0 Assigned ID: 1242 ----- Attempting Submission 1 (Wed Sep 30 21:53:09 GMT 2020) ----- HST Phase I Proposal 1242 successfully submitted. Receipt: # 1242-1 ----- Attempting Submission 2 (Wed Sep 30 22:24:12 GMT 2020) ----- ----- Attempting Submission 3 (Wed Oct 07 14:17:41 GMT 2020) ----- 0 ----- Attempting Submission 1 (Mon Nov 30 19:31:25 GMT 2020) ----- ALMA has revolutionized the study of reionization-era galaxies. With the launch of JWST just over one year away, it is crucial to establish a local reference sample of high-redshift "analog" galaxies covering essential UV, optical and FIR emission lines that will soon become available in the upcoming JWST+ALMA era. A local (z ~ 0.0040705), metal-poor (12 + log(O/H) = 7.76) blue compact dwarf galaxy, Pox 186, exhibits the brightest CIII] 1908 emission (equivalent width ~36 A) observed at any redshifts as revealed in the archival HST/COS observations, along with an extreme [OIII] 88/[CII] 158 (~ 10). This extreme CIII] is comparable to those observed in galaxies at redshifts of z ~ 6-7, when the reionization process is thought to be completed. We request mid-cycle time to obtain COS spectroscopy for this galaxy, to probe Ly$\alpha$ feature (emission and/or absorption) in addition to obtaining high S/N constraints on the UV nebular and stellar lines, as it will allow us to maximize the science return of a multiwavelength initiative involving radio, far-infrared and optical integral field spectroscopy. The proposed mid-cycle HST/COS observations will be very timely as they will provide directions to proposals for the upcoming observations using JWST, targeted to explore the epoch of reionization. We propose to obtain good quality (S/N > 5) HST/COS UV spectrum of Pox 186, the potentially most extreme local analogue of high-redshift (6-7) galaxies. We will use G130M/1291 to cover wavelength range of 1137-1274 A and 1292-1432 A, respectively, which will allow us to probe Ly feature and key stellar features such as C III 1175, N V 1239, which mightbe ubiquitous at high redshifts and will be revealed by JWST observations. The wavelength also covers the low-ionization transitions of Si II (1190, 1193, 1260, 1304 A) and C II (1334 A) and the intermediate ionization transition of Si III (1206 A). The previous UV observations have revealed double-peaked CIV emission. It is not clear whether there is a direct link between the line profiles of CIV and Ly emission. However, if the velocity profile of Lyalpha is similar to CIV in this galaxy, the double-peak of Ly will be resolved by G130M as its spectral resolution is 2 times better than G160M. We prefer COS to STIS as COS is 10 times more sensitive than STIS in the FUV, and its spectral resolution is 50 times better than STIS (7.5 km s-1 for G130 M compared to 360 km s-1 for STIS). Pox 186 is compact and unresolved in F336W, and thus is ideal to be observed by COS which is optimized for observing point sources. We used COS ETC to estimate the exposure times for spectroscopic observations and target acquisition as described below: We extracted the FUV spectrum from the archival STIS observations (PID:8333) and used it in COS ETC for the G130M/1291 setting for FUV spectroscopy. We estimated the required exposure time for achieving S/N = 5 (per resolution element) at wavelengths of 1215 A for grating G130M . Similarly, using the HST/COS NUV spectrum, we also estimated exposure time for obtaining the ACQ/Image using PSA/MirrorA for a recommended S/N~20. We made a conservative estimate of an HST orbit lasting 52 minutes exlcuding overheads related to guide-star (re-)acquistion and FP-POS split suggested by the APT. The above procedure resulted in 2 orbits for G130M. The target is safe for observation as our ETC estimates report no warnings for violations of the local and/or global bright object limit. Moreover, the same target was observed as part of HST-GO-16071. Complying with COS 2025 policy, we will obtain the spectroscopic exposures at FP-POS=3 & 4. The exposures at the two FP-POS will allow us to reduce flat-fielding uncertainties, eliminate grid wire residuals and increase S/N. The G130M has dispersions of 54mA resolution element. We will estimate the approximate spectral resolution by fitting narrow Milky Way absorption features, which we will use to bin the reduced and extracted (via CALCOS pipeline) one-dimensional spectra by averaging over the length of resolution elements (or multiple thereof) to achieve higher S/N per pixel. This will allow us to detect and analyse any weak spectral features. Given that there has been hardly any HI detected in Pox 186 (basis of our JVLA proposal), we do not expect damped Ly associated with Pox 186. In case of Ly absorption, it will blend with the MW Lyalpha absorption. We will retrieve the damped Lya absorption line related to H I gas content of Pox 186 by fitting a theoretical Lya damping profile with velocities corresponding to the MW and our target. We emphasise that geocoronal Lyalpha , if present, is not an issue because the COS aperture is five times wider than the STIS aperture that was used. However, even if we get swamped by the geocoronal, the expected FWHM is still only about 1.1 A (9.97 mA/pix, 109 pix in PSA), and is tolerable for our science. In total, we request for 2 HST orbits to obtain FUV spectra using HST/COS covering a wavelength range of 1137-1274 & 1292-1432 A for Pox 186. The team members possess extensive knowledge and scientific expertise that complement each stage of this investigation. Dr Kumari specialise in local analogues of high-z galaxies. Dr Smit is an expert in high-z galaxies. Dr Leitherer is an expert on properties of massive stars, young stellar populations, population synethesis modeling and star-forming galaxies. All team members are experienced in UV spectroscopy. Dr Kumari is a member of HST/COS instrument team at the STScI. Galaxies 3 false false false false false false false SUPPORTED GALAXY DWARF COMPACT NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 B = 17.93+/-0.53 COS/FUV Spectroscopic No No G130M 1291 1606763093940 /private/var/folders/ty/p02r94wx0vq2kd0c7lkytg7h00018c/T/OPVisit6317713218311771238.xml The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16445 :visit-id "01" :proposal-version -1 :trans-version "20200619" :date "30-Nov-2020 14:04:53.0" :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 104480 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16445 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16445 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2756 :al-overhead-at-end 0 :internal-dur-at-end 76 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16445 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2757 :al-overhead-at-end 0 :internal-dur-at-end 369 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) true 2 0 We notice that BOT/GSC reports a warning about exceeding the local count rate. However, when we ran ETC using already existing FUV and NUV spectra of this target, ETC reported no such warning. We also checked 21.5" arcsec field around the target in a HST/F336W image, which shows that the field does not have any other source other than our target.