------------------------------------------------------------------------ From dmehring@socrates.patnet.caltech.edu Wed Sep 17 14:07:23 1997 From: David Mehringer Date: Wed, 17 Sep 1997 11:07:15 -0700 (PDT) To: gcnews@astro.umd.edu %\input askewmacros.tex %\nopagenumbers %\twelvepoint %\baselineskip 20pt \font\sixrm=cmr5 \documentstyle[12pt,aasms4]{article} \newcommand\cmtwo{cm$^{-2}$ } \newcommand\cmtwon{cm$^{-2}$} \newcommand\cmthree{cm$^{-3}$ } \newcommand\cmthreen{cm$^{-3}$} \newcommand\arcsecn{$^{\prime\prime}$} \newcommand\arcminn{$^\prime$} \newcommand\tsyst{$T_{\rm sys}^{-2}$ } \newcommand\tsystn{$T_{\rm sys}^{-2}$} \newcommand\perbeam{beam$^{-1}$ } \newcommand\perbeamn{beam$^{-1}$} \newcommand\kms{km~s$^{-1}$ } \newcommand\kmsn{km~s$^{-1}$} \newcommand\tr{$T_{\rm r} $} \newcommand\trn{$T_{\rm r}$} \newcommand\vlsr{$v_{\rm LSR}$ } \newcommand\vlsrn{$v_{\rm LSR}$} \newcommand\degn{$^\circ$} \newcommand\slumn{L$_\odot$} \newcommand\slum{L$_\odot$ } \newcommand\smasn{M$_\odot$} \newcommand\smas{M$_\odot$ } \newcommand\htco{H$_2$CO } \newcommand\htcon{H$_2$CO} \newcommand\water{H$_2$O } \newcommand\watern{H$_2$O} \begin{document} \title{VLA Observations of the Sagittarius D Star-Forming Region} \author{David M. Mehringer(1), W. M. Goss(2), D. C. Lis(1), Patrick Palmer(3), and Karl M. Menten(4)} \affil{California Institute of Technology, Downs Laboratory of Physics, MC 320-47, Pasadena, CA 91125} \affil{National Radio Astronomy Observatory, Box O, Socorro, NM 87801} \affil{University of Chicago, Department of Astronomy and Astrophysics, 5640 S. Ellis Ave., Chicago, IL 60637} \affil{Max-Planck-Institut f\"ur Radioastronomie, Auf dem H\"ugel 69, D-53121 Bonn, Germany } \begin{abstract} We have carried out a program of VLA observations of the Sgr D (G1.13--0.10) star-forming region in order to gain a better understanding of this source. Continuum observations at 6 and 18 cm show a region which is dominated by a single compact source. This source is embedded in a halo of ionized gas and there are several compact continuum sources scattered about the field. The supernova remnant G1.05--0.15 is located 5\arcmin\ south of the main H II region. From the continuum observations we determined the physical conditions of the thermal sources in Sgr D. Observations of the 6 cm transition of H$_2$CO which appears in absorption were also carried out to study the distribution and kinematics of molecular material in this region. These data indicate that the distribution of molecular material is clumpy, with apparent optical depths varying by about one order of magnitude within single clouds. In addition, the line widths of the molecular clouds associated with the Sgr D H II region (G1.13--0.10) are $\sim$3 \kmsn, which is more typical of Galactic disk than Galactic center sources. The narrow molecular lines and the presence of higher velocity, broader \htco absorption lines in the Sgr D spectrum indicate that this region is probably located on the far side of the Galactic center region. %suggesting that this region is actually located in the Galactic %disk, rather than near the Galactic center. OH and \water maser observations indicate that there may be at least three sites of very recent star formation in this region. \end{abstract} \keywords{H II regions --- ISM: individual: (Sagittarius D) --- radio continuum: interstellar --- radio lines: ISM} \section{Introduction} The massive star-forming region Sgr D (G1.13-0.10) is a bright radio source with a projected offset of 1$^\circ$ from the Galactic Center. Because it is located near the much more prominent sources Sgr A and Sgr B2, which have received considerably more observational attention, relatively little is known about Sgr D. There have been a few previous observations of this region from which a basic picture has developed. Very Large Array\footnote{The Very Large Array of the National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.} (VLA) radio continuum observations have shown that this region is dominated by a single compact source which is surrounded by a halo of diffuse emission (Odenwald 1989; Liszt 1992). In the 18 cm VLA continuum image of Liszt (1992), there are several compact sources in the 36\arcmin\ field. Also apparent in this image, as well as in the 36 cm image of Gray (1994a) from the Molonglo Observatory Synthesis Telescope, is the supernova remnant (SNR) G1.05--0.15 which is located 5\arcmin\ to the south of the large Sgr D H II region. However, from previous data it is unclear whether the H II region and SNR are actually located close to one another or if their apparent proximity is just a chance projection. The luminosity of the corresponding Sgr D far infrared source is 6 $\times$ 10$^5$ \slum (Odenwald \& Fazio 1984, assuming a distance of 8.5 kpc). Odenwald (1989) has suggested that the morphology of the Sgr D continuum source is consistent with that of a blister H II region. For an expansion velocity of 10 \kmsn, the estimated age is 5 $\times$ 10$^4$ yr. Radio recombination lines observed with the NRAO 43 m telescope show that ionized material in Sgr D has a velocity of --21 \kms (Anantharamaiah \& Yusef-Zadeh 1989). This velocity is forbidden in the sense of Galactic rotation. The associated CS $J$=5$\rightarrow$4 and 7$\rightarrow$6 lines have been observed by Lis (1991) using the Caltech Submillimeter Observatory. These lines have velocities of --16 \kms and are quite narrow (FWHM = 3.7 \kmsn). Such narrow lines are commonly observed in Galactic disk star-forming regions. In contrast, the lines in Galactic center molecular clouds are significantly wider (FWHM = 10 to 20 \kmsn; G\"usten 1989). Thus, from these observations it is unclear where Sgr D is located. %Sgr D appears not to be located in the Galactic Center region. Based on previous single-dish \htco absorption line studies, Liszt (1992) suggested Sgr D may be located either in or beyond the Galactic Center region. On the basis of CS observations, Lis (1991) suggested that this region might be located in the ``Expanding Molecular Ring'' that is at a distance of 160 pc from the Galactic Center. We have undertaken a program of observations targeting Sgr D in order to gain a better understanding of this region. Using the VLA, we have observed continuum emission from this region at 6 cm and have reprocessed the 18 cm data of Liszt (1992). Continuum observations at these two wavelengths allow for the determination of the radio spectra yielding basic information on the sources in this region. We have also observed the 6 cm ground state transition of ortho-\htco in absorption in order to gain a better picture of the detailed distribution of the molecular gas in this region. In addition, OH and \water maser observations were carried out in order to identify sites of very recent star formation. \section{Observations} The 6 cm continuum observations were carried out using the DnC configuration of the VLA in July 1992. This hybrid configuration consists of the southeast and southwest arms in the smallest (D) configuration and the north arm in the larger C configuration. Such a geometry produces a circular beam for sources south of $\delta$ = --15\degn. Five 6 cm continuum fields were observed. A typical resolution was 10\arcsec\ for the uniformly weighted 6 cm continuum images. The 18 cm continuum observations were carried out by Liszt (1992) using the C and D configurations of the VLA. The maximum resolution of these images was 28\arcsec\ $\times$ 15\arcsec\ (P.A.