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12 May 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT        # 3360

PERIOD COVERED: DOYs 129-131

Part 5 of 5

STIS/MA1 9466

SBS 1150+599: A Population III Planetary Nebula?

SBS 1150+599 is a puzzling emission-line object. Optical spectra
reveal only strong Balmer, He II and Ne V lines, along with a hot,
featureless continuum. We have recently partially resolved the HAlpha
emission in a ground-based image, and believe the object to be a new
halo planetary nebula, one of only handful known in the Milky Way. If
correct, its lack of significant O III and other forbidden emission
means that SBS 1150+599 has the lowest metallicity of any known
planetary nebula. Our estimate of the oxygen abundance places it 40
times lower than that of K 648 in the globular cluster M15, the
previous record holder, and would make it one of the most metal-poor
objects in the Galaxy. We propose obtaining ACS images of SBS 1150+
599 to confirm that it is a planetary nebula and to determine its
morphology. Planetary nebulae in old populations may occur due to
binary-star merging, and the morphology may test this hypothesis. We
will also study the UV spectrum of SBS 1150+599 using STIS to confirm
the O/H value and estimate carbon and nitrogen abundances
unobtainable in the optical. 

WFPC2 9336

Expansion distances to the symbiotic Miras He 2-104 and He 2-147

We propose to measure the expansion parallax of the nebulae around
the binary symbiotic Miras He 2-104 {the Southern Crab} and He 2-147
by means of high resolution WFPC2/F658N images to be taken at two
different epochs. Given the large outward velocities of these nebulae
inferred from ground-based spectroscopy, their apparent expansion can
be measured by HST imaging over timescales of only 2-3 years. For He
2-104 we have already obtained ``Epoch 1'' HST images {cf.
STScI-PRC-PR99-32}. Combining the angular and radial velocity
expansions will straightforwardly yield the distance to the proposed
targets. Knowledge of the distance to these nebulae will provide a
solid contribution to a variety of research fields such as {a} the
energetics of nuclear burning in symbiotic binaries containing a
Mira, {b} the pulsation mode of binary Miras, and {c} the viability
of Mira symbiotics as supersoft X-ray sources and potential
progenitors of Type Ia supernovae. HST high resolution imaging of the
nebulae combined with ground-based spectroscopy will also address the
still debated issue of the formation of bipolar nebulae by collimated
outflows from evolved stars.

WFPC2 9710

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans.

WFPC2 9709

POMS Test Proposal: WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure
Parallel program. The program will be used to take parallel images of
random areas of the sky, following the recommendations of the 2002
Parallels Working Group. 

WFPC2 9594

WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt2/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels 

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None 

COMPLETED OPS REQs:
16970-2  Battery 2 Capacity test script {at} 129/1931z

OPS NOTES EXECUTED:
0900-1  COMMAND PROBLEM {at} 129/1303z
0900-1  COMMAND PROBLEM {at} 132/0330z
1108-2  Perform Observation Re-Dumps on the Partial Obs.
        Level {at} 129/1445z, 130/0001z, 130/0003z, 130/1141z,
        130/1143z, 130/1146z, 130/1150z, 130/1153z, 130/1148z,
        130/1315z, 130/1318z, 130/2233z, 130/2235z, 130/2238z,
        130/2239z, 131/1307z, 131/1309z, 131/1311z, 131/1313z,
        131/2039z
1110-0  S/W Dump of HST486 Memory {at} 130/1305z
1111-0  Change Limits MAMA1 Threshold Voltage {at} 130/1622z
0910-2  SI Console response to MCE Resets after FSW 4.8 is
        activated {at} 130/1546z
0916-0  Tabulation of Slew Attitude Error (Miss-distance) {at} 132/0152z

                   SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq             21             21
FGS REacq             28             28
FHST Update           41             41
LOSS of LOCK

SIGNIFICANT EVENTS: None

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