de · anik daigle (u. al) v la dominion radio ysical astroph atory observ atoire observ eral ed f...

D R A O N e w s

N o u v e l l e s de l ' O F R

November 2002

Editor: Andrew Gray

Fren h Translation: Anik Daigle (U. Laval)

Dominion Radio

Astrophysi al Observatory

Observatoire f�ed�eral

de radioastrophysique

Herzberg Institute of Astrophysi s Institut Herzberg d'astrophysique

CONTENTS

From the Dire tor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Comings and Goings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

The New DRAO Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Sta� Pro�le: Charles Kerton, Resear h Asso iate . . . . . . . . . . . . . . . . . . . 4

A Population of Embedded Intermediate-Mass Stars . . . . . . . . . . . . . . . . . 6

H i Tails from Mole ular Clouds near HD 17603 and WR5 . . . . . . . . . . . . . . 7

The SNR CTB87: its environment and distan e . . . . . . . . . . . . . . . . . . . . 7

New Low-noise Ampli�ers for the Synthesis Teles ope . . . . . . . . . . . . . . . . 8

Redu ing Ground Radiation Pi k-up by the Synthesis Teles ope . . . . . . . . . . 9

Absolute Polarimetry at 1.4GHz using the 26-m Teles ope . . . . . . . . . . . . . . 10

Progress on the Canadian Gala ti Plane Survey . . . . . . . . . . . . . . . . . . . 10

News from the Spa e-VLBI Correlator Centre . . . . . . . . . . . . . . . . . . . . . 11

Progress on the LAR Aerostat Experiment . . . . . . . . . . . . . . . . . . . . . . 11

The New Spe trometer for the JCMT: ACSIS . . . . . . . . . . . . . . . . . . . . . 12

Spe trum Management A tivities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

The Synthesis Teles ope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

The 26-m Teles ope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

The Solar Radio Flux Monitor and the Canadian Geospa e Monitoring Programme 13

Call for Observing Proposals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Re ent Papers from DRAO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Observatory Conta t Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2 DRAO News { November 2002

From the Dire tor

This has been a rewarding year for DRAO. As funding

for Canada's Long Range Plan for Astronomy began to

ow, we added a signi� ant number to the group. Look-

ing at the biographi al sket hes of our new olleagues

(see arti le in this Newsletter) I was impressed by the

range and the depth of the talent that we have added. It

is parti ularly gratifying that we have been able to add

two young s ientists to our ontnuing sta�. All told,

DRAO is now nearly �fty people, in luding �ve gradu-

ate students and four postdo toral fellows. It is ex iting

to work with so mu h young talent.

Over the summer we moved into our new building.

We owe a debt of gratitude to Ron Casorso, who steered

the proje t to ompletion, on time and on budget, and

who organized the move into the new spa e. There is

still mu h to be done. Ron is urrently overseeing the

pur hase and installation of s reened rooms, and the

pur hase of furniture, as well as the renovation of the

original DRAO building, dating from 1959.

The Canadian Gala ti Plane Survey (CGPS), as

part of the International Gala ti Plane Survey, ontin-

ues to be a major part of s ienti� life at DRAO and

it is a growing su ess. The total number of papers in

refereed journals from the CGPS now ex eeds 60. In-

reasingly these papers are addressing big-pi ture issues

in Interstellar Medium resear h. 2001 and 2002 were

among DRAO's most produ tive years ever in terms of

s ien e publi ations.

Tom Lande ker

Comings and Goings

There have been many additions to our sta� in the

past year, parti ularly in the last 6 months or so. The

new employees bring with them a diverse range of ba k-

grounds and experien e whi h they will bring to bear on

Long Range Plan proje ts. Some of the following peo-

ple have been mentioned in previous newsletters, but

are in luded here for ompleteness:

Dean Chalmers joined the Canadian Large Adap-

tive Re e tor (CLAR) group in Mar h 2002. Dean is

a Me hani al Engineer, a graduate of the BC Insti-

tute of Te hnology and U. Waterloo. His experien e

in ludes a period with CREO Produ ts in Van ouver,

developer and manufa turer of advan ed te hnology for

the printing industry. Most re ently he has been work-

ing at Peerless Page in Penti ton, a steel fabri ator and

manufa turer of tra tor trailers.

Peter Cimbaro graduated from Okanagan Univer-

sity College (OUC) in 1990 with a Diploma in Computer

Information Systems. He began his areer as a program-

mer, moving gradually towards system administration.

From 1994{2002 he was the Systems Proje t Leader

at Western Star Tru ks, a manufa turer of heavy-duty

transport vehi les employing 600 people in Kelowna.

His responsibilities in luded overseeing omputer opera-

tions, the Help Desk, and systems servi es. Peter joined

DRAO in April 2002 as part of the omputer systems

management team.

Dave Del Rizzo took up an appointment as Tele-

s ope Operator in April 2002. Dave has a B.S . in

Physi s/Astronomy from York University, and began

work at DRAO in 1997 as a Correlator Operator in the

Spa e VLBI Correlator Group. He moved to a tempo-

rary position in the DRAO Operations Group in the

2000 to over for Diane Par hom huk's year-long leave

of absen e. When Diane hose to retire, Dave stayed

on in that position for a further 6 months while the po-

sition was advertised, and was subsequently hosen as

Diane's su essor.

Sean Dougherty took up his appointment as Re-

sear h OÆ er at DRAO in April 2002. He will provide

s ienti� support for the CLAR and will ontinue to

manage the operation of the Spa e VLBI Correlator.

He will also arry on his multi-wavelength resear h on

non-thermal emission from radio stars. Sean re eived

his Ph.D. from U. Calgary in 1993 for work on radio

emission from Be stars. He has held postdo toral ap-

pointments at John Moores University, Liverpool, and

at DRAO, where he worked on the CGPS.

Dave Fort arrived at DRAO in September 2002 to

join the EVLA Correlator team. Dave is a graduate of

U. Toronto (Engineering Physi s). He earned his Ph.D.

at the U. Man hester (Jodrell Bank) in November 1971

in \tape re ording interferometry", now alled VLBI. He

joined the National Resear h Coun il in January 1972,

and worked in the pioneering Canadian VLBI group on

many aspe ts of signal and image pro essing. He left

Ottawa in 1987 to work for JPL in Pasadena, and sin e

that time has been involved in the appli ation of VLBI

te hnology to deep-spa e appli ations.

