Status Report

NASA Hubble Space Telescope Daily Report #4239

By SpaceRef Editor
November 14, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4239


– Continuing to collect World Class Science

PERIOD COVERED: UT November 13, 2006 (DOY 317)



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/WFC 10787

Modes of Star Formation and Nuclear Activity in an Early Universe Laboratory

Nearby compact galaxy groups are uniquely suited to exploring the mechanisms of star formation amid repeated and ongoing gravitational encounters, conditions similar to those of the high redshift universe. These dense groups host a variety of modes of star formation, and they enable fresh insights into the role of gas in galaxy evolution. With Spitzer mid-IR observations in hand, we have begun to obtain high quality, multi-wavelength data for a well-defined sample of 12 nearby {<4500km/s} compact groups covering the full range of evolutionary stages. Here we propose to obtain sensitive BVI images with the ACS/WFC, deep enough to reach the turnover of the globular cluster luminosity function, and WFPC2 U-band and ACS H-alpha images of Spitzer- identified regions hosting the most recent star formation. In total, we expect to detect over 1000 young star clusters forming inside and outside galaxies, more than 4000 old globular clusters in >40 giant galaxies {including 16 early-type galaxies}, over 20 tidal features, approximately 15 AGNs, and intragroup gas in most of the 12 groups. Combining the proposed ACS images with Chandra observations, UV GALEX observations, ground-based H-alpha imaging, and HI data, we will conduct a detailed study of stellar nurseries, dust, gas kinematics, and AGN.

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.

ACS/WFC 10886

The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

As a continuation of the highly successful Sloan Lens ACS {SLACS} Survey for new strong gravitational lenses, we propose one orbit of ACS-WFC F814W imaging for each of 50 high- probability strong galaxy-galaxy lens candidates. These observations will confirm new lens systems and permit immediate and accurate photometry, shape measurement, and mass modeling of the lens galaxies. The lenses delivered by the SLACS Survey all show extended source structure, furnishing more constraints on the projected lens potential than lensed-quasar image positions. In addition, SLACS lenses have lens galaxies that are much brighter than their lensed sources, facilitating detailed photometric and dynamical observation of the former. When confirmed lenses from this proposal are combined with lenses discovered by SLACS in Cycles 13 and 14, we expect the final SLACS lens sample to number 80–100: an approximate doubling of the number of known galaxy-scale strong gravitational lenses and an order-of-magnitude increase in the number of optical Einstein rings. By virtue of its homogeneous selection and sheer size, the SLACS sample will allow an unprecedented exploration of the mass structure of the early-type galaxy population as a function of all other observable quantities. This new sample will be a valuable resource to the astronomical community by enabling qualitatively new strong lensing science, and as such we will waive all but a short {3-month} proprietary period on the observations.

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 10527

Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope Around 20 Sun-like Stars

We propose to use the high contrast capability of the NICMOS coronagraph to image a sample of newly discovered circumstellar disks associated with sun-like stars. These systems were identified by their strong thermal infrared emission with the Spitzer Space Telescope as part of the Spitzer Legacy Science program titled, “The Formation and Evolution of Planetary Systems {FEPS}.” Modelling of the thermal excess emission in the form of spectral energy distributions alone cannot distinguish between narrowly confined high opacity disks and broadly distributed, low opacity disks. However, our proposed NICMOS observations can, by imaging the light scattered from this material. Even non- detections will place severe constraints on the disk geometry, ruling out models with high optical depth. Unlike previous disk imaging programs, our program contains a well defined sample of solar mass stars covering a range of ages from ~10Myrs to a few Gyrs, allowing us to study the evolution of disks from primordial to debris for the first time. These results will greatly improve our understanding of debris disks around Sun- like stars at stellar ages nearly 10x older than any previous investigation. Thus we will have fit a crucial piece into the puzzle concerning the formation and evolution of our own solar system.

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.

S/C 11073

Checkout of ACS Three-Detector Operations

This proposal will perform a brief checkout of the ACS in with three-detectors {WFC/HRC/SBC} powered and available for science operations.

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.


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


10507 – GSAcq (2,1,2) resulted in FLBU (2,0,2) on FGS 2 At AOS (317/15:49:55) GSAcq (2,1,2) scheduled 317/15:44:34-15:51:55 resulted in FLBU (2,0,2) on FGS 2. Due to LOS OBAD #1 data is unavailable till engineering dump is accomplished. No other flags were illuminated. OBAD #2 RSS value = 7.12 a-s. OBAD MAP RSS value = 7.93 a-s

10508 – REacq(2,1,2) resulted in FSBU (2,0,2) on FGS 2 REacq(2,1,2) scheduled at 318/02:42:23 failed to RGA control. Stop flags QF1STOPF and QSTOP was received at 02:45:53. OBAD1 showed errors of V1= -2.71, V2=-5.29, V3=3.89,and RSS=7.10. OBAD2 showed errors of V1=-1.42, V2=-4.10, V3=-0.62, and RSS=4.38. The REacq(2,1,2) at 318/02:42:23 did not fail. The Reacq resulted in fine lock backup(2,0,2)due to QF1STOPF.

The REacq(2,1,2) at 318/04:22:55, resulted in finelock backup (2,0,2) using FGS-2 due to stop flag (QF1STOPF) on FGS-1. Pre-acquisition OBADs had (RSS) values of 14.46 and 4.74 arcseconds.

10509 – GSAcq(2,1,2) results in finelock backup (2,0,2) using FGS-2 GSAcq(2,1,2) scheduled at 318/06:06:24 – 06:14:29 resulted to finelock backup (2,0,2) using FGS-2, due to stop flag (QF1STOPF) on FGS-1. Due to LOS pre-acquisition OBAD1 attitude error correction (RSS) not available. OBAD2 had (RSS) attitude correction of 4.74 arcseconds. Post-acquisition OBAD/MAP had (RSS) value of 6.07 a-s.



                        SCHEDULED      SUCCESSFUL
GSacq               05                    05 

FGS REacq               04                    04
OBAD with Maneuver  20                    20


Flash Report:

ACS SBC Detector .ACS entered its newly modified 3-detector operational configuration (WFMAHVon) at 317/11:38 this morning. As expected the input current increased ~0.9amps, all other voltages, currents and temperatures remain within their normal ranges. The SBC MAMA successfully ramped the HV to its normal level while the WFC and HRC CCD detectors remained enabled.This on-orbit evaluation of 3-detector operations will complete at 317/15:18.In preparation for the new 3-detector configuration, the ACS NSSC1 FSW total input safing limit was patched from 11.5amps to 12.0amps via OPS Request 17961 at 317/10:08.

ACS SBC Detector, part 2.

ACS completed the first phase (~2 orbits) of its on-orbit evaluation of its newly modified 3-detector operational configuration (WFMAHVon) at 317/15:18. ACS successfully transitione back to WFHROper after ramping down the SBC MAMA HV and disabling the SBC detector. ACS NSSC1 Event Flag #2 (prevents SBC stored commanding) was set via stored commanding and will be cleared pending review of result by ACS HRC ARB prior to second phase of the on-orbit evaluation.

SpaceRef staff editor.