• Esi2015Apr

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Observing Programs at Keck Observatory with ESI on Apr 20-21, 2015 for Kirby + Rubin

This page organizes all of the projects for ESI on Apr 20-21. Each program page should include: (i) the optimal setup for the observation; (ii) a target list with finder charts and recommended exposure times; (iii) any additional notes of interest (S/N desired, priority of targets); (iv) Worst conditions (seeing, clouds) under which observations will still be useful.

Goal

This project aims to measure hydrogen and metal line column densities in DLA host galaxies and the material in their surroundings. Starting with the QPQ quasar sample, we have identified pairs with a DLA in one sightline. We then use the other QSO in the pair to probe the CGM of the DLA-host galaxy. We would like to use measurements of the hydrogen and metal columns to constrain the ionization state, metallicity, and mass of gas in the CGM sightline. We will also compare the CGM metallicities and low-ionization metal-line kinematics to those measured in the corresponding DLA sightline.

To accomplish this, we must obtain S/N >~ 10 per pix at the wavelength of the DLA's Lya line in the CGM sightline. We are also aiming for S/N >~5 per pix for the DLA itself, and S/N ~ 10 per pix for the DLA's metal-line transitions. I have noted which QSO provides the CGM and DLA sightlines in the target table below.

More instructions on the observing procedure and on using the finding charts are given below the target table.

Finally, if the seeing is > 1.1", or if you're observing through clouds, the QSO observations are probably not going to be successful. If we don't come close to our S/N goals, the data is of limited use. In addition, it is better to obtain "complete" observations of a single pair than marginal observations of more than one pair.

Here is the current observing plan:

12 degree twilight begins at 09:04 LST (19:30 HT), and then begins at 18:47 LST (05:11 HT) in the morning.

• Starlist: starlist_2015Apr19.txt

• Airmass Chart: airmass_chart_2015A.pdf

• Keck Emphemeris: https://www.ucolick.org/calendar/keckcal2011-20/keck2015.12apr

Backup/Twilight

• CosHalos : Bright quasars in need of NaI absorption (~7000A)

  • High Priority: J1009, J1133, J1241, J1342

• LlsCosLehner: Bright quasars with LLS. We are interested in the LLS's MgII absorption.

Setup

Please use the 0.75" slit in echelle mode, unless conditions are extremely good (< 0.7" seeing). Please obtain calibrations for both the 0.75" and 0.5" slit at the beginning of the night (just in case). All observations should be taken with 1x1 binning. If the total exposure time is over an hour, individual integrations as long as 2400sec can/should be taken.

Timeline (HST / LST)

====== Apr 20 ======

18h52m
08h25m - sunset

19h02m - 19h32m
08h35m - 09h05m: sky flats, 5 x

19h32m - 19h43m
09h05m - 09h16m: standard star Feige 34, 600s, 60s acquisition

19h43m - 19h54m
09h16m - 09h27m: COS Halos target J1009, 600s, 60s acquisition

19h54m - 20h05m
09h27m - 09h38m: COS Halos target J1133, 600s, 60s acquisition

19h57m
09h32m - 18deg twilight ends

20h05m - 22h20m
09h40m - 11h55m: J0939+1847, 900s acquisition, 2hrs exposure

22h20m - 01h15m
11h55m - 14h55m: J1153+3530, 900s acq, 2.75hrs exposure

• Can stay at the pair PA for the full exposure, since we'll be a low airmass (<1.35) the whole time.

01h15m - 04h10m
14h55m - 17h45m: J1725+3038, 900s acq, 2.6hrs exposure (will need at least 2.4hrs more) -- got S/N~5.4 at CIV in CGM, Lya is worse

04h10m - 05h05m
17h45m - 18h40m: J1719+2549, 900s acq, 40min exposure -- only got S/N~4 at CIV in the CGM

04h44m
18h19m - 18deg twilight begins

05h05m - 05h16m
18h40m - 18h51m: standard star BD+33d2642, 600 seconds, 60 seconds acquisition

05h16m
18h51m: sky flats and other calibrations, if not done yet

05h11m
18h45m - 12deg twilight begins

05h50m
19h26m - sunrise

====== Apr 21 ======

18h52m
08h25m - sunset

19h02m - 19h42m
08h35m - 09h15m: sky flats, 5 x

19h42m - 19h57m
09h15m - 09h30m: standard star Feige 34, 600s, 60s acquisition

19h58m
09h32m - 18deg twilight ends

19h57m - 23h12m
09h30m - 12h45m: J0957+6223, 900s, 3hrs exposure -- this pair at am=1.4-1.5 during this window

1. Do first 2x2400s on both QSOs (use the PA of the pair)
2. Then observe just the imag=21.34 (blue) QSO at the parallactic angle for the remaining time
   • (you'll need to use a different set of offsets for this -- see the finder chart for these!)

23h12m - 00h20m
12h45m - 14h00m: start J1529+2314, 900s acq, 1.0hrs exposure

• Will probably want more time here, but J1719 and J1725 need all the help they can get (and they are slightly more valuable).

00h20m - 01h36m
14h00m - 15h15m: J1719+2549, 900s acq, 1hr exposure

15h15m - 18h30m: J1725+3038, 900s acquisition, 3hrs exposure to finish

04h43m
18h19m - 18deg twilight begins

04h57m - 05h08m
18h30m - 18h41m: standard star BD+33d2642, 600 seconds, 60 seconds acquisition

05h08m
18h41m: sky flats and other calibrations, if not done yet

05h10m
18h45m - 12deg twilight begins

05h49m
19h26m - sunrise

* This pair has a separation >20", and so must be observed one at a time.

Low Quality Backups / Already Observed

Finding Charts for QSO Pair Targets

In these charts, the two QSOs are indicated with blue (b/g QSO) and red (f/g QSO) arrows, and the offset star is indicated with a thick red box. (Please ignore the thin red box!) The coordinates at the top (in black) are of the offset star, not the QSOs. The offset star coordinates are also listed in the star list and in the target table above (rather than the coordinates of either QSO). alpha_pos gives the position angle of the pair; this information is also in the star list so that the slit gets set at this angle automatically, but please double check. delta theta gives the separation between the QSOs in arcseconds. The black delta RA and delta Dec (with bars over them) give the offset from the star to the midpoint between the QSOs. These offsets are also included in the star list. A positive RA offset moves the telescope East, and a positive Dec offset moves the telescope North.

The offsets printed in blue and red show how to move from the offset star to the b/g and f/g QSO, respectively. This info should not be needed, however.

Main Pages

• QPQ and CGM of DLAs

• ESI observing cookbook: ESI_obs_cookbook.pdf