Calibration and performance of the NIKA2 camera at the IRAM 30-m Telescope

Open Access

Table 18.

Summary of the main characteristics describing NIKA2 measured performance.

	Array 1 and 3	Array 2	Reference
Reference wavelength [mm]	1.15	2.00
Reference frequency [GHz]	260	150	Sect. 8.1.1
Frequency [GHz]	254.7 and 257.4	150.9	Sect. 2.5
Bandwidth [GHz]	49.2 and 48.0	40.7

Number of designed detectors	1140 and 1140	616	Sect. 2.3
Number of valid detectors ^(a)	952 and 961	553	Sect. 5.3
Fraction of valid detectors [%]	84	90
Pixel size in beam sampling unit ^(b) [λ/D]	1.1	0.87	Sect. 5.2

FWHM^(c) [arcsec]	11.1 ± 0.2	17.6 ± 0.1	Sect. 6.2
Main beam efficiency ^(d) [%]	47 ± 3	64 ± 3	Sect. 6.3
rms FWHM across the FOV [arcsec]	0.6	0.6	Adam et al. (2018)

Reference FWHM ^(e) [arcsec]	12.5	18.5	Sect. 8.1.1
Reference beam efficiency ^(f) [% ]	61 ± 3	72 ± 2	Sect. 8.1.3

rms pointing error [arcsec]	< 3	< 3	Sect. 3.2

Absolute calibration uncertainty [%]	5	5	Sect. 9.1, Appendix A.1
Systematic calibration uncertainty ^(g) [%]	0.6	0.3	Sect. 9.1.3
Point-source rms calibration uncertainty [%]	5.7	3.0	Sect. 9.2

α noise integration in time ^(h)	0.5	0.5	Sect. 10.3

NEFD ⁽ⁱ⁾ [mJy s^1/2]	30 ± 3	9 ± 1	Sect. 10.3
M_s^(j) [arcmin² mJy⁻² h⁻¹]	111 ± 11	1388 ± 174

Notes.

^(a)

Number of usable detectors, which have been selected in at least two FOV reconstructions.

^(b)

Calculated from real array pixel size [2.75 mm/2.0 mm] and unvignetted entrance pupil diameter [27 m].

^(c)

Full width at half maximum of the main beam using the combined results of three methods.

^(d)

Ratio between the main beam and the total beam solid angles including large angular-scale error beams and far side lobes.

^(e)

Full width at half maximum of the beam used in our reference photometric system.

^(f)

Ratio between the reference FWHM beam and the total beam solid angles including large angular-scale error beams and far side lobes.

^(g)

Systematic calibration uncertainties due to the opacity correction using the corrected skydip method estimated at the reference IRAM 30-m Winter observing conditions: 2 mm pwv, 60° elevation.

^(h)

Effective power law of noise reduction with integration time.

⁽ⁱ⁾

NEFD at zero atmospheric opacity.

^(j)

Mapping speed at zero atmospheric opacity.

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