The observations were carried out at the United Kingdom Infrared Telescope (UKIRT) during two observing runs. The first took place between 2-5 October 1994 (UT), the echelle grating, long (300 mm) focal length camera and $58\times62$ pixel SBRC InSb detector of the Cooled Grating Spectrometer 4 (CGS4) were used. The second run was held between 15-17 December 1995 (UT) and CGS4 was used with the echelle grating short (150 mm) focal length camera and $256\times256$ pixel SBRC InSb detector. Spectra were obtained centered at Pa ${\rm\beta }$ (1.28215 $\mu$ m) and at Br ${\rm\gamma }$ (2.16611 $\mu$ m) for a sample of T Tauri stars mainly from the Taurus-Auriga complex. The observed stars are listed in Table 1, with a " $\surd$ '' indicating whether Pa ${\rm\beta }$ and/or Br ${\rm\gamma }$ spectra was taken.

Table 1: Sample of observed stars - Positions, classification (CTTS or WTTS) and spectral types from the Herbig-Bell Catalogue (1988) (HBC) and radial velocities from HBC or from the references indicated in the notes to this table. Tick marks mean that a spectrum was obtained
Star RA(1950) DEC(1950) Type Spec.Ty. $V_{\rm rad}$ Pa ${\rm\beta }$ Br ${\rm\gamma }$

