Daily Rpt #4707

HUBBLE SPACE TELESCOPE

DAILY REPORT #4707

PERIOD COVERED: 5am September 30 - 5am October 1, 2008 (DOY
274/0900z-275/0900z)

OBSERVATIONS SCHEDULED

FGS 11299

Calibrating the Mass-Luminosity Relation at the End of the Main Sequence

We propose to use HST-FGS1R to finish calibrating the mass-luminosity
relation for stars less massive than 0.5 Msun, with special emphasis on
objects near the stellar/substellar border. Our goals are to determine Mv
values to 0.05 magnitude and masses to 5%, and thereby build the fundamental
database of stellar masses that we will use to test theoretical models as
never before. This program uses the combination of HST-FGS3/FGS1R at optical
wavelengths, historical infrared speckle data, ground-based parallax work,
metallicity studies, and radial velocity monitoring to examine nearby,
subarcsecond binary systems. The high precision separation and position
angle measurements with HST-FGS3/FGS1R {to 1 mas in the separations} for
these faint {V = 10-15} targets simply cannot be equaled by any ground-based
technique. As a result of these measurements, we are deriving high quality
luminosities and masses for the components in the systems, and
characterizing their spectral energy distributions from 0.5 to 2.2 microns.
One of the objects, GJ 1245 C with mass 0.074 +/- 0.002 Msun, is the only
object known with an accurate dynamical mass less than 0.10 Msun. The payoff
of this proposal is high because the six systems selected for final
observations in Cycles 15 and 16 have already been resolved during Cycles
5-13 with HST FGS3/FGS1R and contain most of the reddest objects for which
accurate dynamical masses can be determined.


FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11518 - GSAcq 2,3,2 Failed to RGA Hold

GSAcq 2,3,2 scheduled from Day 275/02:34:31 to 02:41:59, failed to RGA Hold.
Mnemonics F2STOPF, QF2STOPF flagged, and upon entry to FN FMT at 02:36:22,
FSTOP, GSTOP and QSTOP also flagged.

Astrometry Observation FGS1 #11299 affected.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 12 10
FGS REacq 01 01
OBAD with Maneuver 26 26

SIGNIFICANT EVENTS:

Flash Report:

As a result of NCS cooler and the Sis being safed, the HST load decreased
from ~75A to ~53A, resulting in a battery heat up with the increased charge
current. Per COP 4.27A the +BB SPA Trim relay (Battery 3) was off-lined as
Battery 3's temperature was demonstrating an increasing warming trend and
was approaching 3.5 DegC, the yellow ground limit. Commanding to off-line
the SPA was performed at DOY 275, 01:04 GMT via Ops Request 18303.