The Optical Gravitational Lensing Ex periment (OGLE): Bohdan’s and Our Great Adventure

1. A. Udalski Warsaw University Observatory The Optical Gravitational Lensing Experiment (OGLE):Bohdan’s and Our Great Adventure

2. OGLE: The Optical Gravitational Lensing Experiment (1992 - ….) http://ogle.astrouw.edu.pl http://bulge.princeton.edu/~ogle

3. Three Phases of the OGLE Project • OGLE-I (1992-1995). 1 m Swope telescope at LCO • OGLE-II (1997-2000). 1.3 m Warsaw telescope • OGLE-III (2001-….). 8k x 8k mosaic CCD

4. OGLE – Early History • May 1990 – first ideas and talks on large scale photometric survey: SNe, 1-m class telescope at Apache Point, NM. • Early 1991 – Evolution toward microlensing and variable stars search. • Mid 1991– OGLE-I team formed. Proposal for telescope time at Las Campanas Observatory – ~50 nights granted in April – September 1992. • Fall 1991 – financing of the Warsaw Telescope accepted. • Apr. 12, 1992 – first images of OGLE-I. • ~2 million stars regularly observed.

5. Las Campanas Observatory, Chile

6. OGLE-I Results. Microlenses: Discovery of the first events toward the GB (1993).

7. First Binary Microlensing (1994)

8. Early Warning System (EWS – 1994)

9. Microlensing Optical Depth: • First empirical determination (1994): τ = 3.3 x 10-6

10. Modeling the Galactic Bar

11. Variable Stars: – Variables in the Galactic Bulge – Variable Stars in Globular Clusters (ωCen, 47 Tuc) – Variable Stars in Dwarf Galaxies: Sculptor, Sagittarius

12. OGLE-II • New telescope – new targets: Magellanic Clouds • New CCD Camera – drift scan mode • ~40 million stars regularly observed • Variable and non-Variable Stars in GB, MC, gravitational micro and lensing • Distance scale

13. 1.3 m Warsaw Telescope at LCO

14. Night at LCO

15. BP at Las Campanas (1)

16. BP at Las Campanas (2)

17. BP at Las Campanas (3)

18. Cepheids in the MC. PL relations. Hubble constant is based on OGLE PL relations

19. RR Lyrae ~7600 in LMC ~600 in SMC ~1900 RRab in GB

20. Pulsating Red Giants

21. Pulsating Red Giants

22. Eclipsing Stars (BP: Good distance indicators)

23. Misterious Periodic Variables

24. BP suggestion: Ellipsoidal variables on eccentric orbits model

25. Miscellaneous Variables Heaviest stars known (>80 M_Sun) RR Lyr in eclipsing systems Double Periodic Variables

26. OGLE BVI Maps of the GB, MC. CMDs

27. Funny Light Curves: OGLE-2002-BLG-360

28. Gravitational Lensing. The Einstein Cross.

29. Ten Years Monitoring of the Einstein Cross

30. Gravitational Lensing: HE1104—1805

31. Miscellaneous PM Catalogs SNe

32. OGLE-III • New 8192 x 8192 pixel mosaic CCD camera (0.26 arcsec/pixel scale): 0.5 x 0.5 sq. degree • 1.3 m OGLE telescope at Las Campanas Observatory, Chile • Data Pipeline: photometry derived with image subtraction method (accuracy up to 3 mmag for the brightest stars over a few months long observing run) • OGLE back in operation on June 12, 2001 • ~200 million stars regularly observed (GB, GD, MC) • Extrasolar planets, low luminosity objects

33. Warsaw Telescope and 8192x8192 pixel Mosaic Camera

34. Extrasolar Planets. • Radio techniques: Pulsar planets. • Spectroscopy: First solar type planets. (51 Peg). ~230 known (< 200pc). • Transit technique: About 20 transiting planets known (five OGLE detections). • Microlensing: Four detections (published).

35. Radio Techniques: Pulsars

36. Spectroscopy

37. Transit Method

38. Transit Method

39. Planetary Microlensing Short-lived anomaly in the light curve of a typical single mass microlensing event.

40. Transit Method Pros: • Photometric survey of thousands stars provides transit candidates. Characteristic shape of the light curve • r/R derived from the depth of transit. In principle R, r, i and u can be derived from the light curve (in real life r, i) • Spectroscopic follow-up provides mass (sin i ~ 1.0) • The only planetary cases with precise parameters derived (mass, radius, density) • Many potential „follow-up” observations: IR, transit spectroscopy, long term transit timing

41. Transit Method Problems: • High accuracy of photometric measuremens is crucial for transit detections (~0.5%) • Several individual transits must be detected to derive the photometric orbit • Not only planets can cause small depth transits: smallest stars (M type) or brown dwarfs can have similar size as Jupiter like planets. Careful spectroscopic follow-up is crucial to confirm planetary status in each case. But less spectroscopic observations is needed because the photometric orbit is known

42. Searches for PhotometricTransits • Follow up of spectroscopically discovered planets (example: the first ever transit detection in HD209458 – 1999) • Wide Field Surveys (several detections) • Deep Surveys: Galactic disk (five first detections of exoplanets with the transit method); Star Clusters

43. Wide Field Surveys Wide Field Surveys Wide Field Surveys • Wide field of ~ 5x5 sq. degree • Small telescopes (10—50 cm) • Bright objects (m<12 mag) • Small number of potential candidates • Precise photometry more difficult • Bright stars – large variety of follow-up observations (IR emission, transit spectroscopy, transit timing) • STARE, TreS, XO, HAT, WASP

44. Deep Surveys • Smaller field of view – typically < 1 sq. degree; large telescopes (1—4 m) • Very precise photometry of fainter stars with reasonable magnitude limit – limit of present spectroscopy (typically I ~ 16.5 mag) • Typical fields: Galactic disk (hundred thousands stars in the line of sight, located at different distances with different reddening etc.); Star Clusters (a few thousand stars located at the same distance, homogeneous, plus foreground and background contamination)

45. Pros and Cons • More observed stars – more candidates • Somewhat less accurate planet parameters (to be refined by next generation giant telescopes) • Smaller number of possible follow-up observations (IR, transit spectroscopy etc.).Long term transit timing OK • Study of planetary systems at much larger distance, in different environment

46. OGLE-III Transit Campaigns:Learning Period • Campaign #1: June-July 2001. Target: Galactic Bulge. ~65 stars with transiting objects found. Transiting objects != planetary candidates • Campaign #2: Feb.-May 2002. Target: Galactic Disk (Carina). ~70 stars with transiting objects discovered

47. OGLE-III Transit Fields: GB vs. Carina

48. What lessons have we learned? • Stellar background • Blending • No large planets ( R > 2 RJUP) • Jupiter-sized stars

49. OGLE-III Transit Campaigns:Routine Campaigns • Campaign #3 & #4 Spring-Summer 2003+2004. Target: Galactic Disk (Car, Cen, Mus). ~40 stars with transiting objects found • Campaign #5 Spring 2005. Galactic Disk (Car): ~20 good transiting objects • Campaign #6 Spring 2006. Galactic Disk (Car): ~25 good transiting objects • Campaign #7 Spring 2007. Galactic Disk (Car): data analyzed.

50. Spectroscopic Follow-up • OGLE Policy: results of photometric transit surveys available in public domain • Spectroscopic follow up of OGLE candidates from Campaigns #1 & #2: Konacki, Torres etal.; Bouchy, Pont, Moutou et al. • Spectroscopic follow-up of OGLE candidates from the next campaigns: Large ESO Programme