=--7\degn). Other relevant parameters for the continuum observations are summarized in Table 1a. The 6 cm \htco observations were carried out using the DnC configuration in July 1992. A single field was observed and the naturally weighted channel images had an angular resolution of 13\arcsec. The \htco observation used the 4IF mode of the VLA correlator. The two IF pairs were centered at +54 and --34 \kmsn. In addition, within both IF pairs, one IF had a total bandwidth of 3.125 MHz (195 \kmsn) and 31 Hanning-smoothed channels giving a spectral resolution of 97.7 kHz (6.0 \kmsn). The other IF within the pair had a total bandwidth of 1.5625 MHz (100 \kmsn) and 63 Hanning-smoothed channels for a spectral resolution of 24.4 kHz (1.5 \kmsn). Thus, the LSR velocity range of --130 to +150 \kms was covered with 6.0 \kms spectral resolution and the LSR velocity range of --90 to +100 \kms was covered with 1.5 \kms spectral resolution. Other relevant \htco observational parameters are summarized in Table 1b. The OH maser observations were carried out at the OH transition frequencies of 1612, 1665, and 1667 MHz so that we could distinguish between maser emission associated with evolved stars or young stellar objects. A single field was observed using the BnA configuration. Both left- and right-hand circularly polarized radiation was observed. The observing band was centered at --15 \kms and had a total bandwidth of 1.5625 MHz (280 \kmsn). This spectral window was divided into 127 Hanning-smoothed channels producing a spectral resolution of 12.2 kHz (2.2 \kmsn). Other relevant parameters for the OH maser observations are summarized in Table 1c. The \water maser observations were carried out using the DnC configuration and two fields were observed. These observations were part of a project to search for masers in several regions near the Galactic center; the results for other regions will be discussed in a future publication (Lis, Menten, \& Mehringer 1997). Two spectral windows were observed simultaneously having center velocities of --45 and +15 \kmsn. Each window had a total bandwidth of 6.25 MHz (90 \kmsn) and was divided into 63 non-Hanning smoothed channels for a nominal spectral resolution of 97.7 kHz (1.3 \kmsn). During post-processing, the data were Hanning smoothed and so the spectral resolution decreased to twice its nominal value. Other relevant parameters for the \water maser observations are summarized in Table 1d. \section{Results and Discussion} \subsection{Radio Continuum Observations} The primary objective of the continuum study was to image the ionized gas in Sgr D at 6 and 18 cm. From these data, the spectra and physical conditions of the sources can be determined. Like previous continuum images of this region, our images show that Sgr D is dominated by a single compact source (source 3 of Liszt 1992 [G1.12-0.10]) that is embedded in a halo of diffuse emission. There are also a number of compact sources scattered about the field. Figure 1 is an 18 cm contour image of the Sgr D region. This image was created using both C- and D-configuration data and has a resolution of 28\arcsec\ $\times$ 15\arcsec\ (P.A. = --7\degn). The source designations of Liszt (1992) are used. The flux density of all sources in the field, including the emission regions in the northeast and northwest portions of Figure 1, is about 25 Jy. Figure 2 is a 6 cm contour image of the Sgr D region. This image is a five field mosaic %that was created using VTESS, an %AIPS maximum entropy deconvolution program. The image and has a resolution of 10\arcsecn. %The H II region Sgr D (G1.13-0.10) consists of a bright (2.3 Jy at 6 cm) compact %source (region 3) that is embedded in a large (7\arcmin\ diameter) %diffuse halo of emission. The 6 cm and 18 cm flux densities of the large Sgr D H II region (G1.13--0.10) are 9.5 and 14.5 Jy, respectively. Some emission at 6 cm was not detected because of missing short antenna spacings which correspond to fringe spacings of $\ga$5\arcminn. Assuming that the 18 cm and 6 cm flux densities are equal which is expected for an optically thin, thermal source, this undetected component has a 6 cm flux density of 5 Jy. %The average undetected 6 cm intensity in this region is 3.4 mJy %beam$^{-1}$ (1 beam = 112 arcsec$^2$), which corresponds to about 5 %$\sigma$. The SNR G1.05--0.15 is located 5\arcmin\ south of the H II region. It is brightened on the northern edge. The SNR flux densities at 6 and 18 cm are 5.0 and 12.3 Jy, respectively. Though some of the emission was probably not recorded at 6 cm because of the missing short spacings, the rising flux density of this source at longer wavelengths is also due to its nonthermal nature; Gray (1994a) reports a 36 cm flux density of 18 Jy. In addition to the Sgr D H II region (G1.13--0.10) and the G1.05--0.15 SNR, the extended emission region G1.4--0.1 is apparent about 15\arcmin\ northeast of Sgr D (G1.13--0.10) in Figure 1. Gray (1994b) has suggested that this region may be an SNR. In the 18 cm image presented here, it has a flux density of about 4 Jy. The observed parameters for the compact sources are presented in Table 2. Listed in this table are the source designation, the peak position, the 6 and 18 cm flux densities ($S_{\rm 6 \ cm}$, $S_{\rm 18 \ cm}$), and the FWHM diameter of the source. Sources which have flux density measurements at both 6 and 18 cm probably have thermal spectra. Source 5 has a greater flux density at 18 cm than at 6 cm. However, this source is embedded in a low intensity extended component, making flux density measurements difficult. Because of the relatively coarse resolution (10\arcsecn) of these observations, most of the compact sources are unresolved. Physical parameters for the H II regions listed in Table 2 are presented in Table 3. In this table are listed the source