100-inch Reflector Research Articles

Finding the Invisible Workers in Astronomy

Why do we remember some scientists while forgetting others who participated in the same knowledge-making process? Mount Wilson Observatory was founded in 1904 by George Ellery Hale near Pasadena in Southern California and is perhaps most famous for astronomer Edwin Hubble and his observations made with the 100-inch reflector telescope, which suggested that our universe is expanding. Moving away from the prominent astronomers, intellectual ideas, and telescopes at Mount Wilson Observatory, this article focuses on the work done by some of the forgotten participants such as human computers, who were mostly women, and telescope assistants, who were men, during the first two decades since its founding. By regarding Mount Wilson Observatory as a factory observatory that carried out specialty production, I narrate scientific knowledge-making from the perspectives of these workers by examining their labor and the products that came out of their labor. These highly skilled individuals carried out various tasks, yet the degree of their participation in scientific activities depended on the supervisor, gender, and geographical space. Efficiency was the primary driving factor in how astronomers delegated work at Mount Wilson Observatory, and gender facilitated the managerial practice of using geographical space to achieve efficiency. Such practice effectively created a glass ceiling only for women, and the gendered workspace may also have contributed toward an epistemic preference by astronomers for observation over computation.

Investigations of the interstellar medium at Washburn Observatory, 1930-58

Between 1930 and 1958, the Washburn Observatory of the University of Wisconsin-Madison was home to pioneering photometric research into the interstellar medium by Joel Stebbins and Albert Whitford. Between 1933 and 1941, Stebbins and Whitford published seminal research on the photometry of stellar reddening, using the Washburn 15-inch refractor and the 60- and 100-inch reflectors at Mount Wilson Observatory. Many factors were responsible for the Washburn Observatory's pre-eminence in this area. This paper reviews their research on interstellar dust during the years 1922-58, the observational technology and scientific methods that were developed at the Washburn Observatory during that time and the scientific discoveries that originated there. We discuss the factors that enabled Washburn Observatory to become a leader in photometry during the first half of the twentieth century. We also draw on the recollections of past and present Washburn Observatory scientists¹ to understand how Washburn's standing led to a subsequent programme of research into the interstellar medium at the University of Wisconsin-Madison. The resulting portrayal of Washburn Observatory provides insights into the evolution of astronomical research in America, from the beginning of the twentieth century until today.

THE MOUNT WILSON HALO MAPPING PROJECT 1975-1985 I: THE UBV(RI)MW PHOTOMETRIC SYSTEM COMPARED WITH OTHER STANDARD SYSTEMS: THE ADOPTED TRIGONOMETRIC HR DIAGRAM IN (R-I)MW AND (V-I)MW

ABSTRACT Photometry of stars is described that defines a UBV(RI)MW photometric system, established between 1975 and 1980 using the Mount Wilson 60-inch and 100-inch reflectors. The MW natural system has been reduced to the UBV(RI)C Cape-Cousins system by linear equations for stars hotter than M0. Strong non-linear color and magnitude equations exit in R and I between the two systems for stars cooler than M0. The non-linearity is due to the change of the effective wavelengths of the red passbands caused by effect of the TiO b ands combines with the substantial difference between red response of the extended S20 cathodes used here and the GaAs cells used by Cousins (1976, 1980a,b), Bessell (1979, 1990), Landolt (1983, 1992), and others for the Cape system. We report (R-I)MW and (V-I)MW colors based on a linear extension of the MW natural system to the red for cool stars with (V-R)Cape greater than 0.8, (V-I)Cape greater than 1.8 (spectral types later than M0), as zero-pointed to the Cape system for bluer stars. Color equations are derived between the MW, the Cape, the Kron-Eggen, and Johnson photometric systems, and also the Hubble Space Telescope (V-I) colors as reduced to the (V-I)C Cape system by Holtzman et al. (1995). The Kron-Eggen and the Cape-Cousins R and I systems differ in their zero points of color and magnitudes, showing that the Kron-Eggen and the Cousins systems are not the same. The appellation of a "Kron-Cousins" photometric system used in much of the current literature is incorrect. Preparatory to determining photometric parallaxes of local higher proper motion M dwarfs in Paper IV, trigonometric HR diagrams are determined in V, (V-R)MW and (V-I)MW on the Mount Wilson system using 160 available parallax stars with parallaxes larger than 0.099 arcsec. A first appendix illustrates the difference in the effective wavelengths of the Cape-Cousins, Kron-Eggen, and Johnson systems for cool stars, based on the observed slope coefficients of the color equations that link them. A second appendix contains explicit color equations based on stars in common between Bessell's (1990) definition of the Cape system for the reddest stars and the Kron-Eggen and the MW photometric systems.

