HUBBLE SPACE TELESCOPE

DAILY REPORT      #4708

PERIOD COVERED: 5am October 1 - 5am October 2, 2008 (DOY 275/0900z-276/0900z)

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.

FGS 11819

Certifying the SMOV4 FGS AMA Stars with FGS1r

This proposal observes the candidate SMOV4 "AMA stars" prior to SM4 to

certify which of them are unresolved point sources, and hence is an

appropriate AMA target. Each target is to be observed in a 1-orbit visit

using FGS1r in its highy angular resolution Transfer mode with two

exposures. Exposure 1 utilizes a 0.8" scan path with 20 scans which will

provide high S/N for the detection of binariy down to ~12 mas, while the

second exposure utilizes a 6" scan path to provide sensitivity to

putative wide companions.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

11519 - GSAcq(1,2,1) failed to RGA Hold (Gyro Control)

           GSAcq(1,2,1) scheduled at 275/16:37:58 - 16:46:03 failed to RGA Hold due

           to (QF1STOPF) stop flag indication on FGS-1.

11520 - OM1EBOXT (STIS MAMA1 Electronics Box Temp) Limit Violation

           At 275/20:26:03, STIS MAMA1 Electronics Box Temperature (OM1EBOXT) began

           flagging out of limit intermittently one count below its red low limit

of 0.0 deg C at -0.15 deg C.

11521 - GSAcq(1,2,1) failed due to SSLEX @ 276/02:14:40z

           During LOS the GSacq(1,2,1) scheduled at 276/02:14:04 failed due to scan

           step limit exceeded on FGS 1.

11522 - GSacq(1,2,1) failed to RGA control.

           During LOS GSacq(1,2,1) scheduled at 276/07:01:44 failed. At AOS stop

           flags QF1STOPF and QSTOP were set for FGS 1. 

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                      SCHEDULED      SUCCESSFUL 

FGS GSacq               15                 12    

FGS REacq               00                 00                     

OBAD with Maneuver 30                 30                        

SIGNIFICANT EVENTS: (None)