designation, the peak emission measure (Peak $EM$), the rms electron number density (RMS $n_{\rm e}$), the mass of the ionized material ($M_{\rm HII}$), the logarithm of the number of ionizing photons ($N_{\rm i}$), and the spectral type of a single zero-age main sequence star ($ZAMS$) that would ionize the gas. An electron temperature of 7,000 K and a distance of 8.5 kpc were assumed for all sources. While we have adopted the distance to the Galactic Center for the distance to Sgr D, it should be kept in mind that Sgr D may be located signifcantly farther than this distance (see below). Peak emission measures and electron densities were computed using the methods of Wood \& Churchwell (1989). Masses were computed for unresolved sources assuming that they are spherical. The number of ionizing photons was computed for all sources using the equations of Mezger \& Henderson (1967), the refinements of Panagia \& Walmsley (1978), and corrections %(mainly in the sense of typographical errors which occur in the equations) % to the latter paper made by Viallefond (1991). The ZAMS star was determined using the data of Panagia (1973). In the case of unresolved sources, the listed emission measure and electron density are lower limits, while the mass of ionized gas is an upper limit. Like Sgr B (e.g., Mehringer et al. 1992), Sgr D has a halo of extended emission. The average 18 cm intensity of this component corresponds to to an emission measure of 4$\times$10$^4$ cm$^{-6}$ pc. For a diameter of 7\arcmin\ (17 pc), the rms electron density is $\sim$50 cm$^{-3}$. The mass of the ionized gas in this component is $\sim$3000 \smasn. These parameters are similar to those found for Sgr B1 and Sgr B2 (Mehringer et al. 1992; Mehringer et al. 1993). In the case of Sgr B1, the associated extended component has an rms electron number density of 80 \cmthree and the mass of ionized material is 5000 \smas (Mehringer et al 1992). In the case of Sgr B2, these parameters are 60 \cmthree and 3000 \smasn, respectively (Mehringer et al. 1993). Odenwald \& Fazio (1984) have estimated the luminosity of Sgr D to be 6($\pm$5) $\times$ 10$^5$ \slum based on far IR measurements. This luminosity is low compared to the radio flux density of 14.5 Jy, assuming all the radio continuum flux is produced by material that is ionized by stars. A single star of spectral type O4 would be sufficient to ionize the gas. However, this star would have a total luminosity of 1.2 $\times$ 10$^6$ \slumn, twice that estimated by Odenwald \& Fazio (although marginally consistent with their uncertainty). However, if the initial mass function (IMF) of stars in Sgr D is similar to the solar neighborhood IMF, then in order to produce the observed radio continuum flux density, the total luminosity of stars in the region would be $\sim$3 $\times$ 10$^6$ \slumn, about six times the value determined by Odenwald \& Fazio. The low luminosity of Sgr D as determined from the far IR data may indicate that there is not enough dust in the immediate vicinity to absorb and re-emit all of the stellar radiation, or that the IMF in Sgr D significantly differs from that in the Solar neighborhood. \subsection{6 cm \htco Absorption Observations} The \htco absorption study was difficult because of the low optical depths toward Sgr D and the low continuum intensities. In addition, the complicated morphology of this region often caused the spectra to have nonlinear baselines, which made it difficult to identify weak lines. A continuum image produced from line-free channels is shown in Figure 3. The letters mark the positions where \htco spectra were taken. The narrow band (1.5625 MHz bandwidth) spectra are displayed in Figure 4a and the wide band (3.125 MHz bandwidth) spectra are presented in Figure 4b. One or more Gaussians were fitted to the narrow band spectra and the results are presented in Table 4. Listed in this table are the source designation, the central position, the mean 6 cm continuum intensity ($\overline{I_{\rm c}}$), the dimensions of the rectangular area over which the spectrum was integrated, the line central velocity (\vlsr), the line FWHM ($\Delta v$), the optical depth at line center ($\tau_0$), and the ratio of the column density of \htco in the lower state to the excitation temperature ($N_{\rm L}/T_{\rm ex}$). This last quantity was calculated using %$${N_L\over T_{ex}} = {6 k\over {8 \pi^3 \nu \mu^2}} \int{\tau %dv,}\hskip 2in (1)$$ %where $\mu$ = 2.33$\times$10$^{-18}$ esu cm is the %dipole moment of %\htco and $\tau = -\ln(1+T_L/T_C)$ is the apparent optical %depth. %Assuming a Maxwellian velocity distribution gives $${N_L\over T_{ex}} = 1.36 \times 10^{13} \tau_0 \Delta v,\hskip 2in (1)$$ where $N_L\over T_{ex}$ has units of cm$^{-2}$ K$^{-1}$ and $\Delta v$, the FWHM of the assumed Gaussian-shaped line profile, has units of \kmsn. Because of the low spectral resolution and narrow line widths, fits were not made for the wide band spectra. Position A corresponds to source 3 (G1.12--0.10) of the continuum study. Because this source is relatively intense, lines with low optical depths ($<$0.10) could be observed. There are four lines for which good fits were obtained (see Table 4). The three lines at negative velocities are narrow ($\Delta v <$5 \kmsn) and the optical depths for all these lines are small ($<$0.3). The \htco absorption feature at --17.1 \kms is very likely due to the molecular cloud associated with the Sgr D H II region (G1.13-0.10); the ionized material has a velocity of --21 \kms (Anantharamaiah \& Yusef-Zadeh 1989). %In addition, %the wide band spectrum of this region shows evidence for a cloud near %--60 \kmsn. Position B includes source 2 (G1.10--0.09) of the continuum study. As at position A, the linewidths for the clouds at negative velocities are $<$5 \kmsn. Because of the low continuum intensity, only clouds with optical depths $\ga$0.4 could be detected. The \vlsr = --18.1 \kms line at position B and the \vlsr = --17.1 \kms line at position A are probably due to the same cloud. The difference in velocities represents a gradient of 0.21 \kms pc$^{-1}$. The difference in optical depth is about a factor of ten, indicating that this feature is quite nonuniform. Similarly, the --14.5 \kms line at position B and the --11.3 \kms line at position A may be due to the same feature. The gradient in this case is 0.68 \kms pc$^{-1}$ and the optical depth difference from position B to position A is about a factor of 2.5. %In addition to the clouds listed in Table 4, the %wide band spectrum also indicates that there may be clouds near +20 %and +120 \kmsn. However, the spectral baseline appears to not be %linear, so