NASA Hubble Space Telescope Daily Report: # 4492
Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal’s listed (and correct) instrument usage and the abstract that follows it.
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT # 4492
PERIOD COVERED: UT November 19, 2007 (DOY 323)
OBSERVATIONS SCHEDULED
WFPC2 10583
Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ? We are requesting 32 HST orbits to help ascertain the nature of the population that gives rise to the observed set of microlensing events towards the LMC. The SuperMACHO project is an ongoing ground-based survey on the CTIO 4m that has demonstrated the ability to detect LMC microlensing events in real-time via frame subtraction. The improvement in angular resolution and photometric accuracy available from HST will allow us to 1} confirm that the detected flux excursions arise from LMC source stars rather than extended objects {such as for background supernovae or AGN}, and 2} obtain reliable baseline flux measurements for the objects in their unlensed state. The latter measurement is important to resolve degeneracies between the event timescale and baseline flux, which will yield a tighter constraint on the microlensing optical depth.
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
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 8794
NICMOS Post-SAA calibration – CR Persistence Part 5
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 DARKs. 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 11197
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 that 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 Phillip’s relation over cosmic time. High signal-to-noise measurements of 16 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. In Cycle 15 we obtained NICMOS photometry of 8 ESSENCE supernovae and are awaiting template observations to place them on the IR Hubble diagram. Here we request another 8 supernovae be studied in the final season of the ESSENCE search. 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 4974
TRTTEST
The Transient Response Test is for the periodic performance monitoring of the FGS 2R servo A mechanism.
WFPC2 11035
Photometric Zero Points Closeout
Updated zero points will be obtained by observing NGC 2419 for which extensive BVRI ground based observations exist, and the field in 47 Tuc used for frequent monitoring of ACS. For NGC 2419 emphasis is given to repeating observations obtained in earlier epochs, and to covering filters near standard BVRI. For 47 Tuc emphasis is given to covering a large set of broadband filters from F300W through F850LP to maximize transformation capabilities between filters of WFPC2 and ACS.
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 11126
Resolving the Smallest Galaxies
An order of magnitude more dwarf galaxies are expected to inhabit the Local Group, based on currently accepted galaxy formation models, than have been observed. This discrepancy has been noted in environments ranging from the field to rich clusters, with evidence emerging that lower density regions contain fewer dwarfs per giant than higher density regions, in further contrast to model predictions. One possible explanation for this involves the effects of reionization on the forming galaxies and naturally explains both the dearth of dwarf galaxies and the apparent environmental dependence. However, before such theories can be fully tested, we require a better understanding of the distribution of dwarf galaxies. Currently, there is no complete census of the faintest dwarf galaxies in any environment. The discovery of the smallest and faintest dwarfs is hampered by the limitations in detecting such faint and low surface brightness galaxies, and this is compounded by the great difficulty in determining accurate distances to, or ascertaining group membership for, such faint objects. The M81 group provides a unique means for establishing membership for galaxies in a low density region complete to magnitudes as faint as M_R ~ -7. With a distance modulus of 27.8, the tip of the red giant branch {TRGB} appears at I ~ 24, just within the reach of ground based surveys. We currently have surveyed a 30 square degree region around M81 with the CFHT/Megacam. From these images we have detected 15 new candidate dwarf galaxies. We propose to use the HST with WFPC2 to image these 15 galaxies in F606W and F814W bands in order to construct a color-magnitude diagram down to I = 25.5 from which to measure accurate TRGB distances to these candidate galaxies and determine star formation and metallicity histories. The overall project will provide a survey of the dwarf galaxies in the M81 group environment with unprecedented completeness to a limit of M_R < -7.
WFPC2 11130
AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II
The recent progress in the study of central black holes in galactic nuclei has led to a general consensus that supermassive {10^6-10^9 solar mass} black holes are closely connected with the formation and evolutionary history of large galaxies, especially their bulge component. Two outstanding issues, however, remain unresolved. Can central black holes form in the absence of a bulge? And does the mass function of central black holes extend below 10^6 solar masses? Intermediate-mass black holes {<10^6 solar masses}, if they exist, may offer important clues to the nature of the seeds of supermassive black holes. Using the SDSS, our group has successfully uncovered a new population of AGNs with intermediate-mass black holes that reside in low-luminosity galaxies. However, very little is known about the detailed morphologies or structural parameters of the host galaxies themselves, including the crucial question of whether they have bulges or not. Surprisingly, the majority of the targets of our Cycle 14 pilot program have structural properties similar to dwarf elliptical galaxies. The statistics from this initial study, however, are really too sparse to reach definitive conclusions on this important new class of black holes. We wish to extend this study to a larger sample, by using the Snapshot mode to obtain WFPC2 F814W images from a parent sample of 175 AGNs with intermediate-mass black holes selected from our final SDSS search. We are particularly keen to determine whether the hosts contain bulges, and if so, how the fundamental plane properties of the host depend on the mass of their central black holes. We will also investigate the environment of this unique class of AGNs.
WFPC2 11218
Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local Group
Planetary nebulae {PNe} in globular clusters {GCs} raise a number of interesting issues related to stellar and galactic evolution. The number of PNe known in Milky Way GCs, 4, is surprisingly low if one assumes that all stars pass through a PN stage. However, it is likely that the remnants of stars now evolving in Galactic GCs leave the AGB so slowly that any ejected nebula dissipates long before the star becomes hot enough to ionize it. Thus there should not be ANY PNe in Milky Way GCs–but there are four! It has been suggested that these PNe are the result of mergers of binary stars within GCs, i.e., that they are descendants of blue stragglers. The frequency of occurrence of PNe in external galaxies poses more questions, because it shows a range of almost an order of magnitude. I propose a Snapshot survey aimed at discovering PNe in the GC systems of Local Group galaxies more distant than the Magellanic Clouds. These clusters, some of which may be much younger than their counterparts in the Milky Way, might contain many more PNe than those of our own galaxy. I will use the standard technique of emission-line and continuum imaging, which easily discloses PNe.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
11072 – GSAcq(1,2,2) failed to RGA Hold (Gyro Control) Upon acquisition of signal (AOS) at 324/02:23:17, the GSAcq(1,2,2)scheduled at 324/02:17:29 – 02:25:34 had failed to RGA Hold due to (QF2STOPF) stop flag indication on FGS-2. Pre-acquisition OBAD1 attitude correction value not available due to LOS. Pre-acq OBAD2 had (RSS) value of 12.62 arcseconds. Post-acq OBAD/MAP not scheduled.
11073 – REAcq (1,2,2) results in FLBU (1,0,1) REAcq (1,2,2) scheduled from 324/06:48:11 – 06:55:43 failed to fine lock back up (FLBU 1,0,1) due to QSTOP flag on FGS2. Pre-acquisition OBAD #1 had an RSS value of 2618.65 arc-seconds and OBAD #2 had an RSS value of 9.11 arc-seconds. An OBAD MAP was not scheduled. No 486 STB messages were noted. This reacquisition is using the same guide stars as were used in HSTAR 11072.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FGS GSacq 05 04 FGS REacq 07 07 OBAD with Maneuver 28 28
SIGNIFICANT EVENTS:
Flash Report: TRTT Successful
The sixteenth run of the Transient Response Trending Test (TRTT) was successfully completed via Ops Request 18156 at 323/15:57z this morning. Analysis will be presented at the next GSAWG meeting.
