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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
COSMOS
ACS Program Summary
Anton Koekemoer
(INS/ACS+WFPC2)
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
ACS Observing Strategy
Survey design:
l 2 deg2 to cover large-scale structure at z ~ 1 - 2
l HST ACS/WFC (40962 pix) - 600 pointings:
– 1 orbit (2000s) / pointing, 4 dithered exp’s
– F814W (“wide I”) ª SDSS i+z
– 50 mas/pixel fi 1010 pixels total (~103 - 104 pix / L* galaxy)
l high sensitivity (I > 27 mag, 10s)
– morphology of L* galaxies for z < 2
l sensitivity + area:
– 106 galaxies
– also enough area to cover unusual objects at higher z
l equatorial (10h00m28.6s, +2°12’21.0”)
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
COSMOS Cluster at STScI
l 6 Linux machines (each 2.4GHz, 4GB RAM, 2 TB disk)
l cosmos1,2: home/archive nodes
l cosmos3,4,5,6: processing nodes
COSMOS1
Head Node
t
Mbi
100
it
b it
Giga
Gb Switch
G
bit
iga
bit
ga
Gi
12x200Gb
RAID 5
Giga
b
Gi g
ab
it
2x2.4GHz CPUs
2Gb RAM
DADS/
ARCHIVE
G ig
abit
COSMOS2
COSMOS3
COSMOS4
COSMOS5
COSMOS6
Archive
Processing
Processing
Processing
Processing
2x2.4GHz CPUs
4Gb RAM
2x2.4GHz CPUs
4Gb RAM
2x2.4GHz CPUs
2Gb RAM
12x200Gb
RAID 5
2x2.4GHz CPUs
4Gb RAM
12x200Gb
RAID 5
2x2.4GHzCPUs
4Gb RAM
12x200Gb
RAID 5
12x200Gb
RAID 5
12x200Gb
RAID 5
COSMOS Pipeline
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
l A series of Python scripts running separately on cosmos
l Steps carried out automatically for all exposures:
OPUS Data
calacs
Raw files delivered to cosmos from Archive
calacs: subtract bias, apply flatfield, etc
associate images
Associate all 4 exposures of each pointing
multidrizzle
Register, CR-clean, drizzle combined image
tweakshift
Correct absolute astrometry (shift, rotate)
mosaic
Drizzle onto final mosaic
As of Jun 2004:
THE LARGEST
HST FIELD!!!!
270 orbits:
– 261 F814W (I)
– +9 F435W (g)
Total # pixels:
~ 4.5 x 109
Coverage:
I: 1.0
°
g+I: 100
’
1°
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
single orbit i-band
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
The 2-band
dataset:
3x3 g+I
AB~27 (10s)
100 sq ’
6x108 pixels
(scale=0.5;
25 mas/pix)
10’
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
Summary
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Anton Koekemoer (INS)
STScI TIPS, 17 June 2004
Status:
l COSMOS is now the largest contiguous HST field ever
observed - 1° x 1° (4x larger than GEMS..sorry GEMS!)
l Cyc 12 in hand (270 orbits), total 600 by end Cyc 13
Properties:
l F814W to AB ~ 27 (10s)
l Full dataset equivalent to a few SNAP pointings
l 2 million galaxies, 3400 X-ray AGN, 120 clusters
For more information see:
http://www.astro.caltech.edu/~cosmos/