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\section{The Reddening and Metallicity}

\subsection{Optical Spectroscopy}

Non-optimal scheduling of a run on the 6.5-m MMT
left us with an opporunity at the end of the night on UT 21 Nov 2003 
to obtain optical
spectroscopy of the H~II region found in HIZSS~3 by Massey et al.\ (2003).
primary goal was to determine the reddening from spectrophotometry of
the H$\beta$ relative to H$\alpha$, with a secondary goal of determining
the oxygen abundance if the [O II] $\lambda 3727$ could be detected despite
the high reddening.  
The data were obtained with the MMT Blue Channel
spectrograph using a 500 l mm${-1}$ grating with a dispersion of 1.18\AA
pixel$^{-1}$ using a 2688x512 CCD.  The slit was opened to 3.5 arcsec,
resulting in a resolution of 10 pixels (12\AA).  No blocking filter was
used in order to maximize the through-put, a choice which we felt was
safe given that first-order H$\alpha$ would be contaminated by second-order
light at 3280\AA.  While this proved to be a good choice for the H~II region,
our bluest flux standards (G191B2B and Feige 34) showed evidence of a 10\%
contamination in the red compared to the flux standard Hilter 600, which
has a large Balmer jump.  We relied upon two observations of the latter
for the flux calibration.  The observations were all made as 8 1200 sec
integrations, with the slit of the spectrograph reset to the parallactic
angle at the beginning of each integration.  

The spectra were extracting using the trace of an observation a the
nearby offset star as the template. There is obvious structure
within the slit due to brightness variations of the nebula, and this
structure changed with the rotation angle.  We therefore measured the
intensity of the strongest lines (H$\alpha$, H$\beta$, and [OIII] $\lambda$ 
5007) from each individual spectrum.  However, N[II] $\lambda 6584$ and
[OII] $\lambda 3727$ are so weak that they could only be measured on
the co-added spectrum.  We show the co-added the spectra in Fig.~X.
The spectra went deep enough to clearly detect [OII].  We show
three pertinent regions in Fig.~\ref{fig:spectra}

The relative emission-line strengths are given in Table~\ref{tab:lines}. 
We see that the line ratio [OIII] $\lambda 5007$ to [OIII] $\lambda 4959$
is 2.8, in good agreement with the 2.9 usually assumed.
The actual H$\alpha$
flux measured is only 
about one-quarter the total H$\alpha$ luminosity measured from direct
images by Massey et al.\ (2003), due presumably to slit losses necessitated
by remaining at the parallactic angle (position angle $\sim 0$ degrees)
which prevented the slit from
being aligned with the H~II region (position angle $\sim 130$ degrees; see
Fig.~3 of Massey et al.\ 2003).


Using the Cardelli, Clayton, \& Mathis (1989) reddening law (A$_{\rm H\beta}=3.609E(B-V)$
and A$_{\rm H\alpha}=2.535 E(B-V)$) and an intrinsic ratio
H$\beta$/H$\alpha$=0.350, we derive a value for $E(B-V)=1.41\pm0.04$,
where the error represents the standard deviation of the mean for the 8
individual ratios.  We give the corrrected flux ratios in Table~\ref{tab:lines}
as well.

Without detecton of the temperature-sensitive [OIII]$\lambda 4363$ line,
we must rely upon the quasi-empirical relations between other emission
line ratios and oxygen abundance in order to get an approximation of the
metallicity of HIZSS~3.  We estimate this three ways:

\noindent
{\bf (1) Classical $R_{\rm 23}$ method.}  The $R_{\rm 23}$ ratio 
$$R_{\rm 23}=\frac{ {\rm [OIII]} \lambda 5007 + {\rm [OIII]}\lambda 4959 + 
{\rm [OII]}\lambda 3727}{{\rm H}\beta}=5.50$$
has been calibrated by Skillman (1989) for the case that the oxygen
abundance is much lower than solar.  Using his formula results in
a value $\log O/H+12=7.5$.

\noindent
{\bf (2) $R_{\rm 23}$ method modified by [OIII]/[NII].}  Edmunds \& Pagel (1984) use a modified version of the
$R_{\rm 23}$ method, which relies upon using the strength of the N[II]$\lambda 6584$ line as an additional calibration of $R_{\rm 23}$. We find 
$$\log \frac{{\rm [OIII]}\lambda 5007 + {\rm [OIII]}\lambda 4959}{{\rm[NII]} \lambda 6584}=2.22,$$ yielding a value of $\log O/H+12=7.8$.

