NASA Hubble Space Telescope Daily Report #4120

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT #4120

PERIOD COVERED: UT May 23, 2006 (DOY 143)

OBSERVATIONS SCHEDULED

ACS/HRC 10542

Charting the Sparkling Star Formation in NGC346

New, stunning V, I images of the youngest and most massive star forming region NGC 346, in the Small Magellanic Cloud, have been recently obtained with the HST/ACS. They reveal a myriad of small compact clusters: some are still embedded in dust, possibly connected by gas and dust filaments. We also discover a rich population of pre-main sequence low mass stars {~3 -0.6 Mo} mainly distributed in the body of NGC 346 and in these compact clusters, which formed with the central cluster {~5My ago}, but have not reached the main sequence yet. The immediate question that emerges is: how did star formation occur in this region? Is there evidence for an age spread among these clusters, that could be indicative of sequential star formation? We are, therefore, requesting an immediate follow up investigation with the ACS/HRC to perform a comprehensive UV/U study of the ten largest clusters identified in the NGC 346 region, with the objective of determining, in combination with the already available deep V, I data, their mass function, their upper mass cut-off, whether mass segregation is present, whether there are age variations, and what is the impact of the stellar feedback, with the final aim to establish how star formation has occured and progressed in this low metallicity environment.

ACS/HRC 10617

HST / Chandra Monitoring of a Dramatic Flare in the M87 Jet

As the nearest galaxy with an optical jet, M87 affords an unparalleled opportunity to study extragalactic jet phenomena at the highest resolution. During 2002, HST and Chandra monitoring of the M87 jet detected a dramatic flare in knot HST-1 located ~1″ from the nucleus. As of late 2004 its brightness has increased fifty-fold in the optical band, and continues to increase sharply; the X-rays show a similarly dramatic outburst. In both bands HST-1 now greatly exceeds the nucleus in brightness. To our knowledge this is the first incidence of an optical or X-ray outburst from a jet region which is spatially distinct from the core source — this presents an unprecedented opportunity to study the processes responsible for non-thermal variability and the X-ray emission. We propose seven epochs of HST/STIS monitoring during Cycle 14, as well as seven epochs of Chandra/ACIS observation {5ksec each}. We also include a brief HRC/ACS observations that will be used to gather spectral information and map the magnetic field structure. The results of this investigation are of key importance not only for understanding the nature of the X-ray emission of the M87 jet, but also for understanding flares in blazar jets, which are highly variable, but where we have never before been able to resolve the flaring region in the optical or X-rays. These observations will allow us to test synchrotron emission models for the X-ray outburst, constrain particle acceleration and loss timescales, and study the jet dynamics associated with this flaring component.

ACS/HRC 10738

Earth Flats

Sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently in the pipeline and to monitor any changes. Weekly coronagraphic monitoring is required to assess the changing position of the spots.

ACS/WFC 10592

An ACS Survey of a Complete Sample 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 ACS/WFC imaging 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, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.

NIC2 10510

Morphology of massive early-type galaxies at z>1.2: constraining galaxy formation models

We ask for NICMOS-NIC2 H-band imaging of a sample of 10 massive early-type galaxies spectroscopically identified at 1.26500A, would map the mass distribution of the bulk of their stellar content. The targets have been revealed by our group on the basis of near-IR spectroscopy obtained in the framework of a spectroscopic survey of a complete sample of bright EROs {Ks<18.5}. Optical and near-IR photometry is available for all the targets, and low resolution near-IR spectra have allowed their identification and redshift measurement. Spectroscopic and photometric data in our hands show that they have already assembled stellar masses greater than 3 10^11 solar masses, and that the mean age of their stellar population is estimated older than 2-3 Gyr for 6 of them and about 1 Gyr for the other 4 galaxies. Thus, they are among the most luminous and massive evolved galaxies detected so far at z>1. Other data are needed to infer how they have assembled such high stellar masses, i.e. to trace back their evolution. The requested observations would allow us to reveal signs of past interaction/merger event. A smooth r^{1/m} profile, coupled with no other signs of interaction/merger {disturbed morphology}, would place the possible merger event of formation 1-2 Gyr before their redshift z pprox 1.5, i.e. at z > 2-3. On the other hand, if signs of recent merger events will be found, the last merger event forming the local massive spheroids will be constrained at 1.5 < z < 2. Thus, the requested HST observations will allow for the first time to see how massive early-type galaxies at z pprox 1.5 look like, constraining in any case the redshift of the possible merging event of their formation.