Ri hard Hellyer joined the DRAO team in April

2002 as a Me hani al Te hnologist with responsibilities

in the CLAR Group and for the DRAO site and infras-

tru ture. Ri hard trained as an Airframe Te hni ian

with the Royal Canadian Air For e in Calgary, but has

followed many lines of work sin e his return to Penti -

ton, his home town, in luding work as an arborist and

a maintenan e ontra tor at DRAO.

Zhang Heng graduated from Jiaotong University

in Shanghai, China, with a degree in Ele tri al Engi-

neering in 1991. Initially he worked in the R&D de-

partment of Anjing, a small ompany in Tianjin, where

he designed analog and digital devi es for use in auto-

mati ontrol systems. In 1997 he moved to Singapore,

where he worked at the AIWA design entre, develop-

ing omponents for onsumer ele troni s. He has been

at DRAO sin e April 2002, and is part of the EVLA

Correlator Group.

Lewis Knee was appointed to the position of Re-

DRAO News { November 2002 3

sear h OÆ er in September 2001. Lewis earned his

Ph.D. from Chalmers Te hni al University in Sweden in

1991, then worked at the SEST sub-millimetre teles ope

in Chile. He has published many papers on mole ular

gas and dust in star-formation regions. As a Resear h

Asso iate at DRAO for the past few years, Lewis has

been working on the Canadian Gala ti Plane Survey,

lately with responsibility for managing the data redu -

tion e�ort. He will ontinue that work, and pursue his

resear h on old H i in the Galaxy, and the impa t of

stellar winds on the ISM.

Zoran Ljusi was appointed as Digital Engineer on

the EVLA Correlator proje t in February 2002. Zoran is

a graduate in Ele tri al Engineering from U. Belgrade.

Sin e his arrival in Canada in 1994 Zoran has been work-

ing in Calgary for Nortel and Wi-LAN.

Rob Reid gained the degrees of B.S . in Physi s

from U. Waterloo, and M.S . in Astronomy from U.

Toronto, where he is now ompleting his Ph.D. His the-

sis des ribes the development of Smear Fitting, a new

te hnique for produ ing images from irregularly sam-

pled interferometri data. Rob will take up an appoint-

ment at DRAO as Postdo toral Fellow in November

2002, working on the CGPS. He will divide his time

between redu ing polarization data and resear h.

Raymond Rusk arrived at DRAO in September

2002 to develop software for ALMA. Raymond has M.S .

degrees from U. Saskat hewan (mathemati al physi s)

and U. Toronto (instrumentation for opti al astronomy),

and a Ph.D. in astronomy from U. Toronto. He worked

at the Defense Resear h Establishment (Pa i� ) in Es-

quimalt, applying ele tromagneti te hniques to under-

water sensing, before moving into the omputer industry

as an analyst. Most re ently he has been working in the

omputer group at HIA in Vi toria, using his spare time

to tea h Software Engineering and Computer S ien e at

the University of Vi toria and Camosun College.

Ralph Webber joined the ACSIS Group in April

2002. He is a graduate of the BC Institute of Te h-

nology, and worked in Van ouver as a ommuni ations

te hnologist with the RCMP before spending 4 years at

DRAO in the early 1990s, ontributing to the develop-

ment of analog and digital systems for the expansion

of the Synthesis Teles ope. He returned to Van ouver

in 1995 to a position with Glenayre Ele troni s, a om-

pany manufa turing equipment for paging infrastru -

ture, where he worked in the Hardware Design Group.

Glenda Wray is our new librarian. Glenda has

a B.A. in Canadian History from UBC, and a Library

Te hni ian Diploma from Langara College. Her areer

has mostly been in the orporate setting, establishing

and maintaining libraries and re ords-management sys-

tems for the Aluminum Company of Canada and Trans

Mountain Pipeline. Glenda subsequently worked with

the library team at the Justi e Institute of BC before

taking a sabbati al to raise her family. She moved from

Van ouver to Kelowna in 2001, and joined DRAO in

August 2002.

Graduate students have been important on the DRAO

s ene for many years. Those working here now are:

Tyler Foster is a graduate of the U. Alberta, with a

B.A. in English Literature (1992), a B.S . in Theoreti al

Physi s (1998), and an M.S . in Astronomy (2000). As

an undergraduate, Tyler worked in CCD resear h with

small teles opes, in luding implementing both software

and hardware for the CCD imager on the Devon Astro-

nomi al Observatory's 0.5m teles ope, and using the

system for photometry of variable stars. Throughout

his areer he has ontributed to publi astronomy edu-

ation. Tyler is urrently working on his Ph.D., using

data from the CGPS and Devon AO to study the stru -

ture of the Milky Way.

Angel Gar ia is a graduate in Engineering Physi s

from U. Alberta (April 2001) and is working towards

her M.S . She is working with Bru e Veidt in devel-

oping low-noise ampli�ers for 1420MHz as part of the

e�ort to redu e the system temperature of the Synthe-

sis Teles ope. She is exploiting new low-noise devi es

developed for the ommuni ations industry. These will

be dire tly onne ted to the wave-guide probes, with

no intervening onne tor, eliminating a sour e of loss.

The te hniques developed will be valuable for ampli�er

development for the CLAR.

Teresia Ng graduated from U. Alberta in Ele tri-

al Engineering in April 2001, and is in the M.S . pro-

gram there, doing her thesis resear h at DRAO. She is

working with Tom Lande ker on te hniques for redu ing

ground noise pi ked up by the antennas of the Synthesis

Teles ope as part of the e�ort to enhan e its sensitivity.

Ed Reid (no relation to Rob Reid above) is a gradu-

ate of U. Alberta, earning his B.E. (Ele tri al) in 1979.

Ed worked for many years in the tele ommuni ations

industry in Alberta, Ontario, and Colorado, in areas

ranging from network engineering to testing of high-

apa ity �bre opti s systems. Feeling that the tele om-

muni ations se tor no longer o�ered the opportunities

for resear h and development that he sought, Ed \re-

tired" to pursue graduate studies. His Ph.D. work is in

designing antennas to be employed in the phased array

feed for the CLAR proje t.

Maik Wolleben arrived at DRAO in May 2002.

Maik did his undergraduate work at the Universities

of Hamburg and Bonn, graduating as Dipl. Phys. from

Bonn. He is now a Ph.D. student working at the Max-

Plan k-Institut f�ur Radioastronomie (MPIfR), pursuing

resear h on the Gala ti polarized emission. As a ol-

laborative proje t between MPIfR and DRAO, Maik

is making polarization observations at 1420MHz using

the DRAO 26-m Teles ope, to omplement observations

at the same frequen y from the E�elsberg 100-m Tele-

s ope. Maik brought a polarimeter from Bonn, and has

adapted the 26-m front-end to polarimetry. He is also


developing alibration and data redu tion pro edures.

