Coralie DRS (June 2015)

This document is to inform you about a few changes in the Coralie operations and data reduction. These changes have been necessary due to the introduction of the Fabry-Pérot mode, which in turn required an update of the calibration sequence and new version of the DRS.

1) A Fabry-Perot calibrator (FP) is now available on Coralie. In has been installed and tested successfully. It replaces the simultaneous thorium (OBFP exposures instead of OBTH). The system works and delivers drift measurement better than 0.5 m/s per night.

2) The new DRS 3.8 is available now for all Geneva-Observers. Instead of logging-in on castor1, log in on castor2 and start the trigger as usual. The is no change in the execution and in the raw directory. Just be informed that the reduced data, msg, calibDB etc. will now appear under /gls/data/DRS-3.8/* instead of /gls/data/*

NOTE: The old DRS is still available on castor1

3) The standard calibration sequences has been optimised. The changes are:
- Only two FAST BIAS (more than sufficient)
- 5 x FF2 instead of 3 x FFC and 3 x FFO. The separate FF exposures were an ‘historical remnant’. We preferred have more of them but to combine the spectral flat-fields of both fibers in single exposures.
- THC added to measure the contamination of the thorium on fiber A
- THO added to measure the contamination of the thorium on fiber B
- 2 x THFP added to allow for simultaneous FP exposures
- Warm-up of the thorium lamp was reduced to 600s, warm-up of TUN lamp to 60s.
- LOFF ‘exposure' added to switch off all lamps at the end of the sequence.

IMPORTANT NOTE: The FF2 exposures will not be processed by the old DRS. If you have to use the old DRS DO NOT FORGET to add 3 x FFO and 3 x FFO exposures after the LOCX exposures during the calibrations.

4) Instead of the simultaneous thorium (OBTH) on the stars, we recommend to use the OBFP instead. This allows to switch OFF the TH lamp and the end of the calibration sequence and will save the TH lamp. This is VERY CRITICAL, since thorium lamps of sufficient quality are not available anymore and we have only 1 spare left!!! If, for some important reason, you want to observe in OBTH, then the TH-lamp should be switched ON again before the start of the night.

IMPORTANT NOTE: Using the OBFP won’t produce ANY RV-OFFSET with respect to OBTH!

IMPORTANT NOTE: In principle there is no need to do any THA2 and THFP during the night anymore. However, we recommend to execute 1 x THA2 and 1 x THFP at the end of the night. You might want to switch ON the thorium lamp manually 10 minutes before to save time (same holds for THA2 and THFP exposures taken during the night, but do not forget to switch it OFF after the use, e.g. by inserting an LOFF exposure after the calibration


Please contact me in case of doubts and let us know any strange behaviour. In case of DRS failures do not hesitate to just continue the observations and just report the failure.

This email will be updated and inserted in the ‘News’ of the EULER web page. The observing check list is being update accordingly.

Best regards,
Francesco

FP 04/06/2015