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This page summarizes the reseach I've done in Astronomy. Click here to see my Curriculum Vitae. Note: I haven't updated this since June 1996.

Want to see the latest version of the guide to creating slit masks for the Double Imaging Spectrograph at Apache Point Observatory? I'll update it as I discover any new information.

I graduated from Denton High School (in Texas) in 1986 and entered the University of Texas at Austin. For my first two years there, I majored in both Computer Science and Astronomy. After two years of programming classes, though, I decided that since my eventual goal is to teach and do research rather than work in industry, I'd rather do something I enjoy. I enjoy Astronomy more, though I still program a fair bit. I'm fluent in Fortran, Pascal, Assembly Language, Modula-2, and C. I taught myself C, and I am always writing programs in C to help my data reduction and so forth.

As an undergraduate in the UT-Austin Department of Astronomy, I worked with Paul Hemenway, a member of the UT-Austin contingent of the HST Astrometry Science Team, on modeling minor planet light curves and several iterations of HST proposals and with Art Whipple on a paper on the statistics of minor planet orbits.

After getting my BS in Astronomy at Texas, I came to the University of Washington to pursue my PhD in the UW Department of Astronomy. Since here, I have done research on Cataclysmic Variable stars (specifically Nova Herculis 1991) with Paula Szkody and others. I am currently working with my thesis advisor, Craig Hogan, on a paper about the calibration of M31 (Andromeda galaxy) and the rotation velocity line widths of galaxies in general.

My thesis will utilize Apache Point Observatory to image very faint galaxies that are associated with (or responsible for) high-redshift Lyman-alpha absorption features in the spectra of quasars. We hope to perform spectroscopy and multi-color photometry on these objects to find out more about very young (or possibly forming) galaxies.

My Papers and Abstracts (reverse order by date)

``SPH Simulations of the Early Universe: Performance of the Dwingeloo Square Kilometer Array''

Ingram, D. R., Katz, N., Weinberg, D. H. and Hernquist, L. 1995 in proceedings of the workshop ``Cold Gas at High Redshift'' (Kluwer Academic, Dordrecht), in press.

Using the results of cosmological simulations evolved with smoothed particle hydrodamics, we can predict the distribution of neutral hydrogen in a (22.2 Mpc)^3 comoving box at high redshifts. By converting these boxes into two-dimensional images, convolving with a Gaussian beam and adding noise appropriate to sensitivity estimates, we have simulated a series of observations by the proposed Square Kilometer Array (SKA). The capability of the SKA to easily detect 10^10 M(sun)/beam concentrations of neutral Hydrogen (``galaxies'') should impose significant constraints upon the large scale structure proposed in a variety of cosmological models.

``Rotational Line Widths and the Size of M31 as a Distannce Calibrator''

Ingram, D. R. and Hogan, C. 1995, AJ 110, 634

Sandage (1993a, 1993b) has presented an argument in favor of low H by equating the diameter of M31 with the mean of a sample of similar galaxies, using this to calibrate the distance scale to Virgo. Here we argue based on a wider sample taken from Tully (1988) that the rotation line width of M31 implies that M31 is not representative of an average-size galaxy. Linear diameters are estimated from line width information and the Tully-Fisher relation in order to estimate a less biased calibration of M31 relative to a sample of similar spirals.

``The Trailblazers''

Ingram, D. R. 1995, Mercury, 24, 25.

A one-page article about my experience as a minority in Astronomy.

``The Masses of V838 Herculis (Nova Herculis 1991) and QZ Aurigae''

Szkody, P. and Ingram, D. 1994, ApJ, 420, 830

The authors have determined H-alpha radial velocity solutions for the two eclipsing novae, V838 Her (Nova Her 1991) and QZ Aur, which yield mass estimates for the stellar components. The results indicate that both objects have relatively massive white dwarfs (> 0.62 solar masses for V838 Her and >0.65 solar masses for QZ Aur), although these limits allow lower masses than theoretical models for fast novae predict. Even though both novae have long periods (7.14 hr and 8.58 hr), there is no visible evidence of the secondary star in the spectrum. The large extent and the brightness of the accretion disk, as deduced from the light curves, make the disk the dominant source of light.

``Mass Estimates of the Fast Novae QZ Aur and Her 1991''

Ingram, D. and Szkody, P. 1993, AAS Poster Paper, 182nd meeting

Abstract similar to above paper.

``CCD Photometry of the Cataclysmic Variable HV Virginis''

Ingram, D. and Szkody, P. 1992, IBVS, 3810, 1

Reports CCD V-band photometry on 1992 April 30 and May 1 indicating the presence of superhumps of 0.2 mag amplitude and 84.1 +/- 0.4 minutes period. Light curves from the two nights are presented and the properties of HV Vir are compared with other large amplitude dwarf novae at high Galactic latitudes.

``Photometry and Spectroscopy of Nova Herculis 1991''

Ingram, D., Garnavich, P., Green, P. and Szkody, P. 1992 PASP, 104, 402

Presents observations of Nova Herculis 1991 obtained during the months of 1991 May-September. Spectral observations a few weeks after outburst constrain the distance to Nova Her to between 6 and 12 kpc and show evidence of dust formation in the expanding shell and line profiles with five components having large expansion velocities. The initial photometric observations of the nova in June showed that the nova had declined approximately ten magnitudes in the V-band from its maximum, and by September, the nova had dimmed by approximately two additional magnitudes. The period derived from the observations agrees with that reported by Leibowitz et al (1992). Periodic eclipses with a depth of about 0.7 V mag are observed, and the depths of the eclipses are constant over a 2- month period while the overall brightness diminished by one magnitude. The long duration of the eclipses indicates an eclipse of an extended source, probably the accretion disk.

``HV Virginis''

Szkody, P. and Ingram, D. 1992, IAUC 5516

Time-resolved CCD photometry of the very-large-amplitude dwarf nova HV Vir on 1992 April 30 and May 1 demonstrates the presence of superhumps of 0.2 mag. amplitude, with a period of 84.1+or-0.4 min. The V-magnitude was about 13.4. Since the superhump period is a few percent longer than the orbital period, HV Vir increases the correlation of large outburst amplitude with orbital periods below the period gap for high- Galactic-latitude dwarf novae. In addition, visual magnitude estimates are reported for the period 1992 April 24 to 30.

``Initial Refinement of Minor Planet Orbits for Pointing and Observation with the Hubble Space Telescope''

Whipple, A. L., Hemenway, P. D. and Ingram, D. 1991, AJ, 102, 816

Refinements of the orbital elements for 24 minor planets that will be observed with the Fine Guidance Sensors (FGSs) on the Hubble Space Telescope are presented. The accuracy of these orbits is discussed in the context of the ephemeris requirements for target acquisition with the FGSs. Comparisons with standard catalog orbits are made to evaluate the suitability of the use of the catalog orbits for HST pointing. The authors find that the orbits published in the most recent Minor Planet Circulars are capable of positional predictions that are accurate at the 1 arcsec level. However, there are still many orbits that have not been revised in the last 10 yr and these should not be used for critical pointing ephemerides. In many cases the orbital elements will have to be refined using recent ground-based observations before a minor planet can be reliably observed by HST.

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