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NASA Hubble Space Telescope Daily Report #4205

Status Report From: Space Telescope Science Institute
Posted: Monday, September 25, 2006

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HUBBLE SPACE TELESCOPE DAILY REPORT # 4205

- Continuing to collect World Class Science

PERIOD COVERED: UT September 22,23,24, 2006 (DOY 265,266,267)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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. The keyword 'USEAFTER=date/time' will also be added to the header of each POST-SAA DARK frame. The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day so each POST-SAA DARK will need to have the appropriate time specified, for users to identify the ones they need. Both the raw and processed images will be archived as POST-SAA DARKSs. Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such maps to remove the CR persistence from the science images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.

ACS/WFC 10997

The Environmental Effects of Large Scale Structures Around the Galaxy Cluster RXJ0152.7- 1357 at z=0.84

Large scale {~10 Mpc} filaments of galaxies associated with X-ray luminous clusters at z~1 have recently been discovered in ground based wide-field observations. This make it possible to investigate the fundamental properties of galaxies {mass, structure and stellar content} in a variety of environments {field, groups, clusters} and compare the environmental effects on galaxy properties at z~1 to those a z~0. We propose to observe filamentary structures around the galaxy cluster RX J0152.7-1357 at z=0.84 in two filters with the Wide Field Camera {WFC} on the ACS to track down morphological and stellar population differences in the cluster environment and in the less massive substructures in the filaments, providing key elements to understand how the correlations we observe between galaxy properties and galaxy location within a cluster are established and evolve with redshift.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and highly non-uniform archive, making comprehensive comparative studies among galaxies essentially impossible. We propose to secure HST's lasting impact on the study of nearby galaxies by undertaking a systematic, complete, and carefully crafted imaging survey of ALL galaxies in the Local Universe outside the Local Group. The resulting images will allow unprecedented measurements of: {1} the star formation history {SFH} of a >100 Mpc^3 volume of the Universe with a time resolution of Delta[log{t}]=0.25; {2} correlations between spatially resolved SFHs and environment; {3} the structure and properties of thick disks and stellar halos; and {4} the color distributions, sizes, and specific frequencies of globular and disk clusters as a function of galaxy mass and environment. To reach these goals, we will use a combination of wide-field tiling and pointed deep imaging to obtain uniform data on all 72 galaxies within a volume-limited sample extending to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the wide-field imaging will cover out to ~1.5 times the optical radius and will reach photometric depths of at least 2 magnitudes below the tip of the red giant branch throughout the limits of the survey volume. One additional deep pointing per galaxy will reach SNR~10 for red clump stars, sufficient to recover the ancient SFH from the color-magnitude diagram. This proposal will produce photometric information for ~100 million stars {comparable to the number in the SDSS survey} and uniform multi-color images of half a square degree of sky. The resulting archive will establish the fundamental optical database for nearby galaxies, in preparation for the shift of high-resolution imaging to the near-infrared.

ACS/HRC 10878

An ACS Prism Snapshot Survey for z~2 Lyman Limit Systems

We propose to conduct a spectroscopic survey of Lyman limit absorbers at redshifts 1.7 < z < 2.2, using ACS/HRC and the PR200L prism. We have selected 100 quasars at 2.3 < z < 2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar sample, for which no BAL signature is found at the QSO redshift and no strong metal absorption lines are present at z > 2.3 along the lines of sight. The survey has three main observational goals. First, we will determine the redshift frequency dN/dz of the LLS over the column density range 16.3

NIC2 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at redshifts exceeding 1 are now the leading obstacles to determining the nature of dark energy. We propose a single, integrated set of observations for Cycle 15 that will provide a 40% improvement in constraints on dark energy. This program will observe known Cepheids in six reliable hosts of Type Ia supernovae with NICMOS, reducing the uncertainty in H_0 by a factor of two because of the smaller dispersion along the instability strip, the diminished extinction, and the weaker metallicity dependence in the infrared. In parallel with ACS, at the same time the NICMOS observations are underway, we will discover and follow a sample of Type Ia supernovae at z > 1. Together, these measurements, along with prior constraints from WMAP, will provide a great improvement in HST's ability to distinguish between a static, cosmological constant and dynamical dark energy. The Hubble Space Telescope is the only instrument in the world that can make these IR measurements of Cepheids beyond the Local Group, and it is the only telescope in the world that can be used to find and follow supernovae at z > 1. Our program exploits both of these unique capabilities of HST to learn more about one of the greatest mysteries in science.

