1. May 31 2008 Prasentation 1 Making and Observation of the Tohoku Univ. Antarctica DIMM Hirofumi OKITA Astronomical Institute Tohoku Univ. (B4)

2. 2 May 31 2008 Prasentation Contents ・ Introduction ・ DIMM ・ Theory ・ Tohoku DIMM ・ Observation ・ Result ・ Future work Antarctica 40cm Telescope with the DIMM

3. 3 May 31 2008 Prasentation The case of the grand base observation, wavefront from the star is not parallel. →It is important to choice Good Seeing Site. Introduction (1) →The Seeing is defined as FWHM of stars at long time exposure. In Space, star’s FWHM is “Rayleigh limit”. So the star size is not “Rayleigh limit”, but expanded image by the air turbulence. But… Raylei gh limit Actual ly seeing Subaru Telescope 0.06 " 0.3"

4. 4 May 31 2008 Prasentation Antarctica Introduction (2) Cord Dry IR Background is very low, and NIR transimittance is very high Many fine days Good seeing Calm weather Downdraft Dome C （ Alt.3250m ） ～ 0.54” The last window to the Universe → → Dome Fuji （ Alt.3810m ） ≦ 0.5” ?? http://en.wikipedia.org/wiki/Showa_Base However, the site testing at Dome Fuji has not been done yet. I made the DIMM, and want to get actually seeing size.

5. 5 May 31 2008 Prasentation DIMM Convert them into seeing value “Classical” DIMM(Differential Image Motiron Monitor) has 2 apature. Star light ↓ The phase shifts by air turbulence DIMM ↓ ↓ Image of two stars Measurement of relative position ↓ ↓

6. 6 May 31 2008 Prasentation Theory (1) Star light at Space ・・・ Parallel ↓ Air turbulence ・・・ wavefront ・・・ phase error Angle of arrival fluctuation ・・・ ・・・ Covariance of α ・・・ Covariance of φ ・・・ Phas structure function Kolmogorov turbulence →

7. 7 May 31 2008 Prasentation Theory (2) Change the angle of arrival fluctuation = Change in position of stars Relationship between Zenith angle correction ・・・ It calculates… D ・・・ Aperture Diameter d ・・・ separation two aperture →From We obtain Seeing size. and FWHM

8. 8 May 31 2008 Prasentation DIMM Hardware Unlike a “classical” DIMM, Tohoku DIMM is “Four aperture DIMM” to get more information of a turbulence layer. Antarctica 40cm Telescope Aperture400mm Focal length5190mm DIMM Separation of diagonal apertures d 250[mm] Aperture diameter D74mm[mm] Apex angle of Wedge prism 30[arcsec] Pixel size Horizontal0.3903[arcsec/pix] Vertical0.4553[arcsec/pix] Wat-100N (Watec Co., Ltd.) Min. 0.001 lx, and Exp. time/gain/gamma Manually changeable Expose time: 1/1000s

9. 9 May 31 2008 Prasentation DIMM Software Software was Developed by Dr. Motohara ( Research Associate, University of Tokyo) Dr.Motohara and UT-DIMM His Software From His software we can get analyzed data (seeing size [arcsec]) but zenith angle is not corrected, so I made zenith angle correction software.

10. 10 May 31 2008 Prasentation Observation Jan 13 2008 Measurement of Pixel size Jan 16 2008 Observation at Sendai Feb 10 2008 Observation at Rikubetsu ( Hokkaido, the North island of Japan) Feb 14 2008 Observation at Rikubetsu Star Saturn Movies

11. 11 May 31 2008 Prasentation Result (1) Sendai Jan 16 2008 Observation at Sendai Average 2.09” Median 2.03”

12. 12 May 31 2008 Prasentation Result (2) Rikubetsu Feb 10 2008 Observation at Rikubetsu Average 1.49” Median 1.48”

13. 13 May 31 2008 Prasentation Result (3) Rikubetsu Feb 16 2008 Observation at Rikubetsu Average 2.81” Median 2.79”

14. 14 May 31 2008 Prasentation Future Work More Observation change in a day change in a season Comparison with Hiroshima Univ. DIMM Check the Value is reasonable Cold Test Camera AD converter PC,etc. We observe more and more at Sendai, and get knowhow and technique. 2010 Observation at Dome Fuji Hiroshima Univ. DIMM ↓