NASA Hubble Space Telescope Daily Report #4923
HUBBLE SPACE TELESCOPE DAILY REPORT #4923
Continuing to Collect World Class Science
PERIOD COVERED: 5am September 2 – 5am September 3, 2009 (DOY 245/09:00z-246/09:00z)
OBSERVATIONS SCHEDULED
ACS/WFC3 11879
CCD Daily Monitor (Part 1)
This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 352 orbits (22 weeks) from 31 August 2009 to 31 January 2010.
COS/NUV 11480
COS NUV Structural and Thermal Stability
The goal of this program is to measure OTA-COS pointing jitter or drifts, over timescales of seconds to hours. In particular, our priorities are to test the level of OSM1 drift, thermal day-night transitions, and orbital ‘breathing’. Pointing-related thermal offsets with their related drifts during thermal settling will be overlaid upon the signatures of the other components of positional change. Three different instrumental configurations/transitions will be tested: NUV and FUV spectroscopy, and NUV imaging using Mirror A, all with the PSA. No FP-POS motions, nor grating changes, will be made during the spectroscopy in order to limit the variables contributing to any changes in position of the spectra.
ID: COS 20 (11480) & COS 35 (11493) This is the NUV portion of this experiment. It was initially estimated to be a 6-orbit program, but has been expanded to 10 orbits in order to improve the statistical sample of the day-night/breathing transitions.
STIS/CCD 11721
Verifying the Utility of Type Ia Supernovae as Cosmological Probes: Evolution and Dispersion in the Ultraviolet Spectra
The study of distant type Ia supernova (SNe Ia) offers the most practical and immediate discriminator between popular models of dark energy. Yet fundamental questions remain over possible redshift-dependent trends in their observed and intrinsic properties. High-quality Keck spectroscopy of a representative sample of 36 intermediate redshift SNe Ia has revealed a surprising, and unexplained, diversity in their rest-frame UV fluxes. One possible explanation is hitherto undiscovered variations in the progenitor metallicity. Unfortunately, this result cannot be compared to local UV data as only two representative SNe Ia have been studied near maximum light. Taking advantage of two new `rolling searches’ and the restoration of STIS, we propose a non-disruptive TOO campaign to create an equivalent comparison local sample. This will allow us to address possible evolution in the mean UV spectrum and its diversity, an essential precursor to the study of SNe beyond z~1.
STIS/CCD 11843
STIS CCD Performance Monitor
This activity measures the baseline performance and commandability of the CCD subsystem. Only primary amplifier D is used. Bias and Flatfield exposures are taken in order to measure bias level, read noise, CTE, and gain. Numerous bias frames are taken to permit construction of “superbias” frames in which the effects of read noise have been rendered negligible. Full frame and binned observations are made, with binning factors of 2 x 1, 1 x 2, 2 x 2. Bias frames are taken in subarray readouts to check the bias level for ACQ and ACQ/PEAK observations. All exposures are internals.
STIS/CCD 11844
CCD Dark Monitor Part 1
Monitor the darks for the STIS CCD.
STIS/CCD 11846
CCD Bias Monitor-Part 1
Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.
STIS/CCD 11850
CCD Sparse Field CTE Internal
CTE measurements are made using the “internal sparse field test”, along the parallel axis. The “Pos=” optional parameter, introduced during Cycle 11, is used to provide off- center MSM positionings of some slits. All exposures are internals.
STIS/CCD/MA1/MA2 11690
EG And: Providing the Missing Link Required for Modeling Red Giant Mass-Loss
For the majority of red giant stars, the basic mass-loss processes at work are unknown. Indeed, for stars of spectral types between K0 III and M5-M6 III, much remains unknown about the regions above the visible photosphere and the transportation of the processed material outwards to the ISM. Eclipsing symbiotic binary systems, consisting of an evolved giant in orbit with a white dwarf, provide an opportunity to take advantage of the finite size of the hot component to probe different levels of the chromosphere and wind acceleration region in absorption. This provides spatially resolved thermal, ionisation and dynamic information on the wind which can then be compared against predictions of hydrodynamical stellar atmosphere codes. The symbiotic binary EG And can be considered as a Rosetta Stone for understanding the winds of these objects. The system is ideal on a number of counts for utilizing the ultraviolet eclipse of the white dwarf (WD) component to probe, layer-by-layer, the thermal and dynamic conditions at the very base of the wind and chromosphere of the RG. This information is vital for constraining, testing and calibrating the new generation of cool giant wind+chromosphere models and is not possible to obtain for isolated RGs. This team has studied the UV eclipses of this system in depth and detail, however in order to definitively constrain the wind acceleration profile and identify the location of the temperature rise just above the photosphere, we require 4 STIS E140M observations of EG And at specific orbital phases. We are also requesting a E230M observation of an isolated spectral standard, corresponding to the RG in the binary, which will help place the EG And results into the context of the general RG population from analysis of the MgII wind diagnostic lines.
STIS/CCD/MA2 11860
MAMA Spectroscopic Sensitivity and Focus Monitor
Monitor sensitivity of each MAMA grating mode to detect any change due to contamination or other causes. Also monitor the STIS focus in a spectroscopic and an imaging mode.
STIS20 11402
STIS-20 NUV MAMA Dark Monitor
The STIS NUV-MAMA dark current is dominated by a phosphorescent glow from the detector window. Meta-stable states in this window are populated by cosmic ray impacts, which, days later, can be thermally excited to an unstable state from which they decay, emitting a UV photon. The equilibrium population of these meta-stable states is larger at lower temperatures; so warming up the detector from its cold safing will lead to a large, but temporary, increase in the dark current.
To monitor the decay of this glow, and to determine the equilibrium dark current for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be taken each week during the SMOV period. Once the observed dark current has reached an approximate equilibrium with the mean detector temperature, the frequency of this monitor can be reduced to one pair of darks per week.
