PNS MANUAL: Taking Flux standards
How to take exposures of flux standardsThe PNS shutter is rather slow.
For calibration of the photometry with bright flux standards the shutter would
introduce large uncertainties. The procedure described below involves leaving
the shutter open, and letting the CCD integration time determine the exposure
time. As the CCDs are windowed, the beginning of the readout is a fast parallel
transfer of the charges, ensuring accurate photometry on the flux standard.
Note that an offest of ~30" should be taken in the dispersion
direction (N-S if PA=0, E-W if PA=90) for all flux standards in order to avoid
the bad column in the centre of EEV13.
Perform the following commands, in sequence:
- Once target acquisition is complete, make sure A&G mirror is OUT
(check A&G mimic display). If it is not, issue AGMIRROR OUT on
- On PNS console issue SHUTO command (opens shutter).
- On PNS console issue MASKO command if there is doubt the mask may
- On DAS console issue fluxstd time "title" (performs a
readout of time seconds). 20 seconds on an 11th mag star works well.
- When finished, issue SHUTC command on PNS console to close shutter.
For list of Galactic PNe, see here.
For a list of suitable La Palma Flux standards, download
These have been selected to have smooth spectra near 500nm,
to be bright (10-12m), and to be South of Zenith from La Palma
(to prevent long slews). The file can be loaded into the WHT catalogue list.
About this Document
We need your input to keep these notes up-to-date. Please add to
this document, or create new ones which can be linked from it. Send your input
by email. Last updated 12-04-2004
Documents of this background colour are part of a set linked from