Status Report

NASA Hubble Space Telescope Daily Report # 4594

By SpaceRef Editor
April 22, 2008
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NASA Hubble Space Telescope Daily Report # 4594


Continuing to collect World Class Science

PERIOD COVERED: UT April 21, 2008 (DOY 112)


ACS/SBC 11151

Evaluating the Role of Photoevaporation of Protoplanetary Disk Dispersal

Emission produced by accretion onto the central star leads to photoevaporation, which may play a fundamental role in disk dispersal. Models of disk photoevaporation by the central star are challenged by two potential problems: the emission produced by accretion will be substantially weaker for low-mass stars, and photoevaporation must continue as accretion slows. Existing FUV spectra of CTTSs are biased to solar-mass stars with high accretion rates, and are therefore insufficient to address these problems. We propose use HST/ACS SBC PR130L to obtain FUV spectra of WTTSs and of CTTSs at low masses and mass accretion rates to provide crucial data to evaluate photoevaporation models. We will estimate the FUV and EUV luminosities of low-mass CTTSs with small mass accretion rates, CTTSs with transition disks and slowed accretion, and of magnetically-active WTTSs.

WFPC2 11024


This calibration proposal is the Cycle 15 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.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration – CR Persistence Part 6

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 11148

High Contrast Imaging of Dusty White Dwarfs

For the past 18 years, only one white dwarf with a circumstellar dust disk was known to exist. In the last two years, six new disks have been discovered. Since all material inwards of a few AU should be scoured clean during post main sequence evolution, the primary explanation is the presence of a planetary system that is perturbing relic planetesimals into the tidal disruption radius of the white dwarf. Dusty disks around white dwarfs should be markers for planets and we propose to use high contrast imaging to search for faint companions down to 6 M_$J$ that may be feeding the disks. White dwarfs are uniquely suited for planet searches, where the planet/white dwarf contrast is less than for main sequence stars.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

We aim to determine physical properties of IR luminous galaxies at 0.3 0.8mJy and their mid-IR spectra have already provided the majority

targets with spectroscopic redshifts {0.31 ULIRGs, as in the local Universe. {2} study the co-evolution of star formation and blackhole accretion by investigating the relations between the fraction of starburst/AGN measured from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the current best estimates of the far-IR emission, thus L{bol} for this sample, and establish if the relative contribution of mid-to-far IR dust emission is correlated with morphology {resolved vs. unresolved}.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks – part II

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 11185

Search for H-poor/He-rich Inclusions and a Solution to the Abundance, Temperature Problems

Our recent abundance survey of a large sample of Galactic planetary nebulae (PNe) has led to the discovery of a group of super-metal-rich nebulae whose spectra are characterized by prominent optical recombination lines (ORLs) from C, N, O, & Ne ions and a large Balmer discontinuity jump. The heavy element abundances derived from ORLs for several PNe are more than an order of magnitude higher than those derived from the traditional method based on collisionally excited lines (CELs), while the Balmer jump yields electron temperatures (Te) significantly lower than values derived from the [O III] 5007/4363 CEL line ratio. A proposition that aspires to explain both the nebular abundance and Te problems is one according to which these nebulae contain (at least) two distinct emission regions – one of “normal” Te (~ 10000 K) and chemical composition (~solar) and another of very low Te that is H- deficient, thus having high helium and metal abundances relative to hydrogen. The latter component emits strong He and heavy element ORLs but essentially no CELs. The consistent picture that emerges from fitting a 2-component photoionization model to the spectroscopic data is that the H-poor component is in high-density inclusions, which provide only a minor fraction of the total nebular mass. We propose to directly detect these inclusions in the planetary nebula M 1-42 using WFPC2 (PC) to make a high spatial resolution image in the He I 5876 A ORL and ratio it to Halpha. With NICMOS (NIC1), we plan to observe the He I 10830 A line, which is substantially collisionally excited, along with Palpha 18760 A. The ratio image of He I 10830 to Palpha is expected to be less likely to show the inclusions, thus serving as an important control to the optical imaging. M 1-42 is one of the most extreme cases of the abundance and Te problem; it is reasonably bright and compact. This program has the potential to resolve a serious challenge to our current understanding of nebular astrophysics.

WFPC2 11222

Direct Detection and Mapping of Star Forming Regions in Nearby, Luminous Quasars

We propose to carry out narrow-band emission line imaging observations of 8 quasars at z=0.05-0.15 with the WFPC2 ramp filters and with the NICMOS narrow-band filters. We will obtain images in the [O II], [O III], H-beta, and Pa-alpha emission line bands to carry out a series of diagnostic tests aimed at detecting and mapping out star-forming regions in the quasar host galaxies. This direct detection of star-forming regions will confirm indirect indications for star formation in quasar host galaxies. It will provide a crucial test for models of quasar and galaxy evolution, that predict the co-existence of starbursts and “monsters” and will solve the puzzle of why different indicators of star formation give contradictory results. A secondary science goal is to assess suggested correlations between quasar luminosity and the size of the narrow-line region.

WFPC2 11312

The Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing Observations with WFPC2

LoCuSS is a systematic and detailed investigation of the mass, substructure, and thermodynamics of 100 X-ray luminous galaxy clusters at 0.151} cluster samples. To complete the all-important high resolution imaging component of our survey, we request deep WFPC2 observations of 20 clusters through the F606W filter, for which wide-field weak-lensing data are already available from our Subaru imaging program. The combination of deep WFPC2 and Subaru data for these 20 clusters will enable us to achieve the science program approved by the Cycle 15 TAC.


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


11262 – GSAcq (1,2,1) failed due to QSTOP flag on FGS 1

At 112/10:33:46 GSAcq (1,2,1) scheduled from 10:30:47-10:38:10 failed due to QF1STOPF and QSTOP Flags on FGS 1. Fine lock was briefly achieved but, no s-curves were observed. Pre-acquisition OBADs RSS values were 3437.94 and 6.55 arc-seconds respectively. Post acquisition OBAD Map RSS value was 3.71 arc-seconds.

Additionally, received 4 ACS 779 Status Buffer Messages (“Fold Mechanism Move was Blocked”) following the failure of the GSacq. This resulted in the TDF to be down when the Fold mechanism move was commanded. Flight Software Error Count (JERRCNT) incremented to 86. OPS Note 1645-15 was executed to change JERRCNT limit to 86.

11264 – GSAcq (2,1,1) failed due to Scan Step Limit Exceeded on FGS 2

REacq (2,1,1) failed 3 times

At Acquisition of Signal (112/18:02:23) GSAcq (2,1,1) scheduled from 16:54:19-17:01:35 had failed due to Scan Step Limit Exceeded on FGS 2. Received QSTEPEXC and QSTOP flags on FGS 2. Pre-acquisition OBADs RSS Error value was 3828.70 and 12.54 arc-seconds respectively. Post acquisition OBAD MAP RSS Error value was 10.15. Awaiting engineering data dump to complete further analysis.

REACQ(2,1,1) at 20:04:12 was successful in obtaining fine lock.

REACQ(2,1,1) at 18:28:19 also failed with 486 ESB message “a0c” (FGS coarse mode angle check failed).

REACQ(2,1,1) at 21:42:05 failed with 486 ESB message “a0c” (FGS coarse mode angle check failed).

REACQ(2,1,1) at 23:28:15 appears to have succeeded, #44 commands did update but entire event happened without telemetry

REACQ(2,1,1) at 01:10:00 failed with 486 ESB message “a0c” (FGS coarse mode angle check failed).




FGS GSacq                08                 06
FGS REacq                06                 03
OBAD with Maneuver       28                 28


SpaceRef staff editor.