2 Imaging observations

We observed HD 199143 and HD 358623 several times with the Son of Isaac (SofI) at the 3.5 m New Technology Telescope (NTT) of the European Southern Observatory (ESO) on La Silla, Chile. The SofI detector is an Hawaii HgCdTe $1024 \times 1024$ array with $18.5~\mu$m pixel sizes. We used the small SofI field with its best pixel scale for better angular resolution and determined the pixel scale by comparing the separations between several stars on other images taken in the same night with 2MASS images of the same fields to be 0.150 $\pm$ $0.002^{\prime \prime}$ per pixel. Darks, flats, and standards were observed in the same nights with the same set-up and data reduction was done with eclipse version 3.8, a C-based software library. While eclipse is made for VLT data reduction, like e.g. the Infrared Imaging And Array Camera (ISAAC), and not guaranteed to work for SofI data, it also does work for SofI imaging data reduction (dark, flat, shift+add); after all, SofI is the Son of Isaac. See Table 1 for the observations log.

   

Table 1: NTT observations log.

Instr.	obs. date	exp. [s]	band	FWHM
HD 199143 at $\alpha = 20:55:47.67$ and $\delta = -17:06:51.0$
SofI	7 Dec. 2000	$560 \times 1.5$	H	0.78 $^{\prime \prime}$
Sharp-I	1 Jul. 2001	$400 \times 0.5$	J	0.56 $^{\prime \prime}$
Sharp-I	1 Jul. 2001	$400 \times 0.5$	H	0.49 $^{\prime \prime}$
Sharp-I	1 Jul. 2001	$1200 \times 0.5$	K	0.40 $^{\prime \prime}$
SofI	8 Jul. 2001	$400 \times 1.3$	H	1.03 $^{\prime \prime}$ (*)
SofI	7 Dec. 2001	$400 \times 1.5$	H	1.02 $^{\prime \prime}$
HD 358623 at $\alpha = 20:56:02.77$ and $\delta = -17:10:54.1$
SofI	7 Dec. 2000	$200 \times 1.2$	H	0.88 $^{\prime \prime}$
Sharp-I	2 Jul. 2001	$400 \times 0.5$	J	0.54 $^{\prime \prime}$
Sharp-I	2 Jul. 2001	$400 \times 0.5$	H	0.41 $^{\prime \prime}$
Sharp-I	2 Jul. 2001	$1500 \times 0.5$	K	0.36 $^{\prime \prime}$
SofI	6 Dec. 2001	$500 \times 1.2$	H	0.79 $^{\prime \prime}$

Remarks: positions given for J2000.0. (*) Not photometric.

Figure 1: HD 199143 and its faint close companion candidate in our SHARP-I images in JHK and our SofI H-band image. The lower right panel (SofI) shows a larger field, where no additional companion candidates are detected.

Figure 2: HD 358623 and its two companion candidates in our SHARP-I images in JHK and our SofI H-band image. The lower right panel (SofI) shows a larger field, where no additional companion candidates are detected.

Then, we observed HD 199143 and HD 358623 at the end of the nights of 1 and 2 July 2001, respectively, using SHARP-I (System for High Angular Resolution Pictures, Hofmann et al. 1992) at the NTT. The targets were placed onto the two lower, i.e. western SHARP-I quadrants, because they have better pixel and flat field characteristics. The data were corrected for bad pixels followed by a sky image subtraction and the application of a flat-field. For each band we then co-added the $256 \times 256$ pixel frames using the brightest pixel as shift-and-add reference (Christou 1991). Exposure times and FWHM in the final co-added images (using the SHARP pixel scale of $0.0491^{\prime \prime}$, see also Neuhäuser et al. 2000a) are given in Table 1.