4 Comments on selected sources

    

0018+729    Recently Snellen et al. (1996) listed a redshift for this source of 0.821, based on a single [O II] identification. In our 3600 s spectrum, no such line is seen. We do detect a single faint emission line at 5960 Å, but this does not agree with the 0.821 redshift. Until a better spectrum becomes available, we consider this source without a reliable redshift determination.

 

 

Table 3: Redshifts + line identifications

Source	Line	Wavelength (Å)	Redshift	Mean	Remarks
0554-026	H$\beta$ 4861	5999	0.234
	[O III] 4959	6120	0.234
	[O III] 5007	6178	0.234
	[O I] 6300	7778	0.235
	[O I] 6364	7858	0.235
	H$\alpha$ 6563+[N II] 6584	8110	0.234
	[S II] 6717/6731	8304	0.235	0.235
0941-080	H$\beta$ 4861	5971	0.228
	[O III] 4959	6088	0.228
	[O III] 5007	6146	0.227
	[O I] 6300	7737	0.228
	[O I] 6364	7831	0.231
	H$\alpha$ 6563+[N II] 6584	8068	0.227
	[S II] 6717/6731	8258	0.228	0.228
1245+676	H$\beta$ 4861	5384	0.1076		absorption
	Mg I 5175	5726	0.1065		absorption
	Fe I 5270	5827	0.1065		absorption
	Fe I 5328	5905	0.1083		absorption
	Na I 5893	6524	0.1071		absorption
	H$\alpha$ 6563+[N II] 6584	7282	0.1078
	[S II] 6717/6731	7446	0.1074	0.1073
1433-040a	H$\beta$ 4861	5616	0.1553		absorption
	Fe II 5018	5781	0.1521		absorption
	Mg I 5175	5961	0.1518		absorption
	Na I 5898	6786	0.1506		absorption
	H$\alpha$ 6563+[N II] 6584			0.152	blends with A-band
1540-077	Mg I 5175	6081	0.175		absorption
	[O I] 6300	7382	0.172
	H$\alpha$ 6563+[N II] 6584	7708	0.173
	[S II] 6717/6731	7879	0.172	0.172
1543+005	[O II] 3727	5802	0.557
	[O III] 4959	7712	0.555
	[O III] 5007	7789	0.556	0.556
1848+283	Si II 1194	4255	2.563
	Ly$\alpha$ 1216	4322	2.554
	N V 1240	4406	2.554
	C IV 1549	5425	2.502		blue arm
	C IV 1549	5457	2.523		red arm
	He II 1640	5836	2.559
	O III] 1663	5897	2.546
	[N II] 1750	6201	2.543
	C III] 1909	6776	2.550	2.544
2050+364	H$\beta$ 4861	6580	0.354
	[O III] 4959	6718	0.355
	[O III] 5007	6783	0.355	0.355

    ^a Not the GPS source, see notes on object.

 

 

Table 4: Emission line fluxes

Source	Redshift	Line	Fluxa	EqWb	FWHM (obs)c	FWHM (int)d
0554-026	0.235	H$\beta$ 4861	11.0	17	33	11
		[O III] 4959	54.7	81	40	21
		[O III] 5007	126.0	181	34	13
		[O I] 6300	9.9	9	39	20
		[O I] 6363	4.6	5	30	-
		H$\alpha$)+[N II]	216.0	229	57	39
		[S II] 6717+6731	25.8	31	34	13
0941-080	0.228	H$\gamma$ 4340	13.5	7	43	25
		H$\beta$ 4861	28.5	9	42	24
		[O III] 4959	49.9	17	36e	16
		[O III] 5007	112.0	33	37e	18
		[O I] 6300	43.7	13	34e	13
		[O I] 6363	10.2	3	41e	23
		H$\alpha$+[N II]	187.0	60	71e	52
		[S II] 6717+6731	83.4	27	44e	26
1540-077	0.172	[O I] 6300	1.6	2	27e	15
		H$\alpha$+[N II]	19.9	21	41e	31
		[S II] 6717+6731	9.8	12	38e	27
1543+005	0.556	[O II] 3727	1.3	12e	32e	7
		[O III] 4959	2.8	9e	40f	17
		[O III] 5007	8.1	22e	73f	43
1848+283	2.544	Ly$\alpha$g 1216	1700	203	47	13
		C IV 1549	1000	150	75	20
		C III] 1909	350	60	148	41

^a In units of 10^-16 ergs s^-1 cm^-2.