NIC3 10761

The X-ray Spectral and Optical/IR Flux Variability in Magnetars

In the last decade it has become clear that there exists a small subset of pulsars that are powered neither by rotation nor accretion but by the decay of their enormous magnetic fields -- magnetars. The origin of the X-ray emission from magnetar-candidate AXPs {Anomalous X-ray Pulsars} is fairly well understood within the framework of the magnetar model. However, where and how the optical/IR emission is produced is unclear. If, as recent models suggest, the optical/IR emission is magnetospheric, then any variation in the optical/IR flux should be accompanied by variation in the X-ray spectra. We therefore propose for joint Chandra-Hubble observations of two magnetar candidates in order to test the optical/IR emission models for magnetars.

NIC3 10632

Searching for galaxies at z>6.5 in the Hubble Ultra Deep Field

We propose to obtain deep ACS {F606W, F775W, F850LP} imaging in the area of the original Hubble Ultra Deep Field NICMOS parallel fields and - through simultaneous parallel observations - deep NICMOS {F110W, F160W} imaging of the ACS UDF area. Matching the extreme imaging depth in the optical and near-IR bands will result in seven fields with sufficiently sensitive multiband data to detect the expected typical galaxies at z=7 and 8. Presently no such a field exist. Our combined optical and near-IR ultradeep fields will be in three areas separated by about 20 comoving Mpc at z=7. This will allow us to give a first assessment of the degree of cosmic variance. If reionization is a process extending over a large redshift interval and the luminosity function doesn't evolve strongly beyond z=6, these data will allow us to identify of the order of a dozen galaxies at 6.56.5. Conversely, finding fewer objects would be an indication that the bulk of reionization is done by galaxies at z=6. By spending 204 orbits of prime HST time we will capitalize on the investment of 544 prime orbits already made on the Hubble Ultra Deep Field {UDF}. We have verified that the program as proposed is schedulable and that it will remain so even if forced to execute in the 2-gyro mode. The data will be non-proprietary and the reduced images will be made public within 2 months from the completion of the observations.

NIC1 10517

Imaging Astrometrically-Discovered Brown Dwarfs

We propose to image the astrometrically discovered companions of three M-dwarfs with NICMOS to more tightly constrain their masses and determine their stellar or sub-stellar natures. Each of these systems has been observed with a sensitive ground-based adaptive optics system and no companions have been detected. NICMOS results will eliminate an ambiguity in the astrometric mass measurements that arises because a companion that contributes significantly to the visible light reduces the motion of the center of light and mimics a small motion of the center of mass. In addition the astrometric measurements made with NICMOS will fix the scale of the system, distinguishing among possible orbits. Finally the color photometry will constrain the spectral types to within a couple of subtypes. When we measure the masses of astrophysical objects, we test and assist the development of the theoretical mass models. Models are based upon parameters such as age and metallicity. Determining the correct mass thus deepens our understanding of the fundamental physics of stars and substellar objects

FGS 10482

Trigonometric Calibration of the Period- Luminosity Relations for Fundamental and First-Overtone Galactic

Cepheids are the primary distance indicators for the extragalactic distance scale and the Hubble constant. The Hubble Constant Key Project set the zero-point for their Cepheid distance scale by adopting a distance to the LMC, averaged over a variety of techniques. However, different methods give an LMC distance modulus ranging from 18.1 to 18.8, and the uncertainty in the Cepheid zero-point is now the largest contributor to the error budget for H_0. Moreover, the low metallicity of the LMC raises additional concerns, since the PL relation probably depends on metallicity. The zero-point can be determined from Hipparcos parallaxes of Galactic Cepheids out to several hundred parsecs, but with a typical parallax error of 0.5-1 mas, the Hipparcos error bars are uncomfortably large for this demanding application. By contrast, HST's FGS1R interferometer can achieve astrometric accuracy of 0.2 mas. We propose to use FGS1R to determine trigonometric parallaxes for a sample of 9 nearby Cepheids, including both fundamental {F} and first-overtone {FO} pulsators. We show that the improvement in the PL relations for F and FO Cepheids will be dramatic. We will determine the PL slopes from our nearby solar- metallicity sample alone, without recourse to nearby galaxies and the issue of [Fe/H] dependence. The zero-point will be determined robustly to about 0.05 mag, based on accurate, purely geometrical measurements. All of this can be achieved in the next few years with HST, without having to wait for the SIM and GAIA missions well into the next decade.