NIC2/ACS/WFC/WFPC2 10532

Kinematics and morphology of the most massive field disk galaxies at z>1

We propose to obtain 1 orbit NIC-2 images of a sample of the 15 most massive galaxies found at $1 < z < 1.3$. These were culled from over 20, 000 Keck spectra collected as part of DEEP and are unique among high redshift massive galaxy samples in being kinematically selected. We intend to test whether these potentially very young galaxies are likely precursors to massive local disks, assuming no further merging. NIC-2 images provide rest-frame optical morphologies that will show whether they are normal disky systems or instead more disturbed looking objects with multiple subcomponents, mergers, peculiar structure, etc. NIC-2 provides near-IR resolutions sufficient to enable measurements of bulges and disks subcomponents. The near-IR will fill a critical gap in the broad-band SED photometry of the galaxy and its subcomponents to estimate mean stellar ages and stellar masses and to assess whether old stellar bulges and disks are in place at that time. Finally, this sample will yield the first statistically significant results on the $z > 1$ evolution of the Tully-Fisher relation for massive galaxies. In addition, we propose parallel observations with ACS WFC {V and I bands} and WFPC2 {I-band}. These will target up to 700 galaxies at redshifts 0.7 … 1.2 for which the DEEP2 survey has obtained precision redshifts and high-resolution kinematic data. The added HST morphology and color information will allow a variety of detailed studies on dynamical, structural, and photometric evolution of galaxies.

NICMOS 8790

NICMOS Post-SAA calibration – CR Persistence Part 1.

A new procedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA. The darks will be obtained in parallel in all three NICMOS Cameras. The POST-SAA darks will be non-standard reference files available to users with a USEAFTER date/time mark.

WFPC2 10628

Determining the Lifetime of Planetary Nebula Knots from Observations of the Core of the Helix Nebula.

Knots within the Planetary Nebulae {PN} are ubiquitous components and form at the interface of the expanding ionized zone and the surrounding dusty and molecule-rich neutral layers. About half of the total mass ejected by the precursor star becomes trappped in the Knots, which will join the Interstellar Medium {ISM} within a few tens of thousands of years. If they survive, they may be the source of the micro-structures that appear to be common in the ISM, a result that would be important in understanding the exchange of matter between stars and the ISM. We propose observations that will characterize the Knots over a wider ionization range and ages than has been done before, which should yield the best model for the Knots and therefore the best prediction of their fates. Knots are not seen within a well defined distance from the central star. We don’t know if this is because they are being destroyed by photoevaporation {since the inner Knots would be the youngest}, an important factor in our modeling. However, the inner core of the Helix Nebula has not been imaged in the HeII emission that dominates the region. We propose eight orbits of observations that will search the inner core of the Helix for undetected knots using the WFPC2 HeII F469N filter and the ACS-WFC F502N filter that isolates [OIII] emission. Our WFPC2 pointing will also allow imaging the best studied knot in HeII, giving us the best possible data for that Knot. These combined results will be modeled with the new Hydro- Cloudy code, allowing us to determine if they will survive the PN stage and become components of the ISM. At no additional cost of observing time we will be able to derive a calibration of the WFPC2 F469N filter, to make unprecedented quality parallel images in molecular hydrogen, and to extended the coverage of high resolution emission-line images of the Helix Nebula.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

This calibration proposal is the Cycle 14 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {both gain 7 and gain 15 — to test stability of gains and bias levels}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. These also provide raw data for generating annual super-bias reference files for the calibration pipeline.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)

HSTARS:

#10273- REACQ(2,1,1) failed, scan step limit exceeded on FGS 2 @143/1140z. REACQ(2,1,1) at 143/11:36:58 failed due to scan step limit exceeded on FGS 2 at 11:40:25. GSACQ(2,1,1) at 10:19:31 was successful. Observations affected: ACS 50 to 52, NICMOS 9 to 10, WFPC 25 TO 27.

#10274- GSAcq(2,1,1) requires 6 CT entries before achieving CT-DV and ultimately Succeeding @138/0339z OTA SE investigation of PTAS TC processing errors reveals that the GSAcq(2,1,1) beginning at 2006.138/03:35:53 entered CT 6 different times before achieving CT-DV. The acquisition ultimately succeeded on both FGSes.

#10275- ReAcq(2,1,1) requires 3 CT entries to achieve CT-DV @140/0157Z OTA SE investigation of PTAS TC processing errors reveals that the ReAcq(2,1,2) beginning at 2006.140/01:53:59 entered CT 3 different times before achieving CT-DV. The acquisition ultimately succeeded on both FGSes.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES:

#1480- Adjust Batt Temp Limits @143/1230z

                           SCHEDULED      SUCCESSFUL    FAILURE TIMES
FGS GSacq                     6                 6
FGS REacq                    10                 9                 (HSTAR 10273)
OBAD with Maneuver       24               24

SIGNIFICANT EVENTS:

Battery 5 Capacity Test Flash Report #1 Commanding for the Battery 5 Capacity Test started on DOY 143/1200GMT (5/23 at 8:00 am) with setting the Battery Pressure Test for a 5-battery system. Battery 5 was taken off-line and battery discharge began on the first opportunity at 1257GMT (5/23 at 8:47 am).

Battery 5 discharge switched from the high rate to the low rate resistor at 2006/143/22:45 GMT (6:45 pm local). Following completion of the discharge, which is expected to occur around 145/1400 GMT (5/25 at 10:00 am local), Battery 5 will be placed back on-line in hardware during orbit night. Battery 5 will be placed back on-line in FSW on 146/1440 GMT (5/26 at 10:40am local). As of 143/23:00, battery 5 discharge at the low rate continues nominally.