NIKA Run 1 offline processing results (FXD)


In principle, efficiencies due to the filtering method have been taken into account

Source

Date

Flux

Stat. Error

Comments

Map

Scan info

Mars

20091024...

130Jy

-

Primary calibrator

AzelMap2_Mars_20091024_60_67.jpg

60-67

3C273

2009102 5 & 7

13.1Jy

0.1

AzelMap2_3C273_20091027_66_67.jpg

66-67

3C345

20091024

5.051Jy

0.009

AzelMap2_3C345_20091024_69_73.jpg

69-72

G34.3

20091024

4.761Jy

0.024

Peak flux, source is extended,

RadecMap2_G34.3_20091024_106_106.jpg

106

K3_50A

20091024

1.442Jy

0.008

Peak flux, source is extended

RadecMap2_K3-50A_20091024_102_104.jpg

102-104

MWC349

20091024

1.364Jy

0.010

AzelMap_MWC349_20091024_94_96.jpg

94-96

B1418+546

20091024

1.18Jy

0.040

Flux decreasing (known reasons)

AzelMap2_B1418+546_20091025_104_126.jpg

75-82

M87

20091027

~0.8Jy

Extended , det. eff decreasing

RadecMap3_M87nowob_20091027_84_95.jpg

84-96

WR147

20091025

263mJy

24

Detected.

AzelMap2_WR147_20091025_129_148.jpg

129-148

Arp220=IC4553

20091025

114mJy

18mJy

AzelMap2_Arp220_20091027_123_165.jpg

B1800+440

20091024

103mJy

7mJy

AzelMap2_B1800+440_20091024_98_99.jpg

98-99

PCyg

20091024

28mJy

4mJy

AzelMap2_PCyg_20091024_85_92.jpg

84-92

Pluto

20091025

12mJy

23

Not detected

AzelMap2_Pluto_20091025_93_102.jpg

93-102

GRB091024

20091024

6.6mJy

4.8mJy

Heavy weight on first 2 scans

18scans, 115-137

M51

20091024

1.5mJy

12mJy

PS flux at the center, no detection

AzelMap2_M51_20091024_108_113.jpg

108-113

Arp220: Expect 43mJy (from 1 to 3 mm PdB interpolate), result a bit high, One article quote 88+-8

G34.3: Sandell gives 12.5 Jy in 27" photometry

WR147: Expected is 200mJy Altenhoff, 1994, but some variability expected

Pluto: 35K (Stern Science 1993, 261, 5129), expect 4 mJy

Note on sensitivity


We neglect atm. opacity effect ( between 5 and 10% at most)

* NEFDscan= 276 mJy s1/2 for 120x120 arcsecond field (eg M51)

NEFDscan= [ NEFDdet/ sqrt(Ndet) ] * sqrt( Omega/ Airy) with Omega being the field solid angle (eg 120x120) and Airy is the Airy solid angle (taken as corresponding to a disk of 19" diameter).

Hence we get NEFDdet=190 mJy s1/2 (compatible with 120 and 90 arcsecond size field observations) For 2 GRB scans, we even got 90 mJy s1/2 but we agree that it is advisable NOT to publish that number as it is not representative of the campaign.

* NEFDairy= NEFDdet/sqrt(Kovers) Kovers=1/0.632=2.5 (pessimistic)

NEFDairy= 120 mJy s1/2

that can be compared with a classical single horn bolometer sensitivity. Let us keep in mind that this is one polarization KID. To really compare we have to divide by a factor between 2 and sqrt(2). We have also purposedly used the average sensitivity of all the kids (as obtained from NEFDscan) and not the best ones. That's another factor 1.5 to 2 if we could homogeneize the array. So, all in all the NIKA Oct 2009 sensitivity becomes (30 to 60 mJy s1/2) comparable to Mambo2 (35 mJy s1/2 at zenith) although at different frequencies

* To convert to NET, we use the total beam of 0.15 arcmin2 as obtained from aperture photometry. This is correct for diffuse extended sources. Mars at 205K is diluted by the beam by a factor 0.103 so that Mars (167 Jy at 2.1mm) is equivalent to a 21.2K blackbody so that NETairy= NEFDairy* 21.2/167Jy=

NETairy = 15 mK s1/2

* Going to a more uncertain number the NEP: Using DeltaNu/Nu=0.3, a total transmission of 0.30 (for example an instrument transmission of 0.6 and a main beam efficiency of 0.5) and one polarization, I get, in agreement with Alessandro, that the power from Mars on the central pixel is 1.4 pW, but I use 0.8 pW to take into account the larger spread of the beam (factor 1.7=3.6/5*2.3) hence the NEFDdet converts to (back to Hz1/2) NEP= sqrt(2) 0.8E-12/167* 190E-3=

NEP = 1.3 E-15 W/sqrt(Hz)

Overall, an increase by a factor 5 in sensitivity is withing reach for the next campaign, by gaining on - the homogeneity - the noise - the spectral bandpass - the straylight

For the article, I would quote NEFDairy (useful for astronomers), NET (useful for cosmology and extended source) and NEP (useful for Kid makers, no kidding)

NIKA1offline (last edited 2010-10-22 09:56:09 by PabloMellado)