FGS 10432

Precise Distances to Nearby Planetary Nebulae

We propose to carry out astrometry with the FGS to obtain accurate and precise distances to four nearby planetary nebulae. In 1992, Cahn et al. noted that ``The distances to Galactic planetary nebulae remain a serious, if not THE most serious, problem in the field, despite decades of study.'' Twelve years later, the same statement still applies. Because the distances to planetary nebulae are so uncertain, our understanding of their masses, luminosities, scale height, birth rate, and evolutionary state is severely limited. To help remedy this problem, HST astrometry can guarantee parallaxes with half the error of any other available approach. These data, when combined with parallax measurements from the USNO, will improve distance measurements by more than a factor of two, producing more accurate distances with uncertainties that are of the order of ~6%. Lastly, most planetary nebula distance scales in the literature are statistical. They require several anchor points of known distance in order to calibrate their zero point. Our program will provide "gold standard" anchor points by the end of 2006, a decade before any anticipated results from future space astrometry missions.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10435 - REacq (2,1,2) failed due to search radius limit exceeded

REacq(2,1,2) scheduled at 266/09:23:24 failed at 09:28:12 due to search radius limit exceeded on FGS 2. OBAD1 showed errors of V1=-62.14, V2=561.17, V3=-12.68, RSS=564.75. OBAD2 showed errors of V1=-5.14, V2=-11.57, V3=-10.76, and RSS=16.62.

10436 - ACS Suspend STB Messages 707 & 715 received

Upon acquisition of signal at 266/16:04:00 observed ACS Suspended at 266/15:21:25. Received ACS STB messages 707 parameter 4003 (octal)(Limit_Check_Failue) and STB 715 parametr 150(octal) (Limits_Suspend_Request). ACS was in operate, spacecraft was in Gyro Hold when anomaly occurred.

10437 - GSacq (2,1,2) failed due to search radius limit exceeded for FGS 2

At AOS 266/22:56:00 GSacq (2,1,2) scheduled from 266/17:33:39 - 17:41:43 failed due to search radius limit exceeded on FGS 2. Also at AOS one a05 (Exceeded SRL) message. OBADs scheduled at 266/17:21:24-17:29:19 and 266/17:29:19-17:33:34 were LOS. At AOS, MAP scheduled at 266/17:41:43-17:44:28 showed the following: V1 - 0.11, v2 - -2.28, v3 - 0.57 and RSS 2.35. OBADs scheduled previous to REacq were LOS. At AOS, MAP scheduled at 266/19:16:57 completed with V1 -0.76, V2 7.63, V3 0.17, RSS 7.67.

10440 - Status Buffer Message (402) during ACS Memory Dump

At 266/18:06:00 status buffer message 402 parameter=16317 (octal) was received during a ACS Memory Dump after Suspend (Ref HSTAR 10436). The memory dump was performed (OPS REQ 17932-0) following ACS Suspend. Procedure JMDMPRAW was used to dump. As procedure JMDMPRAW completed execution, it cleaned up after dump by sending a science data output cease command, the EXEC 402 status buffer resulted.

10441 - GSACQ(2,1,1) failed

GSACQ(2,1,1) at 267/00:13:33 failed to RGA control with QF2STOPF and QSTOP flags set at 00:16:44. No other flags were seen. REACQ(2,1,1) at 01:51:10 also failed (no engineering data is vailable but #44 commands did not change when signal was acquired at 02:20:00).