it is not certain if these ranges of enhanced optical %depth are due to clouds or to the nonlinear baseline. Position C is located in the wishbone shaped region located north of position A. There is only one certain line detection at this position. at --19.6 \kmsn. This line and the --17.1 \kms line at position A are probably due to the same feature. The velocity gradient between position A and C is 0.60 \kms pc$^{-1}$. Position D is located in the brightest part of the SNR. Unlike the other three positions, no lines are detected near \vlsr = --18 \kmsn. Optical depth spectra made by averaging over the entire Sgr D H II region (G1.13--0.10) are displayed in Figure 5 and similar spectra for the G1.05--0.15 SNR are displayed in Figure 6. Because of the complexity of the narrow band spectra and the low spectral resolution of the wide band spectra, attempts to fit Gaussians to these spectra were unsuccessful in most cases. Downes et al. (1980) included Sgr D (G1.13--0.10) and the G1.05--0.15 SNR in their \htco and H110$\alpha$ recombination line survey of Galactic radio sources using the Effelsberg 100 m telescope. A comparison between central velocities of features observed in their study and the present investigation is given in Table 5. For the most part, there is good correspondence between spectral features observed with the 100 m telescope and those observed with the VLA. One notable exception is in the +40 to +90 \kms range toward the Sgr D H II region (G1.13--0.10). However, from the 6 cm \htco spectrum of Wadiak, Rood, \& Wilson (1988) a single, broad absorption feature is quite apparent in this velocity range. This feature is most likely the result of a superposition of several clouds, and so velocity assignments of individual components are somewhat subjective. This is especially true for the 100 m measurements, because the angular resolution is very coarse at 2.6\arcmin. Results of recent studies (e.g., Lis 1991) indicate that Sgr D is not located in the Galactic Center region. The CS line that has a velocity near the recombination line velocity has a width of only 3.7 \kmsn. Such narrow molecular lines are typical of Galactic disk molecular clouds. In contrast, Galactic center molecular clouds usually have much wider lines, in the range of 10 to 20 \kmsn. The present \htco study supports the view that Sgr D is not located in the Galactic Center region. The linewidth of the absorption feature observed near -18 \kms is narrow with widths ranging from 2 to 4 \kmsn. Having determined that Sgr D is not located in the Galactic Center region, the question remains of whether Sgr D is located on the near or far side of the Galactic Center. The \htco spectrum of region B and the \htco spectrum of the entire Sgr D H II region (G1.13--0.10) display significant absorption near +50 \kmsn. This feature is probably due to a Galactic center cloud for the following reasons: 1) the width is significantly greater the 10 \kms and 2) the feature is not near 0 \kms as would be expected if it were located in the Galactic disk at this Galactic longitude. Because \htco in this cloud is observed in absorption toward the Sgr D H II region (G1.13--0.10), Sgr D is probably located beyond the Galactic Center. It is to be noted that, if Sgr D is indeed located on the far side of the Galactic Center, the number of Lyman continuum photons (which scales as $D^2$) and the ZAMS listed in Table 4 represent lower limits, because the distance used in calculating these parameters was taken to be 8.5 kpc, the distance of the Galactic Center. The \htco spectrum of the SNR G1.05--0.15 also displays absorption near +50 \kmsn, indicating that it, too, lies beyond the Galactic Center. However, unlike the Sgr D H II region (G1.13--0.10), no absorption was detected in the SNR spectrum near -18 \kmsn. On the other hand, the single dish observation of Downes et al. (1980) did detect absorption at --16 \kms with $\tau_0$ = 0.07, which is below the detection limit of the present study. Therefore, based on previous data, it appears that the SNR G1.05--0.15 is at least as distant as the H II region Sgr D (G1.13--0.10). \subsection{OH and \water Masers} As discussed in \S 2., OH maser observations at 1612, 1665, and 1667 MHz were carried out so that we could distinguish between masers associated with evolved stars and those associated with young stellar objects, and hence, sites of very recent star formation. Sources displaying 1612 MHz double peaked spectral profiles are almost always associated with evolved stars (Wilson \& Barrett 1972; Likkel 1989). The typical separation of the peaks in 1612 MHz spectra of evolved stars is 30 \kmsn; the great majority are between 20 and 40 \kms (te Lintel Hekkert et al. 1989). We have detected 14 OH maser sites in the field near the Sgr D H II region (G1.13--0.10). The observational parameters of these masers are summarized in Table 6, in which a channel-by-channel listing of maser emission is presented. Listed in this table are the maser designation, the position, transition (1612, 1665, or 1667 MHz), sense of circular polarization, velocity of the channel in which emission occurs (\vlsrn), and flux density of the emission in that channel. In Figure 7, the positions of the OH maser sites are superposed on the 18 cm continuum image. In addition, the positions of two 1720 MHz OH masers (labeled Z1 and Z2) detected by Yusef-Zadeh et al. (1997) are also indicated in this figure. The spectra of all the OH masers are displayed in Figure 8. In addition, two \water maser sites were detected and their parameters are summarized in Table 7, which has a similar format to Table 6 (with the exception that polarization information is not listed because \water masers are not polarized). In Figure 9, the \water maser positions are superposed on the 6 cm continuum image from Figure 2. The spectra of the water masers are displayed in Figure 10. Ten OH maser sites show 1612 MHz emission (all, except maser D, exhibit double peaked profiles), indicating that these masers are probably associated with evolved stars. The four sites for which no 1612 MHz emission was detected are sources A, E, I, and K. In OH maser site A, a single 1667 MHz maser is detected at \vlsr=+104 \kmsn. The high velocity of this maser and the fact that it is not located near a known H II region indicates to us that this maser source is most likely associated with an evolved star. For the same reasons, maser site E, which exhibits 1667 MHz emission near +75 \kmsn, is also most likely an evolved star maser. The velocity of OH maser site I, which exhibits 1665 MHz emission, is --19 \kms which is quite close to that of the