Monitor NGC 2547 data release: Version 1.0

21 January 2008

As part of the Monitor project (Aigrain et al. 2007, MNRAS, 375, 29), a time-domain survey of NGC 2547 was carried out in I-band using the ESO Wide Field Imager mounted on the 2.2m telescope at La Silla, Chile. The survey covers two fields, or ~0.6 sq. deg, observed as adjacent WFI pointings, with a small overlap (~10%). The majority of the survey consists of the I-band time-domain component, observed with a cadence of ~7 minutes. Exposures in V and R bands were also obtained during photometric conditions and good seeing, to produce colour-magnitude diagrams.

All of the data fall under the large programme 175.C-0685, which also includes a similar survey in Blanco-1 (incomplete), and was intended to include a further survey in NGC 2516, which has since been dropped.

The first publication using these data is Irwin et al. 2007, MNRAS, submitted (title "Rotation of low-mass stars in the open cluster NGC 2547"), which contains a membership and rotation analysis, in addition to a description of the reductions.

Overview and field layout

The layout of the two fields is shown in the diagram, with the cluster centre lying approximately at the border between the two fields, which are shown as the outline of the individual WFI CCDs. Field 1 is colour-coded green, and field 2 red.

The table gives the coordinates of the two fields. The N(obs) column shows the total number of I-band time series observations obtained (i.e. number of light curve points).

Field RA [hh:mm:ss] J2000.0 DEC [dd:mm:ss] J2000.0 N(obs)
N2547-1 08:10:25.0 -49:25:00 830
N2547-2 08:10:25.0 -48:55:00 827

Release content

This release contains all of the reduced images and catalogues from the NGC 2547 component of the programme, and the corresponding reduced photometric standards observations in case a more accurate absolute photometric calibration is required by users of the data.

Exposure times were 120s for all I-band images. V and R-band images were taken in pairs of 120s and 1575s to provide a greater dynamic range for the colour magnitude diagram analysis.

Notes on the v1.0 Data Release

Our full data reduction steps are described in Irwin et al. 2007, MNRAS, 375, 1449 and the specifics for NGC 2547 in Irwin et al. 2007, MNRAS, submitted. Images have been astrometrically calibrated against 2MASS (typical RMS accuracy ~0.1-0.2 arcsec), and photometrically calibrated against the standard star observations included in the release.

Data format

Reduced images are supplied using the original ESO filenames prepended with 'LP175C0685.' (file extension .fits). These are multi-extension FITS files, with the same layout as the raw images supplied from the ESO archive.

Catalogues are supplied as FITS binary tables. These are named, corresponding to the image imagename.fits. The format of these files is described in detail under Single band catalogues at this HTTP URL.

Confidence maps are supplied in the files LP175C0685.WFI.I.conf.fits, LP175C0685.WFI.Rc.conf.fits and LP175C0685.WFI.V.conf.fits, for I, R and V bands respectively. These are essentially weight maps, scaled to percentages (i.e. multiplied by 100). The files are suitable for direct input into the CASU pipeline software.

Data retrieval

Due to the large volume of this ADP release, the data has been organised in five packages which may be requested from the ESO archive by clicking on the respective link in the table below. Note that the data volumes of the packages imply restrictions on the possible transport medium. The Catalogues packages contains the full set of 1982 source catalogues extracted from all the images of this release (N2547-1, N2547-2, Standards) and may be transported via FTP or shipped on DVD. In the case of delivery on physical media (DVD, hard disk), please allow several weeks for delivery.

N2547-1 (images and catalogues) 108.3 GB, delivery on USB hard disk only
N2547-2 (images and catalogues) 107.8 GB, delivery on USB hard disk only
Standards (images and catalogues) 40.3 GB, delivery on DVD
Catalogues 8.8 GB, delivery by FTP or DVD
Confidence maps 383.9 MB, delivery by FTP or DVD


When using data products provided in this release, we request that authors refer to the paper Irwin et al. 2007, MNRAS, 375, 1449. In addition, please also use the following statement in your articles when using these data:

Based on observations made with ESO Telescopes at the La Silla or Paranal Observatories under programme ID 175.C-0685.