Identification of the (+2) Sequence of the CN Red System (A2Π-X2Σ) in Carbon Stars

Identification of spectral lines from λ7700 to λ8800 has been carried out in twenty-four carbon stars: AQ And, UU Aur, W CMa, Y CVn, X Cnc, ST Cas, WZ Cas, AX Cyg, RS Cyg, U Cyg, V 460 Cyg, RY Dra, UX Dra, BL Ori, W Ori, RX Peg, Z Psc, 19 Psc, S Set, Y Tau. VY UMa, HD 137613, HD 156074, and HD 182040. The spectrograms used for this purpose were obtained at the coude foci of spectrographs attached to 100-inch reflector of Mt. Wilson, 200-inch reflector of Mt. Palomar, and 74-inch reflector of Okayama. From the microphotometric tracings of each spectrogram, it was found that the main contributors to the spectral features of the region investigated are lines of the CN Red System (A2Π-X2Σ). and lines of the C2 Phillips system (b1Πu–x1Σg) are minor ones.

Mount Wilson Spectra of Standard Stars

We show part of a tracing of π Ceti, an example of a uniform series of high-quality tracings of standard stars covering the wavelength region 3850–4650 Å and derived from 10 Å/mm photographic spectrograms taken with the coudé spectrograph of the Mount Wilson 100-inch reflector.

THE VARIABLE RADIAL VELOCITY OF HE II IN THE SPECTRUM OF NOVA DQ HERCULIS

A radial-velocity variation in the Hen A 4686 emission line of DQ Herculis during its 4h 39m photometric cycle1 has been detected from measurements of 25 spectrograms obtained on four nights in May 1956 with the Newtonian-focus spectrograph of the 100-inch reflector. The dispersion was 180 Â/mm. Settings on the emission lines with a wire micrometer were made in two ways : ( 1 ) an average was taken of measurements on the outer edges of the emission ; (2) the emission line was bisected so that the integrated photographic blackening on each side of the wire was judged to be equal. Method (1) gave a value of K about 50% larger than method (2). At present it is not completely clear which method leads to a more physically meaningful result ; thus the individual radial velocities reported here are means of the two methods of measurement.

Spectrophotometry of Planetary Nebulae.

view Abstract Citations (62) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrophotometry of Planetary Nebulae. Minkowski, R. ; Aller, L. H. Abstract Measurements of the line and continuous spectra of several bright planetary nebulae by methods of photographic spectrophotometry have been carried out with the Cassegrain spectrographs at the 60- and 100-inch reflectors of the Mount Wilson Observatory. The results of extensive observations are reported for NGC 40, NGC 1535, NGC 2022, NGC 2392, and NGC 7662 Additional material has been obtained for IC 351, IC 1747, 1 320, NGC 2165, and NGC 2440 In each object the slit was placed on a selected position in the nebula and the exposures carefully guided The line intensities, expressed on the scale I(Hfl) = 100, are given for lines from the Balmer limit to N 9000 Publication: The Astrophysical Journal Pub Date: July 1956 DOI: 10.1086/146206 Bibcode: 1956ApJ...124...93M full text sources ADS |

