Status Report

NASA Hubble Space Telescope Daily Report #4084

By SpaceRef Editor
April 4, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4084

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT April 03, 2006 (DOY 093)


ACS/HRC 10474

Shooting Stars: Looking for Direct Evidence of Massive Central Black Holes in Globular Clusters

We propose to make observations that directly test the proposition that globular clusters contain massive black holes. Our targets are the bulge globular clusters NGC 6388 and NGC 6441. These are probably among the most massive in the galaxy, but are understudied compared to more familiar objects such as M15. Our analysis suggests that these two clusters are the most likely to show unambiguous evidence for a central massive black hole if such things exist in globular clusters. The observations proposed will give us the first thorough kinematic and photometric studies of these two clusters. The combination of the two epochs will give us proper motions good to of order 6 km/s. In addition, they will provide us with the first good, deep, color-magnitude diagrams for these clusters. These diagrams will be used to investigate the make up of the stellar population in the clusters, to more firmly establish their distances, ages, and metallicities, and to search for a binary sequence.

ACS/HRC 10563

Accurate dark-matter mass profiles in 3 elliptical galaxies as a test of CDM

A critical test of the successful Lambda-CDM picture for structure formation is the measurement of the power law exponent, gamma, of the centre of dark matter density profiles, predicted to lie in the range 1.0-1.5. Measurements of gamma derived from rotation curves of LSB galaxies appear to contradict CDM, but rely on assumptions that are difficult to verify {e.g. axisymmetry}. We have recently demonstrated, using our new `semi-linear’ inversion method, how strong gravitational lensing by galaxies can provide a clean and accurate measurement of gamma, free of such ambiguities. HST images of lensed non-AGN galaxies provide hundreds of resolution elements, each a constraint on the mass profile. Such lenses are exceedingly rare, but we have recently discovered new systems. We propose deep ACS-HRC observations of 3 systems to measure gamma in each, accurate to 0.15 {95% confidence} and to obtain an indication of its variation between galaxies. To establish the required number of orbits we have undertaken an end-to-end simulation of the problem, creating and analysing synthetic ACS images. Additionally the semi-linear method simultaneously reconstructs the pixelised source surface brightness distribution. Our simulations demonstrate that the fine sampling and small pixel scattering of the HRC, resolves the morphology of the sources with exquisite detail.

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 CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e-/DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The first half of the program has a different proposal number: 10729.

ACS/SBC 10535

High Temperature Accretion Flows and Reprocessing in X-ray Binaries: The ADC Source 4U 1822-371

The eclipsing low-mass X-ray binary 4U 1822-371 is the ideal system in which to observe hot accretion and the effects of strong irradiation. Its orbital period is 5.57~hr and its orbital inclination is high enough that flux from the neutron star is blocked by the edge-on accretion disk in the system. Because the neutron star is hidden its Accretion Disk Corona is visible. These ADCs are present in most if not all low-mass X-ray binaries but are generally not visible. 4U 1822-371 provides a unique opportunity to study an ADC and disk irradiation because the eclipse by the secondary star allows their geometry and flux to be mapped. We will perform a multiwavelength light curve synthesis and eclipse analysis of 4U 1822-371. The scientific goal is to map the geometry and flux from its ADC and from its irradiated accretion disk. The crucial and irreplaceable role of HST is to provide the UV data needed to disentangle the ADC from the irradiated accretion disk. We will obtain time-resolved, objective-prism UV spectroscopy of 4U 1822-371 with the ACS/SBC with the PR130L prism, covering most of its orbit and all of the eclipse. This combination will yield excellent orbital light curves in the UV continuum and in the integrated line fluxes.

FGS 10612

Binary Stars in Cyg OB2: Relics of Massive Star Formation in a Super-Star Cluster

We propose to make a high angular resolution SNAP survey of the massive stars in the nearby, super-star cluster Cyg OB2. We will use FGS1r TRANS mode observations to search for astrometric companions in the separation range of 0.01 to 1.00 arcsec and in the magnitude difference range smaller than 4 magnitudes. The observations will test the idea that the formation of very massive stars involves mergers and the presence of nearby companions. Discovery of companions to massive stars in this relatively nearby complex will provide guidance in the interpretation of apparently supermassive stars in distant locations. The search for companions will also be important for verification of fundamental parameters derived from spectroscopy, adjustments to main sequence fitting and distance estimations, determining third light contributions of eclipsing binaries, identifying wide colliding wind binaries, studying the relationship between orbital and spin angular momentum, and discovering binaries amenable to future mass determinations. The massive star environment in Cyg OB2 may be similar to the kinds found in the earliest epoch of star formation, so that a study of the role of binaries in Cyg OB2 will help us understand the formation processes of the first stars in the Universe.

