Status Report

NASA Hubble Space Telescope Daily Report #4708

By SpaceRef Editor
October 3, 2008
Filed under , ,


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


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.


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


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.



                      SCHEDULED      SUCCESSFUL

FGS GSacq               15                 12
FGS REacq               00                 00
OBAD with Maneuver      30                 30


SpaceRef staff editor.