The spectrum of R Geminorum at its unusually bright maximum in 1955.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The spectrum of R Geminorum at its unusually bright maximum in 1955. Keenan, P. C. ; Teske, R. G. Abstract R Geminorum, which is one of the brightest long-period variables having a nearly pure S-type spectrum, normally reaches a visual magnitude near 7.1 at maximum. In 1955 the maximum occurred early in March, about 20 days ahead of the predicted date, and the greatest brightness was 6.6 or 6.7 mag. Spectra covering the range from 5000 A to 8500 A were obtained with the coude' spectrograph of the 100-inch reflector at Mount Wilson both at, and slightly before, maximum. At the bright maximum the temperature, as indicated by the level of excitation of the spectrum, was slightly higher than at a normal maximum. Near magnitude 7.4 on the rising branch of the light curve the 1955 spectrum was similar to that usually observed when the star is several tenths of a magnitude brighter. Thus this Se star behaved much like an Me variable, such as Mira, at its brightest maxima. Among the few strong lines of ionized elements which are observed in the red part of the spectrum of R Gem are those of the heavy metals BalI and Laii. Several resonance lines of the corresponding neutral atoms occur in the same spectral region and are very strong when the star is fainter than one magnitude below maximum. The rapid increase in such ratios as Laii 7o66/LaI 7068 as R Gem passes a magnitude of about 7.5 on the way to maximum indicates that at an effective temperature of the order of 28000K much of the lanthanum is already ionized. This is consistent with the low ionization potential (5.61 e.v.) of Lal, and explains the sudden disappearance of the bands of LaO at about the same temperature. On the other hand, the ZrO bands persist to a higher temperature even though the two molecules are probably of comparable stability. This difference is due to the higher ionization potential (6.95 e.v.) of Zri. Perkins Observatory, Delaware, Ohio. Publication: The Astronomical Journal Pub Date: May 1956 DOI: 10.1086/107316 Bibcode: 1956AJ.....61..181K full text sources ADS | data products SIMBAD (1)

Photoelectric and Spectroscopic Observations of UX Ursae Majoris.

view Abstract Citations (44) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric and Spectroscopic Observations of UX Ursae Majoris. Walker, Merle F. ; Herbig, George H. Abstract Some eighteen hundred photoelectric observations of the eclipsing variable UX UMa were made (by Walker) in three colors with the 60- and 100-inch reflectors at Mount Wilson and are described in Section I. They show the asymmetry and stilistand on the rising branch of principal minimum that were discovered by Linnell. Eclipse is preceded by an increase in light of 0.10 mag. and is (at the present time) followed by a rise of about half that amount. The rapid, irregular fluctuations in the light of the system, also discovered by Linnell, were confirmed; their durations range from 1 to 20 minutes, while their amplitudes in the ultraviolet may be as large as 0.18 mag. They are less conspicuous at longer wave lengths. The depth of primary minimum is not always the same; furthermore, its depth increases, the shorter the wave length of observation. No secondary minimum has been observed. In Section II are described spectroscopic observations made (by Herbig) with a continuous-recording technique and a low- dispersion (430 A/mm at H ) spectrograph at the 36inch Crossley reflector of the Lick Observatory. The spectrum of the primary star is of type 0, with very wide and shallow absorption lines. Narrmv absorption is observed at the H lines in the ultraviolet (particularly H8-H1 1) during the later parts of some cycles. The radial velocity given by these narrow H lines is approximately constant, with a value of about +350 to $400 km/sec. Weak emission at HP and rather strong emission at He ii X 4685, neither of which is of constant intensity, vary in velocity throughout the cycle. The increases in brightness of UX UMa before and after primary minimum are due to an intensification of the continuous spectrum and are not accompanied by an enhancement of the emission lines. The variation of the spectrum of UX UMa through the eclipse cycle, like the details of the light-curve, is not ahvays the same. A tentative model that seems to explain some of the features of this remarkable system is discussed in Section III. Publication: The Astrophysical Journal Pub Date: September 1954 DOI: 10.1086/145914 Bibcode: 1954ApJ...120..278W full text sources ADS | data products SIMBAD (2)

