Department of Physics AstroLab

AstroLab CCD Images

Dome Workstations

CCD images taken with the telescopes are saved on the dome workstations under the "/data/current/" directory. Each directory is encoded with the observing date, e.g. on 2020 April 08 the directory would be created as 20_04_08. In each dated directory the images are numbered starting at 0001.

Capella Server

As well as being saved locally on the dome workstations, the CCD images are also saved on Capella. This server runs in the background keeping the Astrolab ticking over; transferring the CCD images into the archive, telescope logging, weather monitoring, etc. Capella serves a directory via NFS to each dome workstation, i.e. "/remote/current/TELESCOPE" directory where TELESCOPE is the telescope name (draco2, east-14, west-14, far-east-16, etc).

Capella handles the initial processing of the CCD images and transfer these to AstroLab fileserver (Canopus).

Canopus File Server

Canopus serves the following disks to the lab workstations via automounted NFS:
 /mnt/archive             # archived CCD images           READ ONLY
 /mnt/64bin               # data reduction scripts, etc   READ ONLY
 /mnt/cats                # star catalogue data           READ ONLY

Canopus also gathers any Astrolab images taken with the La Palma p5tm telescope from the previous night at 14:30 each day and puts these in the archive.

The CCD images in the archive are stored in following file structure:


Three images for each Durham exposure are initially stored in the archive.

0001.fits.gz, 0002.fits.gz, etc,   are the raw CCD images gzipped
d0001.fits, d0002.fits, etc,       are the dark-subtracted CCD images
ad0001.fits, ad0002.fits, etc,     are the astrometrically calibrated
                                        dark-subtracted CCD images

The "ad" images are only exist when a successful astrometric calibration to Refcat2 catalog has been made; prior to mid-2019 the USNOA2 was used as the base catalogue. The details of the astrometric calibration can be found in the FITS headers. The "A" column in the online telescope logs indicate the number stars used for the astrometric calibration; a dash indicates that this calibration was not successful.

On Your Lab Workstation

For your data analysis on your workstation create a directory structure under the Astrolab home directory (/home/astrolab/). If required copy your images images across from Canopus, e.g.

 mkdir 20_02_08
 cd 20_02_08
 rsync -av /mnt/archive/far-east-20/2020/20_04_08/*  .
                                                     / \

                                    Don't forget the "."
rsync is "a fast and extraordinarily versatile file copying tool".
Back to the AstroLab Home Page jrl 2020-Jun-17 07:21:53 UTC