Two people have re ently departed from DRAO:

B�ulent Uyan�ker andAylin Yar left in June 2002.

They have returned to the Max-Plan k-Institut f�ur Ra-

dioastronomie in Bonn, where B�ulent is working in the

polarization group. At DRAO sin e O tober 1999, B�ulent

developed many data-redu tion te hniques for polar-

ization data, and produ ed polarization images for a

large area of the CGPS. While at DRAO he published

seven papers in the journals from his thesis work and his

DRAO work. After arriving in Mar h 2000, Aylin om-

pleted her Ph.D. thesis while at DRAO, ontributed to

the 26-m Teles ope H i Survey for Phase 2 of the CGPS,

and was involved in several CGPS resear h proje ts. We

thank them both for their many ontributions.

Tom Lande ker

The New DRAO Building

The big news about the new building is that onstru -

tion was �nished on time and on budget, and sta� moved

into their new oÆ es over the summer. The new build-

ing o�ers 10 more oÆ es than the old trailer omplex,

with most already o upied by new sta�, as well as mu h

larger laboratory spa es (both shielded and unshielded),

and an area for developing large me hani al stru tures,

whi h is already seeing use for the LAR proje t.

The major remaining work to be done inside the

building is the onstru tion of a large shielded room on

the main oor, whi h will provide 168 square-metres of

spa e for digital development, in luding a temperature-

ontrolled hamber for temperature y ling and envi-

ronmental testing of new equipment.

As for the old buildings, the original 1959 bri k build-

ing is being renovated to meet urrent health and safety

standards, and on e �nished will house 4 oÆ es, 2 meet-

ing rooms, the library, and the �rst aid room. Part of

the old trailer omplex has been removed, with the re-

mainder seeing ontinued use by the Spa e VLBI orre-

lator, or being onverted to storage.

Below are some pi tures from the new building taken

during the summer, while we were still moving in.

Ron Casorso

Sta� Pro�le: Charles Kerton, Resear h Asso-

iate

Charles was born in 1970 in Middleton, Nova S otia, in

the heart of the Annapolis Valley, an area known for its

fruit, espe ially apples. Little did he know then that

he would move a ross the ountry to Penti ton, in the

heart of the Okanagan Valley, an area known for its fruit

. . . in luding apples!

By the age of 4 Charles was already an international

traveller, thanks to his father's areer in the Canadian

An exterior view of the new building. Note the

wire mesh over the windows, to help redu e interfer-

en e radiated from within.

The upper oor of the new building, looking west.

The open area under the skylight will be used for li-

brary materials and informal meetings.

The lower oor of the new building, looking

east. The large overed area will soon be �lled with a

shielded room for instrument development work.


The large stru ture development area, a

two-storey spa e at the east end of the building for

working on me hani al aspe ts of proje ts su h as the

LAR. Shown are win h frames for the LAR proje t.

Armed For es. Until he was 7, Charles lived in England

and S otland, where he a quired the lo al a ent (whi h

he has sin e lost). His memories of his time there in lude

having to wear the s hool tie, and eating the \horrible

ustard" that was served as part of the s hool lun hes!

Charles Kerton

The remainder of Charles's hildhood was spent in

Nova S otia, where he developed a hobby as a ba k-

yard astronomer. From 1988{1992 Charles attended

Dalhousie University in Halifax and earned a B.S . in

Physi s. It was during this period that he met his wife-

to-be, Joanne, while they both worked as summer stu-

dents at St Mary's University. Charles then went to the

University of Toronto and pi kled up his M.S . in As-

tronomy. He and Joanne were married in 1994, just in

time to y to Hawaii for an extended honeymoon: after

3 years they returned to Toronto, with Charles's M.S .

in Geology & Geophysi s tu ked in their arry-on lug-

gage. While apparently a diversion from his astronomy

areer, this M.S . work was related to the Galileo mis-

sion, and Charles now has a better understanding than

most of us of the vol anism on Io (Charles also says that

he takes perverse pleasure in knowing what is meant by

\ferruginous laterite").

Charles embarked on his Ph.D. at the University of

Toronto in 1996, working on the Mid-Infrared Galaxy

Atlas (MIGA), the 12 and 25�m ounterpart to the In-

frared Galaxy Atlas (IGA) at 60 and 100�m. In 1997

Charles had the opportunity to work with Lloyd Higgs

and Tom Lande ker on the Low-Resolution DRAO Sur-


vey (LRDS) using the 26-m Teles ope at DRAO, supply-

ing short-spa ing information for the Canadian Gala ti

Plane Survey (CGPS) data produ ed by the Synthesis

Teles ope. Upon ompleting his Ph.D. in 1999, Charles

returned to DRAO to take up a Resear h Asso iateship

with the CGPS proje t, and urrently works on redu -

ing the 21- m H i data from the Synthesis Teles ope.

His professional interest in astronomy has not di-

minished his love of the night sky, and he shares this

passion by tea hing ontinuing edu ation ourses in as-

tronomy at the Okanagan University College. When

not involved in astronomi al matters, Charles likes to

hike, read, dabble in wood-working, and (a by-produ t

of having two hildren) try to maintain an indoor fresh-

water e o-system in whi h pet �sh an live long and

happy lives.

Andrew Gray

A Population of Embedded Intermediate-Mass

Stars

Work has re ently been ompleted on a te hnique to de-

te t distant young embedded B stars (and possible lus-

ters) from their imprint on the surrounding interstellar

medium (ISM). H i 21- m and

12

CO (J=1{0) line data

from the Canadian Gala ti Plane Survey (CGPS) were

ombined with mid-infrared images from the Mid ourse

Spa e Experiment (MSX) Gala ti Plane Survey to de-

te t the photo-disso iation regions (PDRs) and mole -

ular gas asso iated with embedded intermediate-mass

stars (aka disso iating stars).

IRAS olours of embedded stars with dete ted

H i emission. Most H ii regions have olours within

the solid outline (Hughes & Ma Leod 1989).