THE SPECTRA OF THREE NOVAE IN SCORPIUS

The spectra of the three novae discovered in Scorpius during 1950 were recorded on a large number of films obtained by Herzog and Zwicky with the 18-inch schmidt camera and objective prism on Palomar Mountain. The spectra are 4.0 mm in length from Ha to K. One slit spectrogram of the first nova was taken by E. R. Dyer with the 100-inch reflector on Mount Wilson. The light-curves of the three novae have been determined by Herzog and Zwicky.1 In the following notes on the spectra, all dates are expressed in UT. Nova No. 1

Six-Color Photometry of Stars. VI. The Colors of Extragalactic Nebulae.

view Abstract Citations (69) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Six-Color Photometry of Stars. VI. The Colors of Extragalactic Nebulae. Stebbins, Joel ; Whitford, A. E. Abstract Photoelectric measures in six colors have been made of eight bright extragalactic nebulae of types E to Sc. As was to be expected from their mixed stellar content, the nebulae show excess radiation in both the ultraviolet and the infrared over that of a star of matching color in the visual-photographic region. With a suitable combination of stars of early and late types, the color can be reproduced over the whole observed range, while the spectrum in the blue-violet would appear to be that of stars of an earlier type than the color class in the same region. There is no need to assume internal space absorption in the nebulae to account for the difference between spectral class and color class. With the 1P21 photomultiplier tube and a two-filter system, magnitudes and colors of E-type nebulae in clusters have been measured with the 100-inch reflector down to lflpg = 18.2. The nebulae are found to be redder in proportion to their velocity of recession until for the Boötes cluster at 70,000,000 parsecs with V = 38,900 km/sec the color excess is 0.52 mag. on the International system, of which 0.22 mag. can be explained by the red shift, and 0.30 mag. is unaccounted for. Following are the tentative con- clusions: 1. The reddening of the nebulae is proportional to the red shift. On the plausible assumption that the unexplained part of the excess is linear with distance, this result supports a linear velocity-distance rela- tion. 2. The excess reddening can be explained as selective absorption by internebular material of mean density ten to one hundred times the smoothed density of the luminous nebulae in all space. The con- siderable inward corrections to the previously assumed distances would, however, be difficult to reconcile with the nebular counts. 3. The excess reddening can be interpreted as an intrinsic change in E-type nebulae in the 2 X 108 years since the observed light left the Boötes cluster. Fading of red supergiants as their energy sources are consumed could provide a mechanism. 4. Both the excess reddening and the ultraviolet excess found in the six-color results will affect the luminosity correction to be applied to a faint nebula with a large red shift. Previous ConcluSions about the interpretation of the nebular counts are therefore open to revision Publication: The Astrophysical Journal Pub Date: November 1948 DOI: 10.1086/145077 Bibcode: 1948ApJ...108..413S full text sources ADS | data products NED (11) Related Materials (12) Part 1: 1943ApJ....98...20S Part 2: 1945ApJ...101...47S Part 3: 1945ApJ...102..318S Part 4: 1946ApJ...103..108S Part 5: 1947ApJ...106..235S Part 7: 1952ApJ...115..292S Part 8: 1954ApJ...120..189S Part 9: 1956ApJ...123..440S Part 10: 1957ApJ...126..266S Part 11: 1964ApJ...139..424S Part 12: 1969ApJ...155..899S Reprint: 1948CMWCI.753....1S

The astrometric orbit of Procyon.

