We discuss BeppoSAX observations and archive ASCA data of NGC 7679, anearby, nearly face-on SB0 galaxy in which starburst and AGN activitiescoexist. The X-ray observations reveal a bright (L0.1-50 keV~ 2.9 x 1043 erg s-1) and variable source having aminimum observed doubling/halving time scale of ~ m10-20 ksec. A simplepower law with photon index of Γ ~ m 1.75 and small absorption(NH < 4× 1020 cm-2) canreproduce the NGC 7679 spectrum from 0.1 up to 50 keV. These X-rayproperties are unambiguous signs of Seyfert 1 activity in the nucleus ofNGC 7679. The starburst activity, revealed by the IR emission, opticalspectroscopy and H α imaging, and dominating in the optical and IRbands, is clearly overwhelmed by the AGN in the X-ray band. Although, atfirst glance, this is similar to what is observed in other starburst-AGNgalaxies (e.g. NGC 6240, NGC 4945), most strikingly here and at oddswith the above examples, the X-ray spectrum of NGC 7679 does not appearto be highly absorbed. The main peculiarity of objects like NGC 7679 isnot the strength of their starburst but the apparent optical weakness ofthe Seyfert 1 nucleus when compared with its X-ray luminosity. To dateNGC 7679 is one of the few Seyfert 1/Starburst composites for which thebroad-band X-ray properties have been investigated in detail. Theresults presented here imply that optical and infrared spectroscopycould be highly inefficient in revealing the presence of an AGN in thesekinds of objects, which instead is clearly revealed from X-rayspectroscopic and variability investigations.
| The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s-1
We present a summary of an identification program of the more than 2000X-ray sources detected during the ROSAT All-Sky Survey (Voges et al.1999) at high galactic latitude, |b| > 30degr , with countrate above0.2 s-1. This program, termed the ROSAT Bright Survey RBS, isto more than 99.5% complete. A sub-sample of 931 sources with countrateabove 0.2 s-1 in the hard spectral band between 0.5 and 2.0keV is to 100% identified. The total survey area comprises 20391deg2 at a flux limit of 2.4 x 10-12 ergcm-2 s-1 in the 0.5 - 2.0 keV band. About 1500sources of the complete sample could be identified by correlating theRBS with SIMBAD and the NED. The remaining ~ 500 sources were identifiedby low-resolution optical spectroscopy and CCD imaging utilizingtelescopes at La Silla, Calar Alto, Zelenchukskaya and Mauna Kea. Apartfrom completely untouched sources, catalogued clusters and galaxieswithout published redshift as well as catalogued galaxies with unusualhigh X-ray luminosity were included in the spectroscopic identificationprogram. Details of the observations with an on-line presentation of thefinding charts and the optical spectra will be published separately.Here we summarize our identifications in a table which contains opticaland X-ray information for each source. As a result we present the mostmassive complete sample of X-ray selected AGNs with a total of 669members and a well populated X-ray selected sample of 302 clusters ofgalaxies with redshifts up to 0.70. Three fields studied by us remainwithout optical counterpart (RBS0378, RBS1223, RBS1556). While the firstis a possible X-ray transient, the two latter are isolated neutron starcandidates (Motch et al. 1999, Schwope et al. 1999).
| A direct view of the AGN powering IRAS12393+3520
We report the first direct X-ray evidence that an AGN is hidden in thecenter of IRAS12393+3520. An ASCA observation of this target unveiled abright (0.5-10 keV luminosity 3.9 x 1042 erg s-1)and variable source, with minimum observed doubling/halving time scalecomprised in the range 30-75 ks. A model composed by a simple power-law,with photon index =~ 1.8 and an absorption edge, whose threshold energyis consistent with K-shell photoionization of Ovii, provides an adequatefit of the spectrum. This suggests that we are observing the emissionfrom the nuclear region through a warm absorber of N_H =~ a few1021 cm-2. If it has internal dust with Galacticgas-to-dust ratio, it could explain the lack of broad Hbeta emission, even in the episodic presence of a broad Halpha emission line. Optical spectra obtained over several years show indeedvariations in the strength of this broad Halpha component. Adistribution of dusty, optically thick matter on spatial scales a fewhundreds parsec, which does not intercept the line of sight towards thenucleus, is probably required to account simultaneously for the relative[OIII] luminosity deficit in comparison to the X-rays. The high IR toX-ray luminosity ratio is most likely due to intense star formation inthe circumnuclear region. IRAS12393+3520 might thus exhibitsimultaneously nuclear activity and remarkable star formation.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| The ROSAT/IRAS Galaxy Sample Revisited
Galaxies in the ROSAT/IRAS sample were selected by their soft X-ray(0.1-2.4 keV) and far-infrared (lambda = 60 μm) emission. Therelatively large uncertainties in the original ROSAT and IRAS positionscaused some contamination by close pairs and forced the exclusion ofmost ``high-flux'' (S > 10 Jy at lambda = 100 μm) IRAS sourcesfrom the original sample. We used new 1.4 GHz VLA images of all objectsnorth of delta = -45 deg along with improved X-ray and far-infraredpositions to eliminate incorrect identifications, many of which appearedto be starburst galaxies with high X-ray luminosities, log [X(ergs^-1)]> 43. We also used VLA images to search for new X-ray identificationsamong the ``high-flux'' sources with delta > -45 deg. Only two werefound, indicating that luminous starburst galaxies have relatively lowsoft X-ray luminosities, in part due to absorption by a denseinterstellar medium. No starburst galaxies in our revised sample haveX-ray luminosities approaching log [X(ergs^-1)] = 43. We conclude thatmost galaxies in the revised ROSAT/IRAS sample contain X-ray-emittingactive galactic nuclei (AGNs) residing in star-forming disks that emitmost of the lambda = 60 μm radiation. Normal and starburst galaxiesprobably do not account for a significant fraction of the soft X-raybackground.