WFC3/ACS/IR 11235
HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe
At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These `luminous infrared galaxies’ (LIRGs) are primarily interacting or merging disk galaxies undergoing enhanced star formation and Active Galactic Nuclei (AGN) activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose NICMOS NIC2 imaging of the nuclear regions of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample (RBGS: i.e., 60 micron flux density > 5.24 Jy). This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity and resolution of NICMOS NIC2 on HST enables a unique opportunity to study the detailed structure of the nuclear regions, where dust obscuration may mask star clusters, AGN, and additional nuclei from optical view, with a resolution significantly higher than possible with Spitzer IRAC. This survey thus provides a crucial component to our study of the dynamics and evolution of IR galaxies presently underway with Wide-Field, HST ACS/WFC3, and Spitzer IRAC observations of these 88 galaxies. Imaging will be done with the F160W filter (H-band) to examine as a function of both luminosity and merger stage: (i) the luminosity and distribution of embedded star clusters, (ii) the presence of optically obscured AGN and nuclei, (iii) the correlation between the distribution of 1.6 micron emission and the mid-IR emission as detected by Spitzer IRAC, (iv) the evidence of bars or bridges that may funnel fuel into the nuclear region, and (v) the ages of star clusters for which photometry is available via ACS/WFC3 observations. The NICMOS data, combined with the HST ACS, Spitzer, and GALEX observations of this sample, will result in the most comprehensive study of merging and interacting galaxies to date.
WFC3/ACS/IR 11563
Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to <0.2L* from Deep IR Imaging of the HUDF and HUDF05 Fields The first generations of galaxies were assembled around redshifts z~7-10+, just 500-800 Myr after recombination, in the heart of the reionization of the universe. We know very little about galaxies in this period. Despite great effort with HST and other telescopes, less than ~15 galaxies have been reliably detected so far at z>7, contrasting with the ~1000 galaxies detected to date at z~6, just 200-400 Myr later, near the end of the reionization epoch. WFC3 IR can dramatically change this situation, enabling derivation of the galaxy luminosity function and its shape at z~7-8 to well below L*, measurement of the UV luminosity density at z~7-8 and z~8-9, and estimates of the contribution of galaxies to reionization at these epochs, as well as characterization of their properties (sizes, structure, colors). A quantitative leap in our understanding of early galaxies, and the timescales of their buildup, requires a total sample of ~100 galaxies at z~7-8 to ~29 AB mag. We can achieve this with 192 WFC3 IR orbits on three disjoint fields (minimizing cosmic variance): the HUDF and the two nearby deep fields of the HUDF05. Our program uses three WFC3 IR filters, and leverages over 600 orbits of existing ACS data, to identify, with low contamination, a large sample of over 100 objects at z~7-8, a very useful sample of ~23 at z~8-9, and limits at z~10. By careful placement of the WFC3 IR and parallel ACS pointings, we also enhance the optical ACS imaging on the HUDF and a HUDF05 field. We stress (1) the need to go deep, which is paramount to define L*, the shape, and the slope alpha of the luminosity function (LF) at these high redshifts; and (2) the far superior performance of our strategy, compared with the use of strong lensing clusters, in detecting significant samples of faint z~7-8 galaxies to derive their luminosity function and UV ionizing flux. Our recent z~7.4 NICMOS results show that wide-area IR surveys, even of GOODS-like depth, simply do not reach faint enough at z~7-9 to meet the LF and UV flux objectives. In the spirit of the HDF and the HUDF, we will waive any proprietary period, and will also deliver the reduced data to STScI. The proposed data will provide a Legacy resource of great value for a wide range of archival science investigations of galaxies at redshifts z~2-9. The data are likely to remain the deepest IR/optical images until JWST is launched, and will provide sources for spectroscopic followup by JWST, ALMA and EVLA.
WFC3/IR 11915
IR Internal Flat Fields
This program is the same as 11433 (SMOV) and depends on the completion of the IR initial alignment (Program 11425). This version contains three instances of 37 internal orbits: to be scheduled early, middle, and near the end of Cycle 17, in order to use the entire 110-orbit allocation.
In this test, we will study the stability and structure of the IR channel flat field images through all filter elements in the WFC3-IR channel. Flats will be monitored, i.e. to capture any temporal trends in the flat fields and delta flats produced. High signal observations will provide a map of the pixel-to-pixel flat field structure, as well as identify the positions of any dust particles.
WFC3/UVIS 11432
UVIS Internal Flats
This proposal will be used to assess the stability of the flat field structure for the UVIS detector. Flat fields will be obtained for all filters using the internal D2 and tungsten lamps.
This proposal corresponds to Activity Description ID WF19. It should execute only after the following proposals have executed: WF08 – 11421 WF09 – 11422 WF11 – 11424 WF15 – 11428
WFC3/UVIS 11905
WFC3 UVIS CCD Daily Monitor
The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).
WFC3/UVIS 11908
Cycle 17: UVIS Bowtie Monitor
Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.
WFC3/UVIS 11912
UVIS Internal Flats
This proposal will be used to assess the stability of the flat field structure for the UVIS detector throughout the 15 months of Cycle 17. The data will be used to generate on- orbit updates for the delta-flat field reference files used in the WFC3 calibration pipeline, if significant changes in the flat structure are seen.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST:
18695-0 – Adjust NCS PID Control Setpoints @ 245/150021z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 8 8
FGS REAcq 8 8
OBAD with Maneuver 6 6
SIGNIFICANT EVENTS:
NCS PID Control Setpoint Adjustment
OR 18695-0 to adjust the NCS PID control setpoint temperature was successfully completed at 145/15:00:21 UTC.
