1. Variable stars, recent observations
Dr. F.-J. (Josch) Hambsch

2. Interests Cataclysmic variables (VSNET, CBA)
RR Lyrae stars (possibly with Blazhko effect)
High Amplitude Delta Scuti (HADS)
Discovery of new variable stars
(Pretty pictures)

3. Observatory in Mol, Belgium
Several scopes (C14, C11, 40cm f/8, 20cm f/8)
STL11K, ST10, ST8 CCD with BVRI photometric filters
Usage each clear night (if at home)
Furthermore, access to scopes in NM, Australia and in planning a
remote Site in Chile with 40cm f/6.8

4. CV‘s
YZ Cnc
BK Lyn
ER UMa
SDSS
....

5. YZ Cnc (CBA collaboration)

6. BK Lyn

7. ER UMa
More than 100 d observations
~ 8000 images

8. SDSS

9. TT Ari max and minimum view
Source: H.-G. Dietrich (BAV)

10. TT Ari

11. TT Ari variability during one night

12. RR Lyrae stars
NSVS
GV And
TU Com
NU Aur
....

13. E = HJD
P = / d
NSVS
Blazhko Effect !!

14. E = HJD
P = / d
GV And
Blazhko Effect !!

15. E = HJD
P = / d
TU Com
Blazhko Effect !!

16. E = HJD
P = / d
NU Aur
Blazhko Effect !!

17. NU Aur
Blazhko period
114.7 d

18. E = HJD
P = / d
VY CrB
Blazhko Effect !!

19. VY CrB
Blazhko period
33.4 d

20. E = HJD
P = / d
DY And
Blazhko Effect !!

21. DY And
Blazhko period
224.8 d

22. CX Lyr
Blazhko period
68.04 d

23. YY Boo (first observation Feb. 5/6)

24. Properties of YY Boo Algol type eclipsing binary
Discovered by Hoffmeister in 1949
Spectral type : F9IV
Period of eclipses: d
Candidate oscillating eclipsing binary according to Mkrtichian et al based on spectral type
But not in list of candidate oEA‘s

25. During decent to the primary minimum

26. Close to the primary minimum

27. B, V filter Light curve Pulsations subtracted according to Frequencies
determined

28. Properties of YY Boo
Oscillations typical for a Delta Scuti type variable
Period of oscillations: ~ 88 min
2nd largest pulsation amplitude among oEA stars after BO Her
Results published in IBVS 5949
Spectroscopic studies under way

29. GSC

30. Conclusions
CV‘s have been recently the main observing targets based on VSNET and CBA alerts
Intensive follow-up of RR Lyr stars with Blazhko effect mainly from NM
Collaboration with P. Wils, P. De Ponthiere and J. Vandenboere