Status Report

NASA Hubble Space Telescope Daily Report #3895

By SpaceRef Editor
July 21, 2005
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT July 05, 2005 (DOY 186)


ACS/HRC 10182

Towards a Comprehensive Understanding of Type Ia Supernovae: The
Necessity of UV Observations

Type Ia supernovae {SNe Ia} are very important to many diverse areas
of astrophysics, from the chemical evolution of galaxies to
observational cosmology which led to the discovery of dark energy and
the accelerating Universe. However, the utility of SNe Ia as
cosmological probes depends on the degree of our understanding of SN
Ia physics, and various systematic effects such as cosmic chemical
evolution. At present, the progenitors of SNe Ia and the exact
explosion mechanisms are still poorly understood, as are evolutionary
effects on SN Ia peak luminosities. Since early-time UV spectra and
light curves of nearby SNe Ia can directly address these questions, we
propose an approach consisting of two observational components: {1}
Detailed studies of two very bright, young, nearby SNe Ia with HST UV
spectroscopy at 13 epochs within the first 1.5 months after discovery;
and {2} studies of correlations with luminosity for five somewhat more
distant Hubble-flow SNe Ia, for which relative luminosities can be
determined with precision, using 8 epochs of HST UV spectroscopy
and/or broad-band imaging. The HST data, along with extensive
ground-based optical to near-IR observations, will be analyzed with
state-of-the-art models to probe SN Ia explosion physics and constrain
the nature of the progenitors. The results will form the basis for the
next phase of precision cosmology measurements using SNe Ia, allowing
us to more fully capitalize on the substantial past {and future}
investments of time made with HST in observations of high-redshift SNe


The Gas Environment of Comet 9P/Tempel 1 During the Deep Impact

This program consists of a series of observations of periodic comet
9P/Tempel 1 in conjunction with NASA’s Deep Impact mission. This
mission is a spacecraft that will release a 360 kg impactor into the
nucleus of the comet on July 4, 2005. Our primary objective is to
study the generation and evolution of the gaseous coma resulting from
this impact. A secondary objective was to obtain wide-band images of
the visual outburst resulting from the impact. The spectroscopic data
can be obtained using two of the prism modes of the ACS’s HRC/PR200L
and SBC/PR130L.


The Co-Evolution of Star Formation and Powerful Radio Activity in

We will carry out a STIS/NUV-MAMA snapshot imaging survey of the most
compact powerful radio galaxies, the Gigahertz Peaked Spectrum {GPS}
sources and Compact Steep Spectrum {CSS} sources. These objects are as
powerful as the large radio doubles but are much smaller {and younger}
and are crucial to our understanding not only of how radio-loud active
galactic nuclei {AGN} form and evolve, but also what role they play in
the evolution of galaxies. A very direct and robust way to address
these issues is by high resolution imaging of the host galaxies of
these sources in the UV. This has never been done before for a sample
of these very compact sources, since previous HST/UV imaging programs
have focussed on the larger radio galaxies. The UV emission can
provide crucial information about any recent star formation that may
have occurred as a result of ongoing accretion, mergers, interactions,
or triggering by the radio source. By comparing the starburst
properties of GPS, CSS, and large scale radio sources, we will be able
to constrain the evolution of massive star formation as a function of
the relative age of the radio source. {Note, due to the failure of
STIS, these observations will be carried out using the ACS/HRC}.


ACS Polarimetry Calibration

Observations are made of the Boomerang Nebula {highly polarized
reflection nebula} to calibrate the ACS polarizers.


Environmental drivers of galaxy evolution: an HST survey of dwarf
galaxy morphologies in the Abell

Galaxies in dense environments are subject to numerous physical
processes that leave a lasting impact, yet studies of galaxy evolution
to date have been limited to the most luminous galaxies — those least
sensitive to environmental influence. We propose to explore the
environmental drivers of DWARF galaxy evolution: with a mosaic of 9×9
ACS pointings in F606W we will determine morphologies for ~1200
galaxies down to M_V=-14 in the A901/902 supercluster, spanning 3×3
Mpc at z=0.16. The deep ACS data will allow us to probe their surface
brightness profiles, shapes, sizes, asymmetry and fine structure such
as tidal features. With the addition of extensive existing multi-
wavelength data, we will probe the dependence of these important
parameters on dark matter content {from weak lensing maps}, the hot
intercluster medium {from deep XMM- Newton imaging}, and local galaxy
density {from hyper-accurate COMBO-17 photometric redshifts with delta
z=0.02 to m_R=24}, thus disentangling the various environmental
processes shaping dwarf galaxy evolution. Furthermore, the 8000+
background galaxies at 0.2 < z <1.0 will be of enormous scientific benefit for additional studies of weak lensing, AGN host galaxies, the morphology-density relation, and the merger rate as a function of redshift.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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.

NIC1/Spacecraft 10382

NICMOS Focus Stability

The purpose of this activity is to determine the best focus. This
program will execute in one month intervals starting about 1 month
after the last execution of proposal 9994 {the previous focus
monitoring program}. The program starts with a focus sweep using only
the NIC1 camera {visit 11}. The following observation is with the NIC2
camera {visit 12} after about 45 days. This pattern is repeated
throughout the period except for Feb 15 where also the NIC3 camera is
used. In total this will result in 9 orbits. Notice that VISIT #1 #2
refers to visits for #1 sequential visit number for a given camera #2
camera in question visit 32 is therefore the third visit for camera 2.

WFPC2 10360


This calibration proposal is the Cycle 13 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
{gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a
monitor for possible buildup of contaminants on the CCD windows.


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


#09873: GSacq(2,1,2) results in finelock backup (2,0,2) scan step lmt
exc on FGS-1 @ 186/19:21:33z The GSacq(2,1,2) scheduled at
186/19:17:36 – 19:25:38 Z resulted in finelock backup (2,0,2) using
FGS-2, due to scan step limit exceeded on FGS-1 during acquisition
walkdown. Secondary FGS-1 achieved CT-DV at 186/19:21:11, and
186/19:23:13, then returned to SSM Control at 186/19:23:21.

#09874: GSacq(2,1,2) results in finelock backup (2,0,2) @
187/00:08:47z The GSacq(2,1,2) scheduled at 187/00:05:26 – 00:13:28
resulted in finelock backup (2,0,2) using FGS-2, due to scan step
limit exceeded on FGS-2.

#09875: GSacq(2,1,2) results in finelock backup (1,0,1) @
187/01:44:44z The GSacq(2,1,2) scheduled at 187/01:41:22 – 01:49:24
resulted in finelock backup (1,0,1) using FGS-1, due to scan step
limit exceeded on FGS-2.

#09876: ND1VSRCV out of limit for one sample @ 187/03:36:11z ND1VSRCV
(Detector 1 VSRC voltage) went out of limit for one sample at 03:36:11
and returned at 03:36:41, reaching maximum value of 5.16182 volts,
limit is 5.15 volts. Similar occurrences documented in HSTAR 9586 and



#01353-0:  EPS Limit Changes During High Sun Time @ 187/0012z

 FGS Gsacq       11         11 
 FGS Reacq       04         04 
 FHST Update     14         14 


SpaceRef staff editor.