0Assigned ID: 445
----- Attempting Submission 1 (Fri Apr 07 08:45:52 GMT 2017) -----
HST Phase I Proposal 445 (BHB-HST25.apt) successfully submitted.
Receipt: # 445-1
----- Attempting Submission 2 (Fri Apr 07 19:29:44 GMT 2017) -----
----- Attempting Submission 3 (Sat Apr 08 05:06:01 GMT 2017) -----I think this is complete -- I have three targets of 5, 5, and 7 orbits respectively. I split the 2 five-orbit targets into two visits each (3 +2) and split the seven orbit target into two visits (4+3). I would strongly prefer the 4+3 for the third target, as opposed to 3+2+2. The S/N is better that way!
Thank you!!-1867991556----- Attempting Submission 1 (Sat Jul 08 02:28:01 GMT 2017) -----Tracing Gas Flows from Halo to Disk: Observing the Milky Way's Galactic FountainGalactic-scale winds are a common feature of galaxy formation models, and are observed ubiquitously across the star-forming sequence down to ~0.5 Msun/yr. However, empirical constraints on the radial density profile and total spatial extent of these winds have been very challenging to obtain. At the same time, direct empirical evidence is scarce for the flows of gas onto galaxy disks that are critical for maintaining star formation. We have devised a simple experiment using blue horizontal branch (BHB) stars in the halo of the Milky Way that will directly map the location and density of diffuse, ionized gas flows between the Galactic disk and halo. This experiment, initiated in Cycle 23, obtains COS FUV spectra of halo BHB stars that sample a range of scale heights to 13 kpc towards the Northern Galactic pole. In this Cycle, we propose to observe 3 additional BHB stars along the complementary sightline to the South, effectively doubling our sightline sample size and permitting a novel test of the symmetry of gas flows at the disk-halo interface. This program allows us to unambiguously track inflowing and outflowing material from the Milky Way via absorption component blueshifts and redshifts. With BHBs at a range of known distances, we will directly determine changes in the gas density and metal mass as it travels through the disk-halo interface. Our experiment will yield the most detailed constraints on the physical state and energetics of the gas in the Milky Way's Galactic Fountain to date. Such constraints are fundamental to understanding the role of feedback in building the Galactic gaseous halo and the extent to which ongoing gas accretion fuels the ISM.From Phase I:
------------
We are targeting blue horizontal branch stars in the halo of the Milky Way toward the South Galactic Pole extending 10 kpc into the halo. Our catalog of blue horizontal branch stars comes from Xue et al. (2011), who selected these stars from SDSS DR8 stars with fiber spectra. Halo blue horizontal branch stars are good `beacons' for four primary reasons: (1) they are blue point sources and therefore have bright continua in the optical over the wavelength range of interest; (2) their UV spectra are characterized by a fairly featureless bright continuum with broad Lyman series lines (Brown et al. 2012) because they are quite metal poor; (3) they are approximate ``standard candles" since their distances can be estimated from multi-band photometry with an accuracy of ~10\% (Deason et al. 2011); and (4) many of them are moving with vradial > 100 km/s which allows us to cleanly separate any absorption features intrinsic to the star from the disk/halo interface gas.
There are three primary requirements that define our Southern sample: (1) The stars must have FUV magnitudes that are bright enough to achieve our required S/N (below) in a reasonable number of orbits (i.e. mFUV < 18.5); (2) The stars must lie at a high absolute galactic latitude (l < -60 deg); and (3) The heliocentric velocity of the stars must have an absolute value greater than 100 km/s to minimize confusion with any lower-velocity features we hope to detect. Criterion 1 limits us to 126 stars and criterion 2 winnows the group to 8 potential stellar targets; criterion 3 limits us to only 4 potential BHB stars (Figure 1A). Ideally, we would like to span a narrow range of x, y values (coordinates in the 2D plane of the disk) such that we are always probing lines of sight within a kpc of each other in the same layer to minimize variations due to differing locations above the disk. This final criterion is crucial for a direct measure of how the properties of gas outside the disk depend on scale height and allows us to guage whether gas is flowing into or out of the disk directly.Only three Southern BHB stars meet these criteria. We are proposing to observe all three, and Table 1 lists their relevant properties.
To achieve our primary goal of detecting the weak FUV absorption features redshifted or blueshifted with respect to strong Galactic absorption features, we require a S/N of 15 - 20 over our wavelength range, and the highest spectral resolution of COS (G160M) with a central wavelength of 1577 Angstroms. These requirements are to ensure an accurate measurement of this weak component and to avoid blending with the disk of the Milky Way. We expect to detect 15 mA features of CIV 1548 at 3sigma, consistent with previous detections of this transition in the halo of the Milky Way and in our own Cycle 23 data. Assessing the signatures of gas inflow and outflow will require an analysis of the absorption line profiles, using two-component models that include the ISM component of the Galaxy (Rubin et al. 2012). This is another reason we require S/N of at least 15 across our spectral range.
