0 Assigned ID: 1860 ----- Attempting Submission 1 (Fri Apr 09 09:19:17 GMT 2021) ----- HST Phase I Proposal 1860 successfully submitted. Receipt: # 1860-1 FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser The warnings on the exposures come from adding post-flash to get up to the new recommendation of 20 electrons/pix to mitigate CTE. APT still has the old recommendation of 12 electrons/pix. This is a resubmission to ensure that STScI has received the phase II file. No details have been changed. -1249727335 ----- Attempting Submission 1 (Thu Jul 29 04:55:42 GMT 2021) ----- HST Phase II Proposal 16749 successfully submitted. Receipt: # 16749-1 ----- Attempting Submission 2 (Fri Jul 30 01:56:12 GMT 2021) ----- APT's post-flash level is the old recommendation of 12 electrons/pix. We have included post-flash to get up to the new recommendation of 20 electrons/pix for CTE mitigation. Starbursting galaxies present the best laboratory to study the CGM since they are likely undergoing strong accretion events which trigger intense star formation-driven outflows. However, very few observations exist that have directly imaged their CGM and quantified the fine-scale substructure. Recent ultra-deep Keck/KCWI observations have mapped optical emission lines in the CGM to a distance of over 30 kpc from IRAS08, a nearby starbursting galaxy with evidence for an ongoing accretion event. These KCWI observations contain bright emission line knots with sizes of order hundreds of parsecs and no evidence of stellar continuum, implying a lack of stars. The properties of these emission knots are consistent with cool, condensing clouds in recent simulations. However, the sizes from KCWI are near the seeing limit, and the continuum measurement is hampered by sky subtraction uncertainties. We aim to use HST to zoom in on this substructure in the CGM of IRAS08 and test hypotheses explaining the sub-kiloparsec features. We propose for 5 orbits of WFC3/UVIS to obtain the Halpha+[NII] (F665N) and broad-band starlight (F467M & F775W) to measure the sizes and fluxes of the CGM emission knots. These data will allow us to differentiate between three possible scenarios giving rise to these knots, including the cool condensing clouds predicted in high resolution simulations, external HII regions, and dwarf galaxies. These observations are part of a larger program to directly image the optical emission lines of the CGM in starbursting galaxies. This HST imaging will therefore be a Rosetta Stone for interpreting future data as we move into the new era of direct imaging of the CGM. Narrowband filter F665N: Using the faintest CGM knot from the KCWI observations, we estimate an Halpha surface brightness by converting the knot's Hbeta surface brightness from KCWI to Halpha assuming no extinction. This gives an Halpha surface brightness of ~1x10^-17 erg s^-1 cm^-2 arcsec^-2. For SNR=10, the WFC3 UVIS ETC requires an exposure time of 1334 s (22.2 min), including a post flash of 16 electrons/pix to reach the recommended threshold of 20 electrons/pix to avoid poor CTE. The orbit visibility of our target is ~58 minutes, which allows for 46.8 min of exposure time per orbit, or two 23 min exposures, given typical overheads of 11.2 min. We opt to increase our exposure times by a factor of 2x in order to identify fainter emission peaks that may have been washed out due to poor spatial resolution in the KCWI data, which will allow us to measure knot sizes. This will increase our S/N to 15 on the nominal CGM knot measurement and serve to help make more robust observations. The F665N filter is likely to have very significant problems with low background, and is our most important filter for characterizing the morphology and size of the knots. We therefore opt to readout a subset of the pixels in the WFC3 array. We will use the 1k x 1k subarray, and use 3 separate pointings centered on the knots, one pointing per orbit. For each orbit we will use the WFC-UVIS-DITHER-LINE-3PT dither pattern. Thus we require 3 orbits with F665N to cover all CGM knots. Broadband filters F467M and F775W: In nearby spiral galaxies the median globular cluster luminosity is M_V~-7.5 mag (Harris 1991). Werk et al (2008) finds that external