Super Seeing from the AATPeter Gillingham

26th March 2003

• 1991 Herstmonceux Conference: “ Super Seeing from the AAT ? ” (Australian Antarctic Territory)

• We believed Antarctic plateau would offer extremely good seeing but likely upset by thermal mixing in boundary layer, something like 100 m deep. High temperature gradient in air near snow -> bad thermal inhomogeneity in even light wind. Likely better on plateau “domes” than at S Pole.

• DIMM and SODAR at S Pole confirmed this. SODAR showed boundary layer up to ~ 300m deep while, above that, scintillation and balloon thermometry indicated ~ 0.2 arcsec.

• Dome C SODAR Feb-June 2003 and DIMM summer 2003/4 indicate this site much better than South Pole and almost certainly better than Mauna Kea or any other mid-latitude site.

~3%

0.4 arcsecPARANAL ~ 3% better than 0.4 arcsec (up to 1995)

from DIMM measurements

Seeing distribution from DIMM at the WHT

site, Canary Islands.

~ 10%

0.4 arcsec

midnight

DIMM data during daytime, Dome C 21/22 Nov 2003 – Sun’s elevation ~ 17 to 5 to 25 deg.

FWHM (arcsec) v local time.

(with no correction for Zenith Distance)

18:00 21:00 00:00 03:00 06:00

1.0

0.6

0.8

21st Nov 22nd Nov

0.2

0.0

0.4

DIMM data during daytime, Dome C 21/22 Nov 2003

18:00 21:00 00:00 03:00 06:00

1.0

0.6

0.8

21st Nov 22nd Nov

0.2

0.0

0.4

< 0.4 arcsec, experienced ~ 3% of time at Paranal

DIMM data during daytime, Dome C 21/22 Nov 2003

18:00 21:00 00:00 03:00 06:00

1.0

0.6

0.8

21st Nov 22nd Nov

0.2

0.0

0.4

< 0.3 arcsec, experienced ~ 0.3% of time at Paranal

Best DIMM data so far from Dome C ( in daylight )

DIMM measures during daytime at Dome C

28th Nov 2003

29th Nov 2003

FWHM arcsec (not corrected for Zenith angle) v local time.

00:00 06:00 12:00 00:0018:00

00:00 06:00 12:00 00:0018:00

-100

-80

-60

-40

-20

0

5

10

15

20

25

20 21 22 23 24 25 26 27 28 29 30

2003 November

temperature deg C

wind speed m/s

day of month (local time)

Temperature and wind speed data from Automated Weather Station at Dome C2. Nov. 2003.

( 3 metre above snow ~ 70 km from Dome C )

Periods in which DIMM measures were recorded

18:00 21:00 00:00 03:00 06:00

1.0

0.6

0.8

0.2

0.0

0.4

-100

-80

-60

-40

-20

0

5

10

15

20

25

20 21 22

2003 November

temperature deg C

wind speed m/s

day of month (local time)

Comparison of DIMM measures from Dome C with simultaneous AWS measures from Dome C2

21/22 Nov 2003

2.0

0.000:00 06:00 12:00 00:0018:00 06:00 12:00 00:0018:00

1.00.8

0.0

0.4

1.2

1.6

Dome C DIMM seeing, arcsec FWHM, Nov 28 and 29

Temperature and wind speed from Dome C2 AWS

Temperature and wind speed record from AWS, Dome C2, Feb 1996

Temperature and wind speed record from AWS, Dome C2, July 1996

Time:

900 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

870 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

840 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

810 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

780 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

750 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

720 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

690 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

660 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

630 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

600 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

570 0 0 223 0 0 0 0 0 0 0 0 0 0 0 0 1199 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 276

540 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

510 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

480 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

450 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

420 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 237 0 0 0 0 0 0 0 0 0 0

390 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

360 0 0 0 0 0 0 0 0 0 0 0 0 393 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

330 0 0 0 0 0 0 0 0 0 0 0 0 326 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