| ROSAT All-Sky Survey observations of IRAS galaxies. I. Soft X-ray and far-infrared properties
The 120 000 X-ray sources detected in the RASS II processing of theROSAT All-Sky Survey are correlated with the 14 315 IRAS galaxiesselected from the IRAS Point Source Catalogue: 372 IRAS galaxies showX-ray emission within a distance of 100 arcsec from the infraredposition. By inspecting the structure of the X-ray emission in overlayson optical images we quantify the likelihood that the X-rays originatefrom the IRAS galaxy. For 197 objects the soft X-ray emission is verylikely associated with the IRAS galaxy. Their soft X-ray properties aredetermined and compared with their far-infrared emission. X-ray contourplots overlaid on Palomar Digitized Sky Survey images are given for eachof the 372 potential identifications. All images and tables displayedhere are also available in electronic form.
| Polarimetry and modelling of narrow-line active galaxies
We present optical spectropolarimetry along with optical and infraredbroad-band filter polarimetry of selected warm [f(25 μm)/f(60μm)>=0.3] IRAS galaxies and other known Seyfert 2 galaxies. Broadlines in polarized flux have been detected in a number of type 2 IRASgalaxies. From a determination of the intrinsic polarization of thescattered radiation it has been possible to model the optical andnear-IR flux density and degrees of polarization, for a number ofobjects, with a cone-based scattering geometry. In all these cases anadditional polarizing mechanism was required to match the near-IR data,and this was successfully modelled by a dichroic view of the near-IRemitting regions through the postulated torus which surrounds the type 1core. For those objects which show broad lines in polarized flux, andfor which the intrinsic polarization of the scattered radiation could becalculated, the inclinations to the line of sight tend to be low. Thebroad Hα luminosities calculated for the IRAS galaxies are moretypical of QSOs than Seyfert 1 galaxies. Only a fraction of the IRASgalaxies observed exhibit broad lines in polarized flux indicating thateither the scattering region is also obscured, or the broad lines arethermally broadened and rendered unobservable, or the unified theory isincorrect. Evidence supporting the former case is presented.
| Starbust activity in x-rays and FIR luminous galaxies: the case of NGC 4619 and IRAS 15564+6359
Not Available
| Classification of IRAS-selected X-Ray Galaxies in the ROSAT All-Sky Survey
To explore the possibility that star-forming galaxies or obscuredSeyfert galaxies, both of which are known to be luminous infraredsources, contribute significantly to the cosmic X-ray background, wehave carried out an extensive program to obtain accurate spectroscopicclassifications of the BoIler et al. (1992) catalog of IRAS sourcesdetected in the ROSAT All-Sky Survey. This has involved careful opticalspectroscopy, a review of the literature, and efforts to reveal thecontaminants in the sample. Classifications have been determined for 210of the 241 X-ray sources in the catalog; 105 are presented here for thefirst time. A large number of IR/X-ray source chance coincidences arefound in this sample; of the 40-50 expected, we have identified 18firmly and have established strong cases for 29 others. Most chancecoincidences involve bright stars or Seyfert galaxies close (inprojection) to IR- bright H II galaxies. Although this work wasmotivated initially by the report that a new class of X-ray-luminous,normal spiral galaxies was to be found in this sample, we find noevidence for such a class. Most of the extragalactic X-ray sources areactive galactic nuclei (AGNs), consistent with the results of previousstudies of X-ray-selected objects. However, many of these AGNs exhibitweak or heavily reddened Seyfert features in their optical spectra. Inaddition, two rare types of AGNs are found in this sample withsurprising frequency: I Zw 1 objects (also called narrow-line Seyfert 1galaxies) and starburst/Seyfert composite galaxies, a new class ofluminous X-ray sources. We have shown that the Boller et al. object202103 - 223434 (= IRAS 20181-2244), reported to be the best example ofa narrow-line quasar, is actually a member of the I Zw 1 class. Theenigmatic starburst/Seyfert composite galaxies have optical spectradominated by the features of H II galaxies but X-ray luminositiestypical for Seyfert galaxies. Close examination of their optical spectrareveals subtle Seyfert signatures: [O III] lines broader than all otherlines in the spectrum and, in some cases, a weak, broad Hαcomponent. Obscuration of the active nucleus is likely to explain theX-ray and optical properties of these objects. We describe a scenario inwhich such optically innocuous, obscured AGNs could comprise animportant new component of the X-ray background.