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The astrometric orbit of Procyon. Strand, K. Aa. Abstract From a series of 105 plates taken with the ~o-inch Yerkes refractor between 1916 and 1949 and a series of 85 plates taken with the ~6-inch McCormick refractor between 1915 and 1942 the astrometric orbit of the brighter component of Procyon and its parallax have been derived. Since the photographic material does not cover the entire period of 40.3 years the micrometer measures made by Aitken and Barnard between 1897 and 1913 were used in establishing the period. The photographic material gives the relative parallax "293 ~ `1006 (p.e.) in close agreement with the value given by Schlesinger's catalogue, and the value I `1194 ~ `1010 for the semi-major axis of the astrometric orbit. Utilizing the series of relative distances between the components observed by Barnard and Aitken the semi-major axis is 4'1520. The adopted value `1295 for the absolute parallax gives the masses 1.630 and .590 for the visual components. The mass for the brighter component is of the expected order of value for an F~ IV star with a bolometric magnitude 2.73. For an independent check on the derived orbital motion and the parallax a series of 17 spectrograms taken at the coude' focus of the 100-inch reflector between 1926 and 1946 have been measured but as yet not fully reduced. Dearborn Observatory, Evanston, Ill. Publication: The Astronomical Journal Pub Date: September 1949 DOI: 10.1086/106262 Bibcode: 1949AJ.....54..196S full text sources ADS | data products SIMBAD (1)

Spectrophotometry of the planetary nebula NGC 7027.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrophotometry of the planetary nebula NGC 7027. Minkowski, R. ; Aller, L. H. Abstract The bright planetary nebula NGC 7027 shows, in addition to a strong continuous spectrum, the richest line spectrum of any gaseous nebula. Standardized spectrograms of this nebula covering the wave length range from NN3300-8800 plus similar plates taken of Vega and E Persei but with the aid of a quartz diffuser permit a determination of the energy distribution in the continuous spectrum and the true relative intensities of the emission lines. The observations were obtained at Mt. Wilson with the 100-inch reflector and at the McDonald Observatory with the 8~-inch reflector. The energy distribution in the Balmer continuum fits the hypothesis of a recombination spectrum at an electron temperature of 100000 and is in reasonably good agreement with Page's results. The energy distribution in the visual and infra-red regions does not fit this simple hypothesis and it is possible that other mechanisms are operative here. The photometry of the continuous spectrum is difficult because of the numerous overlapping emission lines. The intensities of the emission lines range over a factor of five thousand, and it is of interest that Wyse's estimates, made with the aid of a scale plate, show reasonably good agreement with our results over the range XX3700-5000. In the X~~000-6800 interval, Wyse's intensities are systematically larger. A comparison of the line intensities in two different parts of the nebula shows that stratification effects are small but noticeable. Kirkwood Observatory, Bloomington, Ind. Publication: The Astronomical Journal Pub Date: June 1948 DOI: 10.1086/106098 Bibcode: 1948AJ.....53..202M full text sources ADS |

A Search for Faint Blue Stars.

view Abstract Citations (181) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Search for Faint Blue Stars. Humason, M. L. ; Zwicky, F. Abstract Four-color photography has been used in a search for faint blue stars with the 18-inch Schmidt tele- scope at Palomar, undertaken in the hope of finding new white dwarfs. In this Contribution the results are given for stars brighter than magnitude 15.0 pg in two regions (a) the Hyades clustei; (b) the region of the north galactic pole. Spectroscopic observations have been made with the 100-inch reflector. In the Hyades region fourteen blue stars were found, with spectral types ranging from BO to B5. Proper motions are known for ten of these stars. From their motions and spectra, four are shown to be white dwarfs, three of them physical members of the cluster. Absorption lines are wide and shallow in the spectra of two others, whose motions are not known-an in~1ication that they also may be white dwarfs. In the region of the north galactic pole thirty-one blue stars were found. Their spectra range from BO to AO. Proper motions are available for only four stars, one of which, from its motion and spectrum, is a white dwarf. Two other stars, whose motions are unknown, have spectra similar to those of the white dwarfs. The spectra of the remaining twenty-eight stars appear normal; if these objects are high-lumi- nosity blue stars, their distances are exceedingly large. Possibly they belong to the type of stellar popula- tion shown in the Hertzsprung-Russell diagram for globular clusters and designated by Baade as "Type II." If so, their absolute magnitudes are about 0.0, and their distribution in space would be similar to that of the globular clusters and cluster-type variables Publication: The Astrophysical Journal Pub Date: January 1947 DOI: 10.1086/144884 Bibcode: 1947ApJ...105...85H full text sources ADS | data products SIMBAD (48) CDS (1) Author (1) Related Materials (6) Catalog: 2010yCat..11050085H Part 2: 1954AJ.....59..224L Part 3: 1956AJ.....61..261L Part 4: 1956AJ.....61..262L Part 5: 1956AJ.....61..264L Reprint: 1947CMWCI.724....1H

