----- Submission 1 (Mon May 09 15:41:40 GMT 2005) -----
We consulted about "3Gyro Mode" with our coordinator, Alison Vick. The observations
are to take place before May 25, when 3 Gyro mode is still expected to be in operation.
She said this approach was OK. Assigned ID: 1001
----- Submission 1 (Wed Apr 27 19:39:59 GMT 2005) -----
Phase I Proposal 1001 (ogle-2005-blg-071) successfully submitted.
First Mass Measurement of a Planet Found By MicrolensingWe will use ACS to determine the mass of the extra-solar planet found in the ongoing microlensing event OGLE-2005-BLG-071. This source will be imaged in V (F555W) and I (F814W) at two epochs, one "very soon" while the event is still significantly magnified, and the other after 5 months when it has returned to baseline. If the centroid does not move, this will demonstrate that the "blended light" detected in the
event is "perfectly aligned" (within 15 mas, 1 sigma) with the source, and so is almost certainly the lens. V and I photometry will then permit an estimate of its mass and distance. Since the planet-star mass ratio is already known to be 0.007, this will yield a planet mass. Even if the HST images show that the blended light is not aligned with the source (and so is not from the lens), the HST observations will still strongly constrain the mass by helping to measure the "microlens parallax", which when combined with the "angular Einstein radius", determines the mass. Thus, the observations have a very high probability of success. The observations are time-critical because the first one must be taken while the event is still in progress.The target is an ongoing microlensing event with coordinates:
(J2000.0): 17:50:09.77 -34:40:23.3
There will be two observations on ACS HRC, each taking one orbit.
One orbit will be ``as soon as possible'' and the
other on or after 1 October 2005. The protocol for the two orbits
will be the same: 4 I band (F814W) exposures, each 3.75 min, each
separated by dithers as indicated in Phase II form;
then 4 V band (F555W) exposures, each
5.25 min, each separated by dithers as indicated in Phase II form.
At the two epochs, the target will be
(V,I)=(19.8,18.2) [20 May] and
(V,I)=(20.7,18.9) [1 Oct].
This will yield S/N=549 and 395 for the two I-band measurements.
This is more than adequate to centroid to 1 mas, but we expect the
astrometry to be fundamentally limited by crowding, not S/N.
The V images will have lower S/N=339 and 208. They will be
of high enough S/N to check the centroid motion and in addition
will permit precise photometry of any blended light that is not
aligned with the source.
Orbit 1 (ASAP) Orbit 2 (~1 Oct 2005)
Guide Star Acq 6 min Guide Star Acq 6 min
F814W overheads (1.8+2.4) 4.2min F814W overheads (1.8+2.4) 4.2min
4 x 3.75min exp 15 min 4 x 3.75min exp 15 min
3 x 20s dither 1 min 3 x 20s dither 1 min
F555W overheads (1.8+2.4) 4.2min F555W overheads (1.8+2.4) 4.2min
4 x 5.25min exp 21min 4 x 5.25min exp 21 min
3 x 20s dither 1 min 3 x 20s dither 1 min
------------------------------- -------------------------------
total 52.4 min total 52.4 minFirst observation should be done as soon as possible. The precision
obtained from these observations will degrade rapidly the more
they are delayed. Details were given in the DDT proposal, which
was approved.STELLAR POPULATIONS0false0.0falsefalsefalsefalsefalseSUPPORTEDSTARF3-F9Distance to source is unknown, but is believed to be 1 or 2 kpc.I mag: 18.2 [In 2nd visit (~1 Oct), source will be V=20.7, I=18.9]J200017 50 9.7700-34 40 23.30J2000ACS/HRCImagingNoNoF814WACS/HRCImagingNoNoF555WACS/HRCImagingNoNoF814WACS/HRCImagingNoNoF555WPOS-TARGDITHER0.15LINE0.098falsefalse63.5419.89ACS-HRC-DITHER-BOX1false/home/dong/HST/OP-cache/ogle-2005-blg-071-v01.xml
(Tic-Visit
:proposal-id 10707
:visit-id "01"
:proposal-version -1
:trans-version "20050323"
:date "09-May-2005 11:06:54.0"
:trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0
:FATAL-ERRORS 0 :CONTINUABLE-FATALS 0)
:number-of-orbits 1
:saa-model "27"
:si-bright-earth-limb-angle 20.0
:data-volume 147216
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 10707
:visit-id "01"
:obset-id "01"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 10707
:visit-id "01"
:orbit-number 1
:pcs-time 365
:si-vis-utilization 2819
:al-overhead-at-end 0
:internal-dur-at-end 199
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3283
:pcs-gap 0
)
true10/home/dong/HST/OP-cache/ogle-2005-blg-071-v01.xml/home/dong/HST/OP-cache/ogle-2005-blg-071-v02.xmlOur "default option" is for the second visit to take place on or shortly
after 16 Feb 2006 (when schedulability begins, assuming 2 Gyros)
However, if 3 Gyros are operating on 1 Oct 2005, then it would be
possible to observe our field at that time. This would be
somewhat preferable to the above "default option".
(Tic-Visit
:proposal-id 10707
:visit-id "02"
:proposal-version -1
:trans-version "20050323"
:date "09-May-2005 11:07:44.0"
:trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0
:FATAL-ERRORS 0 :CONTINUABLE-FATALS 0)
:number-of-orbits 1
:saa-model "27"
:si-bright-earth-limb-angle 20.0
:data-volume 147216
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 10707
:visit-id "02"
:obset-id "02"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 10707
:visit-id "02"
:orbit-number 1
:pcs-time 367
:si-vis-utilization 2819
:al-overhead-at-end 0
:internal-dur-at-end 199
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3283
:pcs-gap 0
)
true10/home/dong/HST/OP-cache/ogle-2005-blg-071-v02.xml