| Starburst activity in X-ray and FIR luminous galaxies: the case of NGC 4619 and IRAS 15564+6359.
We have analyzed the multiwavelength (soft X-rays to far infrared)energy distribution of IRAS 15564+6359 and NGC 4619, two galaxiespreviously not classified as active galaxies but found during the ROSATAll Sky Survey to be very luminous in the X-ray and far infrared (FIR)ranges. By comparison with population synthesis evolutionary models wehave found that a scenario consisting in very intense starbursts ondusty preexisting galaxies can reproduce the energy output atultraviolet (UV), optical and far infrared wavelengths of both galaxies,as well as their narrow emission lines. The starburst models alone failin principle to explain the rapid X-ray variability in IRAS 15564+6359,underestimate its soft-X-ray emission when in high-state, and fail alsoto explain the presence of broad Lyα and Hα lines in NGC4619, unless the presence of compact supernova remnants is assumed. Onthe other hand, if these galaxies are hosting active sources, the excessin far infrared emission compared to Seyfert 1 galaxies would indicatethat in any case additional intense starbursts processes should betaking place there. The detection of non-absorbed X-ray emission (IRAS15564+6359) as well as a strong Lyα emission line (NGC 4619) onotherwise dusty galaxies points out the existence of a very patchyinterstellar medium, with holes through which the high-energy emissioncan escape. This scenario suggests the existence of similar galaxies inwhich the active source could be completely blocked by gas and dust,being unveiled possibly only at very hard X-rays.
| The CfA Redshift Survey: Data for the NGP +36 Zone
We have assembled redshifts for a complete sample of 719 galaxies withm_zw_ <= 15.5 in the declination range 32.5^deg^ <= δ <=38.5^deg^ and right ascension range 8^h^ <= α <= 17^h^. Wehave determined morphological types for all galaxies in the magnitudelimited sample by direct inspection of the POSS-O plates. 576 of theredshifts are measurements from Mount Hopkins, and 405 are newredshifts. We also include new redshifts for 77 fainter galaxies in thesame strip.
| No X-Ray--luminous Starbursts in the Einstein Medium Sensitivity Survey, Either
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...453..611H&db_key=AST
| Galaxy Properties at the North Galactic Pole. I. Photometric Properties on Large Spatial Scales
A two-color study of the galaxies detected on POSS-I in a 289 squaredegree region centered on the North Galactic Pole is presented. We use avariety of mapping techniques to characterize the large-scale spatialdistribution of galaxies. The depth and sample size of this new surveyallows, for the first time, the isolation of large photometricsubsamples of galaxies in high- and low-density environments on thescale of superclusters. Our principal finding is a statisticallysignificant difference between the mean photometric properties of thesesubsamples in the sense that galaxies in the high-density Coma andfilament environments have redder colors and larger concentrationindices than galaxies drawn from low-density interfilament regions.These results are in accord with the known morphology-density relation.Thus, appropriately chosen photometric and morphological parameters, inconcert with a galaxy surface density map, can be used to selectstructures from the projected galaxy distribution which correspond toregions of high density. An illustration of this point is our discoveryof a concentration of blue galaxies identified in our maps near the coreof the Coma cluster. This feature is comprised of early-type galaxieswhich exhibit signs of current or recent star formation. These resultsare predicated on relations between morphological type and photometricparameters derived from APS scans of POSS-I. We therefore discuss theimage calibration procedures used to compile our catalog of physicallysignificant photometric parameters. We demonstrate the morphologicaltype dependence among quantities such as mean color and imageconcentration index, and the lack of such a dependence for mean surfacebrightness.
| X-ray luminous non-Seyfert galaxies.
