APT generates a warning that some of the exposures have POS TARGs that move the target out of the aperture. This is intentional because those exposures are meant to measure the background away from the target. ----- Attempting Submission 1 (Tue Apr 24 08:27:03 EDT 2007) ----- APT generates a warning that some of the exposures have POS TARGs that move the target out of the aperture. This is intentional because those exposures are meant to measure the background away from the target. Assigned ID: 348 ----- Attempting Submission 2 (Fri Jan 26 14:23:44 EST 2007) ----- Imaging Circumstellar Disks and Envelopes around Proto-Brown Dwarfs Using the Spitzer Space Telescope, we have discovered two young brown dwarfs with Class I spectral energy distributions (i.e., proto-brown dwarfs). We propose to perform broad-band NICMOS imaging of these Class I brown dwarfs to spatially resolve their circumstellar disks and envelopes. If successful, these data would comprise the first measurements of this kind for brown dwarfs and would provide fundamental constraints on models for the formation of brown dwarfs.
We will obtain NIC2 images of 2 protostellar brown dwarfs in the Chamaeleon star-forming region through the F110W, F160W, and F205W filters. These filters are selected because they provide contiguous broad-band near-IR photometry. Each target will be observed in a 6-point dither pattern (NIC-SPIRAL-DITH) that is centered in the NIC2 array. To optimize the sampling of the PSF, we select a subpixel dither spacing of 60.5 pixels, or 4.56775". At each dither position, we will obtain one MULTIACCUM image in each of the 3 filters. The exposure times of the individual images will be 128, 128, and 96 sec in F110W, F160W, and F205W, respectively, which will provide sufficient signal-to-noise for extended emission based on the results from program 7413 for IRAS 04325+2402 C (Hartmann et al. 1999) and the magnitudes of our 2 targets (H=15.3 and 15.2, K_s=13.9 and 13.8). Because the target areas contain only faint sources, we use one of the SPARS modes for SAMP-SEQ. The combination of SPARS16 and NSAMP=10 provides sufficient samples (8-10) for good cosmic ray rejection. Immediately before and after the dither sequence on each target, we will obtain one image in F205W at a position 30" from the target to measure the background. These two chop positions will be on opposite sides of the target. During the exposures with NIC2, we will obtain parallel images with NIC1 through the F160W filter with the maximum exposure times that do not interfere with the NIC2 observations. Each target will be observed in one orbit and one visit. There are no scheduling constraints for this program. STAR FORMATION 12 false 0.0 false false false false false false SUPPORTED STAR BROWN DWARF T TAURI STAR PROTOPLANETARY DISK H=15.2 J2000 11 07 3.6930 -77 24 30.71 J2000 STAR BROWN DWARF PROTOPLANETARY DISK T TAURI STAR H=15.2 J2000 11 06 29.4260 -77 24 58.64 J2000 NIC2 Imaging No No F110W NIC2 Imaging No No F160W NIC2 Imaging No No F205W NIC1 Imaging No No F160W NIC2 Imaging No No F110W NIC2 Imaging No No F160W NIC2 Imaging No No F205W NIC1 Imaging No No F160W POS-TARG DITHER DITHER 4.56775 NIC-XSTRIP-DITH false true 6 0 POS-TARG NIC-SPIRAL-DITH 0 1 false /Bulk1/kluhman/prop/hst/cycle16/classI/phase2/OP-cache/prop-v01.xml (Tic-Visit :proposal-id 11204 :visit-id "01" :proposal-version -1 :trans-version "20070325" :date "20-Apr-2007 16:58:17.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 441696 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11204 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11204 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2974 :al-overhead-at-end 0 :internal-dur-at-end 150 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3355 :pcs-gap 0 ) true 1 0 /Bulk1/kluhman/prop/hst/cycle16/classI/phase2/OP-cache/prop-v01.xml /Bulk1/kluhman/prop/hst/cycle16/classI/phase2/OP-cache/prop-v02.xml (Tic-Visit :proposal-id 11204 :visit-id "02" :proposal-version -1 :trans-version "20070325" :date "20-Apr-2007 17:04:23.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 441696 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11204 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11204 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2974 :al-overhead-at-end 0 :internal-dur-at-end 150 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3355 :pcs-gap 0 ) true 1 0 /Bulk1/kluhman/prop/hst/cycle16/classI/phase2/OP-cache/prop-v02.xml