V773 Tau 4 11 7.29 +28 04 41.2 WTTS K3 V +16b $\surd$ $\surd$

FM Tau 4 11 7.82 +28 05 18.8 CTTS M0 +16: (i) $\surd$ $\surd$

FN Tau 4 11 8.61 +28 20 26.9 CTTS M5 +16; (ii) $\surd$

CW Tau 4 11 11.34 +28 03 27.2 CTTS K3 V +14.5a $\surd$ $\surd$

FP Tau 4 11 43.50 +26 38 57.5 CTTS M4 V +22b $\surd$ $\surd$

CY Tau 4 14 27.67 +28 13 28.6 CTTS M1 V +19.1a $\surd$

DD Tau 4 15 25.10 +28 09 14.6 CTTS M1 +28c $\surd$

Hubble 4 4 15 40.89 +28 12 54.0 WTTS K7 +15.0a $\surd$ $\surd$

BP Tau 4 16 8.61 +28 59 15.3 CTTS K7 V +15.8a $\surd$ $\surd$

LkCa 7 4 16 35.78 +27 42 28.1 WTTS K7,M0V +16.4a $\surd$ $\surd$

DE Tau 4 18 49.84 +27 48 05.2 CTTS M2: V +14.9a $\surd$

RY Tau 4 18 50.85 +28 19 35.0 CTTS K1IV,V +16.4 $\surd$ $\surd$

FS Tau 4 18 57.63 +26 50 30.5 CTTS M1 +16: (iii) $\surd$

T Tau 4 19 4.21 +19 25 05.4 CTTS K0IV,V +19.1a $\surd$ $\surd$

DF Tau 4 23 59.63 +25 35 41.7 CTTS M0,1 V +12b $\surd$ $\surd$

DG Tau 4 24 1.01 +25 59 35.5 CTTS M ? +16: (iv) $\surd$ $\surd$

DI Tau 4 26 38.00 +26 26 20.1 WTTS M0 V +16.0a $\surd$

IQ Tau 4 26 47.67 +26 00 16.3 CTTS M0.5 +15.3a $\surd$

FX Tau 4 27 27.91 +24 20 18.2 CTTS M1 +16.8a $\surd$

DK Tau 4 27 40.48 +25 54 59.0 CTTS K7 V +15.3a $\surd$ $\surd$

ZZ Tau 4 27 49.32 +24 35 56.9 CTTS M3 +15; (v) $\surd$

HL Tau 4 28 44.42 +18 07 36.2 CTTS K7,M2? +17: (vi) $\surd$ $\surd$

XZ Tau 4 28 46.00 +18 07 35.2 CTTS M3 +17; (vii) $\surd$ $\surd$

HK Tau 4 28 48.85 +24 17 56.2 CTTS M0.5 +16.3a $\surd$

Haro 6-13 4 29 13.60 +24 22 42.9 CTTS Cont. +15; (v) $\surd$ $\surd$

GG Tau 4 29 37.06 +17 25 22.3 CTTS K7 V +17.6a $\surd$ $\surd$

GH Tau 4 30 4.79 +24 03 18.3 CTTS M2,3 V +18.4a $\surd$

V807 Tau 4 30 5.2 +24 03 39 CTTS K7 V +1 (viii) $\surd$ $\surd$

GI Tau 4 30 32.33 +24 15 3.1 CTTS K6 V +18.1a $\surd$ $\surd$

GK Tau 4 30 32.76 +24 14 52.4 CTTS K7 V +18.6a $\surd$ $\surd$

DL Tau 4 30 36.02 +25 14 24.0 CTTS K7 V +16.0 (ix) $\surd$ $\surd$

AA Tau 4 31 53.45 +24 22 44.1 CTTS K7 V +16.1a $\surd$ $\surd$

DN Tau 4 32 25.68 +24 08 52.3 CTTS M0 V +16.1a $\surd$ $\surd$

HP Tau 4 32 52.85 +22 48 17.7 CTTS K3 +17.7a $\surd$ $\surd$

DO Tau 4 35 24.18 +26 4 55.2 CTTS M0 V +20:c $\surd$ $\surd$

VY Tau 4 36 17.41 +22 42 02.3 var. M0 V +17.8a $\surd$

DQ Tau 4 43 59.99 +16 54 40.1 CTTS M0,1 V -4:c $\surd$

Haro 6-37/c 4 44 5.90 +16 57 19.2 CTTS K7,M0 +19.5b $\surd$ $\surd$

DR Tau 4 44 13.20 +16 53 23.8 CTTS Cont. +16.7 (x) $\surd$ $\surd$

DS Tau 4 44 39.07 +29 19 56.2 CTTS K5 V +16.3a $\surd$ $\surd$

UY Aur 4 48 35.71 +30 42 13.6 CTTS K7 V +18b $\surd$ $\surd$

GM Aur 4 51 59.76 +30 17 14.7 CTTS K3 V +15.0a $\surd$ $\surd$

SU Aur 4 52 47.84 +30 29 19.4 CTTS G2 III +16.0 $\surd$ $\surd$

RW Aur A 5 4 37.69 +30 20 13.9 CTTS K1 +14:a $\surd$ $\surd$

GW Ori 5 26 20.78 +11 49 52.8 CTTS G5 +33.6a $\surd$ $\surd$

YY Ori 5 32 20.77 -5 59 52.7 CTTS K5 V +12:c $\surd$

TW Hya 10 59 30.08 -34 26 07.4 CTTS K7 V +6:c $\surd$

V1331 Cyg 20 59 32.21 +50 09 55.5 CTTS Cont. -15: (xi) $\surd$ $\surd$

DI Cep 22 54 8.18 +58 23 59.5 CTTS G8 V -10b $\surd$ $\surd$

BM And 23 35 12.41 +48 07 35.9 CTTS K5 V -15.2 (xii) $\surd$ $\surd$