The te hnique was applied to a se tion of the Galaxy

overed by the FCRAO Outer Galaxy Survey (102

Æ

:5 <

l < 141

Æ

:5; �3

Æ

:0 < b < +5

Æ

:4) and has led to the de-

te tion of 15 embedded intermediate-mass stars. PDR

models, ombined with previous observations of early-

type Herbig Ae/Be stars and the non-dete tion of many

of the sour es in OH, H

2

O and CH

3

OH surveys, imply

that the obje ts are � 10

6

years old. The IRAS olors

of the obje ts form a well-de�ned group (see Figure)

and have been ombined with

12

CO and MSX obser-

vations to identify approximately 100 additional IRAS

sour es within the survey area as possible embedded

intermediate-mass stars.

The diÆ ulty in dire tly observing theH i asso iated

with these obje ts is thought to be due to a ombination

of observational and astrophysi al fa tors. The obser-

vational problems of dete ting H i stru tures within the

Gala ti plane will be familiar to most readers. Astro-

physi ally stars like this are expe ted to be quite eÆ-

ient at learing out surrounding material on time s ales

of only 10

6

years (Fuente et al. 1998, 2002). Apparently

a \disso iating star" is a parti ular stage in the early

development of an embedded intermediate mass star|

the star is old enough that it is no longer asso iated

with a o oon of very dense gas, but it is young enough

that stellar winds and heating due to photo-ionization

have not ompletely disrupted the surrounding mole -

ular material and rendered any H i zone undete table

against the general Gala ti H i ba kground (see Fig-

ure). The full study an be found in Kerton (2002).

DSS image of IRAS 00556+6048. Many of the

embedded stars, su h as this one, are visible in the

DSS images and have asso iated opti al nebulosity.

Gray-s ale units are arbitrary data numbers.


Referen es

Fuente, A., Martin-Pintado, J., Ba hiller, R., Neri, R.,

& Palla F. 1998, A&A 334, 253

Fuente, A., Martin-Pintado, J., Ba hiller, R., Rodriguez-

Fran o, A., & Palla, F. 2002, A&A, 387, 977

Kerton, C.R. 2002, AJ, 124, in press

Charles Kerton

H i Tails from Mole ular Clouds near HD17603

and WR5

Using CGPS data, we have dis overed a system of long

narrow H i tails emanating from mole ular louds lo-

ated about 2 kp away in the dire tion of the Perseus

Arm. The main tail appears to stream away from a

mole ular loud of mass 400M

�

with radial velo ities

between 5 and 20km s

�1

. A se ond very narrow tail lies

to the north of and parallel to the main tail. This sys-

tem of tails points toward the luminous stars HD 17603

(O8If) and the Wolf-Rayet starWR5 (see Figure). Both

H i tails from CO louds: H i data (greys ale)

showing tails emanating from CO louds ( on-

tours). The thi k tail points towards the CO loud

G138.14-1.89-48. Both point towards the stars HD

17603 and WR 5.

stars are thought to be at a distan e of about 2 kp ,

whi h agrees with the kinemati distan e of the CO

louds. The tails have a well-de�ned radial velo ity

gradient in the dire tion along the tails suggestive of

a eleration.

We propose that the H i tails are gas disso iated

from the mole ular louds and a elerated away in the

wind of one or perhaps both of the stars. The total mass

of H i in the tails is 1700M

�

, roughly 4 times the mass

in the mole ular louds. The tails are several tens of

parse s long and the dynami al times ale is a few million

years, whi h is of order the Main sequen e lifetime of the

massive stars whi h evolved to be ome HD17603 and

WR5. If one or both of these stars have driven the H i

tails, this must have o urred while they were on the

Main sequen e. If the tails are entrained by a stellar

wind, it is on eivable that sho ks disso iate the gas to

produ e the H i. Alternatively, the disso iation may be

aused by the stellar radiation �eld(s). There is however

no eviden e for the e�e ts of photo-ionization in this

system. The relative narrowness of the tails suggests

that the Ma h number in the driving wind is not very

large (perhaps at most only mildly supersoni ).

The kinemati parameters of theH i ow pla e tough

onstraints on the external wind ow. The required mo-

mentum ux in the external driving wind implies that

a total of � 10

51

erg of available kineti energy (i.e., not

in the form of thermal energy) must have been supplied

by the wind over the lifetime of the tails. This is a se-

vere onstraint, sin e in the basi theory of adiabati

stellar wind bubbles, only a tiny fra tion (� 1%) of the

total energy in the wind is in the form of kineti energy

within the sho ked stellar wind region whi h takes up

the majority of the volume of the wind bubble. How-

ever, mass-loading of an initially supersoni wind from

mass sour es distributed smoothly throughout the re-

gion around the star an redu e the Ma h number of the

wind without having the wind going through a global

sho k near the star. If the mass loading is suÆ iently

heavy, a large fra tion of the stellar wind energy (50% or

more) will remain in the form of kineti energy instead

of thermal energy. A heavily mass loaded wind an

thus in prin iple a ount for the very large amount of

momentum required in our s enario. Heavy mass load-

ing greatly redu es the mass of the swept-up bubble of

ambient gas around the wind bubble, and for HD17603

and WR5 we see no eviden e for a dete table swept-up

shell.

Lewis Knee & Brad Walla e

The SNR CTB87: its environment and distan e

An analysis of H i data from the Canadian Gala ti

Plane Survey (CGPS) and new CO observations in the

dire tion of the supernova remnant CTB87 reveal evi-

den e for a mole ular shell surrounding parts of CTB87

at a radial velo ity of �56km s

�1

(see Figure). There

is no eviden e of intera ting H i or of the existen e of a

stellar wind bubble, indi ating a supernova explosion of

type II and a B2 or later type progenitor star. We estab-

lished a new distan e of 6.1 kp based on the extin tion-

distan e relation introdu ed by Foster & Routledge (see

Figure), whi h agrees with a position in the Perseus


CO and CTB87: CO map at a radial velo ity of -56

km/s. White ontours indi ate the radio emission of

CTB87 at 1420 MHz taken from the CGPS.

arm. Our results ontrast with previous distan e es-

timates based on H i absorption measurements: using

a at rotation urve gives a distan e of about 12 kp .

This dis repan y arises from a signi� ant shift of the

radial velo ities in the dire tion of CTB87 be ause of

the spiral sho k. The new distan e redu es the implied

physi al size and the luminosity of CTB87 by a fa tor

of two and four, respe tively. The properties of this ple-

rioni supernova remnant are then more similar to the

other SNRs of its kind ex ept the Crab Nebula, whi h

is an outstandingly luminous obje t.

