Near-infrared scattered light properties of the HR 4796 A dust ring - A measured scattering phase function from 13.6 to 166.6

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Volume 599 (March 2017)

A&A, 599 (2017) A108

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Table 1

Log of the two sets of SPHERE observations of HR 4796 A.

Date	Set-up	DIT^a (s) ×	Par.	Seeing	Coh.	Wind	True	Platescale^d
		NDIT × NEXP	angle^b (°)	(′′)	time^c (ms)	(m/s)	north^d (°)	(mas/pixel)

2014/05/19	IRDIS H	3 × 15 × 32	8.1; 39.3	0.8; 1.2	2.3; 1.0	10.5	−134.87 ± 0.6	12.238 ± 0.020

2015/02/02	IRDIS H2H3	32 × 8 × 14	−9.3; 39.4	0.6; 0.7	11	3	−134.155 ± 0.006	12.257 ± 0.03
2015/02/02	IFS YJ	64 × 4 × 9	−9.3; 39.4	0.6; 0.7	11	3	−33.65e ± 0.13	7.46 ± 0.02

Notes.

^(a)

DIT is the individual detector integration time.

^(b)

Parallactic angle at the start and end of the observations. For the April 2014 observations, not all the available field rotation was used (see Sect. 2 for details).

^(c)

The coherence time τ₀ is defined as τ₀ = 0.31r₀/v, where r₀ is the Fried parameter measured by the DIMM and v is the maximum of the wind speed measured at30 m height, and 0.4 times the predicted wind speed at an altitude of 400 mbar (Sarazin & Tokovinin 2002).

^(d)

The calibration of the true north and platescale are detailed in Maire et al. (2016). The true north indicated here includes the offset between the pupil-stabilised and field-stabilised mode.

^(e)

A rotation offset of −100.46 ± 0.13° has been measured between IRDIS and the IFS.

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