Status Report

NASA Hubble Space Telescope Daily Report #4064

By SpaceRef Editor
March 7, 2006
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NASA Hubble Space Telescope Daily Report #4064

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT March 06, 2006 (DOY 065)


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 Oct, 2 2005- May, 29-2006. The second half of the program has a different proposal number: 10758.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.

ACS/WFC 10622

ACS Photometric Calibration from Faint Standards

When calibrating photometry, the typical approach is to use short exposures of bright standard stars to calibrate long exposures of faint scientific targets. This is fine for most ground-based telescopes, whose detectors are linear, but presents difficulties when calibrating HST. The resulting HST calibrations are thus extremely sensitive to the accuracy of linearity corrections such as that for CTE loss. We propose a more robust calibration of ACS/WFC using our photometric sequences in Pal 4 and Pal 14 {Saha et al. 2005}. These sequences include stars with 10% photometry down to V=24.2 and I=23.4, a brightness comparable to that of many HST science targets. We believe these data will allow us to determine a complete set of transformations accurate to 1% and relatively insensitive to errors in the CTE correction.

ACS/WFC 10775

An ACS Survey of Galactic Globular Clusters

We propose to conduct an ACS/WFC imaging survey of Galactic globular clusters. We will construct the most extensive and deepest set of photometry and astrometry to-date for these systems reaching a main sequence mass of ~0.2 solar mass with S/N >= 10. We will combine these data with archival WFPC2 and STIS images to determine proper motions for the stars in our fields. The resultant cleaned cluster CMDs will allow us to study a variety of scientific questions. These include [but are not limited to] 1} the determination of cluster ages and distances 2} the construction of main sequence mass functions and the issue of mass segregation 3} the internal motions and dynamical evolution of globular clusters, and 4} absolute cluster motions, orbits, and the Milky Way gravitational potential. We anticipate that the unique resource provided by the proposed treasury archive will play a central role in the field of globular cluster studies for decades, with a stature comparable to that of the Hubble Deep Field for high redshift studies.

ACS/WFC/NIC2 10566

Star Formation in the LMC – The complete IMF of a Stellar Association

We propose to use the large improvement in sensitivity and wide-field resolution provided by ACS to obtain, for the first time, the complete Initial Mass Function {IMF} down to sub-solar masses of a very young stellar association in the Large Magellanic Cloud {LMC}. Such an IMF will serve as a reference IMF typical of low-metallicity regions. We want to obtain VI deep {V ~ 26.5 mag} WFC photometry of the association LH 95 and a nearby background field pointing. Special care will be taken to treat all the complications which arise in the reduction of data for the purpose of calculating the IMF of a young association of stars. Our object of study has been chosen because it is one of the associations, which provide the best combination of spatial resolution, crowding, low extinction, nebular contamination, and background confusion in comparison to others in the Local Group. The region also has the advantage of being very young with indications that it is still forming stars, thus allowing us to search for sub-solar pre-main- sequence stars, as well as for an embedded proto-cluster.

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.

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 10751

WFPC2 CYCLE 14 Intflat Linearity Check and Filter Rotation Anomaly Monitor

Intflat observations will be taken to provide a linearity check: the linearity test consists of a series of intflats in F555W, in each gain and each shutter. A combination of intflats, visflats, and earthflats will be used to check the repeatability of filter wheel motions. {Intflat sequences tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 14 decon proposal 10744 for easier scheduling.} Note: long-exposure WFPC2 intflats must be scheduled during ACS anneals to prevent stray light from the WFPC2 lamps from contaminating long ACS external exposures.


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


10159 – GSAcq(1,2,1) failed to RGA control (T2G) due to scan step limit exceeded on FGS-1 @ 066/08:05:46z

At acquisition of signal 066/08:05:46 the GSAcq(1,2,1) scheduled at 066/07:43:35 – 07:51:12 during ZOE period showed the spacecraft in RGA control, due to scan step limit exceeded indication flag on FGS-1.



                         SCHEDULED      SUCCESSFUL      FAILURE TIMES
FGS GSacq               04                     03                 Hstar # 10159
FGS REacq               08                      08
OBAD with Maneuver  18                      18


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