Phase II Observing Strategy:
-----------------------
We are taking COS/FUV spectra of blue horizontal branch stars with G160M centered at 1577 Angstroms. We require only one CENWAVE setting for this experiment since we are targeting specific absorption lines that will not fall near the gap between segments. Because we have coordinates that are accurate to within 0.1", we skip the ACQ/SEARCH step, and acquire the targets with a PEAKXD exposure followed by a PEAKD exposure. The Exposure times for these acquisitions are set by requiring a S/N of 40 for both segments and both types of acquistions, respectively.
Two of our three targets require 5 orbits, and one requires 7 orbits. In general, the buffer times are quite long, and we thus set the buffer time in the exposure manually to be 100 seconds shorter than the target's exposure time. We proceed by attempting to maximize exposure times while keeping to a minimum of four FP-POS settings per visit.
In our final set-up we achieve S/N of between 13 - 22 across our full wavelength range for all of our targets, which is generally in line with the requirements we outlined in the science case of Phase 1.Galaxies and the IGM6falsefalsetruefalsefalsefalsefalseSUPPORTEDSTARA0-A3 III-IHORIZONTAL BRANCH STARNOJ2000J2000FUV =17.89STARA0-A3 III-IHORIZONTAL BRANCH STARNOJ2000J2000FUV = 17.8STARA0-A3 III-IHORIZONTAL BRANCH STARNOJ2000J2000FUV = 18.19COS/FUVSpectroscopicNoNoG160M1577COS/FUVSpectroscopicNoNoG160M1577COS/FUVSpectroscopicNoNoG160M1577The scheduling data was generated by CASM 25.2.CASM was run in Phase II mode.This is the closest southern BHB at 6.3 kpc. It requires 5 orbits. Per guidelines, and to increase schedulability, I am splitting the 5 orbits into 2 visits -- one of 3 orbits and the other of 2 orbits. both visits will cover all 4 FP-POS and pack the orbits completely with one grating setting and no dither.154122113700077.69643528978702(Tic-Visit
:proposal-id 15154
:visit-id "01"
:proposal-version -1
:trans-version "20170613"
:date "07-Jul-2017 18:40:25.0"
: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 435088
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 15154
:visit-id "01"
:obset-id "01"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 15154
:visit-id "01"
:orbit-number 1
:pcs-time 333
:si-vis-utilization 2869
:al-overhead-at-end 0
:internal-dur-at-end 38
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3202
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "01"
:orbit-number 2
:pcs-time 222
:si-vis-utilization 2979
:al-overhead-at-end 0
:internal-dur-at-end 38
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3202
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "01"
:orbit-number 3
:pcs-time 222
:si-vis-utilization 2979
:al-overhead-at-end 0
:internal-dur-at-end 331
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3202
:pcs-gap 0
)true30The scheduling data was generated by CASM 25.2.CASM was run in Phase II mode.This is the second visit on BHBS-1 target. Only 2 orbits. Will hit all 4 FP-POS in 2 orbits.1531858904000240.79000000000002(Tic-Visit
:proposal-id 15154
:visit-id "02"
:proposal-version -1
:trans-version "20170613"
:date "07-Jul-2017 18:40:27.0"
:trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0
:FATAL-ERRORS 0 :CONTINUABLE-FATALS 0)
:number-of-orbits 2
:saa-model "31"
:si-bright-earth-limb-angle 20.0
:data-volume 365456
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 15154
:visit-id "02"
:obset-id "02"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 15154
:visit-id "02"
:orbit-number 1
:pcs-time 333
:si-vis-utilization 2868
:al-overhead-at-end 0
:internal-dur-at-end 48
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3202
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "02"
:orbit-number 2
:pcs-time 222
:si-vis-utilization 2979
:al-overhead-at-end 0
:internal-dur-at-end 331
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3202
:pcs-gap 0
)true20/private/var/folders/zc/ljhf1lgn10b1yd9ytmwlp4jr00070l/T/OPVisit9124325280631754612.xmlThe scheduling data was generated by CASM 25.2.CASM was run in Phase II mode.This is the second-closest southern BHB at 7.0 kpc. It requires 5 orbit, just like the first one. Per guidelines, and to increase schedulability, I am splitting the 5 orbits into 2 visits -- one of 3 orbits and the other of 2 orbits. both visits will cover all 4 FP-POS and pack the orbits completely with one grating setting and no dither.(Tic-Visit
:proposal-id 15154
:visit-id "03"
:proposal-version -1
:trans-version "20181130"
:date "06-Dec-2018 05:50:24.0"
: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 435056
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 15154
:visit-id "03"
:obset-id "03"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 15154
:visit-id "03"
:orbit-number 1
:pcs-time 333
:si-vis-utilization 2823