**Table 1:** Sample of observed stars - Positions, classification (CTTS or WTTS) and spectral types from the Herbig-Bell Catalogue (1988) (HBC) and radial velocities from HBC or from the references indicated in the notes to this table. Tick marks mean that a spectrum was obtained
Star	RA(1950)	DEC(1950)	Type	Spec.Ty.	$V_{\rm rad}$	Pa ${\rm\beta }$	Br ${\rm\gamma }$
V773 Tau	4 11 7.29	+28 04 41.2	WTTS	K3 V	+16b	$\surd$	$\surd$
FM Tau	4 11 7.82	+28 05 18.8	CTTS	M0	+16: (i)	$\surd$	$\surd$
FN Tau	4 11 8.61	+28 20 26.9	CTTS	M5	+16; (ii)	$\surd$
CW Tau	4 11 11.34	+28 03 27.2	CTTS	K3 V	+14.5a	$\surd$	$\surd$
FP Tau	4 11 43.50	+26 38 57.5	CTTS	M4 V	+22b	$\surd$	$\surd$
CY Tau	4 14 27.67	+28 13 28.6	CTTS	M1 V	+19.1a	$\surd$
DD Tau	4 15 25.10	+28 09 14.6	CTTS	M1	+28c	$\surd$
Hubble 4	4 15 40.89	+28 12 54.0	WTTS	K7	+15.0a	$\surd$	$\surd$
BP Tau	4 16 8.61	+28 59 15.3	CTTS	K7 V	+15.8a	$\surd$	$\surd$
LkCa 7	4 16 35.78	+27 42 28.1	WTTS	K7,M0V	+16.4a	$\surd$	$\surd$
DE Tau	4 18 49.84	+27 48 05.2	CTTS	M2: V	+14.9a	$\surd$
RY Tau	4 18 50.85	+28 19 35.0	CTTS	K1IV,V	+16.4	$\surd$	$\surd$
FS Tau	4 18 57.63	+26 50 30.5	CTTS	M1	+16: (iii)	$\surd$
T Tau	4 19 4.21	+19 25 05.4	CTTS	K0IV,V	+19.1a	$\surd$	$\surd$
DF Tau	4 23 59.63	+25 35 41.7	CTTS	M0,1 V	+12b	$\surd$	$\surd$
DG Tau	4 24 1.01	+25 59 35.5	CTTS	M ?	+16: (iv)	$\surd$	$\surd$
DI Tau	4 26 38.00	+26 26 20.1	WTTS	M0 V	+16.0a	$\surd$
IQ Tau	4 26 47.67	+26 00 16.3	CTTS	M0.5	+15.3a	$\surd$
FX Tau	4 27 27.91	+24 20 18.2	CTTS	M1	+16.8a	$\surd$
DK Tau	4 27 40.48	+25 54 59.0	CTTS	K7 V	+15.3a	$\surd$	$\surd$
ZZ Tau	4 27 49.32	+24 35 56.9	CTTS	M3	+15; (v)	$\surd$
HL Tau	4 28 44.42	+18 07 36.2	CTTS	K7,M2?	+17: (vi)	$\surd$	$\surd$
XZ Tau	4 28 46.00	+18 07 35.2	CTTS	M3	+17; (vii)	$\surd$	$\surd$
HK Tau	4 28 48.85	+24 17 56.2	CTTS	M0.5	+16.3a	$\surd$
Haro 6-13	4 29 13.60	+24 22 42.9	CTTS	Cont.	+15; (v)	$\surd$	$\surd$
GG Tau	4 29 37.06	+17 25 22.3	CTTS	K7 V	+17.6a	$\surd$	$\surd$
GH Tau	4 30 4.79	+24 03 18.3	CTTS	M2,3 V	+18.4a	$\surd$
V807 Tau	4 30 5.2	+24 03 39	CTTS	K7 V	+1 (viii)	$\surd$	$\surd$
GI Tau	4 30 32.33	+24 15 3.1	CTTS	K6 V	+18.1a	$\surd$	$\surd$
GK Tau	4 30 32.76	+24 14 52.4	CTTS	K7 V	+18.6a	$\surd$	$\surd$
DL Tau	4 30 36.02	+25 14 24.0	CTTS	K7 V	+16.0 (ix)	$\surd$	$\surd$
AA Tau	4 31 53.45	+24 22 44.1	CTTS	K7 V	+16.1a	$\surd$	$\surd$
DN Tau	4 32 25.68	+24 08 52.3	CTTS	M0 V	+16.1a	$\surd$	$\surd$
HP Tau	4 32 52.85	+22 48 17.7	CTTS	K3	+17.7a	$\surd$	$\surd$
DO Tau	4 35 24.18	+26 4 55.2	CTTS	M0 V	+20:c	$\surd$	$\surd$
VY Tau	4 36 17.41	+22 42 02.3	var.	M0 V	+17.8a	$\surd$
DQ Tau	4 43 59.99	+16 54 40.1	CTTS	M0,1 V	-4:c	$\surd$
Haro 6-37/c	4 44 5.90	+16 57 19.2	CTTS	K7,M0	+19.5b	$\surd$	$\surd$
DR Tau	4 44 13.20	+16 53 23.8	CTTS	Cont.	+16.7 (x)	$\surd$	$\surd$
DS Tau	4 44 39.07	+29 19 56.2	CTTS	K5 V	+16.3a	$\surd$	$\surd$
UY Aur	4 48 35.71	+30 42 13.6	CTTS	K7 V	+18b	$\surd$	$\surd$
GM Aur	4 51 59.76	+30 17 14.7	CTTS	K3 V	+15.0a	$\surd$	$\surd$
SU Aur	4 52 47.84	+30 29 19.4	CTTS	G2 III	+16.0	$\surd$	$\surd$
RW Aur A	5 4 37.69	+30 20 13.9	CTTS	K1	+14:a	$\surd$	$\surd$
GW Ori	5 26 20.78	+11 49 52.8	CTTS	G5	+33.6a	$\surd$	$\surd$
YY Ori	5 32 20.77	-5 59 52.7	CTTS	K5 V	+12:c	$\surd$
TW Hya	10 59 30.08	-34 26 07.4	CTTS	K7 V	+6:c		$\surd$
V1331 Cyg	20 59 32.21	+50 09 55.5	CTTS	Cont.	-15: (xi)	$\surd$	$\surd$
DI Cep	22 54 8.18	+58 23 59.5	CTTS	G8 V	-10b	$\surd$	$\surd$
BM And	23 35 12.41	+48 07 35.9	CTTS	K5 V	-15.2 (xii)	$\surd$	$\surd$

