Writing a Proposal

Robert LaingGothenburg, Oct 7 2019

What we want you to do over the next 4 days

n Form small groups (7 members is about right)n Pick a science topic

n (Best) one of your ownn (Next best) in discussion with tutorsn (Backup) Selected from the list on the following slides

n We will allocate a tutor to each projectn Please be prepared to compromise: we have a fairly small number of

tutors and only a minority are omniscient.n Decide what array to use for your project (LOFAR, JVLA,

eMERLIN, MeerKAT, ASKAP, MWA, ALMA, NOEMA, EVN, ....)n Decide what configuration, frequency, bandwidth, spectral

configuration to usen Outline the technical justification of an observing proposaln Give a 1-2 slide summary on the last day

What do we want you to do?

ERIS 2019 2

• What wavelength?– Spectral lines + redshift → wavelength (λ)– Continuum emission is trickier: what are the trade-offs

between sensitivity and flux density?• What spatial resolution?

– Resolution (λ/Dmax) + wavelength (λ) → maximum baseline Dmax

• What spectral resolution?– Number of spectral channels

• Maximum scale of structure (λ/Dmin) → minimum baseline Dmin• How many targets?• Where is my target (North or South?)• What arrays can do what I want?

Things to think about (1)

ERIS 2019 3

• Sensitivity– Key parameter is surface brightness (Jy/beam)– Work this out from earlier observations, theory, blind guesswork

….– Bandwidth Δν is important (rms∝Δν-1/2)– Is your target resolved, or is it a point source?– Use a sensitivity calculator to work out how long an observation

you need– Tutors will help you find the right tool (or to do the calculation by

hand if there isn’t one)• Is your observation feasible? • If not:

– Is the resolution too high?– Too many targets?– Wrong frequency?– Is there a better array?

Things to think about (2)

ERIS 2019 4

• Has someone done it before?– Look in telescope archives– Reanalyse old data

• Better reduction with modern tools?• Good enough?

– Even if not good enough• May give a better justification• May be able to combine with new data

• Guide to archives– Wednesday

Things to think about (3)

ERIS 2019 5

• Calibration– What’s the right calibration strategy?

• If you are lucky, the Observatory will do most of this for you – but it is always good to understand why – and sometimes they leave it to you

• Which calibrators and how often to observe them?• Can you self-calibrate?

• Imaging– How complex a field?– Long track or snapshot?– Do you need to combine arrays or configurations?– Some arrays have simulation tools to help you: tutors will

show you how to use them

Things to think about (4)

ERIS 2019 6

• Special considerations– Polarization?– Do you need a special observing mode?– Do you have time constraints (simultaneous observations at

another waveband)– Targets of opportunity?– Do you need additional calibration (e.g. for precise astrometry)?

• Proposal pressure– Some arrays are in high demand; others less so– Some parts of the sky are more popular than others– Some projects can only be scheduled in really good weather (e.g.

night time, low water vapour column) – is yours very demanding?– Check these on telescope web site

Things to think about (5)

ERIS 2019 7

Imaging the radio galaxy NGC6251

Heriot Watt, July 30 2018

Preparatory work:reanalysis of archive data(VLA 1665 MHz)

Sidedness ratio image

Published image of the whole field

n The difficult partn Image the counter-jet with good transverse resolution (>5 resolution

elements) in IQU with reasonable signal-to-noise in the presence of the (very bright) core

n Remove the effects of Faraday rotationn Choice of frequency and configuration

n Maximum resolution ≈1 arcsec (otherwise resolve out counter-jet emission)

n Frequency – sensitivity trade-offs (S ∝ν-0.6)n Higher frequency has smaller primary beamn Minimum frequency ≈4 GHz (otherwise there is significant variation in

Faraday rotation across the beam)n Required rms noise ≈1 µJy/beam IQUn JVLA: 24 hr, B configuration at 4.5-6.5 GHz (with shorter integrations in

C and D configurations for larger scales)

What images do we need?

Heriot Watt, July 30 2018

n Primary beam at 5GHz has HWHM ≈ 230 arcsec at 5.5 GHzn Direction-dependent effects important for the main jet n Counter-jet will only be detected to ≈ 140 arcsec, so should be minimally

affectedn Required dynamic range = 570000:1

n Need good leakage corrections as well as calibrationn VLA correlator “delay clunking” is a problem

n Jansky VLA schedules dynamicallyn We really wanted a 24-hour observation (NGC 6251 is circumpolar) .....n but the referees only gave us B priority ....n ..... so were told that the probability of being scheduled was low unless

we split the observation into 6-hour blocks – and that's what I did ….n … which led to lots of problems (the core varied)

Unwelcome news

Heriot Watt, July 30 2018

n Solar systemn Image the polarized emission from Jupiter's radiation belts

n Galacticn Gaps in GAIA: compare proper motions against precise radio measurements for radio

stars, masers and starspots.n Measure an accurate distance to a high-mass Galactic star-formation regionn Investigate the structure (gaps and spirals) and dust spectrum in a protoplanetary disk.n Measure magnetic fields from observations of masers, molecules and dust in evolved

stars.n Search for methanol masers above 100 GHzn Resolve the black hole shadow in our Galactic Centre.n Estimate the magnetic-field strength in the Galactic Centre accretion flow from Faraday

rotationn Nearby extragalactic

n Image molecular emission and determine the history of star formation in a nearby starburst galaxy.

n Determine the spectral index and polarization of extragalactic supernova remnantsn How are electrons accelerated in cluster radio relics?n Image atomic and/or molecular gas in nearby spiral galaxies n An HI survey complete to z = 0.1

Some possible topics (1)

ERIS 2019 12

n AGNn Simultaneous multifrequency observations of a blazar flare (e.g. triggered

by Fermi-LAT) n M87: what is the connection between gamma-ray flares and radio

emissionn Probe the jet launching scale in AGN at resolutions of a few 10s of

microarcsecondsn Find and map dead and/or restarted radio galaxies

n Distant Galaxies/Cosmologyn Continuum survey of the Hubble Deep Field (cm and mm wavelengths)n A blind survey for redshifted CO emissionn Determine the dynamical mass of a protogalaxy at z = 9 using the [CII]

linen Make the first image of HI fluctuations in the Epoch of Reionizationn Can we detect HI emission in galaxy clusters at z = 1.5?n Find the radio counterpart of a gravitational-wave detection

Some possible topics (2)

ERIS 2019 13

• Please self-organise into small groups• If you are the first to pick a topic, write the title and your name

on the flip chart– If it is your own topic, then please check with the tutors that we

can support you• Others can then sign up• If a topic gets too popular, then we will need to split the group• Process needs to be complete by 0900 on Wednesday – the

main period for working on proposals is 0900-1100.• You can discuss ideas and form groups at the conference

dinner!

Forming Groups

ERIS 2019 14

RadioNethas received funding from theEuropeanUnion’s Horizon 2020 research and innova<onprogrammeundergrantagreementNo730562