Other External SPECROAD Pages:
Installing E-SPECROAD | User's Guide | Version History
|Available Downloads:||Size||Last Updated|
|hectoshell_MacOSX_20130415.tgz||253 K||Mon., Apr. 15, 2013|
|hectoshell_Linux_20130415.tgz||252 K||Mon., Apr. 15, 2013|
|idhenear.600gpm_4800.dat||523 Bytes||Tue., Aug. 5, 2008|
|idhenear.600gpm_4800_best.dat||532 Bytes||Thu., Jun. 4, 2009|
|Hectospec_HeNeAr_600gpm_4800.pdf||499 K||Thu., Jun. 4, 2009|
|Hectospec_HeNeAr_Spectrum.pdf||2430 K||Tue., Aug. 5, 2008|
External SPECROAD or E-SPECROAD came
about when my colleagues and I were awarded time on the Hectospec
multi-fiber spectrometer on the MMT on Mount Hopkins in the summer of 2007.
The MMTO is
a "joint venture" between the University
of Arizona and the Smithsonian Institution (via
Astrophysical Observatory aka SAO). We were awarded
these nights in part because one of my colleagues
is at the University of Minnesota and since the
U of M is a partner on
Binocular Telescope, they have bought into
a certain number of nights at the U of Arizona facilities and so they can apply
Image of the Hectospec Focal Plane showing many of the 300 optical fibers deployed
as well as the two fiber positioning robots in the upper left and lower
right. This image is from the Hectospec
Photo Gallery which also contains
movies of the instrument in action.
Unlike most projects utilitizing the Hectospec, our project
was a stellar spectroscopy project which requires relatively high resolution
spectra at short wavelengths (as opposed to the low resoution red-focused spectra
typical of extragalactic work). As such we used the 600 gpm grating centered
at 4800 Ångstroms
instead of the more commonly used 270 gpm grating. Furthermore,
we were NOT SAO personnel, so we faced a problem of how to reduce our Hectospec
data at our own home institutions without access to SAO computers.
After investigating the use of HSRED,
a series of IDL scripts developed by Richard Cool at the U of Arizona (now
at Princeton), I rejected that approach because the scripts were designed to
work with the 270gpm grating and frankly, I am not an IDL expert. So next I
turned to the Hectospec
IRAF package. This Hectospec package has everything in it
necessary for dealing with the Hectospec data, although you then need to know
what to do with it. Since this was the first time I was reducing
Hectospec data, I was hoping for a more 'cookbook' approach. I knew from talking
to folks at the MMT that there was a set of shell scripts called SPECROAD used
by the SAO folks to automate much of the process of reducing Hectospec data.
It turned out they even provided a version of it the Hectospec
IRAF package (in
Shell/ subdirectory). So rather than re-invent the wheel,
I decided to try to use SPECROAD to
reduce our data.
The Problem with SPECROAD
The SPECROAD scripts
seemed like the safest approach to reducing the Hectospec data. All the steps
for the user were laid out and the scripts could even take advantage of multiple
processors on modern computers to run several IRAF processes in parallel, thus
speeding up data reduction. However, I quickly discovered the existing SPECROAD scripts
had some major issues:
- Nonportability: The SPECROAD scripts
were only designed to run on a Solaris computer at the SAO, with files
in specific hard-coded locations using a specific IRAF environment with
all the IRAF parameters set before the scripts were run. Along with the
issues of simply porting the code to run on a new computer, I was faced
with not knowing which IRAF parameters needed to be set to particular values
ahead of time.
- Lack of Documentation: The
documentation for SPECROAD is frankly inadequate. It was
an in-house tool for the SAO, so the publically-available documentation
consists mostly of one
what the scripts do.
- No Installation Instructions: There were
several IRAF packages to install (available
here). The shell scripts required not only the installation of several
IRAF packages and the compilation of several C programs, they used korn
shell (ksh) which I was unfamiliar with. And, as I would soon discover, the
ksh installed on the Mac had serious bugs in its list handling.
- Undocumented Bugs: The available SPECROAD scripts
had major bugs whose workarounds were undocumented and only available when
I would email someone at the SAO to inquire about them. In one case,
you had to know to actually break out of the script with Control-C, then
run some of the reduction in IRAF, and then restart the script!
- Assumed Availability of Spectral Templates: The SPECROAD scripts
typically relied on pre-set spectral line databases for different grating/central
wavelength configurations instead of having the user exploit the IRAF identify command
to build a database. This was not a bug, but since we were using an 'atypical'
configuration, it proved annoying.
- Assumed Use of Low Resolution Spectra: The SPECROAD scripts
were mostly pre-configured for working with 270gpm gratings and required
some tweaking for 600gpm.
- Inconvienent Backups As Data Reduction Progresses: If
one of the scripts executed by SPECROAD crashed,
you had to dig around subdirectories to "backtrack" the changes before
restarting the script. With disk space not an issue, I prefer monolithic
backups of the entire data directory at certain key points in the data
Reworking SPECROAD into E-SPECROAD
Given these problems with the SPECROAD scripts,
in fall of 2007 I set about to port SPECROAD to
the Mac OS X platform, which is where I do most of my data reduction. As
it turned out, this required extensive minor changes to many of the SPECROAD scripts
to address issues I discovered along the way. Given the extensive changes,
I have called this version of SPECROAD, "External
SPECROAD" or "E-SPECROAD"
because its goal was to make it possible to run the automated SPECROAD scripts
external to SAO. Although Doug
Mink at the SAO helped quite a bit, the SAO is not responsible for this
creation and it is I who should be held accountable for its flaws or freatures.
