0 Assigned ID: 236 ----- Attempting Submission 1 (Thu Apr 09 19:11:08 GMT 2015) ----- HST Phase I Proposal 236 (gies.apt) successfully submitted. Receipt: # 236-1 Dear Nolan and Denise, I have revised again the Phase II proposal for GO 14246. Here are the changes: - I increased the ACQ/IMAGE exposures to reach a S/N=40. - I set Buffer time = exposure time to ensure full read of the buffers. - I adjusted the science exposures to fit in the allotted orbits. Cheers, Doug -889433495 ----- Attempting Submission 1 (Wed Jul 15 19:15:38 GMT 2015) ----- HST Phase II Proposal 14246 (gies.apt) successfully submitted. Receipt: # 14246-1 ----- Attempting Submission 2 (Wed Nov 04 17:14:56 GMT 2015) ----- HST Phase II Proposal 14246 (gies.apt) successfully submitted. Receipt: # 14246-2 ----- Attempting Submission 3 (Wed Nov 11 15:57:14 GMT 2015) ----- APT crashed when attempting this operation. I did inspect images and confirmed the coordinates. The VLT FLAMES Survey of the massive stars in the Tarantula Nebula region of the LMC has led to the discovery of the two fastest rotating stars: VFTS 102 and 285 with V sin i = 610 and 609 km/sec. These two O-dwarfs may be single stars born with extraordinarily high angular momentum or they may have been spun up in a binary system by mass transfer or merger. Extreme rotators like these suffer gravity darkening that makes their equatorial regions cooler than the polar zones, so that the equatorial parts close to the limb contribute less flux and create narrower lines. We show how HST/COS spectroscopy of the far-ultraviolet spectra can be used with the optical rotational line broadening to estimate this gravity darkening effect and to determine the ratios of equatorial to critical rotation velocity for these two stars. This ratio is key to describing the bipolar winds of rapidly rotating stars, and the COS spectra will record the important wind lines in the FUV for comparison with models of asymmetric winds. The COS spectra will yield estimates of the stellar masses, radii, rotation rates, and abundances that will help us assess the origin and destiny of these remarkable stars in particular and massive rotating stars in general. We propose to obtain COS observations of the FUV spectrum of VFTS 102 and 285 using the G130M grating to cover most of the range from 1150 to 1450 with a resolving power of 18,000 (although we may make a modest reduction in resolving power by spectral smoothing in the data analysis stage to increase the signal-to-noise ratio). Our primary goal is to obtain cross-correlation functions of the FUV photospheric lines with model spectra. Numerical tests with model spectra indicate that we can estimate the FWHM of the cross-correlation function to better than 5% accuracy (comparable to the optical measurements of V sin i; Ramirez-Agudelo et al. 2013) with a signal-to-noise ratio of S/N = 10 per resolution element, so our goal is to obtain a S/N = 10 at 1310 in a single visit to each target. This S/N is also adequate for our investigation of the line morphology of the wind lines of Si III 1206, N V 1240, and Si IV 1400. We used the COS ETC and assumed that the spectral energy distributions are given by reddened versions of Castelli & Kurucz model spectra for the spectral classifications of the two targets. The model spectra were normalized using the UIT B1 magnitudes (effective wavelength = 1521 Angstroms) of the targets from Parker et al. (1998, AJ, 116, 180) and B-V colors from Evans et al. (2011), and the extinctions were estimated using intrinsic colors from Wegner (1994) and a ratio of total-to- selective extinction of R = 3.41 (LMC average). The COS ETC gave exposure times of 4500 and 440 seconds for VFTS 102 and 285, respectively (the latter being hotter and less reddened). Following the example in the Instrument Handbook, we would obtain this result through several exposures at each of four FP-POS spectral offsets and two or three CENWAVE positions in order to fill in the gap in spectral coverage between the two COS detectors. All these exposures would be made in standard TIME-TAG mode. We estimate that there are 54 minutes of visibility per orbit for the declination of both targets (delta = -69 deg). In the first orbit, we require 3 minutes for acquisition, 5 minutes for COS FUV acquisition and search, 2 minutes for PEAKXD cross dispersion peakup, and 5 minutes for PEAKD peakup in the dispersion direction. This leaves 39 minutes for science exposures. In succeeding orbits, we need 4 minutes for re-acquisition, yielding a net of 50 minutes for science exposure. Thus, for the fainter target, VFTS 102, we are requesting three orbits (with 4, 4, and 4 sub-exposures for each of 3 CENWAVE positions; this will require orbits 1, 2, and 3, respectively). We can obtain all the sub-exposures (four in each of 2 CENWAVE positions) in a single orbit for the brighter target, VFTS 285. Dr. Hugues Sana kindly provided F275W AB magnitudes for both stars based upon unpublished HST observations: m(F275W) = 15.044 for VFTS-102 m(F275W) = 14.013 for VFTS-285 The COS ETC calculations using these estimates led to exposure times that are a factor of 3.1 and 3.9 times lower for VFTS-102 and VFTS-285, repectively, than given above. Given this uncertainty, the BUFFER-TIME estimates were lowered by these factors (and the recommended 2/3) from the ETC calculations in order to be sure the buffers do not reach full capicity. HOT STARS 12 false true false false SUPPORTED EXT-STAR MAIN SEQUENCE O NO This object was generated by the targetselector and retrieved from the SIMBAD database. UIT m(B1)=14.55 F(1521)=5.5E-15 erg/s/cm^2/Angstrom UCAC4-105-014018 2MASS-J05373924-6909510 J2000 J2000 E(B-V)=0.63+/-0.10 EXT-STAR MAIN SEQUENCE O NO This object was generated by the targetselector and retrieved from the SIMBAD database. UIT m(B1)=12.66 F(1521)=3.1E-14 erg/s/cm^2/Angstrom Note that target VFTS-285 has a close companion VFTS-290 that is similar in brightness at a separation of 4 arcsec. 2MASS-J05381736-6905425 UCAC4-105-014155 J2000 J2000 E(B-V)=0.23+/-0.10 COS/FUV Spectroscopic No No G130M 1309 COS/FUV Spectroscopic No No G130M 1309 1447256783481 /nfs/morgan4/gies/TeX/NASA/HST_VFTS/OP-cache/gies-v01.xml The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. 3 orbit visit (Tic-Visit :proposal-id 14246 :visit-id "01" :proposal-version -1 :trans-version "20150609" :date "11-Nov-2015 10:46:23.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 956736 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14246 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14246 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3221 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14246 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3331 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14246 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3331 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) true 3 0 COS NUV image acquisition sequence. 1447257080076 /nfs/morgan4/gies/TeX/NASA/HST_VFTS/OP-cache/gies-v02.xml The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. 1 orbit visit (Tic-Visit :proposal-id 14246 :visit-id "02" :proposal-version -1 :trans-version "20150609" :date "11-Nov-2015 10:51:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 643648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14246 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14246 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) true 1 0 COS NUV image acquisition sequence.