Roland Kothes, Wolfgang Rei h, Tyler Foster, &

Do-Young Byun

New Low-noise Ampli�ers for the Synthesis Tele-

s ope

I am working on lowering noise in the front-end re eivers

as part of the e�ort to double the sensitivity of the

Synthesis Teles ope. Front-end re eiver noise (34K)

urrently forms a signi� ant fra tion of the Synthesis

Teles ope system temperature (59K). The goal of the

proje t is to produ e a low-noise ampli�er with at least

14K less noise than those urrently operating in the

Synthesis Teles ope.

In 2000 Bru e Veidt and Annie-Claude La hapelle

designed and built the Mark 1, a single-stage low-noise

ampli�er with mat hed probe. The mat hed probe elim-

inates the need for a oaxial able onne tion between

the waveguide and the ampli�er, eliminating a sour e

of loss and alone redu ing system temperature by 5K.

The Mark 1 system used an Agilent pseudomorphi high

Distan e to CTB87: The extin tion as a fun tion

of distan e towards CTB87. The distan e to the SNR

is indi ated.

ele tron mobility transistor (PHEMT; see Figure) and

yielded about 10K less noise than the existing front-end

ampli�ers.

An in onsisten y between the manufa turer's spe -

i� ation for the transistor (spe i� ally the s attering

parameters, ommonly known as S-parameters) and a

software analysis of the ampli�er has led us to design

and build a test �xture to verify the Agilent PHEMT's

S-parameters, and to also test Fujitsu HEMTs. Upon

determining the orre t the S-parameter values, a �nal

analysis of the noise parameters of the Agilent and Fu-

jitsu transistors an be performed.

A new single-stage ampli�er/probe ir uit (the Mark 2)

will then be designed and built to resolve some problems

with the Mark 1. However, it is already known that the

single-stage Mark 2 will not be able to produ e more

than 15{20dB gain (the Mark 1 had a gain of 15 dB),

whi h is not suÆ ient for a radio teles ope front-end


The Mark 1 single-stage ampli�er. The metalli

triangular pat h at the front is the probe that is in-

serted into the waveguide. Just the right of the the

apex of the triangle is the small, bla k PHEMT hip.

Beyond the hip is the transmission line that arries

the signal to the onne tor at the rear of the devi e.

re eiver. The �nal step in the proje t will therefore

be the development of a viable multi-stage, low-noise

ampli�er{the Mark 3.

Angel Gar ia

Redu ing Ground Radiation Pi k-up by the Syn-

thesis Teles ope

The two main sour es of system noise on the Synthe-

sis Teles ope are ground noise and re eiver noise. My

proje t is to examine the me hanisms by whi h ground

radiation enters the antenna and perform experimen-

tal modi� ations on the antenna to lower the ground

noise. Together with the proje t aimed at redu ing the

re eiver noise (see arti le by Gar ia above), the total

antenna noise of the DRAO Synthesis Teles ope will be

halved and the sensitivity at 1420MHz will be doubled.

The main ontributions to ground noise are leak-

age through the mesh, spillover noise, strut s attering,

and edge di�ra tion. The leakage of ground radiation

through the mesh a ounts for 5.9K. Ground radiation

in the spillover region (from the edge of the re e tor

to the horizon) is not inter epted by the re e tor and

thus enters the feed dire tly, ontributing 8.1K. The

support struts s atter the plane wave from the main

re e tor, and produ e large oni al sidelobes known as

s atter ones. Parts of these s atter ones illuminate

the ground and pi k up thermal radiation, ontribut-

ing approximately 5.8K. Di�ra tion of ground radia-

tion around the re e tor rim into the feed ontributes

another 0.6K. Summing all the ontributions, the total

ground noise is 20.4K. (These numbers apply to an-

tenna 7, one of the noisiest anetnnas.)

In an experiment to redu e the leakage through the

mesh, the enter portion of the re e tor of Antenna 7

was overed with aluminum auto-body tape (see Fig-

ure). Sin e the feed illumination tapers o� at the edge

Antenna 7 of the Synthesis Teles ope at DRAO,

showing the aluminum tape overing the entral por-

tion, as des ribed in the text.

of the re e tor dish, the e�e t of mesh leakage is far

more prominent in the dish enter, so shielding only the

enter portion of the re e tor is suÆ ient.

After overing the inner 2m radius of the 9m re-

e tor, the noise temperature was su essfully redu ed

by 4K at all elevations (see Figure). The auto-body

tape is self-adhesive, and was applied dire tly onto the


The system noise temperature on Antenna 7

as a fun tion of elevation. The grey line shows

the noise temperature measured before the re e tor

was shielded. The bla k line shows the noise temper-

ature measured after a 2m radius was overed with

aluminum tape.

re e tor mesh for this experiment. We are now look-

ing at ways to redu e mesh leakage that we an leave

on the dish permanently. Other experiments are also

in progress, in luding modi� ation of the shape of the

struts and redu tion of the spillover ontribution by the

use of shields and fen es on the ground.

Teresia Ng

Absolute Polarimetry at 1.4GHz using the 26-m

Teles ope

The 26-m Teles ope is urrently being prepared for ab-

solute polarization measurements at 1.4GHz. Maik

Wolleben brought an IF-polarimeter from MPIfR and

has in orporated it into the re eiver. The polarimeter

requires ir ular polarization as input, but the re eiver

produ es orthogonal linear polarization, so a quadra-

ture hybrid was installed ahead of the polarimeter. The

hybrid does introdu e ross-talk and non-linearities, so

extensive alibration measurements need to be done to

derive the required orre tion terms. The data pro ess-

ing software is written in glish, a s ripting language

used in the aips++ proje t.

The planned observations will provide data to im-

prove the absolute polarization alibration of the E�els-

berg 1.4GHz Medium Gala ti Latitude Survey. The

data from that survey will be in orporated with the

CGPS 1.4GHz polarization data from the Synthesis Tele-

s ope. Until now the absolute alibration of the E�els-

berg measurements have relied on data obtained with

the Dwingeloo 25-m teles ope in the 1960s and 1970s.

However, the Dwingeloo measurements are severely under-

sampled and are of limited sensitivity (60mK ompared

to 8mK of the E�elsberg measurements). There are

large areas of sky in whi h the polarized intensity drops

below 100mK, leading to problems when trying to use

the Dwingeloo data for alibration.

We plan to observe almost the entire sky visible to

the 26-m Teles ope in drift s an mode. The data will

have signi� antly higher sensitivity than the Dwingeloo

data, allowing improved alibration a ura y. Ea h night

the teles ope will be set at a �xed elevation on the

meridian and drift s ans will be measured for a er-

tain de lination. This method keeps the ground radia-

tion onstant for ea h s an, allowing it to be determined

and subtra ted. Additional elevation s ans will help to

he k ground radiation di�eren es between the s ans.