Sgr D molecular cloud/H II region. Furthermore, this source is projected at the edge of the Sgr D H II region (G1.13-0.10). For these reasons, this maser may be associated with a young stellar object. In addition, this OH maser is nearly coincident with \water maser source 2. The \water masers at this position have velocities ranging between --24 and --7 \kmsn, indicating that they may be located in a bipolar molecular outflow. High velocity molecular outflows traced by \water masers are well known to exist in other Galactic star-forming regions. OH maser K exhibits 1665 MHz emission near +4 \kmsn. In addition, it is located only 8\arcsec\ from source 1b of the continuum study. Unfortunately, this region was not included in the \water maser study, so we do not know if there are also \water masers associated with this source. Three attributes suggest that the OH masers in this region are associated with a young stellar object. They are 1) the lack of detectable 1612 MHz OH maser emission, 2) the proximity to a radio continuum source, and 3) the closeness of the maser velocities to the systemic velocity of the Sgr D H II region (G1.13--0.10). Because it cannot be determined if continuum sources 1a and 1b, which lie well south of the main arc of the SNR G1.05-0.15, are actually associated with the Sgr D molecular cloud, the velocity of these continuum sources may indeed be closer to the velocity of maser source K than the --21 \kms systemic velocity of the ionized material in the main Sgr D H II region (G1.13-0.10). The remaining \water maser, \water maser source 1, is projected only 4\arcsec\ (0.15 pc) south of the peak of the brightest compact continuum source, source 3 (G1.12--0.10). Although this maser has a velocity of +23 \kmsn, which is over 40 \kms different from the Sgr D (G1.13--0.10) systemic velocity, its close proximity to continuum source 3 suggests it is associated with a young stellar object. The high velocity might be the result of the maser being located in a high velocity molecular outflow. We detected no OH masers near this position. Thus this maser source may be similar to most of the \water masers detected by Mehringer, Palmer, \& Goss (1993) in Sgr B1. All but one of the Sgr B1 \water masers do not have OH counterparts, and for this reason Mehringer et al. (1993) concluded that they are most likely associated with young stellar objects rather than evolved stars. A more complete survey of the Sgr D region for \water masers would be interesting, since, as is the case in Sgr B1, there may be many more \water masers associated with young stellar objects awaiting detection. \section{Summary} We have carried out a program of VLA observations in order to gain a better understanding of the Sgr D (G1.13--0.10) massive star-forming region and the G1.05--0.15 SNR. The major results of this study are: \noindent 1) Continuum observations at 6 and 18 cm show that the Sgr D H II region (G1.13--0.10) is dominated by a single compact source. This source is embedded in a 7\arcmin\ diameter halo of ionized material. Numerous sources are located in the 36\arcmin\ field. The rms electron number density of the extended component is 50 \cmthree and it has a total mass of 3000 \smasn. These values are similar to those previously determined for the extended ionized halos of Sgr B1 and Sgr B2. The SNR G1.05--0.15 is located 5\arcmin\ south of the Sgr D H II region, and there is an SNR candidate, G1.4--0.1, located 15\arcmin\ to the northeast of Sgr D (G1.13--0.10). \noindent 2) \htco absorption observations at 6 cm show that the molecular material in this region is clumpy. For example, in one cloud, the apparent optical depth is observed to vary by a factor of ten over a projected distance of about 5 pc. In addition, the molecular clouds associated with the ionized material have narrow ($<$5 \kmsn) linewidths, indicating the this complex is not located in the Galactic Center region. Broad-line absorption features observed at highly positive velocities indicate that both the Sgr D H II region (G1.13--0.10) and the SNR G1.05--0.15 are located beyond the Galactic Center. \noindent 3) OH and \water maser observations indicate that there are probably at least three sites of very recent star formation in this region. Furthermore, these data indicate that the \water masers may be located in high velocity molecular outflows. In addition, the OH maser data indicate that there are at least 12 evolved stars in a 30\arcmin\ diameter field containing Sgr D. \acknowledgements We thank Dr. A. D. Gray for helpful discussions and an anonymous referee for useful comments. \clearpage \begin{thebibliography}{} \bibitem[]{} Anantharamaiah, K. R., \& Yusef-Zadeh, F. 1989, in IAU Symp. 136, The Center of the Galaxy, ed. M. Morris (Dordrecht: Kluwer), 159 \bibitem[]{} Downes, D., Wilson, T. L., Bieging, J., \& Wink, J. 1980, A\&AS, 40, 379 \bibitem[]{}Gray, A. D. 1994a, MNRAS, 270, 835 \bibitem[]{} Gray, A. D. 1994b, MNRAS, 270, 847 \bibitem[]{} G\"usten, R. 1989, in IAU Symp. 136, The Center of the Galaxy, ed. M. Morris (Dordrecht: Kluwer), 89 \bibitem[]{} Likkel, L. 1989, ApJ, 344, 350 \bibitem[]{} te Lintel Hekkert, P., Versteege-Hensel, H. A., Habing, H. J., \& Wiertz, M. 1989, A\&AS, 78, 399 \bibitem[]{} Lis, D. C. 1991, ApJ, 379, L53 \bibitem[]{} Lis, D. C., Menten, K. M., \& Mehringer, D. M. 1997, in preparation \bibitem[]{} Liszt, H. 1992, ApJS, 82, 495 \bibitem[]{} Mehringer, D. M., Palmer, P., \& Goss, W. M. 1993, ApJ, 402, L69 \bibitem[]{} Mehringer, D. M., Palmer, P., Goss, W. M., \& Yusef-Zadeh, F. 1993, ApJ, 412, 684 \bibitem[]{} Mehringer, D. M., Yusef-Zadeh, F., Palmer, P., \& Goss, W. M. 1992, ApJ, 401, 168 \bibitem[]{} Mezger, P. G., \& Henderson, A. P. 1967, ApJ, 147, 471 \bibitem[]{} Odenwald, S. F. 1989, in IAU Symp. 136, The Center of the Galaxy, ed. M. Morris (Dordrecht: Kluwer), 205 \bibitem[]{} Odenwald, S. F., \& Fazio, G. G. 1984, ApJ, 283, 601 \bibitem[]{} Panagia, N. 1973, AJ, 78, 929 \bibitem[]{} Panagia, N., \& Walmsley, C. M. 1978, A\&A, 70, 411 \bibitem[]{} Viallefond, F. 1991, private communication \bibitem[]{} Wadiak, E. J., Rood, R. T., \& Wilson, T. L. 1988, ApJ, 324, 931 \bibitem[]{} Wilson, W. J,, \& Barrett, A. H. 1972, A\&A, 17, 385 \bibitem[]{} Wood, D. O. S., \& Churchwell, E. 1989, ApJS, 69, 831 \bibitem[]{} Yusef-Zadeh, F., Goss, W. M., Robinson, B., et al. 1997, in preparation \end{thebibliography} \clearpage \figcaption{An 18 cm continuum image of the Sgr D region created from the C- and D-configuration data of Liszt (1992). The resolution is 28\arcsec\ $\times$ 15\arcsec\ (P.A.