The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Twentieth Series.

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Twentieth Series. van Maanen, Adriaan Abstract Trigonometric parallaxes determined with the 60- and 100-inch reflectors are given for 25 fields, in- cluding 28 stars. As in the other recent series, most of the stars were placed on the program on account of their large proper motions Publication: The Astrophysical Journal Pub Date: May 1946 DOI: 10.1086/144810 Bibcode: 1946ApJ...103..289V full text sources ADS | Related Materials (1) Reprint: 1946CMWCI.721....1V

The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Nineteenth Series.

The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Nineteenth Series.

THE EXPANDING SHELL AROUND NOVA HERCULIS

The appearance of the expanding nebula around Nova Herculis on photographs obtained with the 100-inch reflector in 1940 was described in a previous note.1 The nebula then appeared as a small elliptical disk of uniform brightness when photographed in the light of the strong N 1 and N 2 emissions. Its surface brightness, both in the photographic and the photovisual range, was so high that the central star was lost in the light of the surrounding nebulosity. Quantitative data, given at the end of the note, indicated, however, that decreasing surface brightness of the nebula due to the expansion would make it possible to distinguish the star in the near future. The present note deals with observations of the nebula during the summer of 1942. Most of the plates during this season were taken at the Cassegrain focus of the 100-inch reflector, which offers the advantage of a large scale (1 mmziSTO). The fact that the Cassegrain arrangement can be used to full advantage only with seeing 6 or better imposed no serious restrictions since the best seeing is required anyhow to photograph details in an object barely 4 seconds of arc in diameter.

The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Seventeenth Series.

view Abstract Citations (16) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Seventeenth Series. van Maanen, Adriaan Abstract Trigonometric parallaxes determined with the 60- and 100-inch reflectors are given for 25 fields, including 26 stars, 20 of which have photographic absolute magnitudes of +10 or fainter; 5 are even +15 or fainter. A list is given of the 21 stars known at present for which the absolute photographic magnitude is fainter than + `5 Publication: The Astrophysical Journal Pub Date: June 1940 DOI: 10.1086/144192 Bibcode: 1940ApJ....91..503V full text sources ADS | Related Materials (1) Reprint: 1940CMWCI.630....1V

The Radial Velocities of 600 Stars and Measures of 69 Spectroscopic Binaries.

view Abstract Citations (27) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Radial Velocities of 600 Stars and Measures of 69 Spectroscopic Binaries. Christie, William H. ; Wilson, O. C. Abstract The radial velocities of 600 stars observed with the 60- and 100-inch reflectors are given. This list is in no way homogeneous and contains stars from several observing lists made up for various investigations. In addition, measures are given for 69 variable-velocity stars, some of which have been observed elsewhere Publication: The Astrophysical Journal Pub Date: July 1938 DOI: 10.1086/143958 Bibcode: 1938ApJ....88...34C full text sources ADS | data products SIMBAD (1) Related Materials (1) Reprint: 1938CMWCI.593....1C

The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors

Trigonometric parallaxes determined with the 60- and 100-inch reflectors-Results are given for 25 fields including 28 stars, 15 of which have photographic absolute magni- tudes of +10 or fainter; 3 are even +15 or fainter. One white dwarf is included, AC+ 7008247, fr which the absolute magnitude is + i i.ç~. For U Geminorum and SS Cygni the absolute parallaxes are +o~oio and -0'~OI2, respectively