10444 - REacq(1,2,1) failed to RGA Control

Upon acquisition of signal at 267/17:01:05, the Target REacq(1,2,1) scheduled at 267/15:51:22 - 15:59:26 was observed to have failed to RGA Hold due to search radius limit exceeded on FGS-1. Per ESB Dump at 267/17:09:00, one 486 ESB "a05" (FGS Coarse Track failed - Search Radius Limit Exceeded) was received at 267/15:56:44. Two ESB 1805 (T2G_MOVING_TARGET_DETECTED) was received at 267/15:48::59, and 267/15:49:04 respectively. Prior OBADs attitude corrections values not available due to LOS. Prior GSacq using same star id was successful. Observations affected none.

COMPLETED OPS REQUEST:

17926-0 - Eclipse Management

17923-1 - Update BM SOC , SOC-1 and SOC-2 following DOY 265 Eclipse Event

17932-0 - Memory dump after ACS Suspend

COMPLETED OPS NOTES: (None)

                         SCHEDULED      SUCCESSFUL 
FGS GSacq               23                      21 
FGS REacq               15                      11 
OBAD with Maneuver  76                      76 

SIGNIFICANT EVENTS:

Flash Report - One eclipse event over the period of GMT 265/10:02 through 265/10:33 occurred near start of orbit day and having a peak darkness of ~88 percent darkness. ROP PS-02 was performed to minimize the impacts from this eclipse on the spacecraft. Increasing the duration of the CSS failure timer was completed prior to the first eclipse event at GMT 265/06:47. Additional steps were also taken to lower the SOC 1 and SOC 2 safemode limits by 10 A-hrs to 202 A-hr and 142 A-hr, respectively. This recommendation was performed as a proactive measure. Following the eclipse, CSS timer was reset to its nominal value at 265/11:54. Update of the SOC 1, SOC 2, Battery Pressure safemode limits and SOC benchmark was also performed to reflect the proper system capacity value as determined from the 2006 battery capacity testing. Preliminary results of the eclipse event showed that at the start of that orbit day the pressure-based SOC was 237 A-hr. Telemetry wasn't available throughout this eclipse. The SOC level reached a maximum value of about 251 A-hr prior to the peak darkness and reduced to about 24 8 A-hr around the time of the peak darkness. It was also determined that the Benchmark Reset Threshold was achieved prior to EON by observing the trickle charge elapse timer in the subsequent orbit after the eclipse.

Flash Report The ACS suspended at 266/15:21:25 GMT. An Ops Briefing was held at 6 pm on September 23, 2006. At 266/15:21:25, ACS 715 and ACS 707 status buffer (STB) messages were received indicating the ACS HRC CEB ASPC2 +35 volt power supply voltage was out of limits low that resulted in the ACS suspend. The event occurred during the transition from SBC to HRC operations. At the time of the anomaly, the vehicle was in an LOS, but outside of the SAA. The data was subsequently dumped with the ACS memory dump indicating the single out of limit violation of the HRC CEB ASPC2 35 volt power supply. ACS commanding has been removed from next week's SMS and replaced with other science. A detailed analysis of the event is underway with a tiger team meeting at 1pm Sunday. A follow-up status meeting is planned with HSTP for 9am Monday in. Actions from the tiger team meeting: -Investigate whether ASPC-2 relay status are analog, if analog assess the raw data for shifts that indicate whether or not all the relays switched. -Provide bus voltage at time of anomaly to tiger team. Presentation is posted at the following web site: http://edocs.hst.nasa.gov/hstsysman/Anomaly%20Documentation/ACS_707- 715_Suspend_DOY266.ppt

Loads for SA268Q03_F1 (with minimal ACS commanding included) generated in response to ACS HSTAR # 10436 were reviewed by the FOT on grave shift. (The STScI worked as late as 2 AM Sunday morning, to complete the SMS delivery.) Following SI SE approval, the loads were then authorized at 267/14:06:50z. First load-after time was 267/17:01:05z (Sunday 1:01 PM Local).

Flash Report - ACS Suspend Status Update Mtg - Monday 9am 3/S107A (by D. Haskins, Sun, 24 Sep 16:29:40) - A status meeting on the ACS suspend event will be held at 9am on Monday, September 25 in 3/S107A.

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