A sampling interval between 2

Æ

and 5

Æ

in de lination

is believed to be suÆ ient to alibrate the E�elsberg

polarization survey.

The re eiver modi� ations have now been done and

the software development is omplete, and observations

began in November 2002.

Maik Wolleben, Tom Lande ker, & Wolfgang Rei h

Progress on the Canadian Gala ti Plane Survey

As mentioned in the previous Newsletter, all 36 H i mo-

sai s from the �rst phase of the Canadian Gala ti Plane

Survey have been ompleted and released to the CGPS

Consortium members. Sin e then, these H i mosai s

have been publi ly released through the Canadian As-

tronomy Data Centre. In addition, all 21 m ontinuum

(C21) mosai s have also been publi ly released. As this

Newsletter goes to press, we are beginning the reation

of the omplete set of 74 m ontinuum (C74) mosai s.

Data pro essing for the se ond phase of the CGPS is

now well under way. Thus far, 71 �elds (of a total of 177

in Phase 2) have been redu ed in H i, 51 in C21, and 13

in C74 (109 of 177 �elds have been observed to date).

On e the se ond Low Resolution DRAO Survey (LRDS

II) of H i with the 26-m Teles ope is omplete, we will

have the low-order spa ings data required to produ e

out �rst Phase 2 H i mosai s.

The Canadian Astronomy Data Centre (CADC) has

laun hed into further development of the CGPS data

server system whi h urrently exists at CADC. It is in-

tended to provide improved data sear h tools as well as

the ability to do some visualization of the data sets be-

fore download. A entral part of this development will

be the utilization of the Aladin system provided by the

Centre de Donnees astronomiques de Strasbourg (CDS),

whi h an be used to display data, overlay ontours

and/or plot obje ts from other data sets. We hope to

announ e the availability of the enhan ed CADC-CGPS

server system in the next Newsletter. Until then, the old

system is still in pla e, with all of the H i, C21, CO, and

HIRES IRAS (12, 25, 60, 100�m) data for Phase 1 avail-

able for download by registered users of the CADC (reg-

ister at http:// ad www.hia.nr . a/ ad /register.html


or http:// ad www.hia.nr . a/ ad /register_fr.html).

Enquiries about the data should be addressed to

Lewis.Knee�nr . a.

Pro essing of 21 m polarization data has been in

hiatus following the departure of B�ulent Uyan�ker. This

autumn a new post-do toral fellow, Robert Reid (U.

Toronto) will join the team at DRAO and get polariza-

tion data pro essing restarted.

Lewis Knee

News from the Spa e-VLBI Correlator Centre

The orbiting radio teles ope, HALCA, the entre-pie e

of the Japanese-led VSOP mission, ontinues observa-

tions of high brightness temperature obje ts well into its

6th year of operation. Indeed, apart from a few minor

attitude adjustments, HALCA has performed awlessly

over the past two years.

Sin e February 2002, when NASA parti ipation in

the mission eased, the mission has on entrated on

ompleting the VSOP Survey proje t, a proje t to sys-

temati ally observe the radio-brightest quasars and AGN.

Canada plays a major role in the Survey proje t, through

orrelation of almost all the survey data at the S2 or-

relation entre at DRAO, and the VSOP data analysis

entre at the University of Calgary.

Now that we are orrelating almost all the obser-

vations made by VSOP, the a tion has been fast and

furious, with a total of 36 experiments ompletely or-

related and shipped o� to the data analysis entre sin e

May, for an average rate of 6 experiments/month.

The Canadian Spa e Agen y and the Joint Sub-

Committee on Spa e Astronomy have been advised that

we anti ipate ompletion of the Survey proje t in Au-

gust 2003. This will require an in rease in the data-

pro essing rate to approximately 8 experiments/month,

a hallenge the orrelator entre sta� are ex ited to

meet!

Re ently the Russian spa e agen y, ROSAVIACOS-

MOS, and the Russian A ademy of S ien e announ ed

that the Russian Radioastron spa e VLBI mission has

been given the number one priority position in the Rus-

sian spa e astronomy programme. The laun h of the

10-m diameter antenna is s heduled for Mar h 15, 2006,

pla ing the spa e raft in an orbit with an apogee alti-

tude near 340,000km and a perigee altitude near 10,000km.

It is expe ted to on entrate its s ienti� e�orts to ob-

servations at 22GHz, o�ering unpre edented angular

resolution.

Of great interest to the S2 Correlator Centre, the

bandwidth of the observations will be 128Mbit/s, and

it is planned that the global S2 network will play a ma-

jor role in the observations and orrelation. The Spa e-

VLBI proje t was originally started in Canada to sup-

port the Radioastron mission, but the laun h date was

ontinually pushed ba k. However, the situation ap-

pears to be very di�erent today, and the various inter-

national parti ipants in the VSOP mission, in luding

us here at DRAO, are now paying lose attention to the

rapidly developing situation of Radioastron in Russia.

Sean Dougherty

Progress on the LAR Aerostat Experiment

Mu h has happened in the LAR Aerostat Experiment

sin e the last issue of DRAO News. Several new peo-

ple began working on the proje t: Ri hard Hellyer and

Dean Chalmers were hired in April, Ri hard as a me-

hani al te hnologist, and Dean as a me hani al engi-

neer. Both have been invaluable in ompleting work for

the �eld trials of the aerostat system. Dean is also in-

volved in design work for me hani al systems that will

be needed for future stages of the proje t, in luding

win h and feed platforms, and re e tor support and a -

tuation. He has been working with people at AMEC

in Van ouver on some of these proje ts. We also have

Matthieu Passard, a me hani al engineering student from

Fran e, working with us until January.

In the �eld, work on the instrument platform and

laun h trailer was ompleted in Mar h, with helium in-

ation taking pla e late in that month. Low-altitude

tests in whi h the aerostat was onstrained by the ground-

handling lines were ondu ted during April to familiar-

ize the ying rew with pro edures for laun hing and

retrieving the aerostat and to verify that the equipment

worked properly. During this phase it was found that

modi� ations to the main win h were needed to in rease

its apa ity. Full altitude tests then began in May, ini-

tially without the instrumentation pa kage, but with

full instrumentation by the end of the month.