WFPC2 10748

WFPC2 CYCLE 14 Standard Darks

This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs.

WFPC2 10749

Earth Flats

This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjuction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-13.


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


10194 – GSAcq (1,2,2) failed due to search radius limit exceeded on FGS 1 @ 093/13:37:22z

At AOS 093/13:36:30, GSAcq (1,2,2) scheduled for 093/13:32:35 – 13:39:53 was observed to have failed due to search radius limit exceeded on FGS 1. Also at AOS, Two ESB “1805” FHST moving target detected noted. Received ESB “a05” Exceeded SRL. OBAD #1 data unavailable. OBAD #2: V1 21.55, V2 15.22, V3 16.87, RSS 31.31. OBAD MAP: V1 -0.19, V2 1.16, V3 -0.33, RSS 1.22. At AOS 093/15:28:10, REAcq (1,2,2) scheduled for 093/15:08:31-15:15:49 was observed to have failed due to search radius limit exceeded on FGS 1. Received ESB “a05” Exceeded SRL. OBAD #1: V1 -38.80, V2 -3244.27, V3 -15.09, RSS 3244.54. OBAD #2: V1 -16.45, V2 17.10, V3 -23.73, RSS 33.56. OBAD MAP: V1 2.01, V2 0.76, V3 1.88, RSS 2.85.

10195 – GSAcq (1,2,2) failed due to search radius limit exceeded on FGS 1 @ 093/16:49:09z

At AOS 093/16:49:09, GSAcq (1,2,2) scheduled for 093/16:44:27 – 16:51:45 was observed to have failed due to search radius limit exceeded on FGS 1. Received ESB “a05” Exceeded SRL. OBAD #1: V1 -184.56, V2 -2100.48, V3 637.18, RSS 2202.75. OBAD #2 V1 -6.01, V2 -5.40, V3 -4.82, RSS 9.41. OBAD MAP unavailable due to LOS. REAcq (1,2,2) scheduled for 093/18:20:23-18:27:41 failed due to search radius limit exceeded on FGS 1. Received ESB “a05” Exceeded SRL. OBAD #2 RSS value = 12.69 arcseconds. OBAD MAP RSS value = 4.26 arcseconds.

10196 – GSacq(2,1,2) failed due to search radius limit exceeded. @ 093/20:12:13z

GSacq(2,1,2) scheduled at 093/20:08:57 failed due to search radius limit exceeded on FGS 1. OBAD1 showed errors of V1= -2370.76, V2=-1278.60, V3=727.90, RSS=2790.19. OBAD2 showed errors of V1=3.32, V2=3.76, V3=-1.04, RSS=5.12.



                         SCHEDULED      SUCCESSFUL      FAILURE TIMES
FGS GSacq               09                     06                Hstar# 
10194,10195 & 10196
FGS REacq                07                    04                Hstar# 
10194,10195 & 10196
OBAD with Maneuver  30                     30


Flash Report – Two Gyro Acquisition Modifications

The first 6 guide star acquisitions have succeeded using the new Primary FGS to Fine Lock (PFFL) Acquisition Logic, and PCS observed no issues with any of the other changes accompanying the logic change. On-orbit performance is close to predicted values for the number of Coarse Track cycles required for CTDV, T2G rates at the transition time to F2G-CT, T2G rate damping time under F2G-CT control, duration of the F2G open-loop walkdown, and Fine Lock walkdown length. The predicted location for Fine Lock Data Valid was verified in flight, demonstrating that observed vehicle drifts during the open-loop F2G interval match predictions. Preliminary results show that vehicle rates in T2G are reduced, as expected, with the new T2G Attitude Hold gains. Preliminary analysis of the control law integral path indicates that peak-to-peak residual environmental torques are now lower with the updated vehicle inertia tensor.

SpaceRef staff editor.