Additional Info on CARMA

 

A.J. Beasley 7/22/2002

 

 

 

 

Sensitivity

 

Continuum Sensitivity

(4 GHz BW, 2-pol)

Angular Resolution & Line Sensitivity

(1km/s channel, 1-pol)

Freq GHz

1-min

mJy

5-hr

mJy

Config

Beam

“

1-min

K

5-hr

K

Beam

“

1-min

K

5-hr

K

100

0.7

0.04

D

6.3

0.4

0.02

2.7

0.7

0.04

230

2.2

0.1

C

2.5

2.4

0.1

1.1

4.4

0.26

(345)

12.0

0.7

B

1.0

14.8

0.8

0.4

36

2.1

 

 

 

A

0.4

92

5.3

0.2

144

8.4

 

Assumptions: Tsys ~80 K at 3mm, 140 K at 1 mm, 70 % efficiency, 6 10.4 m antennas + 9 6.1m antennas (i.e. no SZA).

 

 

Resolution/Configuration

 

CARMA will be a heterogeneous array, comprised of 3 antenna sizes: 10.4m antennas, nine 6.1m antennas and eight 3.5m antennas. CARMA will use 4 configurations (100m – 1500m) to span a range of angular scales from 0.2” to 30”. Addition of the SZA antennas (typically in a compact configuration < 100m in diameter) will enable imaging of angular scales up to 3’. The addition of more antennas will lead to higher-fidelity imaging and the ability to perform effective snapshot observations. Mosaicing observations will be standard.

 

Correlator Specifications

 

The CARMA first-light correlator will be a hardware extension of the FPGA-based COBRA correlator currently nearing completion at OVRO. The 4 GHz first-light bandwidth will be available as eight 500 MHz bands which can be tuned anywhere within the 4 GHz receiver band. Each of these 500 MHz bands can be channelized as indicated in the following table; multiple bands can be glued together to increase total velocity coverage.

 

500 MHz band CARMA correlator performance

Bandwidth (MHz)

Channels

3 mm channel spacing (km/s)

3 mm velocity width (km/s)

1 mm channel spacing (km/s)

1 mm velocity  (km/s)

 

 

 

 

 

 

512

16

96

1536

32

512

256

32

24

768

8

128

128

64

6

384

2

128

64

128

1.5

192

0.5

64

32

128

0.75

96

0.25

32

8

128

0.18

24

0.06

8

2

128

0.05

6

0.01

2