ARCSAT ID NUMBER: AS10

DESCRIPTIVE TITLE: A New Filter to Study Stellar Populations.

PI: Joanne Hughes

OBSERVER(S): Joanne Hughes, Jeff Brown

UNCERTIFIED/UNTRAINED OBSERVERS: N/A

COLLABORATORS: George Wallerstein

CONTACT INFORMATION: jhughes@seattleu.edu 206-303-7378

NUMBER OF WEEKS REQUESTED: 1

TIME REQUESTED: Jan. 26-Feb. 1 or Jan. 19-26 or Dec. 8-14 (if that is
the only option)

INSTRUMENT:SurveyCam

FILTERS: C u'g'r'i' & "W" (That's the 2"x2" filter 8450-8800A that GW
designed and we can send it from MRO)

COMMENTS: I would prefer the late-Jan. 2015 time so that it can be
part of our "observing methods" class, which starts in winter
quarter. We need 2 weeks lead time to get students prepared.

BRIEF SCIENCE JUSTIFICATION:  We propose to use a newly designed
filter (named W: 845-880-nm) to measure the [ЮБ/Fe] ratio in red giants
and  trace the chemical evolution of stars in the Milky Wayт??s globular
clusters, halo and Local Group galaxies. The W-filter will supplement
the broadband Sloan and Washington filters to extend and improve
imaging surveys to fainter stars and systems which spectroscopy cannot
reach on 4-m class telescopes. The new filter will benefit the
astronomical community in general by providing a diagnostic
intermediate-band tool in the near-infrared (800-2500-nm), which is
less affected by interstellar dust than the bluer StrУЖmgren filter
system. This project will benefit the undergraduate research program
at Seattle University by providing training for a number of students
in astronomical observations and data reduction techniques as part of
a new astronomy research methods course. We have designed a program to
test our new filter observationally and theoretically, in preparation
for a proposal to the NSF to buy larger format filters for wide
field-of-view cameras such as the (partial) One-Degree Imager on the
WIYN 3.5-m telescope, and ARCTIC at the Apache Point Observatoryт??s
3.5-m telescope. We will use the newly-acquired 2т??x2т?? filter from
Manastash Ridge Observatory  to start observing globular clusters. We
plan to observe stars with effective temperatures between 4000 and
6000K on the RGB down to the MSTO. The [Fe/H] range will be from 0.0
to -2.5 (and lower in nearby galaxies), with [ЮБ/Fe] from -0.1 to
+0.5. To find the continuum of stars, we will use comparison bands  r'
and i', which are not extremely metallicity-sensitive. We will also
use the Washington C-filter, which is sensitive to both [Fe/H] and
[ЮБ/Fe], and the (g'-i')-color.