3 Results

We detected eight new OH masers out of 27 objects searched. In Table 1 we give their IRAS names, the galactic coordinates, the line frequency, the range of velocity where emission is detected $\Delta V$, the velocity of the strongest feature $V_{\rm p}$ and the peak flux density $S_{\rm p}$. $1\sigma$ noise level is given in parentheses and the left and right circular polarizations are designated by L and R respectively. The OH spectra of the newly detected sources are shown in Fig. 1. The IRAS names of non-detections are listed in Table 2. For all of them $3\sigma$ detection limits were 0.4 to 0.7 Jy. Towards the source 19189+1520 a tentative feature near 0 km s^-1 was seen at 1665 MHz.

For the purpose of source statistics our original list of 74 methanol sources above declination $0^{\circ}$ is reduced to 68 objects, as we excluded a cluster of three sources 19211+1432, 19216+1429 and 19220+1432 severely contaminated by the OH emission from W51 and source 19078+0901 contaminated by the emission from W49, whereas two sources 18496+0004 and 19230+1341 were missed in the survey. We conclude that 49 sources in this sample i.e. 72% are associated with the OH mainline masers.

 

 

Table 1: New 1.6 GHz hydroxyl masers observed towards 6.7 GHz methanol maser sources

IRAS	l	b	Line	$\Delta V$	$V_{\rm p}$	$S_{\rm p}$
			(GHz)	(km s-1)	(km s-1)	(Jy)
05382+3547	173.70	2.89	1.665	-27	-27.3	0.95(0.13)L
				-22	-22.2	0.51(0.12)R
18512+0029	33.70	-0.26	1.665	60, 61	60.8	7.85(0.19)L
				60, 63	60.9	9.54(0.21)R
			1.667	61, 62	61.2	2.49(0.18)L
				61, 66	64.6	5.50(0.20)R
19191+1538	50.31	0.68	1.667	40, 45	42.8	1.37(0.18)L
				41, 45	42.5	1.09(0.23)R
19282+1814	53.63	0.02	1.665	2, 21	7.2	0.47(0.14)L
				3, 21 ?	3.0	0.43(0.15)R
			1.667	-5, 25	-4.1	0.79(0.16)L
					24.5	1.17(0.16)L
				-5, 25	-4.1	0.94(0.15)R
					24.4	1.21(0.15)R
19366+2301	58.77	0.65	1.665	31, 41	32.5	0.54(0.18)L
				31 ?		(0.20)R
			1.667	30, 43 ?	33.8	0.78(0.20)L
				30, 38	33.7	0.80(0.21)R
20062+3550	73.06	1.80	1.665	-2	-2.4	0.76(0.24)L
				-2	-2.4	1.57(0.22)R
21074+4949	90.92	1.51	1.665	-76, -72	-76.0	0.75(0.16)L
					-72.5	0.74(0.16)L
				-76, -72	-76.0	0.83(0.16)R
					-72.6	0.42(0.16)R
22272+6358	108.19	5.52	1.665	-11	-10.9	1.38(0.21)L
				-9	-8.9	0.79(0.25)R
			1.667	-13, -11	-11.7	1.40(0.17)L
				-12, -10	-10.7	1.06(0.20)R

Figure 1: 18 cm spectra of new OH masers. L and R means the left and right circular polarizations respectively. The lower bar in each panel indicates the velocity range of the 6.7 GHz maser emission