Sensitivities

A. 3mm VLBI detection limits

Here we assume optimum weather conditions (low opacity, tau < 0.1, no clouds).

Important: Depending on weather and elevation, Tsys and SEFD could be considerably higher!

Antenna and Receiver properties at 86 GHz:

Station	Diameter (m)	Tsys (K)	Gain (K/Jy)	Eta (%)	SEFD (Jy)	Comment
GBT	100.0	140.0	0.73	26	192	for nighttime observing
Effelsberg	80.0 (eff.)	140.0	0.14	7.7	1000	-
Noema (PdB)	45.0	100.0	0.41	71	244	10x15m
Pico Veleta	30.0	100.0	0.15	60	654	-
Yebes	40.0	180.0	0.10	22	1782	-
VLBA (8x25m)	25.0	100.0	0.04	22	2500	range is: 0.02-0.04 K/Jy
KVN (3x21m)	21.0	200.0	0.061	49	3279	for each 21m antenna
Onsala	20.0	190.0	0.049	43	3878	-
Metsähovi	14.0	200.0	0.010	18	20000	-
LMT (prelim)	50	240.0*	0.39	55	615	-
GLT (prelim)	12	180	0.032	78	5625	-
ALMA	70.7 (eff.)	75.0	1.00	70	74.9	37x12m

7 sigma single baseline detection thresholds (all numbers in mJy):
link to: EVN Sensitivity calculator1 (classic), and EVN Sensitivity calculator2 (new), and GMVA Sensitivity Calculator

-	Noema	Pico Veleta	Yebes	Onsala	Metsähovi	VLBA	GBT	KVN	LMT	ALMA37
Effelsberg	28	45	75	111	251	89-126	25	102	44	15
Noema	-	23	37	55	124	44-62	12	50	22	8
Pico Veleta	-	-	61	90	203	72-102	20	82	36	12
Yebes	-	-	-	148	336	118-168	33	136	59	21
Onsala	-	-	-	-	495	175-248	49	201	87	30
Metsähovi	-	-	-	-	-	398-563	110	456	197	69
VLBA	-	-	-	-	-	141-281	39-55	161-228	70-99	24-34
GBT	-	-	-	-	-	-	-	45	19	7
KVN	-	-	-	-	-	-	-	-	80	28
LMT	-	-	-	-	-	-	-	-	-	12

Baseline Sensitivity:	to Effelsberg: 15-100 mJy
	to IRAM 30m: 12-90 mJy
	to GBT: 12-50 mJy
	to ALMA: 7-30 mJy

Array Sensitivity (1 sigma):	0.097 mJy/hr (Europe+VLBA)
	0.063 mJy/hr (Europe+VLBA+GBT)
	0.035 mJy/hr (Europe+VLBA+GBT+ALMA)

	These numbers have to be increased by a factor of exp(tau*A) , i.e. for tau=0.1 and airmass A= 1/sin (elv) = 2, the factor is 1.22
	Depending on weather, the phase stability and atmospheric coherence time can vary between 10-180 seconds.

Assuming the following observing parameters:

Mode:	MK5B, 2048-16-2 (PFB), single polarisation
Bandwidth:	500 MHz per polarisation
Integration time:	20.0 sec (typical coherence time)
Threshold:	7.*sigma
Sampling:	2 Bit


Useful formulae:

B. Simulated uv-coverage for the Global 3mm-VLBI Array


Below we show 3 types of uv-coverages for sources with different declinations. In these simulations we assumed 12 hrs of observing time, 50% duty cyle, and a VLBI array consisting of 5 European and 8 VLBA antennas. ALMA, the LMT and the KVN are not yet included in the simulation. 1. for a source at dec=70 (click here) 2. for a source at dec=40 (click here) 3. for a source at dec= 0 (click here)

1. uv-plot of a source with a declination of 70 degree

2. uv-plot of a source with a declination of 40 degree

3. uv-plot of a source with a declination of 0 degree