- Nonportability: With the goal of making E-SPECROAD scripts
run on any computer (but my Mac in particular), I set about removing as
much of the site-specific code as possible. There is some minimal editting
that still needs to be done to make the scripts run on a particular computer,
but it is much less extensive than before. I was able to resolve the problem
of unknown "preset" IRAF parameters in June 2008 when Bill Wyatt at the
SAO granted me access to their computers, which allowed me to examine their
setup and configure E-SPECROAD to try to match it.
I also want to
E-SPECROAD would probably not have gotten anywhere without
the efforts of Doug
Mink. He is
an awesome programmer and the person responsible for some commonly used
astronomical packages such as RVSAO and WCSTools.
He was dedicated to the portability of the Hectospec
package for IRAF and so he worked quite hard to port the
portions of the package that relied on in-house, non-IRAF code to IRAF
native code. Without those changes, running E-SPECROAD on
a non-Solaris machine would still be extremely difficult.
- Lack of Documentation: I have tried to provide a more
extended User's Guide to reducing Hectospec data
with External SPECROAD which tells you a little bit of what it does
and what to expect it to do. This isn't quite "Hectospec for Dummies",
but at least it gets you to "Hectospec for Graduate Students".
- No Installation Instructions: I have
documented the system requirements and installation
instructions for E-SPECROAD here.
- Undocumented Bugs: In E-SPECROAD I
have tried to fix as many of the undocumented bugs as I found and dealt
with the requrement of running the IRAF hcal process external
to the script by having it pause and request the user run IRAF separately.
This allows the user to process the data without requireing the user to
interupt the E-SPECROAD scripts.
- Assumed Availability of Spectral Templates: The E-SPECROAD script
starts by copying the HeNeAr spectral line list from the Hectospec IRAF
scripts library and then allows you to build your own spectral line identifications
database of the HeNeAr spectra for your particular set of fibers (through
the identify IRAF
procedure). This was possible with the original SPECROAD scripts,
they just were not really configured to default to this. Another annoyance
related this is that the HeNeAr lamps we used at the Hectospec leaked
out much of their helium some time ago (as of Summer 2008 it does look
like this might have been remedied with a new lamp), so I also allow download
of a more recent
spectral atlas for the lamp
originally provided to me by Susan Tokarz of the Harvard Smithsonian Center
for Astrophysics (CfA) here.
- Assumed Use of Low Resolution Spectra: The E-SPECROAD scripts
now automatically determine the spectral range you are working with. This
allows the E-SPECROAD scripts
to work with both 270gpm or 600gpm data without modifications.
- Inconvienent Backups As Data Reduction Progresses: The E-SPECROAD scripts
now prompt you to make backups of the data directory in its "current
at two points. This allows you to recover fairly easily in the event of
some crashes. The only major annoyance being you need to have a significant
amount of free space available to make the backups, enough to clone the
directory. These backups are optional, but highly recommended.
Funding: The creation of E-SPECROAD was supported by National
Science Foundation Grant AST-0729989 ("RUI: Collaborative Research
to Map the Asymmetric Thick Disk").
Papers Published Using External SPECROAD
- "Kinematics and Metallicities in the Bootes III Stellar Overdensity: a Disrupted Dwarf Galaxy?"
Carlin, J.L., Grillmair, C.J., Munoz, R.R., Nidever, D.L., and Majewski, S.R. 2009, ApJL, 702, L9-L13 (ADS abstract page) (ArXiv) (PDF)
- "A Plethora of AGN Among Lyman Alpha Galaxies at Low Redshift"
Finkelstein, S.L., Cohen, S.H., Malhotra, S., Rhoads, J.E., Papovich, C. 2009, ApJ, 703,
L162 (ADS abstract page) (ArXiv) (PDF)
- "Dust Extinction and Metallicities of Star-Forming Lyman Alpha
Emitting Galaxies at Low Redshift"
Finkelstein, S.L., Cohen, S.H.,
Moustakas, J., Malhotra, S., Rhoads, J.E., Papovich, C. 2011, ApJ, 733, 117. (ADS abstract page) (ArXiv) (PDF)
- "Mapping the Asymmetric Thick Disk: III. The Kinematics and Interaction with the Galactic Bar"
Humphreys, R.M., Beers, T.C., Cabanela, J.E., Grammer, S., Davidson K., Lee, Y.S., and Larsen, J.A..2011 AJ, 141, 131. (ADS abstract page) (ArXiv) (PDF)
- "First spectroscopic measurements of [OIII] emission from Lyman-alpha
selected field galaxies at z ~ 3.1"
McLinden, E.M. , Finkelstein,
S.L., Rhoads, J.E., Malhotra, S., Hibon, P., Richardson, M.L.A., Cresci,G.,
Quirrenbach, A., Pasquali, A., Bian, F., Fan,X., Woodward C.E. 2011,ApJ, 730, 136. (ADS abstract page) (ArXiv) (PDF)