NASA Hubble Space Telescope Daily Report #4125
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT # 4125
PERIOD COVERED: UT May 31, 2006 (DOY 151)
OBSERVATIONS SCHEDULED
ACS/HRC 10145
Physical parameters of the upper atmosphere of the extrasolar planet HD209458b
Every 3.5 days, the transits of the gaseous planet orbiting HD209458 offer the unique opportunity to investigate the spectral features of an extra-solar planetary atmosphere. Using HST, we first discovered the extended upper atmosphere of HD209458b through the detection of a 15% HI Lyman alpha absorption. We concluded that the hydrogen must be escaping the planet with a lower limit rate of 10^10 g/s {Vidal-Madjar et al. 2003}. Additional observations, subsequently allowed to detect OI and CII in the upper atmosphere implying that this atmosphere is hydrodynamically escaping {in “blow off”, Vidal-Madjar et al. 2004}. Here we propose to further study this upper atmosphere to better constrain the “blow off” state by directly estimating the physical conditions and the flow characteristics. In particular we will determine the temperature and density at the base of the upper atmosphere {the thermosphere}, and the density distribution and ionization state just below that level. Comparison between the optical and ultraviolet occultation light curves will provide useful information on the molecular/haze content of the lower atmosphere. The observation of six HD209458b transits with HRC and SBC settings will allow the detection of many lines adressing these issues. The proposed observations will give us for the first time a detailed probe of the atmosphere of an “evaporating” extra-solar planet.With species as abundant as FeII or MgII, the damping wings in the strongest lines will start to form at levels around 1.9% absorption. Due to either the strength of the MgII doublet lines around 280 nm or the packing of FeII lines, strong absorptions arising from the accumulated damping wings should show up clearly in FeII and MgII. All these signatures should be easily detected even with the 40 to 100 Angstrom resolution of the PR200L prism in these spectral regions. In addition to these goals, any signature of molecules {e.g CO below 154 nm}, dust or haze should also show up as broad band absorption in both PR110L and PR200L settings. The estimate of the planet radius at different wavelengths in the UV would become possible for all efficient absorbers in this spectral range. The achievement of 0.1% precision in the occultation curves thus provides sensitivity high enough to potentially lead to important discoveries.
ACS/HRC 10508
Orbits, Masses, and Densities of Three Transneptunian Binaries
The subset of transneptunian objects {TNOs} having natural satellites offers unique opportunities for physical studies of these distant relics from the outer parts of the protoplanetary nebula. HST/ACS is ideally suited to determining orbits of TNO satellites, resulting in the system masses. In conjunction with thermal emission observations by Spitzer, which provides sizes, we can determine the densities of TNOs. Densities offer a powerful window into their bulk compositions and interior structures.
ACS/HRC 10556
Neutral Gas at Redshift z=0.5
Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z>1.65. However, HST has now permitted us to discover 41 DLAs at z<1.65 in our previous surveys. Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe. But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe. Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime. Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7] which we estimate will permit us to discover another 41 DLAs. This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies. Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey.
ACS/HRC 10559
Astrometric monitoring of binary L and T dwarfs
We propose to obtain high angular resolution ACS images of five binary L and T dwarfs in order to determine their orbital parameters and dynamical masses, and directly constrain the evolutionary models of ultracool and substellar objects. The binaries have estimated periods ranging between 5 and 14 years. All of them have already been resolved at least twice {sometimes more} using HST, providing first and second epochs measurements. We propose to obtain two more ACS imaging observations separated by 9 to 12 months during cycle 14. The expected period coverage should therefore range between 35% and 117%, allowing us to compute precise orbital parameters and masses. Our sample is large enough and covers a sufficiently wide range of spectral types {from L3 to T5.5} to allow us to obtain strong constraints the evolutionnary models.
ACS/HRC/WFC 10758
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/HRC/WFPC2/NIC3 10842
A Cepheid Distance to the Coma Cluster
We propose to use the Advanced Camera for Surveys to search for Cepheid variables in two spiral galaxies in the core of the Coma cluster. A direct application of the canonical primary distance indicator at 100 Mpc will measure the far-field Hubble constant free of many of the systematic uncertainties which beset current determinations relying on secondary indicators. Establishing the far-field H_o with Cepheids will provide one of the strongest links in the extragalactic distance scale and will directly calibrate the fiducial fundamental plane of elliptical galaxies in Coma. With ACS/HRC, S/N=5 to 10 or better can be reached for Cepheids with periods of 40d to 70d at mean light in 5 orbits with the F606W filter if H_o=72 km/s/Mpc. Efficient detection and phasing can be done with twelve epochs optimally spaced for periods of 40-70d.
ACS/WFC 10573
Globular Clusters in the Direction of the Inner Galaxy
The age, chemical and kinematic distributions of stellar populations provide powerful constraints on models of the formation and evolution of the Milky Way. The globular clusters constitute an especially useful case because the stars within individual clusters are coeval and spatially distinct. But a serious limitation in the study of many globular clusters — especially those located near the Galactic Center — has been the existence of large absolute and differential extinction by foreground dust. We propose to use the ACS to map the differential extinction and remove their effects in a large sample of globular clusters located in the direction of the inner Galaxy using a technique refined recently by von Braun and Mateo {2001}. These observations and their analyses will let us produce high quality color-magnitude diagrams of these poorly studied clusters that will allow us to determine these clusters’ relative ages, distances and chemistry and to address important questions about the formation and the evolution of the inner Galaxy. Our aim for these ACS observations is to obtain data for the most crowded clusters in the inner Galaxy where the excellent spatial resolution of the ACS is most necessary.
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.
NICMOS 8791
NICMOS Post-SAA calibration – CR Persistence Part 2
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.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
10289 – FGS-1 (EFG1_12T) ” Dome Inside “Temperature Limit Violation @ 151/11:02:44z
At 151/11:02:44 FGS1 mnemonic (EFG1_12T) Dome Temperature broke out of limit Yellow High = 4.1011 deg C intermittently. PRD EU U/L is 4.00 deg C. The spacecraft was in RGA Hold when anomaly occured. The Sun Angle was 189, Off-norminal-roll (OR) was 0.
10290 – OBAD Failed Identification (ESB 1902) @ 151/12:09:38z At 151/12:09:38, OBAD1 failed. One 486 ESB message 1902 (OBAD Failed Identification) was received. OBAD2 had (RSS) value of 64674.20 arcseconds. Pre-acquisition OBAD2 was successful with (RSS) value of 3026.0 arcseconds. Per OPS REQUEST 17543-2, OBAD tables 369 and 370 were dumped at 151/12:15:40 and 151/12:16:37. The subsequent Acq at 151/12:30 was successful.
COMPLETED OPS REQUEST:
17543-2 – Dump OBAD tables after failed OBAD (Generic OR) @ 151/1216z
17764-1 – Batt 5 Rec Conting: Lower VTFE Curves by 100mV @ 151/2004z
17695-2 – Monitor VehConLaw.Integral Path Data via TMDIAG Slot 0 (Generic OR) @ 151/2324z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 09 09
FGS REacq 06 06
OBAD with Maneuver 26 25 (HSTAR # 10290)
SIGNIFICANT EVENTS:
Battery Temperature Flash Report – (Wed, 31 May 20:58:50)
Lowering of the VTFE Curves – Battery 3 rose to 5.668 DegC at 151/1950 GMT (5/31 at 3:50pm). We are currently at a high suntime peak at 68.64 minutes. In order to lower the battery temperatures, the VTFE curves were lowered by 100mV via Ops Request #17764-1 at 151/2003 GMT (5/31 at 4:03pm).