=--6.8\degn). Contour levels are at --10, 3, 5, 10, 15, 20, 30, 50, 70, 100, 150, 250, 450, and 750 mJy \perbeamn. The rms noise is 2 mJy \perbeam and the image has not been corrected for primary beam attenuation.} \figcaption{A 6 cm, five field mosaic of Sgr D. The image was created using VTESS, an AIPS maximum entropy deconvolution routine. The resolution is 10.3\arcsec\ $\times$ 9.7\arcsec\ (P.A.=82\degn). Contours are at --2, 2, 5, 8, 12, 15, 20, 30, 50, 70, 100, 150, 200, 250, and 300 mJy \perbeamn. The rms noise near the center of the image is 0.5 mJy \perbeam and the primary beam response for each field has been taken into account during mosaicing.} \figcaption{A 6 cm continuum image produced from line-free channels of the \htco data. The resolution is 13\arcsec\ $\times$ 12\arcsec\ (P.A.=--33\degn). Contours are at --5, 5, 10, 15, 20, 30, 50, 70, 100, 120, 150, 200, 250, 300, 400, 500, and 600 mJy \perbeamn. The image has not been corrected for primary beam attenuation. The crosses mark the positions at which the \htco spectra displayed in Figure 4 were determined.} \figcaption{\htco apparent optical depth spectra taken at selected positions labeled in Figure 3. a) Narrow (1.5625 MHz) bandwidth spectra. The channel width is 1.5 \kmsn. b) Wide (3.125 MHz) bandwidth spectra. The channel width is 6.0 \kmsn. Note that the the two narrow bandwidth as well as the two wide bandwidth spectra at all positions partially overlap in velocity.} \figcaption{\htco spectra from each of the 4 IFs produced by averaging over the entire Sgr D H II region (G1.13--0.10). Note that the the two narrow bandwidth as well as the two wide bandwidth spectra partially overlap in velocity.} \figcaption{\htco spectra from each of the 4 IFs produced by averaging over the entire G1.05--0.15 SNR. Note that the the two narrow bandwidth as well as the two wide bandwidth spectra partially overlap in velocity.} \figcaption{Contour 18 cm continuum image on which the positions of the OH maser sites are shown. In addition, the two 1720 MHz OH masers detected by Yusef-Zadeh et al. (1997) are indicated. These masers are labeled Z1 and Z2.} \figcaption{Spectra of the OH masers observed in this study. The solid, connected spectra and the dashed, histogram spectra represent the left and right circular polarizations, respectively.} \figcaption{Contour 6 cm continuum image (identical to that in Fig. 2) on which the positions of the two \water masers detected in this study are shown.} \figcaption{Spectra of the \water masers observed in this study. The spectra have been Hanning smoothed; thus the spectral resolution is two channels wide.} \clearpage \begin{deluxetable}{ll} \tablenum{1a} \footnotesize \tablecaption{Parameters for Sgr D Continuum Observations} % \tablewidth{0pt} \tablehead{} \startdata VLA configurations: & C and D (18 cm) \nl & DnC (6 cm) \nl Observing dates: & 1984 May 19 (C array, 18 cm) \nl & 1984 Sep 6 (D array, 18 cm) \nl & 1992 Jul 1 (6 cm) \nl Total observing time: & 7 hr (C array, 18 cm) \nl & 7 hr (D array, 18 cm) \nl & 8 hr (DnC array, 6 cm) \nl %Maximum baselines: & 1.0 km (D array) \nl % & 3.4 km (C array) \nl Angular resolution: & 10\arcsec\ (6 cm) \nl & 15\arcsec $\times$ 28\arcsec\ ($\alpha \times \delta$) (18 cm) \nl Primary beam FWHM: & 9\arcmin\ (6 cm) \nl & 27\arcmin\ (18 cm) \nl Pointing position (18 cm) & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}49.4^{\rm s}$, $\delta$(B1950)=$-27^\circ53^\prime48^{\prime\prime}$ \nl Pointing positions (6 cm) & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}38.0^{\rm s}$, $\delta$(B1950)=$-28^\circ05^\prime00^{\prime\prime}$ \nl & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}22.0^{\rm s}$, $\delta$(B1950)=$-28^\circ05^\prime00^{\prime\prime}$ \nl & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}25.0^{\rm s}$, $\delta$(B1950)=$-28^\circ00^\prime00^{\prime\prime}$ \nl & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}15.0^{\rm s}$, $\delta$(B1950)=$-27^\circ56^\prime00^{\prime\prime}$ \nl & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}36.0^{\rm s}$, $\delta$(B1950)=$-27^\circ54^\prime00^{\prime\prime}$ \nl %Flux density calibrators: & 3C 286 (C \& D array, 18 cm) \nl % & 3C 48 (6 cm continuum \& \htco) \nl %Phase calibrators: & 1730--130 (6 cm continuum \& \htco) \nl % & 1748--253 (C \& D array, 18 cm) \nl %Bandpass calibrator (\htcon):& 1730--130 \nl \enddata \end{deluxetable} \clearpage \begin{deluxetable}{ll} \tablenum{1b} \footnotesize \tablecaption{Parameters for Sgr D \htco Observations} % \tablewidth{0pt} \tablehead{} \startdata VLA configuration: & DnC \nl Observing date: & 1992 Jul 2 \nl Total observing time: & 8 hr \nl %Maximum baselines: & 1.0 km (D array) \nl % & 3.4 km (C array) \nl Angular resolution: & 13\arcsec \nl Primary beam FWHM: & 9\arcmin\ \nl Pointing position & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}25.0^{\rm s}$, $\delta$(B1950)=$-28^\circ00^\prime00^{\prime\prime}$ \nl %Bandpass calibrator (\htcon):& 1730--130 \nl % Note: rest freq in observe file was 4829.6569, I will adjust tables % with v_LSR to be consistent with rest freq given below. Difference % is v_{rf=4829.6594}=v_{rf=4829.6569}+0.155 km/s \htco 1$_{10}$--1$_{11}$ rest frequency: & 4829.6594 MHz \nl Spectrometer configuration: & 63/31 frequency channels \nl & 1.5625/3.125 MHz IF bandwidth \nl & 24/97 kHz (1.5/6.0 \kmsn) channel width \nl & IF pairs centered at --33.9 and +53.9 \kms \nl & on-line Hanning smoothing \nl \enddata \end{deluxetable} \clearpage \begin{deluxetable}{ll} \tablenum{1c} \footnotesize \tablecaption{Parameters for Sgr D OH Maser Observations} % \tablewidth{0pt} \tablehead{} \startdata VLA configuration: & BnA \nl Observing date: & 1993 Feb 14 \nl Total observing time: & 3 hr \nl %Maximum baselines: & 1.0 km (D array) \nl % & 3.4 km (C array) \nl Angular resolution: & 6\arcsec $\times$ 4\arcsec\ (P.A.