1. Rapid follow-up of gamma- ray bursts with Watcher John French School of Physics University College Dublin

2. Overview Background on multi-wavelength observations of GRBs and their afterglows and what we can learn from them Where robotic telescopes fit into the picture, and some results obtained from small robotic telescopes The Watcher instrument, software and site

3. Multi-wavelength observations of GRBs Most astrophysical sources are studied over a broad spectral range during a long observational period GRBs were discovered in late 60’s, no counterparts at other wavelengths observed until 1997 Multi-wavelength observations constrained models and continue to provide new information

4. First afterglow detections Italian-Dutch satellite BeppoSAX first to accurately localise GRBs First multi-wavelength counterparts detected:  X-ray: 970111  Optical: 970228  Radio: 970508 BeppoSAX X-ray afterglow of 970228

5. Information from afterglows Measurement of redshifts finally confirmed cosmological origin of GRBs Fireball model fits observations GRBs occur in galaxies Ejecta moves relativistically Some GRBs may be associated with death of high-mass stars

6. Fireball model Large quantity of energy (~ 10 51 - 10 54 ergs) released very rapidly (~ 0.1 - 100 sec.) in a compact source (~ 10 6 cm) Jet of highly relativistic ejecta emitted (Γ > 100) Collisions within ejecta produce γ-rays and prompt optical/X-ray emission Blast wave created when ejecta meets local medium produces afterglow

7. Fireball model Internal shocks: γ-rays / prompt optical Reverse shock: prompt optical / X-rays Forward shock: afterglow (optical / X- ray / radio)

8. The role of robotic telescopes HETE and INTEGRAL missions provided accurate localisations rapidly Unpredictable transient nature, short duration Bright (m v ~9–18 mag.) optical flash predicted Ideally suited to follow-ups with small robotic telescopes ROTSE, LOTIS, RAPTOR, PROMPT, TAROT

9. Prompt emission: GRB990123 First GRB with optical detection while burst was still in progress ROTSE, 4 x 200mm telephoto lenses First image 22 s. after trigger (T 90 =110 s.) 8.9 mag. optical flash, z = 1.6 → brightest object ever observed Optical emission uncorrelated with γ-rays → reverse shock

10. ROTSE Observations of GRB990123

11. GRB 041219 First prompt optical detection since 990123 RAPTOR, 40cm, New Mexico First image 115 s. after trigger (T 90 = 520s), peak m r = 18.6 Similar γ-ray light curve to 990123, but with correlated optical emission Internal shocks driven into burst ejecta by variations in central engine

12. 041219 and 990123 in γ-rays and optical 041219: Optical flash (red) during primary γ- ray peak (black) 990123: Optical flash comes after secondary γ-ray peak

13. High redshift: GRB 050904 z = 6.29, second most distant object ever observed, universe at 6% of current age TAROT 25cm, 86 s. after trigger (T 90 = 200s), peak m I = 14.1 Extremely bright X-ray peak temporally coincident with optical flash Possible reactivation of central engine

14. Afterglow: GRB 060206 Afterglow observed by RAPTOR beginning 48.1 min. after trigger (T 90 ~ 7 s) Flux rises sharply by ~1 mag., peak at ~16.4 mag. 60 min. after trigger → never seen before in optical Subsequent decay fit by power-law model

15. The SWIFT mission Launched 11/04, multi- wavelength mission γ-ray (BAT), X-ray (XRT), UV & optical (UVOT) Rapid localisations ~ 3 arcmin. with BAT 0.3 – 0.5 arcsec. with XRT/UVOT 148 Bursts detected since launch ~ one every 3 days (61 with optical transients)

16. Gamma-ray burst Coordinates Network (GCN) Automated system to rapidly distribute GRB positions to sites worldwide via the internet Reporting of observations via GCN Circulars allows coordination of subsequent observations

17. Watcher: Site Boyden Observatory, South Africa (29°S,26°E) Altitude 1387m, ~300 clear nights/year Accessible: 24km from Bloemfontein Manned site, support from University of the Free State Physics Dept. and technicians Microwave link to University network (64 KB/s) 1.6m telescope available for coordinated observations

18. Watcher: Site

19. Watcher Schematic

20. Watcher: Instrument 40cm, f/14.25 Cassegrain telescope Apogee AP6e CCD, 1024x1024 24µm pixels, ~1.5 s. readout 15’ x 15’ FOV, 0.85”/pixel Fast-slewing robotic mount (Paramount ME) Focuser, filter wheel (BVRI filters)

21. Watcher: Hardware Motorised roll-back roof with custom control electronics Weather station: precipitation, wind, cloud cover Uninterruptible power supply Webcam 2 PCs running Linux (400 GB storage capacity)

22. RTS2 Software Developed since 2000 by Czech BART group Sophisticated, reliable, controls wide range of hardware Currently runs 6 telescopes on 3 continents  BART: Czech Republic  BOOTES-1A & 1B: Spain (under repair)  BOOTES-IR: 60cm, Spain  FRAM: Pierre-Auger South, Argentina  Watcher: South Africa

23. RTS2 Features Enables fully automatic operation of a remote observatory without human intervention 2 observational modes: autonomous or user- specified schedules Database of targets, observations, image data Customisable target-specific scripting Automatic astrometry of images (JIBARO) Communication with users via email/SMS

24. RTS2 Structure Groups of C++ executables communicating over TCP/IP via custom library rts2-centrald (observatory control centre) device daemons (hardware interface) executing daemons (selector, executor, process images / GRB alerts) client-side monitoring programs database querying & update tools

25. Watcher Commissioning Operational since late March ‘06 Rapid response times (11 s. and 18 s.) during installation GRB 060413, first observations 4h13m after trigger, no new source down to 16.5 mag. (GCN 4960) First light image of M42

26. Future Extra-solar planet transits / microlensing events Blazar monitoring Observations of INTEGRAL sources Coordinate with other robotic telescopes