:al-overhead-at-end 0
:internal-dur-at-end 124
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3156
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "03"
:orbit-number 2
:pcs-time 302
:si-vis-utilization 2853
:al-overhead-at-end 0
:internal-dur-at-end 38
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3156
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "03"
:orbit-number 3
:pcs-time 302
:si-vis-utilization 2853
:al-overhead-at-end 0
:internal-dur-at-end 331
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3156
:pcs-gap 0
)true30The scheduling data was generated by CASM 25.2.CASM was run in Phase II mode.This is the second visit on BHBS-2 target. Only 2 orbits. Will hit all 4 FP-POS in 2 orbits.154459943800070.23634000000001(Tic-Visit
:proposal-id 15154
:visit-id "04"
:proposal-version -1
:trans-version "20170613"
:date "07-Jul-2017 18:42:47.0"
:trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0
:FATAL-ERRORS 0 :CONTINUABLE-FATALS 0)
:number-of-orbits 2
:saa-model "31"
:si-bright-earth-limb-angle 20.0
:data-volume 348080
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 15154
:visit-id "04"
:obset-id "04"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 15154
:visit-id "04"
:orbit-number 1
:pcs-time 333
:si-vis-utilization 2872
:al-overhead-at-end 0
:internal-dur-at-end 38
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3216
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "04"
:orbit-number 2
:pcs-time 222
:si-vis-utilization 2993
:al-overhead-at-end 0
:internal-dur-at-end 331
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3216
:pcs-gap 0
)true20/private/var/folders/zc/ljhf1lgn10b1yd9ytmwlp4jr00070l/T/OPVisit254083595406740661.xmlThe scheduling data was generated by CASM 25.2.CASM was run in Phase II mode.This is the third (and last) southern BHB at 10.0 kpc. It requires 7 orbits. I am splitting the 7 orbits into 2 visits -- one of 3 orbits and the other of 4 orbits. This gives better S/N and better achieves our goals than a 3-2-2 scenario. Both visits will cover all 4 FP-POS and pack the orbits completely with one grating setting and no dither.(Tic-Visit
:proposal-id 15154
:visit-id "05"
:proposal-version -1
:trans-version "20181130"
:date "06-Dec-2018 05:54:21.0"
: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 435056
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 15154
:visit-id "05"
:obset-id "05"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 15154
:visit-id "05"
:orbit-number 1
:pcs-time 333
:si-vis-utilization 2809
:al-overhead-at-end 0
:internal-dur-at-end 124
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3142
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "05"
:orbit-number 2
:pcs-time 302
:si-vis-utilization 2839
:al-overhead-at-end 0
:internal-dur-at-end 38
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3142
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "05"
:orbit-number 3
:pcs-time 302
:si-vis-utilization 2839
:al-overhead-at-end 0
:internal-dur-at-end 331
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3142
:pcs-gap 0
)true30/private/var/folders/zc/ljhf1lgn10b1yd9ytmwlp4jr00070l/T/OPVisit11220293111567802625.xmlThe scheduling data was generated by CASM 25.2.CASM was run in Phase II mode.This is the third (and last) southern BHB at 10.0 kpc. It requires 7 orbits. I am splitting the 7 orbits into 2 visits -- one of 3 orbits and the other of 4 orbits. This gives better S/N and better achieves our goals than a 3-2-2 scenario. Both visits will cover all 4 FP-POS and pack the orbits completely with one grating setting and no dither.
This is the second visit of 4 orbits.(Tic-Visit
:proposal-id 15154
:visit-id "06"
:proposal-version -1
:trans-version "20181130"
:date "06-Dec-2018 05:56:02.0"
:trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0
:FATAL-ERRORS 0 :CONTINUABLE-FATALS 0)
:number-of-orbits 4
:saa-model "31"
:si-bright-earth-limb-angle 20.0
:data-volume 321840
:tdrss-contact-duration 0
:coron NIL
)
(Tic-Obset
:proposal-id 15154
:visit-id "06"
:obset-id "06"
:pcs-mode "FGS"
)
(Tic-Orbit
:proposal-id 15154
:visit-id "06"
:orbit-number 1
:pcs-time 333
:si-vis-utilization 2809
:al-overhead-at-end 0
:internal-dur-at-end 124
:dark-offset NIL
:dark-utilization 0
:max-dark-utilization 1920
:low-sky "N"
:pcs-visibility 3142
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "06"
:orbit-number 2
:pcs-time 302
:si-vis-utilization 2840
: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 3142
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "06"
:orbit-number 3
:pcs-time 302
:si-vis-utilization 2840
: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 3142
:pcs-gap 0
)
(Tic-Orbit
:proposal-id 15154
:visit-id "06"
:orbit-number 4
:pcs-time 302
:si-vis-utilization 2840
: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 3142
:pcs-gap 0
)true40