=20\degn) \nl Primary beam FWHM: & 27\arcmin\ \nl Pointing position & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}30.0^{\rm s}$, $\delta$(B1950)=$-28^\circ00^\prime40^{\prime\prime}$ \nl OH $^2\Pi_{3/2}\ J=3/2\ F=1-2$ rest frequency: & 1612.2310 MHz \nl OH $^2\Pi_{3/2}\ J=3/2\ F=1-1$ rest frequency: & 1665.4018 MHz \nl OH $^2\Pi_{3/2}\ J=3/2\ F=2-2$ rest frequency: & 1667.3590 MHz \nl Spectrometer configuration: & simultaneous observations of RCP and LCP radiation \nl & 127 frequency channels \nl & 1.5625 MHz IF bandwidth \nl & 12 kHz (2.2 \kms @ 1665 MHz) channel width\nl & IF pair centered at --15 \kms \nl & on-line Hanning smoothing \nl \enddata \end{deluxetable} \clearpage \begin{deluxetable}{ll} \tablenum{1d} \footnotesize \tablecaption{Parameters for Sgr D \water Maser Observations} % \tablewidth{0pt} \tablehead{} \startdata VLA configuration: & DnC \nl Observing date: & 1993 Jan 31 \nl Total observing time: & 1 hr \nl Angular resolution: & 3\arcsec \nl Primary beam FWHM: & 2\arcmin\ \nl Pointing positions & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}32.0^{\rm s}$, $\delta$(B1950)=$-28^\circ00^\prime45^{\prime\prime}$ \nl & $\alpha$(B1950)=$17^{\rm h}45^{\rm m}24.0^{\rm s}$, $\delta$(B1950)=$-28^\circ01^\prime35^{\prime\prime}$ \nl \water $6_{1,6}-5_{2,3}$ rest frequency: & 22235.08 MHz \nl Spectrometer configuration:& 63 frequency channels \nl & 6.25 MHz IF bandwidth \nl & 98 kHz (1.3 \kmsn) channel width\nl & IF pairs centered at --45 and +15 \kms \nl & no on-line Hanning smoothing, data smoothed offline \nl \enddata \end{deluxetable} \clearpage \begin{deluxetable}{lccrrr} \tablenum{2} \tablecolumns{6} \footnotesize \tablecaption{Observational Parameters of Continuum Sources in Sgr D} \tablehead{\colhead {Source} & \colhead{$\alpha$(B1950)} & \colhead{$\delta$(B1950)} & \colhead{$S_{\rm 6\ cm}$} & \colhead{$S_{\rm 18\ cm}$} & \colhead {FWHM} \\ \colhead{} & \colhead{h m s} & \colhead{\degn\ \arcmin\ \arcsec} & \colhead{(mJy)} & \colhead{(mJy)} & \colhead {\arcsec} } \startdata % peak 22.8 mJy in 6 cm 10.25x9.65 resolution map 1a & 17 45 46.2 & --28 11 03 & 17 & ... & $<$10 \nl % peak 21.1 mJy in 6 cm 10.25x9.65 resolution map 1b & 17 45 45.3 & --28 10 57 & 33 & ... & $<$10 \nl % peak 20.5 mJy in 6 cm 10.25x9.65 resolution map 2 & 17 45 24.4 & --28 02 35 & 60 & 30 & $\le$10 \nl % peak 522 mJy in 6 cm 10.25x9.65 resolution map 3 & 17 45 32.2 & --28 00 44 & 2300 & 1900 & 20 $\times$ 10 \nl % peak 26.7 mJy in 6 cm 10.25x9.65 resolution map 4 & 17 45 01.0 & --27 53 42 & 33 & 12 & $<$10 \nl % peak 16.0 mJy in 6 cm 10.25x9.65 resolution map 5 & 17 45 42.4 & --27 51 02 & 17 & 46 & $<$10 \nl % peak 20.7 mJy in 18 cm 25.47 X 13.59 cm 10.25x9.65 resolution map 6 & 17 46 10.5 & --27 51 58 & ... & 51 & $<$15 \nl % peak 16.7 mJy in 18 cm 25.47 X 13.59 cm 10.25x9.65 resolution map 7 & 17 45 01.6 & --27 42 11 & ... & 160 &$\sim$50 $\times$ 75 \nl %not convincing enough to say there's a source there %&8&17&45&47.0&--27&43&48&...&13&$<$10&\cr %& &\multispan{9}&\cr % peak 26.7 mJy in 18 cm 25.47 X 13.59 cm 10.25x9.65 resolution map 9 & 17 46 44.6 & --27 45 01 & ... & 47 & $\le$15 \nl % peak 9.93 mJy in 6 cm 10.25x9.65 resolution map 10 & 17 45 15.0 & --27 51 27 & 11 & ... & $<$10 \nl \enddata \end{deluxetable} \clearpage \begin{deluxetable}{lccrrr} \tablenum{3} % parms calculated assuming t=7000 K, d=8.5 kpc \tablecolumns{6} \footnotesize \tablecaption{Derived Physical Parameters of Continuum Sources in Sgr D} \tablehead{ \colhead{Source} & \colhead{Peak $EM$} & \colhead{RMS $n_{\rm e}$} & \colhead{$M_{\rm HII}$} & \colhead{$\log N_{\rm i}$} & \colhead{$ZAMS$} \\ \colhead{} & \colhead{10$^6$ cm$^{-6}$ pc} & \colhead{10$^3$ cm$^{-3}$} & \colhead{M$_\odot$} & \colhead{photons s$^{-1}$} & \colhead{} } \startdata 1a & 0.09 & $>$0.5 & $<$1.5 & 47.1 & B0 \nl 1b & 0.08 & $>$0.4 & $<$2.1 & 47.4 & B0 \nl 2 & 0.08 & $\ge$0.4 & $\le$2.8 & 47.7 & O9.5 \nl 3 & 2.1 & 1.9 & 29 & 49.2 & O5.5 \nl 4 & 0.11 & $>$0.5 & $<$2.1 & 47.4 & B0 \nl 5 & 0.06 & $>$0.4 & $<$1.5 & 47.1 & B0 \nl 6 & 0.02 & $>$0.2 & $<$4.5 & 47.5 & B0 \nl 7 & 0.02 & 0.1 & \dots & 48.0 & O9 \nl %&&8&0.01&$>$0.2&$<$1.0&46.77&B0.5&\cr %&& &\multispan{9}&\cr 9 & 0.03 & $>$0.2 & $<$4.3 & 47.5 & B0 \nl 10 & 0.04 & $>$0.3 & $<$1.2 & 46.9 & B0 \nl \enddata \end{deluxetable} \clearpage \begin{figure} \plotone{table4new.ps} \end{figure} \clearpage \begin{deluxetable}{crr} \tablenum{5} \tablecaption{Comparison of VLA and Bonn \htco Line Center Velocities \tablenotemark{a,b}} \tablehead{\colhead {Source} & \colhead{Bonn} & \colhead{VLA} } \startdata Sgr D & --64.0 & --65(2) \nl & --17.0 & --17.1(1.5)\tablenotemark{c} \nl & --11.0 & --11.0(1.5)\tablenotemark{c} \nl & --5.0 & --6.5(1.5)\tablenotemark{c} \nl & ... & +41,7(0.7) \nl & ... & +78.4(0.4) \nl & +84.0 & ... \nl & +123.0 & +115(6)\tablenotemark{c} \nl G1.05 & ... & --67.8(0.9) \nl & --16.0 & ... \nl & --1.0 & --1.2(0.3) \nl & +71.0 & +71.4(0.3) \nl & +125 & +129(2) \nl \enddata \tablenotetext{a}{Units are \kmsn.} \tablenotetext{b}{Uncertainties in the Bonn center velocities are $\pm$0.5 \kmsn.} \tablenotetext{c}{Gaussian fit failed. Velocity refers to channel containing local maximum and the uncertainty is equal to the channel width.} \end{deluxetable} \clearpage \begin{deluxetable}{rrrrcrr} \tablenum{6} \tablecolumns{7} \tablecaption{Observational Parameters of OH Masers Toward Sgr D\tablenotemark{a}} \tablehead{\colhead {Source} & \colhead {$\alpha$(B1950)} & \colhead{$\delta$(B1950)} & \colhead{Transition} & \colhead{Pol.} & \colhead{\vlsr} & \colhead{Flux Density} \\ & \colhead{h m s} & \colhead{\degn\ \arcmin\ \arcsec} & \colhead{MHz} & & \colhead{\kms} & \colhead{mJy} } \startdata A & 17 44 31.23(0.02) & --28 10 37.9(0.5) & 1667 & L & +104 & 130 \nl & & & 1667 & R & +104 & 170 \nl B & 17 44 37.93(0.02) & --27 51 38.0(0.5) & 1612 & L & +53 & 180 \nl & & & 1612 & L & +55 & 270 \nl & & & 1612 & L & +85 & 130 \nl & & & 1612 & L & +87 & 150 \nl % for some reason, the original RCP intensities are much too low % by factors of 3-4. Maybe I mistakenly used the unPBcored maps. % commenting out the original lines and putting in the correct % values 02jun97. % & & & 1612 & R & +53 & 80 \nl % & & & 1612 & R & +55 & 70 \nl % & & & 1612 & R & +85 & 90 \nl % & & & 1612 & R & +87 & 70 \nl & & & 1612 & R & +53 & 180 \nl & & & 1612 & R & +55 & 310 \nl & & & 1612 & R & +85 & 150 \nl & & & 1612 & R & +87 & 170 \nl C & 17 44 46.37(0.03) & --28 05 31.4(0.6) & 1612 & L & +37 & 90 \nl & & & 1612 & L & +40 & 210 \nl & & & 1612 & L & +42 & 60 \nl & & & 1612 & L & +69 & 80 \nl & & & 1612 & L & +71 & 140 \nl & & & 1612 & R & +37 & 100 \nl & & & 1612 & R & +40 & 210 \nl & & & 1612 & R & +42 & 50 \nl & & & 1612 & R & +69 & 90 \nl & & & 1612 & R & +71 & 130 \nl D & 17 44 53.20(0.09) & --27 48 25.3(0.8) & 1612 & L & +15 & 90 \nl & & & 1612 & R & +15 & 100 \nl \tablebreak E & 17 45 05.11(0.04) & --28 07 55.2(0.5) & 1667 & L & +75 & 100 \nl & & & 1667 & L & +77 & 70 \nl & & & 1667 & R & +75 & 90 \nl & & & 1667 & R & +77 & 50 \nl F & 17 45 13.96(0.07) & --28 19 22.3(0.6) & 1612 & L & +62 & 210 \nl & & & 1612 & L & +98 & 140 \nl & & & 1612 & L & +101 & 130 \nl & & & 1612 & R & +62 & 220 \nl & & & 1612 & R & +98 & 180 \nl & & & 1612 & R & +101 & 200 \nl G & 17 45 18.15(0.02) & --27 56 52.0(0.4) & 1612 & L & --63 & 480 \nl & & & 1612 & L & --60 & 430 \nl & & & 1612 & L & --45 & 80 \nl & & & 1612 & L & --42 & 330 \nl & & & 1612 & L & --40 & 1030 \nl & & & 1612 & L & --38 & 70 \nl & & & 1612 & R & --63 & 500 \nl & & & 1612 & R & --60 & 430 \nl & & & 1612 & R & --45 & 80 \nl & & & 1612 & R & --42 & 370 \nl & & & 1612 & R & --40 & 1090 \nl & & & 1612 & R & --38 & 80 \nl \tablebreak & & & 1665 & L & --61 & 110 \nl & & & 1665 & L & --59 & 130 \nl & & & 1665 & L & --57 & 70 \nl & & & 1665 & L & --48 & 120 \nl & & & 1665 & L & --46 & 160 \nl & & & 1665 & L & --44 & $<$60 \nl & & & 1665 & R & --61 & 150 \nl & & & 1665 & R & --59 & 140 \nl & & & 1665 & R & --57 & $<$50 \nl & & & 1665 & R & --48 & 80 \nl & & & 1665 & R & --46 & 160 \nl & & & 1665 & R & --44 & 70 \nl & & & 1667 & L & --63 & 60 \nl & & & 1667 & L & --61 & 160 \nl & & & 1667 & L & --59 & 160 \nl & & & 1667 & L & --57 & 60 \nl & & & 1667 & L & --48 & 70 \nl & & & 1667 & L & --46 & 230 \nl & & & 1667 & L & --44 & 250 \nl & & & 1667 & L & --41 & 50 \nl \tablebreak & & & 1667 & R & --63 & 60 \nl & & & 1667 & R & --61 & 160 \nl & & & 1667 & R & --59 & 160 \nl & & & 1667 & R & --57 & 60 \nl & & & 1667 & R & --48 & 70 \nl & & & 1667 & R & --46 & 230 \nl & & & 1667 & R & --44 & 250 \nl & & & 1667 & R & --41 & 50 \nl H & 17 45 23.01(0.01) & --27 59 00.0(0.2) & 1612 & L & +37 & 430 \nl & & & 1612 & L & +40 & 170 \nl & & & 1612 & L & +62 & $<$50 \nl & & & 1612 & L & +64 & 200 \nl & & & 1612 & R & +37 & 420 \nl & & & 1612 & R & +40 & 160 \nl & & & 1612 & R & +62 & 40 \nl & & & 1612 & R & +64 & 240 \nl I & 17 45 39.25(0.02) & --28 00 15.1(0.1) & 1665 & L & --22 & 50 \nl & & & 1665 & L & --19 & 130 \nl & & & 1665 & L & --17 & 40 \nl & & & 1665 & R & --22 & $<$40 \nl & & & 1665 & R & --19 & $<$40 \nl & & & 1665 & R & --17 & $<$40 \nl \tablebreak J & 17 45 40.59(0.04) & --28 13 31.2(0.3) & 1612 & L & --17 & 140 \nl & & & 1612 & L & --15 & 160 \nl & & & 1612 & L & --13 & 60 \nl & & & 1612 & L & +15 & 80 \nl & & & 1612 & L & +17 & 100 \nl & & & 1612 & L & +19 & 170 \nl & & & 1612 & L & +21 & 200 \nl & & & 1612 & R & --17 & 110 \nl & & & 1612 & R & --15 & 150 \nl & & & 1612 & R & --13 & 90 \nl & & & 1612 & R & +15 & 90 \nl & & & 1612 & R & +17 & 90 \nl & & & 1612 & R & +19 & 150 \nl & & & 1612 & R & +21 & 190 \nl K & 17 45 45.74(0.04) & --28 10 52.2(0.4) & 1665 & L & 0 & 120 \nl & & & 1665 & L & +3 & 270 \nl & & & 1665 & L & +5 & $<$40 \nl & & & 1665 & L & +7 & $<$40 \nl & & & 1665 & R & 0 & $<$40 \nl & & & 1665 & R & +3 & 70 \nl & & & 1665 & R & +5 & 70 \nl & & & 1665 & R & +7 & 70 \nl \tablebreak L & 17 45 51.51(0.03) & --27 53 37.8(0.4) & 1612 & L & +28 & 40 \nl & & & 1612 & L & +69 & 50 \nl & & & 1612 & R & +28 & 30 \nl & & & 1612 & R & +69 & 60 \nl M & 17 46 12.09(0.02) & --27 41 01.4(0.1) & 1612 & L & --142 & 1350 \nl & & & 1612 & L & --140 & 1300 \nl & & & 1612 & L & --115 & 2910 \nl & & & 1612 & L & --113 & 360 \nl & & & 1612 & R & --142 & 1430 \nl & & & 1612 & R & --140 & 1480 \nl & & & 1612 & R & --115 & 3170 \nl & & & 1612 & R & --113 & 410 \nl N & 17 46 22.09(0.09) & --27 48 08.4(0.8) & 1612 & L & +92 & 120 \nl & & & 1612 & L & +108 & 160 \nl & & & 1612 & R & +92 & 120 \nl & & & 1612 & R & +108 & 170 \nl \enddata \tablenotetext{a}{Maser spots are tabulated which have intensities greater than 6 $\sigma$.} \end{deluxetable} \clearpage \begin{deluxetable}{crrrr} \tablenum{7} \tablecolumns{5} \tablecaption{Observational Parameters of H$_2$O Masers Toward Sgr D\tablenotemark{a,b}} \tablehead{\colhead{Source} & \colhead {$\alpha$(B1950)} & \colhead{$\delta$(B1950)} & \colhead{\vlsr} & \colhead{Flux Density} \\ & \colhead{h m s} & \colhead{\degn\ \arcmin\ \arcsec} & \colhead{\kms} & \colhead{mJy} } \startdata 1 & 17 45 32.24(0.03) & --28 00 48.4(0.3) & +22.9 & 130 \nl & & & +24.2 & 120 \nl 2 & 17 45 39.29(0.02) & --28 00 15.7(0.2) & --23.9 & 7200 \nl & & & --22.6 & 12400 \nl & & & --21.3 & 9800 \nl & & & --20.0 & 4200 \nl & & & --18.7 & 1100 \nl & & & --16.0 & 900 \nl & & & --9.5 & 1200 \nl & & & --8.1 & 2100 \nl & & & --6.8 & 1200 \nl \enddata \tablenotetext{a}{Maser spots are tabulated which have intensities greater than 6 $\sigma$.} \tablenotetext{b}{The data have been Hanning smoothed so that the actual spectral resolution is 2.6 \kmsn.} \end{deluxetable} \clearpage \begin{figure} \plotone{SGRD.LBAND} \end{figure} \clearpage \begin{figure} \plotone{SGRD.CBAND} \end{figure} \clearpage \begin{figure} \plotone{SGRD.H2CO} \end{figure} \clearpage \begin{figure} \plotone{SPEC1} \end{figure} \clearpage \begin{figure} \plotone{SPEC3} \end{figure} \clearpage \begin{figure} \plotone{SPEC2} \end{figure} \clearpage \begin{figure} \plotone{SPEC4} \end{figure} \clearpage \begin{figure} \plotone{SGRDGLOBAL02} \end{figure} \clearpage \begin{figure} \plotone{G1.05GLOBAL02} \end{figure} \clearpage \begin{figure} \plotone{SGRD.OHMASERS} \end{figure} \clearpage \begin{figure} \plotone{a-d_spec.ps} \end{figure} \clearpage \begin{figure} \plotone{e-g_spec.ps} \end{figure} \clearpage \begin{figure} \plotone{g-j_spec.ps} \end{figure} \clearpage \begin{figure} \plotone{k-n_spec.ps} \end{figure} \clearpage \begin{figure} \plotone{SGRD.H2OMASERS} \end{figure} \clearpage \begin{figure} \plotone{h2o_spec.ps} \end{figure} \end{document} (with a radius equal to the geometric mean of the semi-major and semi-minor axes) \begin{deluxetable}{crrrrrrrr} \font\small=cmr6 \tablewidth{0pc} \tablecolumns{9} \small \tablecaption{\htco Parameters for Positions in Sgr D} \tablehead{ \colhead{Source} & \colhead{$\alpha$} & \colhead{$\delta$} & \colhead{$\overline{I_{\rm c}}$} & \colhead{Box Size} & \colhead{\vlsr} & \colhead{$\Delta v$} & \colhead{$\tau_0$} & \colhead{$N_{\rm L}/T_{\rm ex}$} \\ \colhead{} & \colhead{h m s} & \colhead{\degn\ \arcmin\ \arcsec} & \colhead{(mJy \perbeamn)} & \colhead{\arcsec $\times$\arcsec} & \colhead{\kms} & \colhead{\kms} & \colhead{} & \colhead{10$^{13}$ cm$^{-2}$ K$^{-1}$} } \startdata A & 17 45 32.2 &--28 00 44 & 440 & 20 $\times$ 20 & --17.1(0.1) & 4.3(0.2) & 0.092(0.004) & 0.54(0.03) \nl & & & & & --11.3(0.1) & 3.0(0.2) & 0.276(0.005) & 1.13(0.08) \nl & & & & & --6.0(0.1) & 3.0(0.3) & 0.039(0.005) & 0.16(0.03) \nl & & & & & +32.7(0.6) & 18.0(1.5) & 0.013(0.002) & 0.32(0.06) \nl B & 17 45 24.4 & --28 01 36 & 23 & 12 $\times$ 12 & --18.1(0.1) & 2.8(0.2) & 1.0(0.1) & 3.8(0.5) \nl & & & & & --14.5(0.1) & 3.1(0.3) & 0.7(0.1) & 3.0(0.5) \nl & & & & & +54.9(0.4) & 14(1) & 0.63(0.07) & 12(2) \nl & & & & & +95.8(0.6) & 8(2) & 0.4(0.1) & 4.4(1.5) \nl C & 17 45 26.5 & --27 59 36 & 45 & 20 $\times$ 20 & --19.6(0.1) & 2.0(0.5) & 0.21(0.05) & 0.6(0.2) \nl D & 17 45 31.6 & --28 04 08 & 10 & 68 $\times$ 20 & --65.6(0.7) & 7(2) & 0.28(0.09) & 3(1) \nl & & & & & --0.8(0.2) & 5.1(0.4) & 1.0(0.1) & 6.9(0.9) \nl & & & & & +59.8(0.4) & 9(1) & 0.29(0.05) &3.5(0.7) \nl & & & & & +74.6(0.1) & 10.6(0.2) & 1.41(0.04) & 20.3(0.7)\nl \enddata \end{deluxetable} ----- End Included Message -----