^b Measured equivalent width [Å].

^c Measured FWHM [Å].

^d FWHM [Å] after instrumental and redshift corrections. Instrumental resolution is taken to be 30 Å for CRYOCAM and 20 Å for EFOSC1, based on skylines.

^e After smoothing spectrum with a 3 pixel boxcar.

^f After smoothing spectrum with a 5 pixel boxcar.

^g Line flux includes contributions by Si II 1194, Si III 1206, and N V 1240.

Figure 1: Optical spectra for the sources with identified lines. Features not related to the source, e.g., the atmospheric absorption bands A and B, are indicated in italics. Fluxes are in units of 10-17 ergs s-1 cm-2 Å-1

Figure 2: GPS quasar 1848+283. Note the overlap between the red and blue arms of the spectrograph around C IV. Units and markings are identical to Fig. 1

0159+839    Spoelstra et al. (1985) classified this object as 17$^{\rm th}$ mag "stellar'' object. Our spectrum does not show any prominent emission lines though, only a possible line partly absorbed by the A-band (around 7600 Å).

0316+161    This faint galaxy has long defied a proper redshift assessment, and our 3600 s exposure also proved too shallow.

0437-454    Our optical identification agrees with the one given by Jauncey et al. (1989). Unfortunately, our spectrum does not show any significant features.

0500+019    This source has already been described in Paper I, but Stickel et al. (1996) later suggested the GPS source to be a background quasar, based on a single unidentified emission line at 6543 Å. Our 1995 redshift measurement (z=0.583) would therefore be of an intervening galaxy. However, we do not see any evidence of this 6543 Å line in our spectrum, nor does our Hubble Space Telescope NICMOS J and K band data show a hint of this quasar--galaxy superposition (cf. De Vries 1999). The recent H I absorption redshift of 0.58472 (Carilli et al. 1998) is therefore intrinsic and not due to an intervening absorber, as Stickel et al. suggest.

0507+179    We tentatively confirm the z= 0.416 redshift based on the better signal-to-noise spectrum of Perlman et al. (1998). In our 3600 s exposure faint emission features may be identified with [O II] at 5263 Å, and [O III] at 7107 Å, resulting in redshifts of 0.412 and 0.419 respectively. Without the Perlman et al. spectrum these identifications would be very tentative though. This source is most likely a BL Lac object, with a foreshortened radio structure due to the orientation in the sky, and not an intrinsically small radio source like the GPS.

0554-026    The radio position given by Spoelstra et al. (1985) for this object was accurate only within 10 arcsec and close to a stellar object. We initially used this position, thereby obtaining a spectrum of this star. At a later stage, we discovered that the radio position given by McEwan et al. (1975) corresponds with the galaxy approximately 10 arcsec to the northeast of the star (cf. Paper I). During the 1996 Kitt Peak run we obtained a good quality emission spectrum for this galaxy (cf. Fig. 1), and were able to determine its 0.235 redshift.

0602+780    Spoelstra et al. (1985) listed the identification as an empty field, but Stanghellini et al. (1993) detected a very faint object close to the radio position. Unfortunately, this object proved too faint to produce a significant signal on a 4 m-class telescope within an hour.

0703+468    Like 0602+780, this source is taken from the Spoelstra et al. (1985) radio spectral sample. Stanghellini et al. (1993) identified this source with a 23$^{\rm rd}$ mag object. Our 3600 s spectrum proved inadequate.

0742+103    After combining 600 s exposures in R ($\times2$), V, and I band, creating a wide passband 2400 s exposure, we were just able to detect an optical counterpart to the radio source. Its brightness is on the order of 24$^{\rm th}$ magnitude. This identification agrees with the Fugmann et al. (1988) identification. Larger telescopes are needed to properly assess the source morphology and redshift.

0802+212    The optical counterpart is the faint patch of emission due south of the brighter point source. It is accurately centered on the radio position. The spectrum proved featureless, however.