In this early testing it qui kly be ame obvious that

learning to ope with the wind was our biggest hal-

lenge. It does not take mu h of a breeze for the \sail

area" of the aerostat to pose real problems for ground-

handling operations. The rotating boom whi h allows

the aerostat to weather-vane when tied down to the

laun h trailer has proved to be invaluable. Re ords from

the site weather station showed that the almest time of

day during the summer months is between about 10pm

and 10am, so laun hes were undertaken before dawn,

with the aerostat being retrieved on e winds rea hed a

speed of about 4m s

�1

(14 kmh).

Winds have also been a problem when the aerostat

is stored in the hangar. The present, open-ended de-

sign allows a onsiderable amount of wind to enter the

hanger and bu�et the aerostat, whi h is not good for

long-term durability. In order to alleviate this prob-

lem, a 6m extension to the length of the hangar and a

urtain-style door are being installed to provide better

prote tion for the aerostat.

Other hallenges that we have fa ed so far have ranged

from problems with the instrumentation and data a qui-


The aerostat in ight over the White Lake basin

in May. Note one of the peripheral tethers rising

from the foreground. The point at whi h the three

peripheral tethers meet is approximately 200m above

the ground. The aerostat ies on a single tether above

this point, with the length of that tether being one

of the variables under test. At the time of this photo

the tether length was 20m. Experien e qui kly showed

that longer is better, and the length now used is 150m

sition systems to workmanship issues with the onstru -

tion of the aerostat. These have now all been over ome,

but at the ost of delaying the data a quisition phase of

the proje t by several months. Nonetheless, several sets

of good quality data for use in verifying models of the

system performan e have been obtained. These data

are being sent to Meyer Nahon at M Gill University,

who developed the models, for analysis. Initial results

look promising, with motion of the platform seeming to

be dominated by slow, large-s ale motions.

To date, tests have used three �xed-length tethers

atta hed to on rete an hors, with the length of ea h

tether determining the azimuth and zenith angle being

tested. We are now preparing for the next phase of the

proje t, in whi h win hes will be deployed in pla e of

the on rete blo ks to provide dynami ontrol of the

instrument platform's position. Win hes and mounting

frames have been delivered and are being readied for

use. The design of a ontrol system has begun, and will

draw on the analysis of results of existing ight tests.

Initially we will be using 3 win hes, but will ultimately

use 6 win hes to provide better zenith angle overage.

Andrew Gray

The New Spe trometer for the JCMT: ACSIS

Sin e the last newsletter there have been a number of de-

velopments on erning the Auto-Correlation Spe trom-

eter Imaging System (ACSIS) being developed for the

JCMT. The orrelator hardware, developed by Tom Burgess,

is now omplete and four rates of hardware have been

built. Tom is now working on the �nal produ tion of

the samplers, that will turn the sixteen signals from the

345-GHz HARP re eiver into digital data. The data

rate from the samplers is extremely high. In total they

present 64 giga-samples per se ond to the orrelators.

Several ra ks of equipment are needed to house, ool

and inter onne t the ACSIS IF, orrelator and redu -

tion hardware. Ralph Webber joined the ACSIS team

in April and is developing this infrastru ture to do this.

An essential part of ACSIS is the IF system. Mu h

of this hardware is in the pro ess of being built by Brian

For e at the JAC. A key omponent of this system,

the Down-Converter Module, is being built by Murnadi

Communi ations of Calgary. After reviewing the design

last February they were awarded a ontra t in August

to make several key modi� ations to the DCM and build

prototype and produ tion units. We re ently attended

a system design review of their work and are happy to

report that it is thorough, well underway and on tra k.

Prototype assembly and testing is planned to begin in

January, while delivery of prototypes is s heduled for

April. The produ tion units will be delivered in bat hes

beginning in June and ending in July.

The third key part of ACSIS is the redu tion sys-

tem. This system produ es alibrated spe tra, at a

20Hz dump rate, that an be gridded and displayed in

real-time. The software runs on an array of Linux om-

puters and is being developed using Glish and aips++.

The system will be apable pro essing up to 10MB of

data per se ond, something few teles ope systems an

mat h. To handle these speeds ACSIS will likely run

on an array of sixteen dual-pro essor Linux- omputers,

whi h will be pur hased in the se ond quarter of 2003.

In total the system will have 16GB of memory and over

2TB of disk storage. An initial version of the redu tion

software was ompleted in September and was re ently

tested by the proje t s ientist, Bill Dent (UKATC). The

�nal version of the software should be omplete by July,

with �nal integration and ommissioning of ACSIS in

the fourth quarter of 2003.

Gary Hovey

Spe trum Management A tivities

As the 2003 World Radio Conferen e approa hes, there

is in reasing pressure to get the important issues in ra-

dio astronomy prote tion addressed. The three main

areas of a tivity are: (i) the ongoing work at evaluating

the interferen e threats and prote tion needs for ea h

individual band allo ated to radio astronomy, (ii) the

perfe tion of tools for use by operators of servi es posing

potential threats to radio astronomy in estimating what

problems they will ause, and to whom, and (iii) produ -


ing do uments ontaining information needed for (i) and

(ii). The misunderstandings out there have to be heard

to be believed. This year, Ken has attended meetings in

Washington and Geneva to work on the studies and the

tools, attended two meetings with Industry Canada in

Ottawa. With help by DRAO sta�, we have produ ed

a do ument des ribing the nature of radio astronomi al

observations and the prote tion needs, and persuaded

Industry Canada to propose this formally in Geneva.

This is slow work, sometimes terrifying and other

times tedious. However, lear windows in the radio

spe trum are as important to radio astronomers as the

radio teles opes that look through them. Conta t

Ken.Tapping�nr . a for more information on the spe -

trum management a tivities at DRAO.

Ken Tapping

The Synthesis Teles ope

Observing with the Synthesis Teles ope has generally

gone well in the past 6 months, with the ex eption of

a failure of the main uninterruptible power supply in

the Blo khouse. One battery shorted out, ausing all

of the batteries to fail. It is likely that a power spike

asso iated with this in ident prompted the hard-drive

in the main observing omputer to also fail. To ut

a long story short, it was more than 2 weeks before

everything was up and running again. While su h delays

are frustrating, this in ident will not signi� antly delay

ompletion of observing for Phase 2 of the Canadian

Gala ti Plane Survey, whi h remains on tra k to �nish

in early 2004.

Experiments are on-going to in rease the sensitivity

of the Synthesis Teles ope at 21 m. This work in ludes

investigating new ampli�ers and ways of redu ing the

amount of ground noise being pi ked up by the anten-

nas. Reports on this work are ontained elsewhere in

this newsletter.

