NRT photo (c) JP.Letourneur

NRT call for observing programmes - semester 2022A

Deadline : 11 November 2021


General Information

The Nancay Radio Telescope (NRT, France) is a high sensitivity (1.4 K/Jy at 21cm) meridian telescope (the tracking duration is 1 hour, and varies approximately as 1/cos(DEC) ) with full polarization capability in the frequency range from 1.1 GHz to 3.5 GHz. The declination limit is > -39 deg. It is operated by the Observatoire de Paris, the Centre National de la Recherche Scientifique and also funded by the Region Centre-Val de Loire.

The NRT proposal call is open to the international community.

The Key Project (KP) status is intended for applications requesting large amounts of telescope time (> 1000 hours for 2 years) or for long term monitoring programmes. This status is granted for two years, and up to 70% of the available observing time is devoted to KPs.

Key Projects and standard proposals are evaluated by the Programme Committee.

Main criteria used for evaluation and rating:

Observations and data processing can be done remotely. It is of course possible to observe and process the data from Nancay.

The Meudon, Orleans and Nancay scientific and technical staff provide support for proposal preparation, observing, and data processing if requested.


Proposal Preparation

Use the following .tex and .sty files to prepare your observing time request proposal:
NRTprop.tex
proposal_NRT.sty

The perl script requestTable6.perl may be used to fill the standard NRT request table. This script reads an ASCII list of sources and produces latex tables to be used in the proposal.

All proposals must be written in English.

Proposals (in .tex and .pdf format) are to be submitted by email to L. Guillemot, chairman of the Programme Committee (lucas.guillemot at cnrs-orleans.fr).


Proposal Grading and Statuses

Rating and time allocation

Observing time is allocated on the basis of two semesters per year, A and B, with a proposal selection process. The Nancay Radio Telescope (NRT) Programme Committee ("Comite des Programmes", hereafter CdP) meets twice a year.

Proposals are rated considering scientific value in view of the information provided, technical feasibility, possible character of urgency, and the report from previous observations if any. Scientific context or background must be included. Publications obtained with the NRT data are considered as mandatory for pursuing long-term projects. A priority grade P is given, according to the scale below. The grade and the CdP's comments are a synthesis of the contributions from all the referees. As some applications are not homogeneous, each may be affected several grades referring to different parts. The actual time allocation is fixed according to both the priority rating and the right ascension distribution, because of the severe limits in telescope tracking ; indeed, top priority programmes may suffer from significant cuts when applying for a similar R.A. range, whereas at under subscribed R.A., lower priority programmes are likely to be scheduled.

The rating is made in accordance with the following scale :


Key Programme status

This status is given to programmes with great scientific interest as well as clear reliability of the observing protocol and technical choices, and which require important telescope resources (> 1000 hours), or to long term monitoring projects. Among the criteria used are how the proposal fit in the international context, the scientific interest, the technical justification and the publication plan, if any. Also the strength and the quality of the team (papers published in the field) will be appreciated. Users have to ask this status in the proposal form. The status holds for 2 years, starting with the semester following the CdP meeting. Follow-up full applications are not needed anymore during this period, but a summary of the science goals is needed for each semester application. Users must provide after one year, by the date of the Call for proposal deadline, 1) a progress report; 2) a brief log of the observations (done/still to do) and of major problems if any; and 3) the source list. Also users must give the standard “observing time” table every semester, so that their time can actually be inserted into the schedule. The key programme status and a top priority rating are not always linked: this means in the case the quality of the project would lower somewhat (e.g. lack of information), the rate and time allocation would be lowered accordingly.

After these 2 years, the status is NOT maintained by default. A new complete proposal, explicitly detailed and justified, is due.


Cancelled observations

A significant amount of time is reserved for maintenance and for Target of Opportunity (ToO) observations. Moreover, along the semester the telescope scheduling is flexible as it is set monthly. Nevertheless, it may happen exceptionally that current observations need to be cancelled, in order to observe ToO events or to perform urgent technical work. If this has to happen, P.I.s are advised, and cancelled observations may be re-allocated as soon as possible during the current semester, or during the next one if no other option exists. On the other hand, observing time lost because of weather or of "minor" bugs is not renewed systematically.


Technical Information

The NRT can observe any source at a declination DEC > -39°. This is a transit instrument, for which the maximum integration time per day for a source at DEC = 0° is typically about one hour (ON + OFF); this time increases as 1/cos (DEC), while the efficiency decreases.

An old support page can be found at this address: old support page.


Focal and receiver systems (FORT = Foyer Optimise pour le RadioTelescope)

Two receivers are available, allowing a continuous frequency coverage. The Low Frequency system (1.1-1.8 GHz) provides optimum characteristics for the HI 21 cm and OH 18 cm lines. The High Frequency system (1.7-3.5 GHz) includes the 9 cm lines. The corrugated horns can be rotated by plus or minus 90°. Up to two linear plus two circular polarizations can be recorded simultaneously. Cross-polarization and complete Stokes parameters are available for the Low Frequency system in a limited configuration (some L.O.s have a fixed value); their extension and precision improvement are still under development. Meanwhile, it is recommended to use the horn rotation to extract the Stokes parameters properly.

The IF bandwidth is 400 MHz. The digital auto-correlator has a total bandwidth that can be set from 200 kHz to 50 MHz. The 8192 frequency channels should be splitted into at least 2 banks and up to 8 banks. Up to 4 independent frequencies can be recorded simultaneously. Continuum measurements can be performed through 8 dedicated channels; the frequency and bandwidth corresponds to the auto-correlator setup. Configuration changes can be programmed to be performed by the real-time computer even within a single observation.


Beam size and efficiencies

The half power beam widths are respectively about: 4’ (RA) x 22’ (DEC), 3.5’ x 19’ and 2’ x 10’ at 21, 18 and 11 cm. The corresponding point source efficiency at DEC = 0° is about 1.4 K/Jy at 21 cm and 0.8 K/Jy at 11 cm. The efficiency does not show significant variation between the different polarizations. The system temperatures are about 35 K at 21 and 45 K at 11 cm. The r.m.s. continuum confusion levels due to background sources are respectively 20, 15 and 7 mJy at 21, 18 and 11 cm. The above values are indicative and are susceptible to be updated.


Data handling

Data reduction can be achieved on the site or remotely with a Linux workstation. Raw data must be pre-processed with the dedicated Nancay "NAPS" software. Data reduction can then be performed with the Nancay "SIR" software, or data can be exported in FITS format for further processing instead. Please note that the FITS export has been tested successfully with the CLASS package, but that there is still a difficulty when exporting into AIPS++; that option cannot be guaranteed at the moment.


Contacts

For more information please contact at Meudon campus at internet adresses @obspm.fr : Jean-Michel.Martin (astronomer); at Orleans campus at internet adresses @cnrs-orleans.fr : icognard (astronomer, scientific director), lucas.guillemot (chairman of the CdP); or at the Nancay Radio Telescope at internet adresses @obs-nancay.fr : Bruno.DaSilva, Laurence.Alsac (engineers).

We suggest that any new user of the NRT contacts one of the persons above. Because pulsar observations use dedicated instrumentations, people who wish to apply for pulsar observations are highly encouraged to contact Ismael Cognard (Orleans).



Last updated 2021/10/12 by Lucas Guillemot, chairman of the programme committee.