HII regions are comprised of associations of clusters. Those associations have magnitudes of M_V~-8 mag and sizes of 50-70 pc, which is similar to our resolution limit. If we consider a point source with M_V~-8 AB mag (apparent magnitude of 26 mag) at the distance of IRAS08, we can make a 5 sigma detection in F467M just under 1 orbit of HST time (including overheads). We can obtain a similar detection limit in F775W. We will use a full orbit for each filter with the WFC3-UVIS-DITHER-LINE-3PT dither pattern. To mitigate the CTE, the broadband filters require lower levels of post-flash, and therefore we can readout the entire field. Reduced-gyro operations are likely to have minimal impact given the small number of orbits requested and minimal adjustments in each orbit. Dr. Nikole Nielsen lead the reduction and analysis of the KCWI data, and the subsequent discovery of the emission knots. They are an expert in CGM studies of galaxies, and have lead several papers using absorption line studies. Nielsen has recently been using KCWI to study the CGM of nearby galaxies and mapping Lyman alpha at z=2. A/Prof Deanne Fisher is lead investigator of the KCWI program to map emission lines in the CGM of nearby galaxies. Fisher has over 15 years of experience in detailed surface photometry of galaxies (e.g. Fisher et al. 2008; Kormendy, Fisher et al. 2009), and has lead multiple HST programs doing high spatial resolution observations (e.g Fisher et al. 2017), as well as ultra deep imaging with space observations (Fisher et al. 2014 Nature) in a wide variety of wavelenghts (UV, optical, IR and radio). A/Prof Glenn Kacprzak is an expert in studies of the CGM, and especially in the area of accretion onto galaxies (Kacrpzak 2017). A/Prof John Chisholm is a Hubble Fellow, and has extensive experience working with HST data (e.g. Chisholm et al. 2015,2017). Chisholm has lead 6 HST GO programs and 1 HST AR program. They have worked on many aspects of the CGM and stellar populations with both imaging and spectroscopy. Prof Chris Martin is a world expert on imaging the CGM. They are the PI of the KCWI instrument, which is currently the workhorse instrument for CGM imaging projects at both low and high redshift. Martin was PI of the GALEX space telescope and has worked with HST previously, leading their own HST program. Intergalactic Medium and the Circumgalactic Medium Galaxies 6 false false false false false false false false SUPPORTED GALAXY STARBURST This object was generated by the target selector and retrieved from the SIMBAD database. We have offset the target coordinates slightly from SIMBAD to ensure the central disk is not in the CCD gap with the UVIS-CENTER aperture and to allow for a wider orient range for schedulability. Using the UVIS aperture reduces the available orient range. J2000 J2000 EXT-MEDIUM DAMPED LYMAN ALPHA CLOUD EMISSION LINE NEBULA HII REGION IGM KNOT J2000 J2000 10^-16 erg s^-1 cm^-2 arcsec^-2 EXT-MEDIUM DAMPED LYMAN ALPHA CLOUD EMISSION LINE NEBULA HII REGION IGM KNOT J2000 J2000 10^-16 erg s^-1 cm^-2 arcsec^-2 EXT-MEDIUM DAMPED LYMAN ALPHA CLOUD EMISSION LINE NEBULA HII REGION IGM KNOT J2000 J2000 10^-16 erg s^-1 cm^-2 arcsec^-2 WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F467M WFC3/UVIS Imaging No No F775W POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 1 false 1627475498693 /home/nikki/Proposals/HST/cycle29/OP-cache/cgm_knots-v01.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. We have offset the target coordinates slightly from SIMBAD to ensure the central disk is not in the CCD gap with the UVIS-CENTER aperture and to allow for a wider orient range for schedulability. Using the UVIS aperture reduces the available orient range. 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Post-flash added to get the background levels to the new recommendation of 20 electrons/pix. 1627524851615 /home/nikki/Proposals/HST/cycle29/OP-cache/cgm_knots-v02.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. 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Post-flash added to get the background levels to the new recommendation of 20 electrons/pix. Post-flash added to get the background levels to the new recommendation of 20 electrons/pix.