Andrew Gray

The 26-m Teles ope

Observing time on the 26-m Teles ope has been at a

premium lately. Over the past summer a signi� ant

amount of observing time was allo ated to Heather

Cameron (U. Toronto graduate student) for a study of

the feasibility of using the Teles ope to measure ab-

sorption of linear polarization in the H i spe tral-line

as a means of determining distan es to polarized emis-

sion regions. The Teles ope is now being used by Maik

Wolleben (U. Bonn) for ontinuum polarization mea-

surements that will be used to supplement polarization

measurements made at E�elsberg. In between these

a tvitities, the Teles ope ontinues to survey the Phase

2 region of the Canadian Gala ti Plane Survey to pro-

vide short-spa ing information for the Synthesis Tele-

s ope observations.

Longer-term, experimental proje ts of the type de-

s ribed above are ideal for the 26-m Teles ope, and

provide a valuable opportunity for students to obtain

hands-on experien e with radio-astronomy equipment.

Appli ations for observations using the 26-m Teles ope

in this way may be made at any time, and are s heduled

on a priority basis. Conta t Ken.Tapping�nr . a for

more details.

Ken Tapping

The Solar Radio Flux Monitor and the Canadian

Geospa e Monitoring Programme

Over the years, the NRC's solar radio ux data, known

internationally as the 10.7 m Solar Flux, has be ome

more widely used in the spa e s ien e, environmental,

and industrial areas than in the mainstream of astron-

omy. To move the programme more into the spa e area,

we made a proposal to the Canadian Spa e Agen y to

ome in as a partner to manage and operate the pro-

gramme. Tom Lande ker and Ken Tapping made pre-

sentations to the CSA in St Hubert, and Ken has at-

tended two more meetings sin e. We obviously tou hed

the right spot. Our ideas are now part of a proposal for

a Canadian Geospa e Monitoring Programme, whi h is

a partnership of the CSA, NRC, and Canadian universi-

ties, to bring together the di�erent geospa e monitoring

programmes and spa e s ien e a tivities into a single

onsortium, with better s ienti� and industrial on-

ne tions.

Over the next year we expe t to start an upgrade of

the solar radio fa ilities at DRAO, and the in orporation

of our data into a ommon Canadian data site. We

will ontinue building our s ienti� partnerships, and of

ourse, attend more meetings.

In the age where Spa e Weather and the environ-

ment are important issues, and there is need for fo ussed

guidan e in Canada's in reasing a tivities in spa e, the

CGMP has the potential to be onsiderably more than

the sum of its parts.

Ken Tapping

Call for Observing Proposals

Proposals are invited for observations to be made

with the DRAO Synthesis Teles ope and/or the 26-m

Teles ope. Instru tions for appli ations are given below.

In both ases, ele troni proposal submissions should be

emailed to Andrew Gray (Andrew.Gray�nr . a).

The Synthesis Teles ope o�ers simultaneous, wide-

�eld imaging of radio ontinuum at 408 and 1420MHz

(the latter with polarization), andH i-line emission (256-

hannel spe trometry). It is suitable for a wide range of


proje ts, and in the past has been used for everything

from solar system to extragala ti studies. We wel ome

new proposals for teles ope time overing any area of

radio-astrophysi s. Proposals are a epted at any time,

and are subje ted to external peer review. Proposals

granted time are s heduled as soon as possible after re-

eipt.

Cover-sheets and a full des ription of the Synthesis

Teles ope and its apabilities are available at

http://www.drao.nr . a, or from the anonymous ftp

area at DRAO|just follow this pro edure:

ftp ftp.drao.nr . a

Name: anonymous

Password: your e-mail address

d pub/drao_info

dir

get �lename

The 26-m Teles ope is equipped for spe tral-line

observing in the approximate frequen y range 1300{

1700MHz, wherever man-made transmissions and in-

terferen e permit. Other kinds of observation may be

possible through spe ial arrangements. The instrument

is typi ally used for medium and long-term observing

programmes, but short-term ones are also undertaken.

Appli ations should in lude a des ription of the pro-

gramme, s ienti� relevan e, and time needed. Propos-

als are a epted at any time, and are subje ted to inter-

nal peer review. Proposals granted time are s heduled

as soon as possible after re eipt.

Further information on the 26-m Teles ope is avail-

able at http://www.drao.nr . a, or onta t Ken Tap-

ping (Ken.Tapping�nr . a).

Re ent Papers from DRAO

Names of DRAO workers are shown in bold in the fol-

lowing. New papers:

Belostotski, L., Lande ker, T.L., & Routledge, D.

A te hnique for mi rowave ranging and remote phase

syn hronization, Trans. IEEE, IM-51, 551

Brunt, C.M. 2003, Large-s ale Turbulen e in Mole u-

lar Clouds, ApJ, in press.

Brunt, C.M. 2003, The Universality of Turbulen e in

the Mole ular Interstellar Medium and its Exploitation

as a Distan e Estimator, ApJ, in press.

Brunt, C.M., Kerton, C.R. & Pomerleau, C. 2003,

An outer Galaxy mole ular loud atalog, ApJS, in press.

Kerton, C.R. 2002, Dete ting embeded intermediate-

mass stars using mid-infra-red and 21- m H i emission,

AJ, in press.

Kerton, C.R. & Brunt, C.M. The Asso iation of

IRAS Sour es and

12

CO emission in the outer Galaxy,

A&A, submitted.

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Stars in Supernova Remnants, eds. P. O. Slane & B. M.

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Kothes, R., & Uyan�ker, B., & Yar, A. 2002, The

distan e to the SNR CTB109 dedu ed from its environ-

ment, ApJ, 576, 169

Uyan�ker, B., & Kothes, R. 2002, A Large Atomi

Hydrogen Shell in the Outer Galaxy: SNR or Stellar

Wind Bubble?, ApJ, 547, 805

Uyan�ker, B., & Lande ker, T. L. 2002, A Highly

Ordered Faraday-Rotation Stru ture in the Interstellar

Medium, ApJ, 575, 225

Observatory Conta t Information

Dominion Radio Astrophysi al Observatory

Herzberg Institute of Astrophysi s

National Resear h Coun il Canada

People to Conta t:

Dire tor : Tom Lande ker

Future Radio Teles opes: Peter Dewdney

Spa e-VLBI : Sean Dougherty

Administration : Cindy Furtado

Operations Manager : Andrew Gray

Engineering : Gary Hovey

Solar Programme : Ken Tapping

Computing : Tony Willis

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Phone: +1 250 493 2277

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