Status Report

NASA Hubble Space Telescope Daily Report #4240

By SpaceRef Editor
November 16, 2006
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NASA Hubble Space Telescope Daily Report #4240


– Continuing to collect World Class Science

PERIOD COVERED: UT November 14, 2006 (DOY 318)


ACS/WFC 10885

Deep Photometry of NGC 1569: Understanding the Closest and Strongest Starburst of the Nearby Universe

Massive starbursts drive the evolution of galaxies at high redshift, but they can only be studied in detail in the nearby Universe where they are much rarer. The dwarf irregular galaxy NGC 1569 at 2.2 Mpc is the closest example of a true starburst. It has sustained exceptionally high star formation {SF} activity over the last Gyr, 2-3 orders of magnitude higher than in normal dwarf irregulars and spirals. This SF has been probed extensively by previous HST observations that have reached just below the tip of the red giant branch {RGB}. But the data have not been able to constrain the more ancient SF history {SFH}, so that our understanding remains very incomplete. It is an open question whether NGC 1569 just started to form stars around 1 Gyr ago, or whether significant SF was already active before that. We do not know what triggered the recent SF, how long the current intense SF activity has been going on, and whether such SF activity has been a more common occurrence in the past history of this galaxy. More importantly, most of these questions remain unanswered for other starburst galaxies in the nearby and distant universe as well. HST is the only telescope that can do the necessary crowded-field photometry to resolve these issues. We propose to use ACS/WFC to build a deep I vs. V-I color-magnitude diagram {CMD} that goes some 4 magnitudes deeper than the RGB tip. This will detect and characterize the red clump {RC} and horizontal branch {HB} features. The CMD will be interpreted by fitting synthetic CMDs constructed from evolutionary tracks to infer the SFH. The joint constraints from the presence, apparent magnitude, and width of the RC, HB and RGB features will independently constrain both the age and metallicity of the old and evolved stellar population of NGC 1569, the presence of multiple bursts if any, and their duration and metallicity spread. This will reveal the evolutionary status over cosmic time, and more generally will constrain the processes at play in the origin and evolution of galaxies. This project is only possible because of the high sensitivity of ACS, and it can be done very efficiently because of the location of NGC 1569 in the CVZ. Since NGC 1569 is so close, it may be the only nearby starburst for which these issues can be addressed in the foreseeable future.

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.

NIC2 10893

Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble Diagram

We propose building a high-z Hubble Diagram using type Ia supernovae observed in the infrared rest-frame J-band. The infrared has a number of exceptional properties. The effect of dust extinction is minimal, reducing a major systematic tha may be biasing dark energy measurements. Also, recent work indicates that type Ia supernovae are true standard candles in the infrared meaning that our Hubble diagram will be resistant to possible evolution in the Phillips relation over cosmic time. High signal-to-noise measurements of 9 type Ia events at z~0.4 will be compared with an independent optical Hubble diagram from the ESSENCE project to test for a shift in the derived dark energy equation of state due to a systematic bias. Because of the bright sky background, H-band photometry of z~0.4 supernovae is not feasible from the ground. Only the superb image quality and dark infrared sky seen by HST makes this test possible. This experiment may also lead to a better, more reliable way of mapping the expansion history of the universe with the Joint Dark Energy Mission.

NIC2, ACS/WFC 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.

WFPC2 10745


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.


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


10511 – GSAcq(2,3,2) required multiple attempts to achieve CT-DV GSAcq(2,3,2) scheduled for 314:04:28:37 required two attempts to achieve CT-DV on FGS2. The acquisition was successful.

10512 – GSAcq (2,1,2) failed due to Scan Step Limit Exceeded on FGS 2 Immediately after AOS(318/18:37:00) @ 318/18:37:28 GSAcq (2,1,2) scheduled from 318/18:34:04-18:41:24 failed due to scan step limit exceeded on FGS 2. OBAD #2 RSS value = 7.36 a-s. OBAD MAP RSS value = 3.38 a-s.

10513 – GSacq(2,1,2) failed due to search radius limit exceeded. GSacq(2,1,2) scheduled at 319/02:54:24 failed at 02:59:28 due to search radius limit exceeded on FGS 2. 486 STB message “a05” FGS coarse track failed-search limit exceeded was received. OBAD1 showed errors of V1=-6754.80, V2=301.24, V3=250.42, and RSS=6766.15. OBAD2 showed errors of V1=-6.08, V2=-5.13, V3=-2.55, and RSS=8.35.

Subsequent REacqs(2,1,2) at 319/04:21:12, 319/06:00:51, 319/07:37:10 and 319/08:48:43 all failed to RGA Hold due to search radius limit exceeded on FGS-2. Additional 486 ESB message “a05” associated with each REacq was received.


17949-1 – Uplink Atmospheric Density Parameter

17950-1 – Enable Dynamic Inertia

17953-2 – FSW 3.0B EEPROM Installation


                SCHEDULED      SUCCESSFUL
FGS GSacq              04             02
FGS REacq              07             03
OBAD with Maneuver 22             22


Flash Report: FSW 3.0B EEPROM Installation & Atmospheric Density Update FSW 3.0B was successfully installed in HST486 EEPROM via OR 17953.

SpaceRef staff editor.