Demonstrating the MaNGA Instrument at APO

23 01 2013

MaNGA (Mapping Nearby Galaxies at APO) is one of the three surveys planned for the fourth generation of SDSS starting in 2014 http://www.sdss3.org/future/. The team has now successfully demonstrated instrumentation and observing procedures at Apache Point Observatory on the Sloan Foundation 2.5-m telescope.

The big technical challenge for the MaNGA instrument team has been to develop new bundle heads for the fibers which feed the BOSS spectrograph. These bundles enable many fibers to be places in a hexagonal grid across a galaxy:

MaNGA_galaxy_illustration

This will allow for resolved (or “integral field unit”; IFU) spectroscopy across the galaxy. The MaNGA survey will use these fiber bundles (which will vary in size from 19 to 127 fibers per bundle) to observe 10,000 nearby galaxies from 2014-2020.

Thanks to hard work from the instrument and data teams and support from the staff at APO and from SDSS-III, the MaNGA prototype IFU bundles have now successfully installed into an SDSS cartridge and used to obtain on-sky data along with to afternoon tests and calibrations.

Installation and First Light

MaNGA_ifu_bundle_installation
Nick MacDonald (UW) and Niv Drory (UNAM) led the installation of the MaNGA hardware, including the IFU bundles and 150 individual fibers, into the SDSS bright-time cartridge #1. With help from UW grad student Nell Byler and a few other helpful hands, the installation proceeded smoothly in about a day and a half.

MaNGA_plugging

MaNGA_plugging_1
Ting Xiao (SHAO) and Nell Byler (UW) inspected projected overlays on the first plate (top left) to determine which fibers and bundles should be plugged according to David Wake’s (Wisconsin) design. Veteran Sloan pluggers Francis Cope (APO) and Diana Holder (APO) then prepared the plate for the cartridge (top center) and plugged it (bottom and top right), providing valuable feedback about bending stresses in the fibers and the ease of plugging a complicated plate design.

MaNGA_v_grooves
Paul Harding (CWRU), Mike Blanton (NYU), and especially David Schlegel (LBNL) provided their expertise with remote support regarding cartridge layout, plate overlays, and the auto mapper that determines which fibers have been plugged into which holes. The fibers in each bundle are then spread out flat into “V grooves” (bottom right) where the light will be passed to the spectrograph to be spread out into its constituent wavelengths.

MaNGA_mounting
SDSS engineers Joe Huehnerhoff (UW) and Bob Pfaffenberger (APO) helped load the plugged MaNGA cartridge into the telescope for the first time. Behind the scenes, SDSS observer Kaike Pan drafted a series of scripts and tests that, thanks in part to quick off-site analysis by Renbin Yan, enabled the team to use the SDSS control software to carry out MaNGA observations. A day or two later, sunset at the 2.5 meter followed by First (Astronomical) Light for the MaNGA prototypes and a happy team at 4am local time.

MaNGA_slice_127_1comp

The highlight so far has been dithered observations of a plate designed to target stars and sample the PSF. MaNGA focused on several regions with 2-3 stars per bundle and MaNGA software pipeline developers David Law and Brian Cherinka (both U. of Toronto) have advanced the reduction pipeline to the point where they can produce preliminary 3D reconstructed data cubes from these observations! Here is an example of taken a 127-fiber bundle (top right) to observe a 25″x25″ region of the sky (SDSS image top center). Each fiber resulted in a spectrum . Integrating these spectra recovers the re-constructed image of these three stars as seen through the MaNGA IFU (top left).


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