Proc. SPIE. 9910, Observatory Operations: Strategies, Processes, and Systems VI
KEYWORDS: Stars, Cameras, Sensors, Calibration, Spectroscopy, Spectroscopy, Imaging spectroscopy, Molybdenum, Target acquisition, James Webb Space Telescope, James Webb Space Telescope, Camera shutters
The Near-Infrared Spectrograph (NIRSpec) is the work-horse spectrograph at 1-5microns for the James Webb Space Telescope (JWST). A showcase observing mode of NIRSpec is the multi-object spectroscopy with the Micro-Shutter Arrays (MSAs), which consist of a quarter million tiny configurable shutters that are 0. ′′20×0. ′′46 in size. The NIRSpec MSA shutters can be opened in adjacent rows to create flexible and positionable spectroscopy slits on prime science targets of interest. Because of the very small shutter width, the NIRSpec MSA spectral data quality will benefit significantly from accurate astrometric knowledge of the positions of planned science sources. Images acquired with the Hubble Space Telescope (HST) have the optimal relative astrometric accuracy for planning NIRSpec observations of 5-10 milli-arcseconds (mas). However, some science fields of interest might have no HST images, galactic fields can have moderate proper motions at the 5mas level or greater, and extragalactic images with HST may have inadequate source information at NIRSpec wavelengths beyond 2 microns. Thus, optimal NIRSpec spectroscopy planning may require pre-imaging observations with the Near-Infrared Camera (NIRCam) on JWST to accurately establish source positions for alignment with the NIRSpec MSAs. We describe operational philosophies and programmatic considerations for acquiring JWST NIRCam pre-image observations for NIRSpec MSA spectroscopic planning within the same JWST observing Cycle.
From 2008 December to 2012 September, the NICI (Near-Infrared Coronagraphic Imager at the Gemini-South 8.1-m) Planet-Finding Campaign (Liu et al. 2010) obtained deep, high-contrast AO imaging of a carefully selected sample of over 200 young, nearby stars. In the course of the campaign, we discovered four co-moving brown dwarf companions: PZ Tel B (36±6 MJup, 16.4±1.0 AU), CD-35 2722B (31±8 MJup, 67±4 AU), HD 1160B (33+12 -9 MJup, 81± AU), and HIP 79797Bb (55+20-19MJup, 3 AU from the previously known brown dwarf companion HIP 79797Ba), as well as numerous stellar binaries. Three survey papers have been published to date, covering: 1) high mass stars (Nielsen et al. 2013), 2) debris disk stars (Wahhaj et al. 2013), and 3) stars which are members of nearby young moving groups (Biller et al. 2013). In addition, the Campaign has yielded new orbital constraints for the ~8-10 MJup planet Pic β (Nielsen et al. 2014) and a high precision measurement of the star-disk offset for the well-known disk around HR 4796A (Wahhaj et al. 2014). Here we discuss constraints placed on the distribution of wide giant exoplanets from the NICI Campaign, new substellar companion discoveries, and characterization both of exoplanets and circumstellar disks.
Our team is carrying out a multi-year observing program to directly image and characterize young extrasolar
planets using the Near-Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1-meter telescope. NICI
is the first instrument on a large telescope designed from the outset for high-contrast imaging, comprising a
high-performance curvature adaptive optics (AO) system with a simultaneous dual-channel coronagraphic imager.
Combined with state-of-the-art AO observing methods and data processing, NICI typically achieves ≈2
magnitudes better contrast compared to previous ground-based or
space-based planet-finding efforts, at separations
inside of ≈2". In preparation for the Campaign, we carried out efforts to identify previously unrecognized
young stars as targets, to develop a rigorous quantitative method for constructing our observing strategy, and to
optimize the combination of angular differential imaging and spectral differential imaging. The Planet-Finding
Campaign is in its second year, with first-epoch imaging of 174 stars already obtained out of a total sample of
300 stars. We describe the Campaign's goals, design, target selection, implementation, on-sky performance, and
preliminary results. The NICI Planet-Finding Campaign represents the largest and most sensitive imaging survey
to date for massive
(>~ 1 MJup) planets around other stars. Upon completion, the Campaign will establish the best
measurements to date on the properties of young gas-giant planets at
-> 5-10 AU separations. Finally, Campaign
discoveries will be well-suited to long-term orbital monitoring and detailed spectrophotometric followup with
next-generation planet-finding instruments.
Wide Field Camera 3 (WFC3), a panchromatic imager being developed for the Hubble Space Telescope (HST), is now
fully integrated and has undergone extensive ground testing at Goddard Space Flight Center, in both ambient and
thermal-vacuum test environments. The thermal-vacuum testing marks the first time that both of the WFC3 UV/Visible
and IR channels have been operated and characterized in flight-like conditions. The testing processes are completely
automated, with WFC3 and the optical stimulus that is used to provide external targets and sources being commanded
by coordinated computer scripts. All test data are captured and stored in the long-term Hubble Data Archive. A full suite
of instrument calibration tests have been performed, including measurements of detector properties such as dark current,
read noise, flat field response, gain, linearity, and persistence, as well as total system throughput, encircled energy,
grism dispersions, IR thermal background, and image stability tests. Nearly all instrument characteristics have been
shown to meet or exceed expectations and requirements. Solutions to all issues discovered during testing are in the
process of being implemented and will be verified during future ground tests.