Not Available
| The true nature of IRAS-selected, X-ray-luminous 'normal' galaxies in the ROSAT all-sky survey
Luminous star-forming galaxies have often been suggested as potentiallysignificant contributors to the cosmic X-ray background (XRB). Interestin this possibility has been rekindled by a recently published sample of244 IRAS/ROSAT galaxies that includes 20 with extreme X-ray luminosities(LX = 1042-44 ergs/s) that are claimed to be'normal' spiral galaxies. To investigate whether or not these 20X-ray-luminous spirals are truly normal star-forming galaxies, we havereexamined their classifications by obtaining new optical spectra of 13of them, and by locating spectra in the literature for four. Our resultsindicate that 13 of the 17 objects are previously unrecognized Seyfertgalaxies. Of the four star-forming non-Seyfert galaxies found in thissample, three are incorrectly identified as X-ray sources. Only one H IIgalaxy is a confirmed X-ray source, but it has LXapproximately equal to 1042 ergs/s and is only about twice asluminous as the most luminous normal spirals detected previously atX-ray wavelengths. Thus, there are no H II galaxies with LXsubstantially in excess of 1042 ergs/s, and claims of a newclass of X-ray-luminous spiral galaxies are not supported by this study.
| X-ray luminous IRAS galaxies
A sample of 14,708 extragalactic IRAS sources selected from the PointSource Catalog via statistical classification has been cross-correlatedwith the ROSAT All Sky Survey (Boller et al., 1992). A total of 244galaxies emerge as being detected both by ROSAT and IRAS. The mostinteresting point is the discovery of a dozen 'normal' spirals whoseX-ray luminosities reach nearly 10 exp 43 erg/s (0.1-2.4 kV), higherthan previous detection limits of a few 1041 erg/s. We obtained opticalspectra for nine of them, showing Seyfert spectra for three of theobjects (thus previous misclassifications), spectra close to LINERs fortwo further objects and normal IRAS galaxy spectra for the last four. Inthe case of 'normal' galaxies the source of energy is not clear yet andcould be related to the high rate of star formation likely to occur inthe central regions or also to a low level active nucleus. The study ofthese objects is of interest to the nature of LINERs and, moregenerally, to possible relations between AGN and starbursts (Sanders etal., 1988).
| The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
| ROSAT All Sky Survey observations of IRAS galaxies
Cross-correlations are established between 14,708 selected IRAS sourcesand the ROSAT All Sky Survey X-ray sources. The resulting catalog of 244IRAS galaxies positionally coincident with ROSAT X-ray sources ispresented. For 222 of them, optical counterparts could be identified bya comparison with the NASA/IPAC Extragalactic Database. An unexpectedresult was the discovery of several spiral galaxies with luminosities upto 10 exp 43 erg/s, well above those found with the Einstein satellite.
| The case low-dispersion northern sky survey. XII - A region in southern Canes Venatici
Positions, estimated magnitudes, and finding charts (when necessary) areprovided for 194 blue and/or emission-line galaxies, 15 H II regions inseven galaxies, 157 unresolved blue and/or emission-line objects,including QSO candidates, and 32 known and suspected blue stars in a 107sq deg region in Canes Venatici. The objects, whose blue magnitudes aremostly within the range 15-18, were identified on low-dispersionobjective-prism plates taken with the Burrell Schmidt telescope at KittPeak.
| H I survey of face-on galaxies - The frequency of distortions in H I disks
The full results of an H I survey of face-on galaxies are presented andit is shown that narrow H I profiles are rare in normal spiral galaxies.This is due in part to the wider-than-expected range of the integraldispersion and in part to the frequent occurrence of large-scaledistortions in the H I disk. These factors reduce the number of galaxieswith half-power widths less than 30 km/s to about 24 percent of thosethat would occur if galaxies generally had quiescent, coplanar H Idisks. Two useful subsets may be drawn from this study of 212 face-ongalaxies with axial ratios greater than 0.87. Fifty-two spirals of allmorphological types have half-power widths smaller than 100 km/s and maybe used for studies that benefit from a small velocity spread and anenhanced beam-filling factor. About 40 galaxies have velocity widthsmuch larger than expected and are of interest in studies of dynamicallypeculiar systems.
| A survey of galaxy redshifts. IV - The data
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.
| Flocculent and grand design spiral structure in field, binary and group galaxies
A 12-division morphological system emphasizing arm continuity, lengthand symmetry has been developed for the classification of all spiralgalaxies according to the regularity of their spiral arm structure. Armclassifications were tabulated for 305 barred and nonbarred spiralgalaxies; of these, 79 are isolated, 52 are binary and 174 are ingroups. Among the isolated SA galaxies, 68 + or - 10% have irregular andfragmented, or 'flocculent', spiral structures. Only 32 + or - 10% havesymmetric spiral arms in the classic grand design pattern. Flocculentspirals are the most common structures of galaxies without companions orbars. Since flocculent galaxies may have bars and companions, and granddesign galaxies may have neither bars nor companions, such perturbationsare neither perfectly effective nor always necessary in the driving ofgrand design patterns.
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