The spectral coverage is approximately $1200\ {\rm km\ s}^{-1}$ at Pa ${\rm\beta }$ and approximately $1400\ {\rm km\ s}^{-1}$ for spectra from the UT94 run and approximately $3600\ {\rm km\ s}^{-1}$ at Pa ${\rm\beta }$ and approximately $3800\ {\rm km\ s}^{-1}$ at Br ${\rm\gamma }$ for spectra from the UT95 run. All observed spectra were sampled twice per resolution element ( $R = 16\,000$ for UT94 and $R = 20\,500$ for UT95). The slit size used was for the UT94 run: $1\hbox{$^{\prime\prime}$ }.25 \times 90\hbox{$^{\prime\prime}$ }$ with pixel size $1\hbox{$^{\prime\prime}$ }.25$ in the dispersion direction and $2\hbox{$^{\prime\prime}$ }.2$ in the spatial direction for both Pa ${\rm\beta }$ and Br ${\rm\gamma }$ setups; and for the UT95 run: $1\hbox{$^{\prime\prime}$ }.2 \times 90\hbox{$^{\prime\prime}$ }$ and the pixel size $1\hbox{$^{\prime\prime}$ }.2$ in the dispersion direction and $1\hbox{$^{\prime\prime}$ }.8$ and $1\hbox{$^{\prime\prime}$ }.7$ in the spatial direction, respectively for the Pa ${\rm\beta }$ and Br ${\rm\gamma }$ wavelength regions. In both runs flat field frames were obtained for flat fielding and a number of standard stars were observed for correction of the atmospheric transmission and of the instrumental response. During the UT95 run a number of late type main sequence stars were also observed. For more details on the observational procedures and observing logs refer to Folha (1998).

The data reduction followed the general procedure described by Puxley et al. (1992) for the reduction of spectra obtained with CGS4. It was carried out using CGS4DR, Figaro and IDL routines written specifically for this work. Spectral images were masked to avoid bad pixels and vignetted areas of the detector, de-biased and flat-fielded. Sky subtraction was achieved by subtracting sky frames from object frames. The spectra were optimally extracted using Figaro's implementation of the optimal extraction algorithm developed by Horne (1986) and, when needed, de-rippled using the deripple_spectrum task in CGS4DR. CVF fringing affected spectra of the Br ${\rm\gamma }$ window obtained on the UT95 run and the fringing pattern was removed by filtering the spectra using standard Figaro tasks. Wavelength calibration was achieved by using OH airglow emission lines, telluric absorption lines and, in some cases, photospheric absorption lines. The uncertainty in the wavelength calibration is: 8-9 ${\rm km\ s}^{-1}$ at Pa ${\rm\beta }$ and 4-9 ${\rm km\ s}^{-1}$ at Br ${\rm\gamma }$ spectra from UT94 and 6-8 ${\rm km\ s}^{-1}$ at Pa ${\rm\beta }$ and 14-17 ${\rm km\ s}^{-1}$ at Br ${\rm\gamma }$ from UT95. Correction of the atmospheric transmission and instrumental response was achieved by dividing the spectra of the target stars by the spectrum of one of the observed standard stars and multiplying the result by a black body spectrum of the appropriate effective temperature. Finally, spectra had their continuum normalized to unity by dividing the spectra by a cubic spline fit to the continuum. For more details on the data reduction procedure refer to Folha (1998).

2 Observations and data reduction