\noindent
{\bf (3) $R_{\rm 23}$ method modified by [OIII]/[OII]}. McGaugh 
(1991) instead calibrates
the $R_{\rm 23}$ value with the relative strengths of [OIII] and [OII]:
$$\log \frac{{\rm [OIII]}\lambda 5007 + {\rm [OIII]}\lambda 4959}{{\rm[OII]} 
\lambda 3727}=0.35.$$  This yields a value of  $\log O/H+12=7.85$.

We conclude that the the $\log O/H+12\sim 7.8$, comparable to other 
metal-poor irregular galaxies in the Local Group, i.e., IC 1613
($\log$ O/H+12=7.85, Talent 1980), WLM ($\log$ O/H+12=7.77, Hodge \& Miller 1985),
and Pegasus ($\log$ O/H+12=7.93, Skillman, Bomans, \& Kobulnicky (sp?) 1997). For comparison,
the oxygen abundances of the LMC ans SMC are 8.37 and 8.13, respectively
(Russell \& Dopita 1990), while that of the solar neighborhood is 8.70
(Esteban \& Peimbert, 1995).


\subsection{Narrow-band Imaging}

The ESO observations provide another powerful way of determining the
reddening to HIZSS~3, namely by comparing the flux of the H~II region
at P$\beta$ (1.28$\mu$m) to that at H$\alpha$.  This technique has
been recently exploited to good advantage in a study of spiral galaxies by 
Jones, Elston, \& Hunter (2002).  The only complication is the lack of
spectrophotometric standards in the NIR, necessitating the use of 
model atmospheres with JHK standards.  We are indebted to L. Jones for 
correspondance and advice on this subject.

The UKIRT standards (Hawarden et al.\ 2001) FS~112 (G0) and FS~121 (K3) 
were observed through the ISAAC narrow band 1.28$\mu$m filter (NB1.28) and $J_s$ 
filters, as was the HIZSS~3 field.  We adopted the Kurucz (1992) Atlas 9 
$\log g=4.5$ 6000$^\circ$K and 4750$^\circ$K models for these two stars,
and computed their average flux over the NB1.28 filter with respect to
the Atlas 9 Vega model.  We then scaled the fluxes using the catalog J and
K values. The relative count rates agreed with the relative fluxes to better
than 10\%, giving us confidence in our procedure.  In order to deterine
an emission-line flux for a line-source, we must also take into account the
width of the filter; we computed $\int T_\lambda {\rm d}\lambda/T_{\rm 1.28\mu m}=194$, where $T_\lambda$ is the transmission of the filter as a function of
wavelength.  (See Jacoby, Africano, and Quigley 1987, but beware of an
error in equation 3, in which $F_N(i)$ is used in place of the correct quantity
$F_(i)$).  The P$\beta$ count rate was then measured after 
aligning the J$_s$ image to P$\beta$, and subtracting after matching the
PSFs by convolution and scaling.  The derived flux at P$\beta$ is
 $9.88\times10^{-15}$
ergs cm$^{-2}$ s$^{-1}$.  The observed ratio (P$\beta$/H$\alpha=8.7\times10^{-2}$)$_{\rm obs}=0.45$ (where
the flux at H$\alpha$ has been taken from Massey et al.\ 2003)
can be compared to the intrinsic ratio (P$\beta$/H$\alpha=8.7\times10^{-2}$)$_{\rm int}=5.71\times 10^{-2}$
(Osterbrock 1974).  Combined with the Cardelli et al.\ (1989) reddening
law, we then derive $E(B-V)=1.32$.  This value is in very good agreement
with the value found from our optical spectroscopy, $E(B-V)=1.41$.


\begin{references}

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\end{references}

\begin{deluxetable}{l c  c}
\pagestyle{empty}
\tabletypesize{\scriptsize}
\tablewidth{0pc}
\tablenum{1}
\tablecolumns{3}
\tablecaption{\label{tab:lines}Relative Emission-line Strengths} 
\tablehead{
\colhead{Spectral Line}
&\colhead{Uncorrected Flux} 
&\colhead{Corrected Flux}
}
\startdata
~[OII]$\lambda 3727$  & 0.033 & 0.60 \\
~[OIII]$\lambda 4959$ & 0.10  & 0.35 \\
~[OIII]$\lambda 5007$ & 0.29  & 0.98 \\
~H$\beta$             & 0.087 & 0.35 \\
~H$\alpha$            & 1.000 & 1.00 \\
~[NII]$\lambda 6584$  & 0.0080 & 0.0080\\
\enddata
\end{deluxetable}


\begin{figure}
\epsscale{0.45}
\plotone{figXa.eps}
\plotone{figXb.eps}
\plotone{figXc.eps}
\caption{\label{fig:spectra} Three spectral regions in our summed spectrum
of the H~II region in HIZSS~3 are shown.
}
\end{figure}

\end{document}