300 0 0 243 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

270 0 0 383 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 100 0 0 0 0 0 0

210 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

180 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 438 0 0 0 0 229 0 0 0 0 0 0 0 0 0 0 0 0 0

150 0 0 0 0 0 0 0 0 0 0 0 0 79 0 0 0 0 0 394 405 516 0 475 296 0 0 0 210 0 174 133 0 0 0 0 0 0 0 0 0 0

120 0 0 0 0 0 0 0 0 0 0 0 0 66 0 0 391 304 261 310 351 438 0 421 266 295 0 0 172 0 143 114 0 0 0 0 0 76 0 0 0 0

90 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 437 292 207 211 306 318 0 338 188 233 0 0 139 0 97 94 0 0 0 0 0 0 0 0 0 0

60 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 382 204 114 106 0 136 0 0 94 0 0 0 0 0 52 0 0 0 0 0 0 0 0 0 0 0

30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 249 125 122 172 0 250 0 0 153 0 0 0 0 0 80 0 0 0 0 0 0 0 0 0 0 0

CT2Altitude m

11pm3am

CT2 data from SAODAR, for 7th Feb., 2003, at 30 min intervals.

Note build-up of returns when Sun was high.

For 24 out of 41 sets of data, no significant returns at any height from 30 to 900 metres.

Time:

900 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

870 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

840 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 133 0 0 0 0 0

810 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 133 0 0 0 0 232 0 0 0 0 0 0 0 0 0 118 0 0 0 0 0

780 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

750 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 124 0 0 0 0 0

720 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 106 0 0 0 0 0

690 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

660 153 0 0 0 0 0 126 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

630 160 0 0 0 0 0 124 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

600 174 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

570 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 109 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

540 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

510 0 0 0 0 0 0 0 173 110 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

480 0 0 0 0 0 0 0 0 135 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 94 0 0 0 0 0 0

450 0 0 0 0 0 0 0 132 141 0 0 0 0 100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 112 195 0 0 0 0 0

420 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

390 0 0 0 0 0 0 0 104 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

360 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

330 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

300 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

270 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 55 0 0 0 0 0

210 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 50 0 0 0 0 0

180 0 0 0 0 0 0 0 31 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 90 0 0 0 0 0 0 0 0 0 0 0 0 0 0

150 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

120 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

90 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

60 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CT2Altitude m

11pm3am

CT2 data from SODAR for 21st June 2003. For 30 out of 41 sets of data, no significant returns at any height.

0

50

100

150

200

250

300

350

400

350-400

300-350

250-300

200-250

150-200

100-150

50-100

0-50

30 m

900 m

time of day7th Feb 2003

height

CT2

0

50

100

150

200

250

300

350

400

350-400

300-350

250-300

200-250

150-200

100-150

50-100

0-50

CT2 record for 21st June 2003

0

10

20

30

40

1-Feb 3-Mar 2-Apr 2-May 1-Jun

Number of SODAR data sets each day ( out of 41 sets at 30 minute intervals) which gave no significant return at any height.

Number of SODAR data sets each day, out of 41 at 30 min intervals, which gave no significant return at any height

0

10

20

30

40

50

60

70

80

0 300 600 900

Mean CT2 value for each

month as function of

height

height (m)

Feb.

Mar.

Apr.May

Jun.

Mean SODAR measures as a function of height, month by month at Dome C in 2003.

Mean SODAR measures as a function of height, month by month at Dome C in 2003

Comparison of wind speed from Dome C2 AWS with that at 30 m height from SODAR at Dome C.

Wind speed (m/s)

from AWS at Dome C2, height ~ 3 m

Wind speed (m/s)

from SODAR at Dome C, height 30 m

AWS data from Dome Fuji

~ 77 deg S

3810 m

Jun 2003

Sep2003

Aug 2003

Jul 2003

• Super Seeing from the Antarctic Plateau?

• Is it now time to remove “?” ?

• YES !