ANTENNA SITES

Table 1 gives the surveyed geographic locations of the 10 antennas comprising the VLBA, plus the 2-character codes used to identify the antennas (Napier 1995). The antennas are ordered East through West. All locations are based on the WGS84 ellipsoid used by the GPS system¹, with Earth radius $a=6378.137$ km and flattening $1/f=298.257223563$. See Napier (1995) for further site information.

Table 1: Geographic Locations and Codes

	North	West
	Latitude	Longitude	Elevation	Code
Location	[ $^{\circ}\ '\ ''$]	[ $^{\circ}\ '\ ''$]	[m]
Saint Croix, VI	17:45:23.68	64:35:01.07	16	SC
Hancock, NH	42:56:00.99	71:59:11.69	296	HN
North Liberty, IA	41:46:17.13	91:34:26.88	222	NL
Fort Davis, TX	30:38:06.11	103:56:41.34	1606	FD
Los Alamos, NM	35:46:30.45	106:14:44.15	1962	LA
Pie Town, NM	34:18:03.61	108:07:09.06	2365	PT
Kitt Peak, AZ	31:57:22.70	111:36:44.72	1902	KP
Owens Valley, CA	37:13:53.95	118:16:37.37	1196	OV
Brewster, WA	48:07:52.42	119:40:59.80	250	BR
Mauna Kea, HI	19:48:04.97	155:27:19.81	3763	MK

Several other radio telescopes often participate in VLBI observing in conjunction with the VLBA. These include the Very Large Array (VLA), either with up to 27 antennas added in phase (Y27) or with a single antenna (Y1); the Green Bank Telescope (GBT); Arecibo; Effelsberg; the European VLBI Network (EVN); plus (occasionally) various geodetic antennas or the NASA Deep Space Network. For details on how to propose for these extra telescopes, see Section 21.1.

A total of up to 100 hours per four-month trimester has been reserved for a High Sensitivity Array (HSA) composed of the VLBA, Y27, GBT, Arecibo, and Effelsberg; the HSA is described at http://www.nrao.edu/HSA/ . In this context, users should be aware that Arecibo only operates at frequencies up to 10 GHz, and can view sources only within about $19.7^\circ$ of its zenith; see http://www.naic.edu for further information about Arecibo's properties. The VLA and GBT are NRAO facilities, while Arecibo is operated by the National Astronomy and Ionosphere Center, and Effelsberg is operated by Germany's Max Planck Institut für Radioastronomie (MPIfR). Table 2 lists the locations of the HSA telescopes.

Table 2: Locations of Other HSA Telescopes

	North	West
	Latitude	Longitude	Elevation	Code
Location	[ $^{\circ}\ '\ ''$]	[ $^{\circ}\ '\ ''$]	[m]
Arecibo, PR	18:20:36.60	66:45:11.10	497	AR
Green Bank, WV	38:25:59.24	79:50:23.41	807	GB
VLA, NM	34:04:43.75	107:37:05.91	2115	Y27
Effelsberg, Germany	50:31:30	$-$6:53:00.3	319	EB