pulsar observations at effelsberg - university of...
TRANSCRIPT
Krabi, 2007Michael Kramer
Pulsar Observations at EffelsbergMax-Planck-Institut für Radioastronomie, Bonn, GermanyMax-Planck-Institut für Radioastronomie, Bonn, Germany
Contact: Axel Jessner ([email protected])Contact: Axel Jessner ([email protected])
Krabi, 2007
The MPIfR Pulsar Group
• Reduced but constant activities in
recent years (timing, simultaneous
observations, studies of the Crab etc.)
• Important partner in European
collaboration (EPN, PulSE, EPTA)
• Group slowly growing again:
Axel Jessner (Effelsberg)
Bernd Klein (former PhD student, now Head of Digital Group)
Kosmas Lazarides (new PhD student)
Richard Wielebinski (emeritus)
• Valuable support from Anton Zensus (exec. Director)
Krabi, 2007
Effelsberg telescpope
• Diameter 100m
• Weight 3200 t
• Surface accuracy: <0.5mm
• Track/Positioning 1.5mm
• Slewing speed ~20deg/min
• Elev/Dec limit (7/~-30deg)
• Gain 1.5 K/Jy
• Superb high-freq. capabilities
• Fast frequency switching
• New adaptive sub-reflector
• Good/Bad weather observing plans
• Most common projects:
- spectroscopy, VLBI, mm-VLBI, continuum & HI
- Pulsars (at best times ~10-15%)
Krabi, 2007
Receivers
• Currently:800 MHz – 87 GHz
• Almost continuous coverage up to 50 GHz
Krabi, 2007
Receivers
Krabi, 2007
Receivers
• Currently:800 MHz – 87 GHz
• Almost continuous coverage up to 50 GHz
Krabi, 2007
Receivers
• Currently:800 MHz – 87 GHz
• Almost continuous coverage up to 50 GHz
• Located either in primeor secondary focus
• Mostly LHC/RHC• Several IFs:
150MHz/750MHz• Above 10 GHz, signal
detection in focus cabinproviding bandwidths<2 GHz for pulsars, thensignals brought down asV/f rates
Secondary focus:
Krabi, 2007
Receivers
Best receivers for pulsar work: 1.4 GHz, 2.7 GHz, 4.9 GHz, 8.4 GHz:
Krabi, 2007
EPOS
• Three different backends:
- PUB86 (incoherent)
accepting signals from
hardware dedisperser
or narrow/broadband
polarimeters
- Pulsar2000 (searching)
accepting signals from various
filterbanks
- EBPP (coherent)
• In many cases, different
combination of signal paths
possible.
Krabi, 2007
EPOS – PUB86 system
• Mostly used for
- high-frequency observations (hence 16bits/sample)
- Single-pulse and polarization observations
• Control of cal-signal switchable with pulse period
• Access to broad-band (2GHz) polarimeters
• Pulse periods 1.024ms-9.392s, min sampling 0.2µs
• Single pulse datarates: sustained P>300ms, burst P>50ms
Krabi, 2007
Pulsar2000 & Transient recorder
Pulsar2000:
- Data acquisition system for 64 V/f signals
- High-frequency searches (8x4 MHz / 8x60 MHz, 60x0.667 MHz
- Recorded on swappable disks
- 8/16 bits/sample depending on sampling time
Transient recorder:
- Used for giant pulse observations
- 500 MHz bandwidth
- Sampling time 2 ns
- 8 bits/sample
Jessner et al. (2004)
Krabi, 2007
Effelsberg Berkeley Pulsar Processor
• Similar to ABPP/GBPP etc
• On-board coherent
de-dispersion
• Up to 112 MHz
• Polarization: 28 MHz
• 4 bits/sample
• In operation for MSP timing
since Oct 1996
• See Gemma’s talk for example
Krabi, 2007
Effelsberg Upgrade
In October 2006, new 6.5-m adaptiveSub-reflector was installed. Two purposes:
- Improving gain at highest frequencies- Easy switching between PFK and SFK
Krabi, 2007
Effelsberg Upgrade
• Up to three receivers in prime focus cabin• Prime focus receiver retractable within a few minutes:
• Switching between secondary focus receivers still within seconds
Krabi, 2007
Effelsberg Upgrade
• Mirror accuracy better than 0.05mm!• Huge improvements in high-frequency gain:
Still not optimized!
Krabi, 2007
New 20-cm 7-beam receiver
• New receiver to be used for:- ESA’s search for space debris - HI Contninuum survey- Pulsar Galactic Plane & All-sky survey
Krabi, 2007
Effelsberg Multibeam Surveys
• Limited clean band at 20cm: only about 100-120 MHz bandwidth
• Due to larger gain, same sensitivity as Parkes Multibeam Surveys
• JBO/MPIfR/UWV collaboration
• Probably using 2 LOFAR boards processing 4 dual-pol signals each
• Galactic Plane Survey and all-Northern-Sky Survey
• Aiming for about 0.5MHz filters
• Planned for end of 2007/early 2008
• Ideal as back-up programme
• To be operated by telescope controllers
• Written to disks and transferred to
JBO for processing
• Possible processing also at Effelsberg
Krabi, 2007
Further improvements
• Most backends are at least 5-10 years old!
• While old EPOS backend good for high very frequencies,
urgent improvements needed for searching and timing
- several in-house developments possible:
Expertise available (Bernd Klein) but no manpower!
- purchase of ATNF Pulsar-Digital-Filterbank
to be installed in early 2008 (see Dick’s talk)
- New search backends for multibeam surveys
- support from JBO wherever needed/possible
Pulsars@Effelsberg still alive!