Megacam Imaging of the Extended Groth Strip

M. Ashby, B. McLeod, J.-S. Huang, P. Barmby, G. Fazio, C.

Papovich, S. Willner

Vital Statistics

• 36 E2V 42-90 CCDs: 2048x4608 pixels

• Pixel size: 13.5 microns (0.08 arcsec)

• Field of view: 25’x25’

• Filters: u’ g’ r’ i’ z’ (330-1000nm)

Megacam Performance• Gain: 3-4 e-/ADU

• Read noise: 4-5e- at 200kHz

• Read time (2x2bin): 25sec including all overheads

• CCD Temps: -115C to -130C depending on focal plane location

Quantum Efficiency

0

10

20

30

40

50

60

70

80

90

100

350 450 550 650 750 850 950

Wavelength (nm)

Pe

rce

nt

Specification

00014-02-03

00014-05-05

8434-18-05

00014-06-03

8434-12-03

8434-12-05

9283-10-04

8352-09-04

8351-02-04

00091-20-03

00091-09-03

00101-01-05

00014-10-05

00014-20-04

00184-05-03

00014-10-03

00184-17-05

00014-10-04

00184-05-04

00184-16-04

00184-08-03

00183-01-03

00183-01-04

00184-14-05

00184-16-03

00184-16-05

00091-05-04

00091-16-05

00183-03-04

00091-05-03

00091-02-04

00237-02-04

Image Quality

PIXEL POSITION

FWHM(ARCSEC)

Data Reduction Procedure

• Basic calibrations done with IRAF/mscred

overscan, badpix, bias, flatten

• i’ and z’ require defringing – either IRAF or custom program

• wcs solution done with megawcs script

Astrometry

RADec

RAErr(”)

DecErr(”)

Error relative to 2Mass catalog: 0.16”

Astrometry

RADec

RAErr(”)

DecErr(”)

Error relative to sdss catalog: 0.09”

Data Reduction Procedure

• Basic calibrations done with IRAF/mscred

overscan, badpix, bias, flatten

• i’ and z’ require defringing – either IRAF or custom program

• wcs solution done with megawcs script

• photometry – not yet fully automated

At this point in time: 5% is easy; 1% hard

300mmx300mmSloan-r filterby Sagem

Quantum Efficiency

0

10

20

30

40

50

60

70

80

90

100

350 450 550 650 750 850 950

Wavelength (nm)

Pe

rce

nt

Specification

00014-02-03

00014-05-05

8434-18-05

00014-06-03

8434-12-03

8434-12-05

9283-10-04

8352-09-04

8351-02-04

00091-20-03

00091-09-03

00101-01-05

00014-10-05

00014-20-04

00184-05-03

00014-10-03

00184-17-05

00014-10-04

00184-05-04

00184-16-04

00184-08-03

00183-01-03

00183-01-04

00184-14-05

00184-16-03

00184-16-05

00091-05-04

00091-16-05

00183-03-04

00091-05-03

00091-02-04

00237-02-04

Photometric Solution

• Take a sequence of exposures, putting the same star on many different chips

• Make a master catalog of all the photometry of every star

• Perform least squares solution minimizing the scatter in the multiple observations of each star

Free Parameters

• Chip-zero point: c0 + c1 * x + c2 * y

-color term: (not yet tested)

• Exposure– zero point

SDSS

Megacam

Goals

• Construct u-band LF at z=1 for comparison with GALEX low-z data

• Search for Ly-break dropouts to characterize galaxy population out to z~6

U-band data

• 300-600sec/dither position

• 5 dithers/pointing

• 25 pointings

• Redshifts for LF from DEIMOS

Search for Ly-break dropouts

• u’ g’ R z=3 (Megacam + Megacam + Subaru)• g’ R z’ z=4 (Megacam + Subaru + Megacam) • R F814W z’ z=5 (Subaru +HST + Megacam)• F814W z’ J z=6 (HST + Megacam +SWIRC)• z’ J H (Megacam + SWIRC + SWIRC)• getting close to epoch of reionization• With IRAC data will be able to draw connections

between Ly-break population and IR luminous population