0904+039    The radio source is identified with a 22$^{\rm nd}$ mag object, which appears slightly extended in our I band image. This source seems to reside in a small group of objects (presumably galaxies).

0914+114    The source spectrum features one bright emission line, which initially was interpreted by us as H$\alpha$ at z= 0.178 Subsequent scrutiny did cast some doubt on this, and in a higher resolution spectrum taken in 1998 we do not find any evidence for this emission feature.

0941-080    This interacting binary source (cf. De Vries 1999) has a prominent emission line spectrum. The redshift is 0.228, based on 7 identified spectral features. The GPS source is associated with the northern galaxy.

1045+019    Gopal-Krishna et al. (1983) list this as an empty field, and after 600 s in R we have to agree. The radio spectrum of the source appears rather flat (O'Dea et al. 1990), so this might not even be a true GPS source. Stanghellini et al. (1990) detected faint extended radio emission associated with this source, strengthening its non-GPS nature.

1245+676    Our redshift determination of z= 0.1073 agrees very well with the recent one by Falco et al. (1998): 0.1073 $\pm$ 0.0002.

1433-040    This source is identified in the NED database as 4C -04.51, which is incorrect. The correct radio position of 4C -04.51 is 14$^{\rm h}$35$^{\rm m}$49 $.\!\!^{\rm s}$05 -5$^\circ$16$^\prime$12 $\hbox{$.\!\!^{\prime\prime}$ }$3 (J2000), based on the NRAO/VLA Sky Survey (NVSS) catalog. The position listed in Table 1 for 1433-040 is also from the NVSS catalog, which we feel is more accurate than the Texas 365 MHz position (Douglas et al. 1996). We obtained a spectrum for the object close to the Spoelstra et al. (1985) position, which is not the correct radio position either (14$^{\rm h}$35$^{\rm m}$39 $.\!\!^{\rm s}$83 -4$^\circ$13$^\prime$46 $\hbox{$.\!\!^{\prime\prime}$ }$4). The redshift listed in Table 3 is therefore of an unrelated field galaxy.

1540-077    Our redshift determination for this source is 0.172, based on 4 identified lines.

1543+005    The literature redshift of 0.55 is an estimate given in Heckman et al. (1994). Incidentally, it turned out to be an accurate estimate; we measured a redshift of 0.556.

1601-222    Even despite the large R-value of $\sim$3, we feel confident the (large) galaxy seen close to the radio position is indeed the host. Actually, the best radio position is within the optical extent of the galaxy. Our identification of this source confirms the earlier identification of Drinkwater et al. (1997). Our spectrum is featureless.

1648+015    The source spectrum is featureless. The optical identification agrees with Drinkwater et al. (1997).

1732+094    This object is rather faint ($\sim$21$^{\rm st}$mag), and in close proximity to a very bright star, making it hard to assess its redshift. Our spectrum proved too shallow.

1815-553    The spectral range of 5000-10000 Å is probably too red for this object, as it seems to be very blue. It appears significantly brighter on the IIIa-J plate of Jauncey et al. (1989). Our (red) spectrum is featureless. This object, based on its colors, is probably a quasar.

1848+283    The spectrum of this quasar was taken with FOS on the INT, which had a blue and a red arm of the spectrometer. Unfortunately, the C IV emission line landed on either edge of the spectral arm. Therefore, the small overlap region does not quite match up (cf. Fig. 2).

1942+772    This source is from the fainter (in radio luminosity) GPS sample of Snellen et al. (1998a). Our K band image provides a definite determination of the optical counterpart and its overall morphology, something not clear in the images presented by Snellen et al. (1998a).

2121-014    This source has been imaged by us before (Paper I), where we barely detected it in the i band. In the image presented here, its double structure stands out for the first time. It is not clear whether the radio source resides in the eastern or western component. Both are presumably individual galaxies, engaged in close interaction.

2128+048    Our identification agrees with the initial one made by Biretta et al. (1985). They already noted its redness ( $R-I~\approx~1.5$), something which is confirmed here by its relative brightness in K.

2322-040    Our image provides a larger field of view than the identification frame of Stanghellini et al. (1993). The galaxy appears to be a regular elliptical, possibly a member of a small group of galaxies.